研究者詳細 - 加来田　博貴

論文 - 加来田　博貴

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Structural basis for the full and partial agonist activities of retinoid X receptor α ligands with an iso-butoxy and an isopropyl group. 国際誌

Daisuke Imai, Nobutaka Numoto, Hiroaki Tokiwa, Hiroki Kakuta, Nobutoshi Ito

Biochemical and biophysical research communications 734 150617 - 150617 2024年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Retinoid X receptors (RXRs) belong to a retinoid-binding subgroup of the nuclear receptor family, and their synthetic agonists have been developed as therapeutics for glucose and lipid metabolism, inflammation, and inflammatory bowel disease, although RXR agonists could cause side effects such as hypothyroidism, hypertriglyceridemia, and hepatomegaly. We previously reported novel full and partial agonists, NEt-3IB and NEt-4IB, which reduce the side effects, but the molecular basis of their different activity was not clear. In this study, we report the crystal structures of the ligand-binding domain of human RXRα complexed with NEt-3IB and NEt-4IB. Detailed comparisons of the two structures showed that the full agonist, NEt-3IB, is more stably accommodated in the ligand-binding pocket due to the interactions of the bulky iso-butoxy group with helices 5 and 7. The stabilization of these helices led to the stabilization of helix 12, which is important for formation of the coactivator-binding site. The structures shed light on the novel mechanism of the regulation of RXR activity through the interaction between the bound agonist and helix 7, an interaction that was not previously considered important.

DOI： 10.1016/j.bbrc.2024.150617

Simple Fluorescence Labeling Method Enables Detection of Intracellular Distribution and Expression Level of Retinoid X Receptors 査読

Yukina Tanaka, Michiko Fujihara, Yuta Takamura, Mayu Kawasaki, Shogo Nakano, Makoto Makishima, Hiroki Kakuta

ACS Medicinal Chemistry Letters 2024年5月

Direct evaluation of polarity of the ligand binding pocket in retinoid X receptor using a fluorescent solvatochromic agonist. 査読国際誌

Kizuku Miura, Michiko Fujihara, Masaki Watanabe, Yuta Takamura, Mayu Kawasaki, Shogo Nakano, Hiroki Kakuta

Bioorganic & medicinal chemistry letters 96 129536 - 129536 2023年10月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

High selectivity of small-molecule drug candidates for their target molecule is important to minimize potential side effects. One factor that contributes to the selectivity is the internal polarity of the ligand-binding pocket (LBP) in the target molecule, but this is difficult to measure. Here, we first confirmed that the retinoid X receptor (RXR) agonist 6-(ethyl(1-isobutyl-2-oxo-4-(trifluoromethyl)-1,2-dihydroquinolin-7-yl)amino)nicotinic acid (NEt-iFQ, 1) exhibits fluorescence solvatochromism, i.e., its Stokes shift depends on the polarity of the solvent, and then we utilized this property to directly measure the internal polarity of the RXRα-LBP. The Stokes shift of 1 when bound to the RXRα-LBP corresponded to that of 1 in chloroform solution. This finding is expected to be helpful for designing RXR-selective ligands. A similar approach should be appliable to evaluate the internal polarity of the LBPs of other receptors.

DOI： 10.1016/j.bmcl.2023.129536

Ligand Screening System for the RXRα Heterodimer Using the Fluorescence RXR Agonist CU-6PMN 査読

Mayu Kawasaki, Tomoharu Motoyama, Shoya Yamada, Masaki Watanabe, Michiko Fujihara, Akira Kambe, Shogo Nakano, Hiroki Kakuta, Sohei Ito

ACS Medicinal Chemistry Letters 14 ( 3 ) 291 - 296 2023年2月

Structural characterization of 1,3-bis-tert-butyl monocyclic benzene derivatives with agonistic activity towards retinoid X receptor alpha. 査読国際誌

Susumu Kodama, Shuzo Matsumoto, Yuta Takamura, Michiko Fujihara, Masaki Watanabe, Atsushi Ono, Hiroki Kakuta

Toxicology letters 373 76 - 83 2022年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Retinoid X receptor alpha (RXRα) plays pivotal roles in multiple biological processes, but limited information is available on the structural features of chemicals that show low affinity for RXRα, but nevertheless cause significant activation, though these may represent a human health hazard. We recently discovered that several industrial chemicals having 1,3-bis-tert-butylbenzene as a common chemical structure exhibit agonistic activity towards rat RXRα. In this study, we explored the structure-activity relationship of 1,3-bis-tert-butyl monocyclic benzene derivatives for RXRα activation by means of in vitro and in silico analyses. The results indicate that a bulky substituent at the 5-position is favorable for agonistic activity towards human RXRα. Since 1,3-bis-tert-butyl monocyclic benzene derivatives with bulky hydrophobic moieties differ structurally from known RXRα ligands such as 9-cis-retinoic acid and bexarotene, our findings may be helpful for the development of structural alerts in the safety evaluation of industrial chemicals for RXRα-based toxicity to living organisms.

DOI： 10.1016/j.toxlet.2022.11.003

Analysis of absorption-enhancing mechanisms for combinatorial use of spermine with sodium taurocholate in Caco-2 cells. 査読国際誌

Masato Maruyama, Yohei Nishida, Hironori Tanaka, Takako Minami, Ken-Ichi Ogawara, Masateru Miyake, Yuta Takamura, Hiroki Kakuta, Kazutaka Higaki

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V 180 332 - 343 2022年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Previously, we reported that the combined use of spermine (SPM) and sodium taurocholate (STC) (SPM-STC) significantly improves the oral absorption of rebamipide (BCS class IV) and pulmonary absorption of interferon-α without any harmful histopathological changes in the gastrointestinal tract and lungs, respectively. In the present study, we examined the effect of SPM-STC on the transport of fluorescein isothiocyanate-labeled dextrans (FDs) across Caco-2 cell monolayers and attempted to clarify the mechanisms underlying the transport enhancement caused by SPM-STC. SPM-STC were found to significantly enhance the transport of FDs, while the treatment with SPM-STC was not harmful, and the decrease in transepithelial electrical resistance was transient and reversible. The voltage-clamp study clearly indicated that the opening of the paracellular route could be mainly responsible for the enhanced transport of FD-4. As for the mechanisms, it was found that SPM-STC caused a significant increase in membrane fluidity, which would lead to the enhanced transport of small-molecule drugs such as rebamipide. Since SPM-STC increased intracellular Ca2+ via Ca2+ uptake through Ca2+ channels and Ca2+ release from the endoplasmic reticulum stimulated by the IP3 pathway, the subsequent possible activation of the MLCK signaling pathway would have led to the contraction of the actin-myosin ring. The rearrangement of tight junction-constituting proteins induced through the MAPK pathway has also been suggested as a possible mechanism for opening tight junctions. Claudin-4, a key protein constituting the tight junction, merged with F-actin along with the plasma membrane, was significantly decreased, which would be at least partial structural evidence for the tight-junction opening.

DOI： 10.1016/j.ejpb.2022.10.020

Teratogenicity and Fetal-Transfer Assessment of the Retinoid X Receptor Agonist Bexarotene. 査読国際誌

Yuta Takamura, Izumi Kato, Manami Fujita-Takahashi, Midori Azuma-Nishii, Masaki Watanabe, Rui Nozaki, Masaru Akehi, Takanori Sasaki, Hiroyuki Hirano, Hiroki Kakuta

ACS pharmacology & translational science 5 ( 9 ) 811 - 818 2022年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Bexarotene, a retinoid X receptor (RXR) agonist, is used to treat cutaneous T-cell lymphoma, and drug repositioning research has also been reported, despite warnings of teratogenicity. However, fetal transfer of bexarotene and its effect on rat fetal bone formation have not been examined. In this study, we conducted a detailed teratogenicity and fetal transferability assessment of bexarotene in rats. Repeated administration of bexarotene during pregnancy caused marked fetal atrophy and bone dysplasia. Although fetal transfer was not detectable by dynamic imaging of [11C]bexarotene by means of positron emission tomography, transfer to the fetus was confirmed by using a gamma counter. Similar levels were found in mother and fetus. In addition, we found that bexarotene was accumulated in the placenta. These findings will be useful for the toxicity assessment of bexarotene as well as for drug discovery research targeting RXR agonists, which are expected to have therapeutic effects in various diseases.

DOI： 10.1021/acsptsci.2c00126

Identification of a Vitamin-D Receptor Antagonist, MeTC7, which Inhibits the Growth of Xenograft and Transgenic Tumors In Vivo. 査読国際誌

Negar Khazan, Kyu Kwang Kim, Jeanne N Hansen, Niloy A Singh, Taylor Moore, Cameron W A Snyder, Ravina Pandita, Myla Strawderman, Michiko Fujihara, Yuta Takamura, Ye Jian, Nicholas Battaglia, Naohiro Yano, Yuki Teramoto, Leggy A Arnold, Russell Hopson, Keshav Kishor, Sneha Nayak, Debasmita Ojha, Ashoke Sharon, John M Ashton, Jian Wang, Michael T Milano, Hiroshi Miyamoto, David C Linehan, Scott A Gerber, Nada Kawar, Ajay P Singh, Erdem D Tabdanov, Nikolay V Dokholyan, Hiroki Kakuta, Peter W Jurutka, Nina F Schor, Rachael B Rowswell-Turner, Rakesh K Singh, Richard G Moore

Journal of Medicinal Chemistry 65 ( 8 ) 6039 - 6055 2022年4月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Vitamin-D receptor (VDR) mRNA is overexpressed in neuroblastoma and carcinomas of lung, pancreas, and ovaries and predicts poor prognoses. VDR antagonists may be able to inhibit tumors that overexpress VDR. However, the current antagonists are arduous to synthesize and are only partial antagonists, limiting their use. Here, we show that the VDR antagonist MeTC7 (5), which can be synthesized from 7-dehydrocholesterol (6) in two steps, inhibits VDR selectively, suppresses the viability of cancer cell-lines, and reduces the growth of the spontaneous transgenic TH-MYCN neuroblastoma and xenografts in vivo. The VDR selectivity of 5 against RXRα and PPAR-γ was confirmed, and docking studies using VDR-LBD indicated that 5 induces major changes in the binding motifs, which potentially result in VDR antagonistic effects. These data highlight the therapeutic benefits of targeting VDR for the treatment of malignancies and demonstrate the creation of selective VDR antagonists that are easy to synthesize.

