Faculty Profiles - Otsuka Motoyuki

Papers - Otsuka Motoyuki

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Roles of circular RNAs in the pathogenesis and treatment of pancreatic cancer. Reviewed International journal

Takahiro Seimiya, Motoyuki Otsuka, Mitsuhiro Fujishiro

Frontiers in cell and developmental biology 10 1023332 - 1023332 2022

Language：English Publishing type：Research paper (scientific journal)

Circular RNAs are single-stranded RNAs with a covalently closed structure formed by the process of back-splicing. Aberrant expression of circular RNAs contributes to the pathogenesis of a wide range of cancers. Pancreatic cancer is one of the most lethal cancers due to diagnostic difficulties and limited therapeutic options. Circular RNAs are emerging as novel diagnostic biomarkers and therapeutic targets for pancreatic cancer. Moreover, recent advances in the therapeutic application of engineered circular RNAs have provided a promising approach to overcoming pancreatic cancer. This review discusses the roles of circular RNAs in the pathogenesis of pancreatic cancer and in potential treatment applications and their usefulness as diagnostic biomarkers.

DOI： 10.3389/fcell.2022.1023332

Evidence-based clinical practice guidelines for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis 2020. International journal

Motoyuki Otsuka

Hepatology research : the official journal of the Japan Society of Hepatology 51 ( 10 ) 1013 - 1025 2021.9

Language：English Publishing type：Research paper (scientific journal)

Nonalcoholic fatty liver disease (NAFLD) has become a serious public health issue not only in Western countries but also in Japan. Within the wide spectrum of NAFLD, nonalcoholic steatohepatitis (NASH) is a progressive form of disease that often develops into liver cirrhosis and increases the risk of hepatocellular carcinoma (HCC). While a definite diagnosis of NASH requires liver biopsy to confirm the presence of hepatocyte ballooning, hepatic fibrosis is the most important prognostic factor in NAFLD. With so many NAFLD patients, it is essential to have an effective screening method for NAFLD with hepatic fibrosis. As HCC with non-viral liver disease has increased markedly in Japan, effective screening and surveillance of HCC are also urgently needed. The most common death etiology in NAFLD patients is cardiovascular disease event. Gastroenterologists must, therefore, pay close attention to CVD when examining NAFLD patients. In the updated guidelines, we propose screening and follow-up methods for hepatic fibrosis, HCC, and CVD in NAFLD patients. Several drug trials are ongoing for NAFLD/NASH therapy, however, there is currently no specific drug therapy for NAFLD/NASH. In addition to vitamin E and thiazolidinedione derivatives, recent trials have focused on sodium glucose co-transporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) analogues, and effective therapies are expected to be developed. These practical guidelines for NAFLD/NASH were established by the Japanese Society of Gastroenterology in conjunction with the Japan Society of Hepatology. Clinical evidence reported internationally between 1983 and October 2018 was collected, and each clinical and background question was evaluated using the Grades of Recommendation Assessment, Development and Evaluation (GRADE) system. This English summary pro- vides the core essentials of these clinical practice guidelines, which include the definition and concept, screening systems for hepatic fibrosis, HCC and CVD, and current therapies for NAFLD/NASH in Japan.

DOI： 10.1111/hepr.13688

Evidence-based clinical practice guidelines for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis 2020.

Motoyuki Otsuka

Journal of gastroenterology 56 ( 11 ) 951 - 963 2021.9

Language：English Publishing type：Research paper (scientific journal)

Nonalcoholic fatty liver disease (NAFLD) has become a serious public health issue not only in Western countries but also in Japan. Within the wide spectrum of NAFLD, nonalcoholic steatohepatitis (NASH) is a progressive form of disease that often develops into liver cirrhosis and increases the risk of hepatocellular carcinoma (HCC). While a definite diagnosis of NASH requires liver biopsy to confirm the presence of hepatocyte ballooning, hepatic fibrosis is the most important prognostic factor in NAFLD. With so many NAFLD patients, it is essential to have an effective screening method for NAFLD with hepatic fibrosis. As HCC with non-viral liver disease has increased markedly in Japan, effective screening and surveillance of HCC are also urgently needed. The most common death etiology in NAFLD patients is cardiovascular disease (CVD) event. Gastroenterologists must, therefore, pay close attention to CVD when examining NAFLD patients. In the updated guidelines, we propose screening and follow-up methods for hepatic fibrosis, HCC, and CVD in NAFLD patients. Several drug trials are ongoing for NAFLD/NASH therapy, however, there is currently no specific drug therapy for NAFLD/NASH. In addition to vitamin E and thiazolidinedione derivatives, recent trials have focused on sodium glucose co-transporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) analogues, and effective therapies are expected to be developed. These practical guidelines for NAFLD/NASH were established by the Japanese Society of Gastroenterology in conjunction with the Japan Society of Hepatology. Clinical evidence reported internationally between 1983 and October 2018 was collected, and each clinical and background question was evaluated using the Grades of Recommendation Assessment, Development and Evaluation (GRADE) system. This English summary provides the core essentials of these clinical practice guidelines, which include the definition and concept, screening systems for hepatic fibrosis, HCC and CVD, and current therapies for NAFLD/NASH in Japan.

DOI： 10.1007/s00535-021-01796-x

Humanized virus-suppressing factor inhibits hepatitis B virus infection by targeting viral cell entry. Reviewed International journal

Yu Miyakawa, Motoyuki Otsuka, Kazuma Sekiba, Kazuyoshi Funato, Kazuhiko Koike

Heliyon 7 ( 7 ) e07586 2021.7

Language：English Publishing type：Research paper (scientific journal)

Although nucleos(t)ide analogs and interferons suppress hepatitis B virus (HBV) replication, they must be taken continuously and have a low response rate. Therefore, therapeutics for HBV with novel modes of action are needed. Humanized virus-suppressing factor (hzVSF) is a monoclonal antibody against vimentin that exhibits broad-spectrum antiviral activity. Here, hzVSF significantly inhibited HBV infection. Although hzVSF inhibited HBV RNA production, it did not affect viral transcription from minicircle DNA mimicking covalently closed circular DNA. Additionally, hzVSF did not inhibit viral protein or DNA release from infected cells. Rather, hzVSF inhibited the cell entry of viral preS1 peptides, possibly by altering intracellular vimentin localization, which is important for HBV cell