DOI： 10.1021/acs.jmedchem.1c01878

Increased Molecular Flexibility Widens the Gap between Ki and Kd values in Screening for Retinoid X Receptor Modulators 査読

Masaki Watanabe, Mariko Nakamura-Nakayama, Michiko Fujihara, Mayu Kawasaki, Shogo Nakano, Hiroki Kakuta

ACS Medicinal Chemistry Letters 13 ( 2 ) 211 - 217 2022年1月

A Retinoid X Receptor Agonist Directed to the Large Intestine Ameliorates T-Cell-Mediated Colitis in Mice 査読国際誌

Ryohtaroh Matsumoto, Daisuke Takahashi, Masaki Watanabe, Shunsuke Nakatani, Yuta Takamura, Yuji Kurosaki, Hiroki Kakuta, Koji Hase

Frontiers in Pharmacology 12 715752 2021年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers Media SA

Retinoid X receptor (RXR) is a nuclear receptor that heterodimerizes with several nuclear receptors, integrating ligand-mediated signals across the heterodimers. Synthetic RXR agonists have been developed to cure certain inflammatory diseases, including inflammatory bowel diseases (IBDs). However, pre-existing RXR agonists, which are lipophilic and readily absorbed in the upper intestine, cause considerable adverse effects such as hepatomegaly, hyperlipidemia, and hypothyroidism. To minimize these adverse effects, we have developed an RXR agonist, NEt-3IB, which has lipophilic and thus poorly absorptive properties. In this study, we evaluated the effects of NEt-3IB in an experimental murine colitis model induced through the adoptive transfer of CD45RB<sup>high</sup>CD4<sup>+</sup> T cells. Pharmacokinetic studies demonstrated that the major portion of NEt-3IB was successfully delivered to the large intestine after oral administration. Notably, NEt-3IB treatment suppressed the development of T cell-mediated chronic colitis, as indicated by improvement of wasting symptoms, inflammatory infiltration, and mucosal hyperplasia. The protective effect of NEt-3IB was mediated by the suppression of IFN-γ-producing Th1 cell expansion in the colon. In conclusion, NEt-3IB, a large intestine-directed RXR agonist, is a promising drug candidate for IBDs.

DOI： 10.3389/fphar.2021.715752

Creation of Fluorescent RXR Antagonists Based on CBTF-EE and Application to a Fluorescence Polarization Binding Assay 査読

Maho Takioku, Yuta Takamura, Michiko Fujihara, Masaki Watanabe, Shoya Yamada, Mayu Kawasaki, Sohei Ito, Shogo Nakano, Hiroki Kakuta

ACS Medicinal Chemistry Letters 2021年6月

In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography 招待査読

Yuta Takamura, Hiroki Kakuta

Journal of Medicinal Chemistry 64 ( 9 ) 5226 - 5251 2021年5月

Discovery of a “Gatekeeper” Antagonist that Blocks Entry Pathway to Retinoid X Receptors (RXRs) without Allosteric Ligand Inhibition in Permissive RXR Heterodimers 査読

Masaki Watanabe, Michiko Fujihara, Tomoharu Motoyama, Mayu Kawasaki, Shoya Yamada, Yuta Takamura, Sohei Ito, Makoto Makishima, Shogo Nakano, Hiroki Kakuta

Journal of Medicinal Chemistry 64 ( 1 ) 430 - 439 2021年1月

Fluorescence properties of retinoid X receptor antagonist NEt-SB 査読

Shoya Yamada, Yuta Takamura, Michiko Fujihara, Mayu Kawasaki, Sohei Ito, Shogo Nakano, Hiroki Kakuta

Bioorganic & Medicinal Chemistry Letters 31 127666 - 127666 2021年1月

A Retinoid X Receptor Agonist Directed to the Large Intestine Ameliorates T-Cell-Mediated Colitis in Mice. 査読国際誌

Ryohtaroh Matsumoto, Daisuke Takahashi, Masaki Watanabe, Shunsuke Nakatani, Yuta Takamura, Yuji Kurosaki, Hiroki Kakuta, Koji Hase

Frontiers in pharmacology 12 715752 - 715752 2021年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Retinoid X receptor (RXR) is a nuclear receptor that heterodimerizes with several nuclear receptors, integrating ligand-mediated signals across the heterodimers. Synthetic RXR agonists have been developed to cure certain inflammatory diseases, including inflammatory bowel diseases (IBDs). However, pre-existing RXR agonists, which are lipophilic and readily absorbed in the upper intestine, cause considerable adverse effects such as hepatomegaly, hyperlipidemia, and hypothyroidism. To minimize these adverse effects, we have developed an RXR agonist, NEt-3IB, which has lipophilic and thus poorly absorptive properties. In this study, we evaluated the effects of NEt-3IB in an experimental murine colitis model induced through the adoptive transfer of CD45RBhighCD4+ T cells. Pharmacokinetic studies demonstrated that the major portion of NEt-3IB was successfully delivered to the large intestine after oral administration. Notably, NEt-3IB treatment suppressed the development of T cell-mediated chronic colitis, as indicated by improvement of wasting symptoms, inflammatory infiltration, and mucosal hyperplasia. The protective effect of NEt-3IB was mediated by the suppression of IFN-γ-producing Th1 cell expansion in the colon. In conclusion, NEt-3IB, a large intestine-directed RXR agonist, is a promising drug candidate for IBDs.

DOI： 10.3389/fphar.2021.715752

Convenient Retinoid X Receptor Binding Assay Based on Fluorescence Change of the Antagonist NEt-C343. 査読

Hiroki Kakuta

Journal of Medicinal Chemistry 64 ( 1 ) 861 - 870 2020年12月

担当区分：最終著者,　責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：American Chemical Society (ACS)

Retinoid X receptor (RXR) modulators (rexinoids) are considered to have therapeutic potential for multiple diseases, such as Alzheimer's disease and Parkinson's disease. To overcome various disadvantages of prior screening methods, we previously developed an RXR binding assay using a fluorescent RXR ligand, CU-6PMN (4). However, this ligand binds not only at the ligand-binding domain (LBD) but also at the dimer-dimer interface of hRXRα. Here, we present a new fluorescent RXR antagonist 6-[N-ethyl-N-(5-isobutoxy-4-isopropyl-2-(11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxamido)phenyl)amino]nicotinic acid (NEt-C343, 7), which emits strong fluorescence only when bound to the RXR-LBD. It allows us to perform a rapid, simple, and nonhazardous binding assay that does not require bound/free separation and uses a standard plate reader. The obtained Ki values of known compounds were correlated with the Ki values obtained using the standard [³H]9cis-retinoic acid assay. This assay should be useful for drug discovery as well as for research on endocrine disruptors, functional foods, and natural products.

DOI： 10.1021/acs.jmedchem.0c01883

Paclitaxel and Sorafenib: The Effective Combination of Suppressing the Self-Renewal of Cancer Stem Cells 査読国際誌

Hend M Nawara, SAID M AFIFY, Ghmkin Hassan, Maram H. Zahra, Marwa Atallah, Hager Mansour, Hagar A. Abu Quora, Md Jahangir Alam, Amira Osman, Hiroki Kakuta, Hiroki Hamada, Akimasa Seno, Masaharu Seno

Cancers 12 ( 6 ) 1360 - 1360 2020年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：{MDPI} {AG}

"Combination therapy", which is a treatment modality combining two or more therapeutic agents, is considered a cornerstone of cancer therapy. The combination of anticancer drugs, of which functions are different from the other, enhances the efficiency compared to the monotherapy because it targets cancer cells in a synergistic or an additive manner. In this study, the combination of paclitaxel and sorafenib in low concentration was evaluated to target cancer stem cells, miPS-BT549cmP and miPS-Huh7cmP cells, developed from mouse induced pluripotent stem cells. The synergistic effect of paclitaxel and sorafenib on cancer stem cells was assessed by the inhibition of proliferation, self-renewal, colony formation, and differentiation. While the IC50 values of paclitaxel and sorafenib were approximately ranging between 250 and 300 nM and between 6.5 and 8 µM, respectively, IC50 of paclitaxel reduced to 20 and 25 nM, which was not toxic in a single dose, in the presence of 1 µM sorafenib, which was not toxic to the cells. Then, the synergistic effect was further assessed for the potential of self-renewal of cancer stem cells by sphere formation ability. As a result, 1 µM of sorafenib significantly enhanced the effect of paclitaxel to suppress the number of spheres. Simultaneously, paclitaxel ranging in 1 to 4 nM significantly suppressed not only the colony formation but also the tube formation of the cancer stem cells in the presence of 1 µM sorafenib. These results suggest the combination therapy of paclitaxel and sorafenib in low doses should be an attractive approach to target cancer stem cells with fewer side effects.

DOI： 10.3390/cancers12061360

Maternal gut microbiota in pregnancy influences offspring metabolic phenotype in mice 査読国際誌

Ikuo Kimura, Junki Miyamoto, Ryuji Ohue-Kitano, Keita Watanabe, Takahiro Yamada, Masayoshi Onuki, Ryo Aoki, Yosuke Isobe, Daiji Kashihara, Daisuke Inoue, Akihiko Inaba, Yuta Takamura, Satsuki Taira, Shunsuke Kumaki, Masaki Watanabe, Masato Ito, Fumiyuki Nakagawa, Junichiro Irie, Hiroki Kakuta, Masakazu Shinohara, Ken Iwatsuki, Gozoh Tsujimoto, Hiroaki Ohno, Makoto Arita, Hiroshi Itoh, Koji Hase

Science 367 ( 6481 ) 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

<jats:p>Antibiotics and dietary habits can affect the gut microbial community, thus influencing disease susceptibility. Although the effect of microbiota on the postnatal environment has been well documented, much less is known regarding the impact of gut microbiota at the embryonic stage. Here we show that maternal microbiota shapes the metabolic system of offspring in mice. During pregnancy, short-chain fatty acids produced by the maternal microbiota dictate the differentiation of neural, intestinal, and pancreatic cells through embryonic GPR41 and GPR43. This developmental process helps maintain postnatal energy homeostasis, as evidenced by the fact that offspring from germ-free mothers are highly susceptible to metabolic syndrome, even when reared under conventional conditions. Thus, our findings elaborate on a link between the maternal gut environment and the developmental origin of metabolic syndrome.</jats:p>

DOI： 10.1126/science.aaw8429

Reversal of established liver fibrosis by IC-2-engineered mesenchymal stem cell sheets 査読国際誌

Noriko Itaba, Yohei Kono, Kaori Watanabe, Tsuyoshi Yokobata, Hiroyuki Oka, Mitsuhiko Osaki, Hiroki Kakuta, Minoru Morimoto, Goshi Shiota

Scientific Reports 9 ( 1 ) 6841 - 6841 2019年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media {LLC}

Chronic hepatitis viral infection, alcoholic intoxication, and obesity cause liver fibrosis, which progresses to decompensated liver cirrhosis, a disease for which medical demands cannot be met. Since there are currently no approved anti-fibrotic therapies for established liver fibrosis, the development of novel modalities is required to improve patient prognosis. In this study, we clarified the anti-fibrotic effects of cell sheets produced from human bone marrow-derived mesenchymal stem cells (MSCs) incubated on a temperature-sensitive culture dish with the chemical compound IC-2. Orthotopic transplantation of IC-2-engineered MSC sheets (IC-2 sheets) remarkably reduced liver fibrosis induced by chronic CCl4 administration. Further, the marked production of fibrolytic enzymes such as matrix metalloproteinase (MMP)-1 and MMP-14, as well as thioredoxin, which suppresses hepatic stellate cell activation, was observed in IC-2 sheets. Moreover, the anti-fibrotic effect of IC-2 sheets was much better than that of MSC sheets. Finally, knockdown experiments revealed that MMP-14 was primarily responsible for the reduction of liver fibrosis. Here, we show that IC-2 sheets could be a promising therapeutic option for established liver fibrosis.

DOI： 10.1038/s41598-019-43298-0

Competitive Binding Assay with an Umbelliferone-Based Fluorescent Rexinoid for Retinoid X Receptor Ligand Screening. 査読国際誌

Shoya Yamada, Mayu Kawasaki, Michiko Fujihara, Masaki Watanabe, Yuta Takamura, Maho Takioku, Hiromi Nishioka, Yasuo Takeuchi, Makoto Makishima, Tomoharu Motoyama, Sohei Ito, Hiroaki Tokiwa, Shogo Nakano, Hiroki Kakuta

Journal of Medicinal Chemistry 62 ( 19 ) 8809 - 8818 2019年10月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Ligands for retinoid X receptors (RXRs), "rexinoids", are attracting interest as candidates for therapy of type 2 diabetes and Alzheimer's and Parkinson's diseases. However, current screening methods for rexinoids are slow and require special apparatus or facilities. Here, we created 7-hydroxy-2-oxo-6-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2H-chromene-3-carboxylic acid (10, CU-6PMN) as a new fluorescent RXR agonist and developed a screening system of rexinoids using 10. Compound 10 was designed based on the fact that umbelliferone emits strong fluorescence in a hydrophilic environment, but the fluorescence intensity decreases in hydrophobic environments such as the interior of proteins. The developed assay using 10 enabled screening of rexinoids to be performed easily within a few hours by monitoring changes of fluorescence intensity with widely available fluorescence microplate readers, without the need for processes such as filtration.

DOI： 10.1021/acs.jmedchem.9b00995

3H-Imidazo[4,5-b]pyridine-6-carboxylic acid derivatives as rexinoids with reduced teratogenicity 査読国際誌

Yuta Takamura, Manami Takahashi, Midori Nishii, Osamu Shibahara, Masaki Watanabe, Michiko Fujihara, Hiroki Kakuta

Bioorganic & Medicinal Chemistry Letters 29 ( 15 ) 1891 - 1894 2019年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier {BV}

Several retinoid X receptor (RXR) ligands (rexinoids), such as bexarotene (1), exhibit teratogenicity, which is a serious impediment to their clinical application. We considered that rexinoids with a lower level of maximal RXR transcription activation (i.e., partial agonists) and lower lipid solubility might show weaker adverse side effects. Based on this idea, we modified our previously reported pentamethyltetralin-type RXR partial agonists 5 and 6 to reduce their lipophilicity. Here, we report a new RXR partial agonist, 3-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2-(trifluoromethyl)-3H-imidazo[4,5-b]pyridine-6-carboxylic acid (8, CATF-PMN), which showed greatly reduced teratogenicity in zebrafish embryos.

DOI： 10.1016/j.bmcl.2019.05.050

Correction to Synthesis of ¹¹C-Labeled RXR Partial Agonist 1-[(3,5,5,8,8-Pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)amino]benzotriazole-5-carboxylic Acid (CBt-PMN) by Direct [¹¹C]Carbon Dioxide Fixation via Organolithiation of Tri 査読

Shibahara O, Watanabe M, Takamura Y, Yamada S, Akehi M, Sasaki T, Akahoshi A, Hanada T, Hirano H, Nakatani S, Nishioka H, Takeuchi Y, Kakuta H

Journal of Medicinal Chemistry 62 ( 9 ) 4780 - 4781 2019年5月

Fluorine-18 (¹⁸F)-labeled retinoid x receptor (RXR) partial agonist whose tissue transferability is affected by other RXR ligands. 査読国際誌

Takamura Y, Shibahara O, Watanabe M, Fujihara M, Yamada S, Akehi M, Sasaki T, Hirano H, Kakuta H

Bioorganic & medicinal chemistry 27 ( 14 ) 3128 - 3134 2019年5月

A partial agonist for retinoid X receptor mitigates experimental colitis. 査読国際誌

Masayoshi Onuki, Masaki Watanabe, Narumi Ishihara, Koichiro Suzuki, Kei Takizawa, Masato Hirota, Takahiro Yamada, Aiko Egawa, Osamu Shibahara, Midori Nishii, Michiko Fujihara, Makoto Makishima, Daisuke Takahashi, Yukihiro Furusawa, Hiroki Kakuta, Koji Hase

International immunology 31 ( 4 ) 251 - 262 2019年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is an intractable disease of the gastrointestinal tract. Multiple environmental factors, including food ingredients, have been implicated in the development of these diseases. For example, animal fat-rich diets are predisposing factors for ulcerative colitis, whereas n-3 unsaturated fatty acids such as docosahexaenoic acid (DHA) show protective effects in experimental colitis and are negatively correlated with the incidence of ulcerative colitis and Crohn's disease. Given that DHA exhibits agonistic activity on retinoid X receptor (RXR), activation of RXR could be a therapeutic strategy for IBD. However, conventional full RXR agonists are known to show considerable adverse effects. We therefore took advantage of a partial RXR agonist, CBt-PMN, to minimize the adverse effects, and evaluated its efficacy in dextran sodium sulfate-induced colitis. Administration of CBt-PMN efficiently ameliorated the symptoms of colitis. This effect was attributed to the down-regulation of pro-inflammatory cytokines such as Tnf and Il6 in colon-infiltrating monocytes. Down-regulation of pro-inflammatory cytokines by CBt-PMN was also evident in lipopolysaccharide-stimulated bone marrow-derived macrophages (BMDMs). Among many RXR-associated nuclear receptors, activation of peroxisome proliferator-activated receptor δ (PPARδ) and nuclear hormone receptor 77 (Nur77) suppressed cytokine production by BMDMs. These observations suggest that the activation of PPARδ/RXR and Nur77/RXR heterodimers by CBt-PMN through the permissive mechanism is responsible for diminishing the monocyte-mediated inflammatory response in the gut. Our data highlight the importance of RXR activation in the regulation of colitis.

DOI： 10.1093/intimm/dxy089

変形性関節症:from bench to bedside 関節軟骨のバイオイメージング

大橋俊孝, 加来田博貴, 大野充昭, 西田圭一郎

日本整形外科学会雑誌 93 ( 2 ) S331 - S331 2019年3月

A retinoid X receptor partial agonist attenuates pulmonary emphysema and airway inflammation. 査読国際誌

Daisuke Morichika, Nobuaki Miyahara, Utako Fujii, Akihiko Taniguchi, Naohiro Oda, Satoru Senoo, Mikio Kataoka, Mitsune Tanimoto, Hiroki Kakuta, Katsuyuki Kiura, Yoshinobu Maeda, Arihiko Kanehiro

Respiratory research 20 ( 1 ) 2 - 2 2019年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

BACKGROUND: Retinoid X receptors (RXRs) are members of the nuclear receptor (NR) superfamily that mediate signalling by 9-cis retinoic acid, a vitamin A derivative. RXRs play key roles not only as homodimers but also as heterodimeric partners, e.g., for retinoic acid receptors, vitamin D receptors, and peroxisome proliferator-activated receptors. The NR family may also play important roles in the development of emphysema. However, the role of RXRs in the pathogenesis of emphysema is not well defined. METHODS: We developed a novel RXR partial agonist (NEt-4IB) and investigated its effect and mechanism compared to a full agonist (bexarotene) in a murine model of emphysema. For emphysema induction, BALB/c mice received intraperitoneal cigarette smoke extract (CSE) or intratracheal porcine pancreas elastase (PPE). Treatment with RXR agonists was initiated before or after emphysema induction. RESULTS: Treatment with NEt-4IB significantly suppressed the increase in static lung compliance and emphysematous changes in CSE-induced emphysema and PPE-induced established and progressive emphysema. NEt-4IB significantly suppressed PPE-induced neutrophilic airway inflammation and the levels of keratinocyte chemoattractant (KC), C-X-C motif ligand5 (CXCL5), interferon (IFN)-γ and IL-17. NEt-4IB also improved the matrix metalloproteinase-9 (MMP-9)/tissue inhibitor of metalloproteinase-1 (TIMP-1) imbalance and the reduced anti-oxidant activity in bronchoalveolar lavage (BAL) fluid. NEt-4IB suppressed PPE-induced vascular endothelial growth factor (VEGF) expression in the airway. Treatment with NEt-4IB and bexarotene significantly suppressed the increase in static lung compliance and emphysematous changes. However, adverse effects of RXR agonists, including hypertriglyceridemia and hepatomegaly, were observed in bexarotene-treated mice but not in NEt-4IB-treated mice. CONCLUSION: These data suggest that RXRs play crucial roles in emphysema and airway inflammation, and novel partial RXR agonists could be potential therapeutic strategies for the treatment of PPE- and CSE-induced emphysema.

DOI： 10.1186/s12931-018-0963-0

Dual conformation of the ligand induces the partial agonistic activity of retinoid X receptor α (RXRα). 査読国際誌

Miyashita Y, Numoto N, Arulmozhiraja S, Nakano S, Matsuo N, Shimizu K, Shibahara O, Fujihara M, Kakuta H, Ito S, Ikura T, Ito N, Tokiwa H

FEBS letters 593 ( 2 ) 242 - 250 2019年1月

Problems with laboratory notebooks in academia and how to resolve them

Kakuta, H.

Yakugaku Zasshi 139 ( 6 ) 2019年

Towards further sharing of knowledge and activities on standards of quality assurance (Qa) across industry, academia and government to promote research integrity and accelerate drug discovery

Kakuta, H., Sudo, H.

Yakugaku Zasshi 139 ( 6 ) 2019年

Retinoid X Receptor Antagonists

Masaki Watanabe, Hiroki Kakuta

International Journal of Molecular Sciences 19 ( 8 ) 2354 - 2354 2018年8月

Retinoid X Receptor Antagonists

Hiroki Kakuta

International Journal of Molecular Sciences 2018年8月

Strategy for Tumor-Selective Disruption of Androgen Receptor Function in the Spectrum of Prostate Cancer 査読国際誌

Rayna Rosati, Lisa Polin, Charles Ducker, Jing Li, Xun Bao, Dakshnamurthy Selvakumar, Seongho Kim, Besa Xhabija, Martha Larsen, Thomas McFall, Yanfang Huang, Benjamin L Kidder, Andrew Fribley, Janice Saxton, Hiroki Kakuta, Peter Shaw, Manohar Ratnam

Clinical cancer research : an official journal of the American Association for Cancer Research 24 ( 24 ) 6509 - 6522 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）

PURPOSE: Testosterone suppression in prostate cancer is limited by serious side effects and resistance via restoration of androgen receptor (AR) functionality. ELK1 is required for AR-dependent growth in various hormone-dependent and castration-resistant prostate cancer models. The amino-terminal domain of AR docks at two sites on ELK1 to coactivate essential growth genes. This study explores the ability of small molecules to disrupt the ELK1-AR interaction in the spectrum of prostate cancer, inhibiting AR activity in a manner that would predict functional tumor selectivity. EXPERIMENTAL DESIGN: Small-molecule drug discovery and extensive biological characterization of a lead compound. RESULTS: We have discovered a lead molecule (KCI807) that selectively disrupts ELK1-dependent promoter activation by wild-type and variant ARs without interfering with ELK1 activation by ERK. KCI807 has an obligatory flavone scaffold and functional hydroxyl groups on C5 and C3'. KCI807 binds to AR, blocking ELK1 binding, and selectively blocks recruitment of AR to chromatin by ELK1. KCI807 primarily affects a subset of AR target growth genes selectively suppressing AR-dependent growth of prostate cancer cell lines with a better inhibitory profile than enzalutamide. KCI807 also inhibits in vivo growth of castration/enzalutamide-resistant cell line-derived and patient-derived tumor xenografts. In the rodent model, KCI807 has a plasma half-life of 6 hours, and maintenance of its antitumor effect is limited by self-induced metabolism at its 3'-hydroxyl. CONCLUSIONS: The results offer a mechanism-based therapeutic paradigm for disrupting the AR growth-promoting axis in the spectrum of prostate tumors while reducing global suppression of testosterone actions. KCI807 offers a good lead molecule for drug development.

DOI： 10.1158/1078-0432.ccr-18-0982

DOI： 10.1158/1078-0432.CCR-18-0982

Retinoid X receptor antagonists

Watanabe, M., Kakuta, H.

International Journal of Molecular Sciences 19 ( 8 ) 2018年

Retinoid X Receptor Antagonists

Hiroki Kakuta

International journal of molecular sciences 2018年

Synthesis of 11C-Labeled RXR Partial Agonist 1-[(3,5,5,8,8-Pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)amino]benzotriazole-5-carboxylic Acid (CBt-PMN) by Direct [11C]Carbon Dioxide Fixation via Organolithiation of Trialkyltin Precursor and PET Imagin・・・査読国際誌

Osamu Shibahara, Masaki Watanabe, Shoya Yamada, Masaru Akehi, Takanori Sasaki, Akiya Akahoshi, Takahisa Hanada, Hiroyuki Hirano, Shunsuke Nakatani, Hiromi Nishioka, Yasuo Takeuchi, Hiroki Kakuta

Journal of Medicinal Chemistry 60 ( 16 ) 7139 - 7145 2017年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Synthesis of 11C-Labeled RXR Partial Agonist 1-[(3,5,5,8,8-Pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)amino]benzotriazole-5-carboxylic Acid (CBt-PMN) by Direct [11C]Carbon Dioxide Fixation via Organolithiation of Trialkyltin Precursor and PET Imaging Thereof

DOI： 10.1021/acs.jmedchem.7b00817

Effect of a retinoid X receptor partial agonist on airway inflammation and hyperresponsiveness in a murine model of asthma. 査読国際誌

Utako Fujii, Nobuaki Miyahara, Akihiko Taniguchi, Naohiro Oda, Daisuke Morichika, Etsuko Murakami, Hikari Nakayama, Koichi Waseda, Mikio Kataoka, Hiroki Kakuta, Mitsune Tanimoto, Arihiko Kanehiro

Respiratory research 18 ( 1 ) 23 - 23 2017年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

BACKGROUND: Retinoid X receptors (RXRs) are members of the nuclear receptor (NR) superfamily that mediate signaling by 9-cis retinoic acid, a vitamin A (retinol) derivative. RXRs play key roles not only as homodimers but also as heterodimeric partners-e.g., retinoic acid receptors (RARs), vitamin D receptors (VDRs), liver X receptors (LXRs), and peroxisome proliferator-activated receptors (PPARs). The NR family was recently associated with allergic diseases, but the role of RXRs in allergen-induced airway responses is not well defined. The goal of this study is to elucidate the role of RXRs in asthma pathogenesis and the potency of RXR partial agonist in the treatment of allergic airway inflammation and airway hyperresponsiveness using a murine model of asthma. METHODS: We investigated the effect of a novel RXR partial agonist (NEt-4IB) on the development of allergic airway inflammation and airway hyperresponsiveness (AHR) in a murine model of asthma. Balb/c mice were sensitized (days 0 and 14) and challenged (days 28-30) with ovalbumin (OVA), and airway inflammation and airway responses were monitored 48 h after the last OVA challenge. NEt-4IB was administered orally on days 25 to 32. RESULTS: Oral administration of NEt-4IB significantly suppressed AHR and inflammatory cell accumulation in the airways and attenuated the levels of TNF-α in the lung and IL-5, IL-13 and NO levels in bronchoalveolar lavage (BAL) fluid and the number of periodic acid Schiff (PAS)-positive goblet cells in lung tissue. Treatment with NEt-4IB also significantly suppressed NF-κB expression. CONCLUSION: These data suggest that RXRs may be of crucial importance in the mechanism of allergic asthma and that the novel RXR partial agonist NEt-4IB may be a promising candidate for the treatment of allergic airway inflammation and airway hyperresponsiveness in a model of allergic asthma.

DOI： 10.1186/s12931-017-0507-z

Effect Of A Retinoid X Receptor Partial Agonist On The Development Of Emphysema And Airway Inflammation In A Murine Model Of Emphysema 査読

D. Morichika, A. Kanehiro, H. Kakuta, A. Taniguchi, U. Fujii, N. Oda, N. Miyahara, K. Kiura, M. Tanimoto

AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE 195 2017年

Retinoid X Receptor Ligands with Anti-Type 2 Diabetic Activity

Hiroki Kakuta

Current topics in medicinal chemistry 2017年

Treatment With Novel Retinoid X Receptor Partial Agonist Attenuates Eosinophilic Airway Inflammation And Airway Hyperresponsiveness 査読

U. Fujii, A. Kanehiro, N. Miyahara, N. Oda, D. Morichika, A. Taniguchi, G. Ikeda, H. Nakayama, K. Waseda, E. Murakami, H. Kakuta, M. Kataoka, K. Kiura, M. Tanimoto

AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE 193 2016年

Retinoid x receptor ligands with anti-type 2 diabetic activity

Morishita, K.-I., Kakuta, H.

Current Topics in Medicinal Chemistry 16 ( 30 ) 2016年

RXR Partial Agonist Produced by Side Chain Repositioning of Alkoxy RXR Full Agonist Retains Antitype 2 Diabetes Activity without the Adverse Effects 査読

Kohei Kawata, Ken-ichi Morishita, Mariko Nakayama, Shoya Yamada, Toshiki Kobayashi, Yuki Furusawa, Sakae Arimoto-Kobayashi, Toshitaka Oohashi, Makoto Makishima, Hirotaka Naitou, Erika Ishitsubo, Hiroaki Tokiwa, Akihiro Tai, Hiroki Kakuta

JOURNAL OF MEDICINAL CHEMISTRY 58 ( 2 ) 912 - 926 2015年1月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We previously reported RXR partial agonist CBt-PMN (1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid: <bold>5</bold>, EC50 = 143 nM, E-max = 75%), which showed a potent glucose-lowering effect without causing serious adverse effects. However, it remains important to elucidate the structural requirements for RXR efficacy and the glucose-lowering effect because RXR-permissive heterodimers such as PPAR/RXR or LXR/RXR are reported to be activated differently depending upon the chemical structure of RXR agonists. In this work, we show that an RXR partial agonist, NEt-4IB (6-[ethyl-(4-isobutoxy-3-isopropylphenyl)amino]pyridine-3-carboxylic acid: <bold>8b</bold>, EC50 = 169 nM, E-max = 55%), can be obtained simply by repositioning the side chains (interchanging the isobutoxy and isopropoxy groups) at the hydrophobic moiety of the RXR full agonist NEt-3IB (6-[ethyl-(3-isobutoxy-4-isopropylphenyl)amino]pyridine-3-carboxylic acid: <bold>7b</bold>, EC50 = 19 nM). NEt-4IB (<bold>8b</bold>) showed antitype 2 diabetes activity without the above side effects upon repeated oral administration to mice at 10 mg/kg/day, similarly to <bold>5</bold>.

DOI： 10.1021/jm501863r

Positron emission tomography to elucidate pharmacokinetic differences of regioisomeric retinoid x receptor agonists 査読

Toshiki Kobayashi, Yuki Furusawa, Shoya Yamada, Masaru Akehi, Fumiaki Takenaka, Takanori Sasaki, Akiya Akahoshi, Takahisa Hanada, Eiji Matsuura, Hiroyuki Hirano, Akihiro Tai, Hiroki Kakuta

ACS medicinal chemistry letters 6 ( 3 ) 334 - 338 2015年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

RXR partial agonist NEt-41B (2a, 6-[ethyl-(4-isobutoxy-3-isopropylphenyl)amino]pyridine-3-carboxylic acid: EC50 = 169 nM, E-max = 55%) showed a blood concentration higher than its Emax after single oral administration at 30 mg/kg to mice, and repeated oral administration at 10 mg/kg/day to KK-A(y) mice afforded antitype 2 diabetes activity without the side effects caused by RXR full agonists. However, RXR full agonist NEt-3IB (la), in which the isobutoxy and isopropyl groups of 2a are interchanged, gave a much lower blood concentration than 2a. Here we used positron emission tomography (PET) with tracers [C-11] la, [C-11]2a and fluorinated derivatives [F-18] lb, [F-18]2b, which have longer half-lives, to examine the reason why la and 2a exhibited significantly different blood concentrations. As a result, the reason for the high blood concentration of 2a after oral administration was found to be linked to higher intestinal absorbability together with lower biliary excretion, compared with la.

DOI： 10.1021/ml500511m

Involvement of glucocorticoid receptor activation on anti-inflammatory effect induced by peroxisome proliferator-activated receptor γ agonist in mice. 査読国際誌

Yamamoto A, Kakuta H, Sugimoto Y

International immunopharmacology 22 ( 1 ) 204 - 8 2014年

Interspecies comparison of hepatic metabolism of six newly synthesized retinoid X receptor agonistic compounds possessing a 6-[N-ethyl-N-(alkoxyisopropylphenyl)amino]nicotinic acid skeleton in rat and human liver microsomes 査読

Yoshiki Murakami, Yasumasa Shimizu, Akemi Ogasawara, Satoshi Ueshima, Mariko Nakayama, Kohei Kawata, Hiroki Kakuta, Tetsuya Aiba

Drug development and industrial pharmacy 40 ( 8 ) 1065 - 1071 2014年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：INFORMA HEALTHCARE

Objective: The hepatic metabolism of six compounds newly synthesized as retinoid X receptor agonists was characterized in rat and human liver microsomes to examine the relationship between their hepatic metabolism profiles and side chain structures, considering the interspecies difference.
Materials and methods: The compounds used have a 6-[N-ethyl-N-(3-alkoxy-4-isopropylphenyl)amino]nicotinic or 6-[N-ethyl-N-(4-alkoxy-3-isopropylphenyl)amino]nicotinic acid skeleton, in which the isopropoxy, isobutoxy or cyclopropylmethoxy group is employed for the alkoxy group. These compounds were incubated with the microsomes, and their Michaelis-Menten parameters were determined. The incubation study was also performed with various cytochrome P450 (CYP) inhibitors to examine their susceptibilities to the inhibitors. In addition, a molecular docking simulation was conducted to assess the compound's spatial configuration with the CYP isoform when necessary.
Results: The Michaelis-Menten parameters determined are comparable between rats and humans for the compounds having 3-isobutoxy, 4-isobutoxy, 4-isopropoxy and 4-cyclopropylmethoxy groups. However, it was indicated that all compounds except that having the 3-isobutoxy group are metabolized in a different manner between rats and humans. That is, the extent of the contribution of each CYP isozyme is different between those two species. A molecular docking simulation showed that the spatial configuration of the compound to be associated with CYP2D6 markedly changes depending on whether the isobutoxy group is situated at the 3- or 4-position.
Conclusion: A slight difference in the side chain structures markedly alters the compound's metabolic profile, which amplifies the interspecies difference regarding the profile, increasing the difficulty in characterizing the profile in humans with the structural-property relationship and interspecies extrapolation.

DOI： 10.3109/03639045.2013.807278

In vitro anti-proliferative and anti-angiogenic activities of thalidomide dithiocarbamate analogs 査読

Bishoy Y A El-Aarag, Tomonari Kasai, Magdy A H Zahran, Nadia I Zakhary, Tsukasa Shigehiro, Sreeja C Sekhar, Hussein S Agwa, Akifumi Mizutani, Hiroshi Murakami, Hiroki Kakuta, Masaharu Seno

International immunopharmacology 21 ( 2 ) 283 - 292 2014年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Inhibition of angiogenesis is currently perceived as a promising strategy in the treatment of cancer. The anti-angiogenicity of thalidomide has inspired a second wave of research on this teratogenic drug. The present study aimed to investigate the anti-proliferative and anti-angiogenic activities of two thalidomide dithiocarbamate analogs by studying their anti-proliferative effects on human umbilical vein endothelial cells (HUVECs) and MDA-MB-231 human breast cancer cell lines. Their action on the expression levels of IL-6, IL-8, TNF-alpha, VEGF(165), and MMP-2 was also assessed. Furthermore, their effect on angiogenesis was evaluated through wound healing, migration, tube formation, and nitric oxide (NO) assays. Results illustrated that the proliferation of HUVECs and MDA-MB-231 cells was not significantly affected by thalidomide at 625-100 mu M. Thalidomide failed to block angiogenesis at similar concentrations. By contrast, thalidomide dithiocarbamate analogs exhibited significant anti-proliferative action on HUVECs and MDA-MB-231 cells without causing cytotoxicity and also showed powerful anti-angiogenicity in wound healing, migration, tube formation, and NO assays. Thalidomide analogs 1 and 2 demonstrated more potent activity to suppress expression levels of IL-6, IL-8, TNF-alpha, VEGF(165), and MMP-2 than thalidomide. Analog 1 consistently, showed the highest potency and efficacy in all the assays. Taken together, our results support further development and evaluation of novel thalidomide analogs as antitumor and anti-angiogenic agents. (C) 2014 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.intimp.2014.05.007

Mechanism of retinoid X receptor partial agonistic action of 1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid and structural development to increase potency 査読

Fuminori Ohsawa, Shoya Yamada, Nobumasa Yakushiji, Ryosuke Shinozaki, Mariko Nakayama, Kohei Kawata, Manabu Hagaya, Toshiki Kobayashi, Kazutaka Kohara, Yuuki Furusawa, Chisa Fujiwara, Yui Ohta, Makoto Makishima, Hirotaka Naitou, Akihiro Tai, Yutaka Yoshikawa, Hiroyuki Yasui, Hiroki Kakuta

Journal of medicinal chemistry 56 ( 5 ) 1865 - 1877 2013年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We have reported that retinoid X receptor (RXR) partial agonist 1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-1H-benzotriazole-5-carboxylic acid (CBt-PMN, 4a) shows a significant antidiabetes effect in the KK-A(y) type 2 diabetes model mice, with reduced side effects compared to RXR full agonists. To elucidate the mechanism of the RXR partial agonist activity of 4a, we synthesized derivatives of 4a, evaluated their RXR agonist activity, and performed structure-activity relationship analysis. Reporter gene assay revealed that though 6b, which possesses an amino group at the 2-position of 5-carboxybenzimidazole, showed RXR full-agonist activity, compounds 6d and 6e, which possess an oxygen atom and a sulfur atom at the corresponding position, respectively, showed weak RXR agonist activity. On the other hand, 6c, which has a trifluoromethyl group at the corresponding position, acts as an RXR partial agonist, having similar E-max (67 +/- 2%) and lower EC50 (15 +/- 0 nM) compared to those of 4a (E-max = 75 +/- 4%, EC50 = 143 +/- 2 nM). A fluorescence polarization assay of cofactor recruitment confirmed that fluorescein-labeled D22 coactivator peptide was less efficiently recruited to RXR by 4a and 6c than by LGD1069 (1), a known RXR full agonist. Electrostatic potential field calculations and computational docking studies suggested that full agonists show an electrostatic attraction, which stabilizes the holo structure and favors coactivator recruitment, between the side chain at the benzimidazole 2-position and the a-carbonyl oxygen of asparagine-306 in helix 4 (H4) of the RXR receptor. However, RXR partial agonists 4a and 6c lack this interaction. Like 4a, 6c showed a significant antidiabetes effect in KK-A(y) type 2 diabetes model mice with reduced levels of the side effects associated with RXR full agonists. These findings should aid the design of new RXR partial agonists as antitype 2 diabetes drug candidates.

DOI： 10.1021/jm400033f

RXR Partial Agonist CBt-PMN Exerts Therapeutic Effects on Type 2 Diabetes without the Side Effects of RXR Full Agonists 査読

Hiroki Kakuta, Nobumasa Yakushiji, Ryosuke Shinozaki, Fuminori Ohsawa, Shoya Yamada, Yui Ohta, Kohei Kawata, Mariko Nakayama, Manabu Hagaya, Chisa Fujiwara, Makoto Makishima, Shigeyuki Uno, Akihiro Tai, Ami Maehara, Masaru Nakayama, Toshitaka Oohashi, Hiroyuki Yasui, Yutaka Yoshikawa

ACS medicinal chemistry letters 3 ( 5 ) 427 - 432 2012年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Treating insulin resistance and type 2 diabetes in rodents, currently known retinoid X receptor (RXR) agonists induce significant adverse effects. Here we introduce a novel RXR partial agonist CBt-PMN (11b), which shows a potent glucose-lowering effect and improvements of insulin secretion and glucose tolerance without the serious adverse effects caused by RXR full agonists. We suggest that RXR partial agonists may be a new class of antitype 2 diabetes drug candidates.

DOI： 10.1021/ml300055n

Relevance of nuclear receptor expression in a Tchreg cell line, HOZOT: RXRα and PPARγ negatively regulate IFN-γ production. 査読

Suzuki M, Takeuchi M, Tsuji-Takayama K, Harashima A, Otani T, Toraya T, Kakuta H, Yamasaki F, Nakamura S, Kibata M

Results in immunology 2 158 - 165 2012年

Feasibility of structural modification of retinoid X receptor agonists to separate blood glucose-lowering action from adverse effects: studies in KKA(y) type 2 diabetes model mice 査読

Hiroki Kakuta, Fuminori Ohsawa, Shoya Yamada, Makoto Makishima, Akihiro Tai, Hiroyuki Yasui, Yutaka Yoshikawa

Biological & pharmaceutical bulletin 35 ( 4 ) 629 - 633 2012年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PHARMACEUTICAL SOC JAPAN

Retinoid X receptor (RXR) agonists are reported to exhibit blood glucose-lowering action owing to peroxisome proliferator-activated receptor (PPAR)/RXR or liver X receptor (LXR)/RXR activation, but may also cause adverse effects such as blood triglyceride elevation. In order to examine the feasibility of separating the glucose-lowering action from the adverse effects, we examined the effects of RXR agonists (NEt-TMN), NEt-3IB, and NEt-3IP, which have different heterodimer-activating patterns, in KKA(y) type 2 diabetes model mice. We found that NEt-3IB induced lower degrees of hepatomegaly and blood triglyceride (TG) elevation than the other RXR agonists, even though all of them showed similar blood glucose-lowering action on repeated administration. These findings indicate that structural modification of RXR agonists is a potentially effective strategy to reduce adverse effects while retaining desired activities.

DOI： 10.1248/bpb.35.629

Involvement of the Retinoid X Receptor Ligand in the Anti-Inflammatory Effect Induced by Peroxisome Proliferator-Activated Receptor γ Agonist In Vivo. 査読

Yamamoto A, Kakuta H, Miyachi H, Sugimoto Y

PPAR research 2011 840194 2011年

An arylidene-thiazolidinedione derivative, GPU-4, without PPARγ activation, reduces retinal neovascularization. 査読

Nakamura S, Hayashi K, Takizawa H, Murase T, Tsuruma K, Shimazawa M, Kakuta H, Nagasawa H, Hara H

Current neurovascular research 8 ( 1 ) 25 - 34 2011年

Design and synthesis of novel cyclooxygenase-1 inhibitors as analgesics: 5-amino-2-ethoxy-N-(substituted-phenyl)benzamides 査読

Ryosuke Fukai, Xiaoxia Zheng, Kazunori Motoshima, Akihiro Tai, Futoshi Yazama, Hiroki Kakuta

ChemMedChem 6 ( 3 ) 550 - 560 2011年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

We previously found that N-(4-aminophenyl)-4-trifluoromethyl-benzamide (TFAP), a COX-1 inhibitor, exhibits an analgesic effect without causing gastric damage. Unfortunately, TFAP causes reddish purple coloration of urine, and its analgesic effect is less potent than that of indomethacin. Herein we describe our study focusing on the development of 4- and 5-amino- 2-alkoxy-N-phenylbenzamide scaffolds, designed on the basis of the structures of TFAP and parsalmide, another known COX-1 inhibitory analgesic agent. 5-Amino-2-ethoxy-N-(2-or 3-substituted phenyl) benzamide derivatives exhibited analgesic activity in a murine acetic acid induced writhing test. Among these compounds, 5-amino-2-ethoxy-N-(2-methoxyphenyl) benzamide (9v) possesses potent COX-1 inhibitory and analgesic activities, similar to those of indomethacin. In addition, 5-amino- 2-ethoxy-N-(3-trifluoromethylphenyl)benzamide (9g) showed a more potent analgesic effect than indomethacin or 9v without causing apparent gastric damage or coloration of urine, although its COX-1 inhibitory activity was weaker than that of indomethacin or 9v. Thus, 9g and 9v appear to be promising candidates for analgesic agents and are attractive lead compounds for further development of COX-1 inhibitors.

DOI： 10.1002/cmdc.201000462

Pharmacokinetic properties of newly synthesized retinoid X receptor agonists possessing a 6-[N-ethyl-N-(3-alkoxy-4-isopropylphenyl)amino]nicotinic acid skeleton in rats 査読

Akemi Ogasawara, Yoshiki Murakami, Nobumasa Yakushiji, Fuminori Ohsawa, Jun-Ichi Kusaba, Tetsuya Aiba, Yuji Kurosaki, Hiroki Kakuta

Drug development and industrial pharmacy 37 ( 9 ) 1060 - 1067 2011年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：INFORMA HEALTHCARE

Objective: The pharmacokinetic properties of three newly synthesized retinoid X receptor (RXR) agonists were evaluated in rats to elucidate the structural factor influencing their pharmacokinetic properties. Material and methods: Three RXR agonists possessing a common 6-[N-ethyl-N-(3-alkoxy-4-isopropylphenyl)amino]nicotinic acid skeleton and side chain structures that are slightly different from each other were prepared as we previously reported (Takamatsu et al., ChemMedChem, 2008; 3: 780-787). The plasma concentration profiles of these compounds were evaluated following the intravenous and intra-intestinal administrations. Their hepatic metabolism was characterized using rat liver microsomes. Results: Based on the plasma concentration profile, NEt-3IP (3-isopropoxy) was shown to have a distribution volume of 4.53 L/kg, and to be cleared from the body with an elimination half-time of 0.95 h. The bioavailability of NEt-3IP is 16.4%, whereas those of the isobutoxy analog NEt-3IB and the cyclopropylmethoxy analog NEt-3cPM are 46.5% and 22.6%, respectively. Subsequently, in the experiments using rat liver microsomes, the K-m and V-max values of NEt-3IP were determined as 7.85 mu M and 0.48 nmol/min/mg protein, respectively. This K-m value is nearly the same as those of NEt-3IB and NEt-3cPM, but the V-max value is noticeably smaller. Additionally, it was revealed that the CYP family mainly metabolizing NEt-3IP is different from those metabolizing the other analogs. Conclusion: Based on these findings, the pharmacokinetic properties of the compounds possessing this type of the skeleton seem to be largely influenced by a slight modification of the side chain structure.

DOI： 10.3109/03639045.2011.559247

Replacement of the hydrophobic part of 9-cis-retinoic acid with cyclic terpenoid moiety results in RXR-selective agonistic activity 査読

Takashi Okitsu, Kana Sato, Kinya Iwatsuka, Natsumi Sawada, Kimie Nakagawa, Toshio Okano, Shoya Yamada, Hiroki Kakuta, Akimori Wada

Bioorganic & medicinal chemistry 19 ( 9 ) 2939 - 2949 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Retinoid X receptor (RXR) agonists are interesting candidates for the treatment of metabolic syndrome. 9-Cis-retinoic acid (9cRA: 1) is a natural RXR agonist, that also works as a retinoic acid receptor (RAR) agonist. This fact prompted us to study the structure-activity relationship (SAR) of RXR agonists derived from 1. Though 3 and 4, in which the cyclohexene part of 1 is replaced with bulkier hydrophobic moieties, show RXR-selective agonistic activity, some analogs containing other ring structures show RAR agonistic activity. Thus, we were interested in establishing what kind of ring skeleton is required for RXR-selective agonistic activity. In this study, we systematically prepared 5 and 6, in which the cyclohexene ring of 1 is replaced with various cyclic terpenoid moieties, and evaluated their RXR and RAR agonistic activities. Our previously reported CsF-promoted Stille coupling reaction was employed as a key step for the comprehensive synthesis of 5 and 6. The results of transcriptional assay showed that compounds 5b-f, which possess a menthane skeleton, exhibit RXR-selective agonistic activity. These results should be helpful for the design of superior RXR-selective agonists based on the structure of 1. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmc.2011.03.033

Discovery of a Potent Retinoid X Receptor Antagonist Structurally Closely Related to RXR Agonist NEt-3IB 査読

Mariko Nakayama, Shoya Yamada, Fuminori Ohsawa, Yui Ohta, Kohei Kawata, Makoto Makishima, Hiroki Kakuta

ACS medicinal chemistry letters 2 ( 12 ) 896 - 900 2011年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We discovered a potent retinoid X receptor (RXR) antagonist, 6-[N-ethyl-N-(5-isobutoxy-4-isopropyl-2-(E)-styrylphenyl)amino]nicotinic acid (13e), that is structurally closely related to the RXR full agonist 6-[N-ethyl-N-(3-isobutoxy-4-isopropylphenyl)amino]nicotinic acid (NEt-3IB) (4). Compound 13e was synthesized via a simple route from 11, a methyl ester precursor of 4. Because 11 possesses high electrophilic reactivity because of the amino and alkoxy groups, it was readily transformed to 12 by iodization, and the iodine atom of 12 was converted to a C-C or C-N bond by means of palladium-catalyzed reaction to afford 13. Transcriptional activation assay revealed that 13g (in which the iodine atom was replaced with an amino group) is a weak RXR agonist, while 13d (a phenyl group), 13e (a styryl group), and 13f (an anilino group) are RXR antagonists. Among them, 13e was found to be more potent than the known RXR antagonist PA452 (9).

DOI： 10.1021/ml200197e

Cyclic-tri(N-methyl-meta-benzamide)s: substituent effects on the bowl-shaped conformation in the crystal and solution states 査読

Kakuta, H, Azumaya, I, Masu, H, Matsumura, M, Yamaguchi, K, Kagechika, H, Tanatani, A

Tetrahedron 66 ( 42 ) 8254 - 8260 2010年10月

Fluorescent retinoid X receptor ligands for fluorescence polarization assay 査読

Yamada S, Ohsawa F, Fujii S, Shinozaki R, Makishima M, Naitou H, Enomoto S, Tai A, Kakuta H.

Bioorganic & medicinal chemistry letters 20 ( 17 ) 5143 - 5146 2010年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Retinoid X receptor (RXR) agonists are candidate agents for the treatment of metabolic syndrome and type 2 diabetes via activation of peroxisome proliferator-activated receptor (PPAR)/RXR or liver X receptor (LXR)/RXR-heterodimers, which control lipid and glucose metabolism. Reporter gene assays or binding assays with radiolabeled compounds are available for RXR ligand screening, but are unsuitable for high-throughput screening. Therefore, as a first step towards stabilizing a fluorescence polarization (FP) assay system for high-throughput RXR ligand screening, we synthesized fluorescent RXR ligands by modification of the lipophilic domain of RXR ligands with a carbostyril fluorophore, and selected the fluorescent RXR agonist 6-[ethyl(1-isobutyl-2-oxo-4-trifluoromethyl-1,2-dihydroquinolin-7-yl) amino] nicotinic acid 8d for further characterization. Compound 8d showed FP in the presence of RXR and the FP was decreased in the presence of the RXR agonist LGD1069 (2). This compound should be a lead compound for use in high-throughput assay systems for screening RXR ligands. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2010.07.011

Modification at the Lipophilic Domain of RXR Agonists Differentially Influences Activation of RXR Heterodimers 査読

Fuminori Ohsawa, Ken-Ichi Morishita, Shoya Yamada, Makoto Makishima, Hiroki Kakuta

ACS medicinal chemistry letters 1 ( 9 ) 521 - 525 2010年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

RXR permissive heterodimers are reported to be activated differently depending upon the chemical structure of RXR agonists, but the relationship of agonist structure to differential heterodimer activation has not been explored in detail. In this study, we performed systematic conversion of the alkoxy side chain of 5a (6-[ethyl-(3-isopropoxy-4-isopropylphenyl)amino]nicotinic acid, NEt-3IP) and evaluated the RXR-, PPAR/RXR-, and LXR/RXR-agonist activities of the products. The cyclopropylmethoxy analogue (5c) showed similar RXR- and LXR/RXR-agonistic activities to the benzyloxy analogue (51) and n-propoxy analogue (5k) but exhibited more potent PPAR/RXR-agonistic activity than 51 or 5k. Differential modulation of RXR heterodimer-activating ability by conversion of the alkoxy group located in the lipophilic domain of the RXR-agonist common structure is expected be a useful approach in the design of new RXR agonists for the treatment of hyperlipidemia or type 2 diabetes.

DOI： 10.1021/ml100184k

Identification of urine metabolites of TFAP, a cyclooxygenase-1 inhibitor 査読

Hiroki Kakuta, Ryosuke Fukai, Zheng Xiaoxia, Fuminori Ohsawa, Takeshi Bamba, Kazumasa Hirata, Akihiro Tai

Bioorganic & medicinal chemistry letters 20 ( 6 ) 1840 - 1843 2010年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Only a few COX-1-selective inhibitors are currently available, and the research on COX-1 selective inhibitors is not fully developed. The authors have produced several COX-1 selective inhibitors including N-(5-amino-2-pyridinyl)-4-trifluoromethylbenzamide: TFAP (3). Although 3 shows potent analgesic effect without gastric damage, the urine after administration of 3 becomes red-purple. Since the colored-urine should be avoided for clinical use, in this research we examined the cause of the colored-urine. UV-vis spectra and LC-MS/MS analyses of urine samples and metabolite candidates of 3 were performed to afford information that the main reason of the colored urine is a diaminopyridine (4), produced by metabolization of 3. This information is useful to design new COX-1 selective inhibitors without colored urine based on the chemical structure of 3. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2010.01.161

Effect of 5-aminosalicylate on allergic rhinitis model in mice 査読

Shoji Kuyama, Atsuki Yamamoto, Mayu Sugiyama, Hiroki Kakuta, Yukio Sugimoto

International immunopharmacology 10 ( 6 ) 713 - 716 2010年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Previous studies have shown that peroxisome proliferator-activated receptor gamma (PPAR gamma) is involved in allergic rhinitis. It has been reported that 5-aminosalicylate (5-ASA) has an affinity for PPAR gamma, but the effects of 5-ASA on the nasal symptoms of allergic rhinitis are unclear. This study aimed to clarify the effects of 5-ASA on nasal symptoms in an allergic rhinitis model in mice. Female BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) and aluminium hydroxide hydrate gel (alum) on days 0, 5, 14 and 21. Seven days later, mice were sensitized by the intranasal application of OVA thrice a week. 5-ASA was also administered orally after instillation of the antigen from day 28. The severity of allergic rhinitis was assessed by determining the extent of 2 nasal allergic symptoms-sneezing and nasal rubbing. In addition, serum OVA-specific immunoglobulin E (IgE) antibody, interleukin (IL)-4, and IL-10 levels in nasal lavage fluid and histamine sensitivity were determined. Repeated oral administration of 5-ASA attenuated the progression of nasal symptoms in sensitized mice in a dose-dependent manner. Additionally, 5-ASA prevented an increase in histamine sensitivity. Finally, 5-ASA inhibited both OVA-specific IgE antibody and IL-4 production; however, it had no effect on IL-10 levels. These results indicate that 5-ASA has a prophylactic effect on allergic rhinitis. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.intimp.2010.03.007

Modification at the acidic domain of RXR agonists has little effect on permissive RXR-heterodimer activation 査読

Shuji Fujii, Fuminori Ohsawa, Shoya Yamada, Ryosuke Shinozaki, Ryosuke Fukai, Makoto Makishima, Shuichi Enomoto, Akihiro Tai, Hiroki Kakuta

Bioorganic & medicinal chemistry letters 20 ( 17 ) 5139 - 5142 2010年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Retinoid X receptors (RXRs) function as homo-or heterodimers with other nuclear receptors, such as peroxisome proliferator-activated receptors (PPARs), which are targets for treatment of hyperlipidemia and type 2 diabetes, or liver X receptors (LXRs), which are involved in glucose/lipid metabolism. PPAR/RXR or LXR/RXR are known as permissive RXR-heterodimers because they are activated by RXR agonists alone. Interestingly, the pattern of RXR-heterodimer activation is different depending on the RXR agonist structure, but the structure-activity relationship has not been reported. Here we show that modification or replacement of the carboxyl group in the acidic domain of RXR agonists has little or no effect on permissive RXR-heterodimer activation. Phosphonic acid (9), tetrazole (10), and hydroxamic acid (12) analogues were synthesized from the common bromo intermediate 7. Except for 9, these compounds showed RXR full-agonistic activities in the concentration range of 1-10 mu M. The order of agonistic activity toward both PPAR gamma/RXR alpha and LXR alpha/RXR alpha was the same as it was for RXR, that is, 11 > 10 > 12. These results should be useful for the development of RXR agonists with improved bioavailability. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2010.07.012

Replacing alkyl sulfonamide with aromatic sulfonamide in sulfonamide-type RXR agonists favors switch towards antagonist activity 査読

Ken-ichi Morishita, Nobumasa Yakushiji, Fuminori Ohsawa, Kayo Takamatsu, Nobuyasu Matsuura, Makoto Makishima, Masatoshi Kawahata, Kentaro Yamaguchi, Akihiro Tai, Kenji Sasaki, Hiroki Kakuta

Bioorganic & medicinal chemistry letters 19 ( 3 ) 1001 - 1003 2009年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Retinoid X receptor (RXR) ligands are attractive candidates for clinical application because of their activity against tamoxifen-resistant breast cancer, taxol-resistant lung cancer, metabolic syndrome, and allergy. Though several RXR ligands, especially RXR antagonists, have been reported, the rational molecular design of such compounds is not well advanced. 4-[N-Methanesulfonyl-N-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl) amino] nicotinic acid (5a) is a moderately RXR alpha-preferential agonist, and we examined the feasibility of replacing the methyl group on the sulfonamide with a longer alkyl chain or an aromatic ring as an approach to produce new RXR antagonists. Several of the resulting benzenesulfonanilide-type compounds showed RXR antagonist activity. This design strategy should be a useful approach for addressing the lack of structure diversity of RXR antagonists. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2008.11.086

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation 査読

Xiaoxia Zheng, Hiroyuki Oda, Shun Harada, Yukio Sugimoto, Akihiro Tai, Kenji Sasaki, Hiroki Kakuta

Journal of pharmaceutical sciences 97 ( 12 ) 5446 - 5452 2008年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JOHN WILEY & SONS INC

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4'-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the C(max) value (1.2 mu M) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC(50) value (3.2 mu M). On the other hand, ZXX2-79 (4b) (SO(2)NH derivative of ZXX2-77 (4a); 4-amino-4'-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC(50) = 12 mu M, COX-2 IC(50) = 150 mu M) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (C(max) - 16 mu M at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage. (C) 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5446-5452, 2008

DOI： 10.1002/jps.21388

Design and synthesis of benzenesulfonanilides active against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus 査読

Kensuke Namba, Xiaoxia Zheng, Kazunori Motoshima, Hidetomo Kobayashi, Akihiro Tai, Eizo Takahashi, Kenji Sasaki, Keinosuke Okamoto, Hiroki Kakuta

Bioorganic & medicinal chemistry 16 ( 11 ) 6131 - 6144 2008年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Vancomycin is mainly used as an antibacterial agent of last resort, but recently vancomycin-resistant bacterial strains have been emerging. Although new antimicrobials have been developed in order to overcome drug-resistant bacteria, many are structurally complex beta-lactams or quinolones. In this study, we aimed to create new anti-drug-resistance antibacterials which can be synthesized in a few steps from inexpensive starting materials. Since sulfa drugs function as p-aminobenzoic acid mimics and inhibit dihydropteroate synthase (DHPS) in the folate pathway, we hypothesized that sulfa derivatives would act as folate metabolite-mimics and inhibit bacterial folate metabolism. Screening of our sulfonanilide libraries, including benzenesulfonanilide-type cyclooxygenase-1-selective inhibitors, led us to discover benzenesulfonanilides with potent anti-methicillin-resistant Staphylococcus aureus (MRSA)/vancomycin-resistant Enterococcus (VRE) activity, that is, N-3,5-bis(trifluoromethyl) phenyl-3,5-dichlorobenzenesulfonanilide (16b) [MIC = 0.5 mu g/mL (MRSA), 1.0 mu g/mL (VRE)], and 3,5-bis(trifluoromethyl)-N-(3,5-dichlorophenyl) benzenesulfonanilide (16c) [MIC = 0.5 mu g/mL (MRSA), 1.0 mu g/mL (VRE)]. These compounds are more active than vancomycin [MIC = 2.0 mu g/mL (MRSA), 125 mu g/mL (VRE)], but do not possess an amino group, which is essential for DHPS inhibition by sulfa drugs. These results suggested that the mechanism of antibacterial action of compounds 16b and 16c is different from that of sulfa drugs. We also confirmed the activity of these compounds against clinical isolates of Gram-positive bacteria. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmc.2008.04.040

Reduction of lipophilicity at the lipophilic domain of RXR agonists enables production of subtype-preference: RXRα-preferential agonist possessing a sulfonamide moiety 査読

Kayo Takamatsu, Atsushi Takano, Nobumasa Yakushiji, Ken-ichi Morishita, Nobuyasu Matsuura, Makoto Makishima, Hamed Ismail Ali, Eiichi Akaho, Akihiro Tai, Kenji Sasaki, Hiroki Kakuta

ChemMedChem 3 ( 3 ) 454 - 460 2008年

Cyclooxygenase-1-selective inhibitors are attractive candidates for analgesics that do not cause gastric damage. design and in vitro/in vivo evaluation of a benzamide-type cyclooxygenase-1 selective inhibitor 査読

Hiroki Kakuta, Xiaoxia Zheng, Hiroyuki Oda, Shun Harada, Yukio Sugimoto, Kenji Sasaki, Akihiro Tai

Journal of medicinal chemistry 51 ( 8 ) 2400 - 2411 2008年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Although cyclooxygenase-1 (COX-1) inhibition is thought to be a major mechanism of gastric damage by nonsteroidal anti-inflammatory drugs (NSAIDs), some COX-1-selective inhibitors exhibit strong analgesic effects without causing gastric damage. However, it is not clear whether their analgesic effects are attributable to COX-1-inhibitory activity or other bioactivities. Here, we report that N-(5-amino-2-pyridinyl)-4(trifluoromethyl)benzamide (18f, TFAP), which has a structure clearly different from those of currently available COX-1-selective inhibitors, is a potent COX-1-selective inhibitor (COX-1IC(50) = 0.80 +/- 0.05 mu M, COX-2IC(50) = 210 I mu M). This compound causes little gastric damage in rats even at an oral dose of 300 mg/kg, though it has an analgesic effect at as low a dose as 10 mg/kg. Our results show that COX-1-selective inhibitors can be analgesic agents without causing gastric damage.

DOI： 10.1021/jm701191z

The first potent subtype-selective retinoid X receptor (RXR) agonist possessing a 3-isopropoxy-4-isopropylphenylamino moiety, NEt-3IP (RXRalpha/beta-dual agonist) 査読

Kayo Takamatsu, Atsushi Takano, Nobumasa Yakushiji, Kazunori Morohashi, Ken-ichi Morishita, Nobuyasu Matsuura, Makoto Makishima, Akihiro Tai, Kenji Sasaki, Hiroki Kakuta

ChemMedChem 3 ( 5 ) 780 - 787 2008年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

Retinoid X receptor (RXR) agonists (rexinoids) ore attracting much attention for their use in treatment of cancers, including tomoxifen-resistant breast cancer and toxol-resistant lung cancer, and metabolic disease. However, known RXR agonists have a highly lipophilic character. In addition, no subtype-selective RXR agonists have been found. We previously reported on RXR alpha-preferential agonist 4-[N-methanesulfonyl-N-(5,5,8,8-tetromethyl-5,6,7,8tetrahydro-2-naphthyl)amino]benzoic acid (6a). The RXR agonistic activity is much less than that of well-known RXR agonists. To develop potent, less-lipophilic, and subtype-selective RXR agonists, we created new RXR agonists possessing alkoxy and isopropyl groups as a lipophilic domain of the common structure of well-known RXR agonists. As a result, compounds possessing branched alkoxy groups, 6-[N-ethyl-N-(3-isopropoxy-4-isopropylphenyl)amino]nicotinic acid (NEt-3IP: 7a) and 6-[N-ethyl-N-(3-isobutoxy-4-isopropylphenyl)amino]nicotinic acid (NEt-3IB: 7c), showed RXR agonistic activity as potent as, or more potent than, the activities of representative RXR agonists. Moreover NEt-3IP (7a) was found to be the first RXR alpha/beta-selective (or RXR alpha/beta-dual) agonist. Being potent, less lipophilic, and having RXR subtype-selective activity, NEt-3IP (7a) is expected to become a new drug candidate and to be a useful biological toot for clarifying each RXR subtype function.

DOI： 10.1002/cmdc.200700313

Pyridinium cationic-dimer antimalarials, unlike chloroquine, act selectively between the schizont stage and the ring stage of Plasmodium falciparum 査読

Mai Yoshikawa, Kazunori Motoshima, Kanji Fujimoto, Akihiro Tai, Hiroki Kakuta, Kenji Sasaki

Bioorganic & medicinal chemistry 16 ( 11 ) 6027 - 6033 2008年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Malaria is a leading cause of death in developing countries, and the emergence of strains resistant to the main therapeutic agent, chloroquine, has become a serious problem. We have developed cationic-dimer type antimalarials, MAP-610 and PMAP-H10, which are structurally different from chloroquine. In this study, we introduced several substituents on the terminal phenyl rings of PMAP-H10. The electronic and hydrophobic properties of the substituents were correlated with the antimalarial activity and cytotoxicity of the compounds, respectively. Studies with synchronized cultures of malarial plasmodia showed that our cationic-dimers act selectively between the schizont stage and the ring stage of the parasitic cycle, unlike chloroquine, which has a stage-independent action. Thus, the mechanism of action of our antimalarials appears to be different from that of chloroquine, and our compounds may be effective against chloroquine-resistant strains. (C) 2008 Published by Elsevier Ltd.

DOI： 10.1016/j.bmc.2008.04.051

Necessity is the mother of invention: an ingenious method for leukocyte-targeted delivery of siRNA in stabilized nanoparticles demonstrates a role of cyclin D1 in inflammation

Hiroki Kakuta

ChemMedChem 2008年

Necessity is the mother of invention: An ingenious method for leukocyte-targeted delivery of siRNA in stabilized nanoparticles demonstrates a role of cyclin D1 in inflammation

Kakuta, H.

ChemMedChem 3 ( 7 ) 2008年

Analgesic agents without gastric damage: Design and synthesis of structurally simple benzenesulfonanilide-type cyclooxygenase-1-selective inhibitors (vol 15, pg 1014, 2007) 査読

Xiaoxia Zheng, Hiroyuki Oda, Kayo Takamatsu, Yukio Sugimoto, Akihiro Tai, Eiichi Akaho, Hamed Ismail Ali, Toshiyuki Oshiki, Hiroki Kakuta, Kenji Sasaki

BIOORGANIC & MEDICINAL CHEMISTRY 15 ( 9 ) 3299 - 3300 2007年5月

Antimalarial cation-dimers synthesized in two steps from an inexpensive starting material, isonicotinic acid 査読

Kazunori Motoshima, Yoshiko Hiwasa, Mai Yoshikawa, Kanji Fujimoto, Akihiro Tai, Hiroki Kakuta, Kenji Sasaki

ChemMedChem 2 ( 10 ) 1527 - 1532 2007年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

Malaria is one of the three major serious infectious diseases in the world. As the area affected by malaria includes a large proportion of developing countries, there is a need for new antimalarials that can be synthesized and supplied inexpensively. To generate low-cost antimalarials, the MAP series 6-10, bis-cation dimers, synthesized by amidating the carboxyl group of isonicotinic acid (11) with various amines and by cationizing the nitrogen atoms of the pyridine ring with the corresponding alkyl bromides, were designed. This design enabled expansion of the structural variations of bis-cation-type antimalarial compounds. The compounds bearing alkyl or phenyl groups in the amide moieties showed remarkable antimalarial activities in vitro. Moreover, 1, 1'-(1, 12-dodecanediyl)bis[4-[(buthylamino)carbonyl]pyridinium bromide], MAP-412 (6d), exhibited a potent antimalarial activity (ED50 = 8.2 mg kg-(1)). Being prepared at low cost our biscation-type antimalarial compounds may be useful as lead compounds for inexpensive antimalarials.

DOI： 10.1002/cmdc.200700107

Analgesic agents without gastric damage: design and synthesis of structurally simple benzenesulfonanilide-type cyclooxygenase-1-selective inhibitors 査読

Xiaoxia Zheng, Hiroyuki Oda, Kayo Takamatsu, Yukio Sugimoto, Akihiro Tai, Eiichi Akaho, Hamed Ismail Ali, Toshiyuki Oshiki, Hiroki Kakuta, Kenji Sasaki

Bioorganic & medicinal chemistry 15 ( 2 ) 1014 - 1021 2007年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

In order to create novel analgesic agents without gastric disturbance, structurally simple cyclooxygenase-1 (COX-1) inhibitors with a benzenesulfonanilide skeleton were designed and synthesized. As a result, compounds 11f and 15a, which possess a p-amino group on the benzenesulfonyl moiety and p-chloro group on the anilino moiety, showed COX-1-selective inhibition. Moreover compound 11f, which is the most potent compound in this study showed more potent analgesic activity than that of aspirin at 30 mg/kg by po. The anti-inflammatory activity and gastric damage, however, were very weak or not detectably different from aspirin. Since the structure of our COX-1 inhibitors are very simple, they may be useful as lead compounds for superior COX-1 inhibitors as analgesic agents without gastric disturbance. (c) 2006 Published by Elsevier Ltd.

DOI： 10.1016/j.bmc.2006.10.029

Antimalarial effect of bis-pyridinium salts, N,N'-hexamethylenebis(4-carbamoyl-1-alkylpyridinium bromide) 査読

Kanji Fujimoto, Daiki Morisaki, Munehiro Yoshida, Tetsuto Namba, Kim Hye-Sook, Yusuke Wataya, Hiroki Kourai, Hiroki Kakuta, Kenji Sasaki

Bioorganic & medicinal chemistry letters 16 ( 10 ) 2758 - 2760 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

The in vitro antimalarial activity of bis-pyridinium salts, N,N'-hexamethylenebis(4-carbamoyl-1-decylpyridinium bromide) and their derivatives, against the Plasmodium falciparum FCR-3 strain (ATCC 30932, chloroquine-sensitive) was evaluated. All test compounds exhibited antimalarial activity over a concentration range of 3.5 mu M to 10 nM. The chain length of the N1-alkyl moiety was found to be very beneficial in terms of antimalarial activity, and in this series of compounds, the most appropriate N1-alkyl chain length was found to be eight. (C) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2006.02.030

Membrane permeabilization by non-steroidal anti-inflammatory drugs 査読

Tomisato W, Tanaka K, Katsu T, Kakuta H, Sasaki K, Tsutsumi S, Hoshino T, Aburaya M, Li D, Tsuchiya T, Suzuki K, Yokomizo K, Mizushima T.

Biochemical and biophysical research communications 323 ( 3 ) 1032 - 1039 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

The cytotoxicity of non-steroidal anti-inflammatory drugs (NSAIDs) is involved in the formation of NSAID-induced gastric lesions. The mechanism(s) behind these cytotoxic effects, however, is not well understood. We found here that several NSAIDs tested caused hemolysis when employed at concentrations similar to those that result in cytotoxicity. Moreover, these same NSAIDs were found to directly permeabilize the membranes of calcein-loaded liposomes. Given the similarity in NSAID concentrations for cytotoxic and membrane permeabilization effects, the cytotoxic action of these NSAIDs may be mediated through the permeabilization of biological membranes. Increase in the intracellular Ca2+ level can lead to cell death. We here found that all of NSAIDs tested increased the intracellular Ca2+ level at concentrations similar to those that result in cytotoxicity. Based on these results, we consider a possibility that membrane permeabilization by NSAIDs induces cell death through increase in the intracellular Ca2+ level. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2004.08.205

Specific nonpeptide inhibitors of puromycin-sensitive aminopeptidase with a 2,4(1H,3H)-quinazolinedione skeleton 査読

Hiroki Kakuta, Aya Tanatani, Kazuo Nagasawa, Yuichi Hashimoto

Chemical & pharmaceutical bulletin 51 ( 11 ) 1273 - 1282 2003年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PHARMACEUTICAL SOC JAPAN

Potent, specific, chemically stable and non-peptide/small-molecular inhibitors of puromycin-sensitive aminopeptidase, such as 3-(2,6-diethylphenyl)-2,4(1H,3H)-quinazolinedione (PAQ-22, 5), were prepared by the structural development of a potent PSA inhibitor, 2-(2,6-diethylphenyl)-1,2,3,4-tetrahydroisoquinoline-1,3-dione (PIQ-22, 4). The design was carried out partly by applying electrostatic potential field information obtained from PIQ-22 (4) and its derivatives based on thalidomide (2). This information revealed that a positive electrostatic potential field around the benzylic methylene in the tetrahydroisoquinoline ring is necessary for potent activity. Lineweaver-Burk plot analysis showed that PAQ-22 (5) and its derivatives inhibit puromycin-sensitive aminopeptidase (PSA) in a non-competitive manner. These potent and specific PSA inhibitors showed dose-dependent cell invasion-inhibitory activity in a Matrigel assay using mouse melanoma B16F10/L5 cells, in spite of their low cell toxicity.

DOI： 10.1248/cpb.51.1273

Cyclooxygenase inhibitors derived from thalidomide 査読

Mamiko Suizu, Yohei Muroya, Hiroki Kakuta, Hiroyuki Kagechika, Aya Tanatani, Kazuo Nagasawa, Yuichi Hashimoto

Chemical & pharmaceutical bulletin 51 ( 9 ) 1098 - 1102 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PHARMACEUTICAL SOC JAPAN

Several N-3,5-dimethylphenylphthalimide analogs possessing more potent cyclooxygenase-inhibiting activity than that of aspirin were prepared during structural development studies based on thalidomide. Substituent effects on the activity were investigated.

DOI： 10.1248/cpb.51.1098

Fluorescent bioprobes for visualization of puromycin-sensitive aminopeptidase in living cells 査読

Hiroki Kakuta, Yukiko Koiso, Kazuo Nagasawa, Yuichi Hashimoto

Bioorganic & medicinal chemistry letters 13 ( 1 ) 83 - 86 2003年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Non-peptide, small-molecular, non-competitive inhibitors of puromycin-sensitive aminopeptidase (PSA), that is, 3-(2,6-diethylphenyl)-2,4(1H,3 H)-quinazolinedione (PAQ-22, 3) and its 1N-methyl analogue (MPAQ-22 4), were structurally modified to afford fluorescent bioprobes, ANTAQ (5) and DAMPAQ-22 (6). The cellular localization of PSA could be visualized by the use of these fluorescent bioprobes. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/s0960-894x(02)00845-4

DOI： 10.1016/S0960-894X(02)00845-4

Specific inhibitor of puromycin-sensitive aminopeptidase with a homophthalimide skeleton: Identification of the target molecule and a structure-activity relationship study 査読

M Komoda, H Kakuta, H Takahashi, Y Fujimoto, S Kadoya, F Kato, Y Hashimoto

BIOORGANIC & MEDICINAL CHEMISTRY 9 ( 1 ) 121 - 131 2001年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

2-(2,6-Diethylphenyl)-1,2,3,4-tetrahydroisoquinoline-1,3-dione (2: PIQ-22) was found to be a potent and specific inhibitor of puromycin-sensitive aminopeptidase (PSA). Lineweaver-Burk plot analysis showed that PSA is inhibited by PIQ-22 in a non-competitive manner. Structure-activity relationship studies indicated that tautomerism of the imidobenzoylketone group in the cyclic imide moiety of the PIQ-22 skeleton is important for the inhibitory activity. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0968-0896(00)00231-5

Novel Specific Puromycin-sensitive Aminopeptidase Inhibitors: 3-(2,6-Diethylphenyl)-2,4(1H,3H)quinazolinedione and N-(2,6-Diethylphenyl)-2-amino-4H-3,1-benzoxazin-4-one 査読

Hiroki Kakuta, Yukiko Koiso, Hiroyasu Takahashi, Kazuo Nagasawa, and Yuichi Hashimoto

HETEROCYCLES 55 ( 8 ) 1433 - 1438 2001年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japan Institute of Heterocyclic Chemistry

Novel specific PSA (puromycin-sensitive aminopeptidase) inhibitors, 3-(2,6-diethylphenyl)-2,4(1H, 3H)-quinazolinedione (3: PAQ-22) and N-(2,6-diethylphenyl)-2-amino-4H-3,1-benzoxazin-4-one (4: PAZOX-22), were designed and synthesized. These compounds are chemically much more stable than the known specific PSA inhibitor PIQ-22 (2), and the enzyme specificity and inhibitory activity to PSA are similar to those of 2. The inhibitory manner of these compounds was found to be a non-competitive mode by Lineweaver- Burk plot analysis.

DOI： 10.3987/com-01-9247

Aromatic layered guanidines bind sequence-specifically to DNA minor groove with precise fit 査読

Ryuuta Fukutomi, Aya Tanatani, Hiroki Kakuta, Nobuo Tomioka, Akiko Itai, Yuichi Hashimoto, Koichi Shudo, Hiroyuki Kagechika

Tetrahedron Letters 39 ( 36 ) 6475 - 6478 1998年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier Ltd

Tetraguanidines (1 and 2) with an aromatic multilayered structure exhibit potent binding to a specific site of DNAS with binding constants of the order of 107 M-1 as deduced from Scatchard analysis of ultrafiltration data and simulation of CD titration curves. NMR spectra of the complexes indicated that 1 and 2 bind DNAs sequence-specifically at the minor groove, as predicted by computational docking studies.

DOI： 10.1016/s0040-4039(98)01378-1

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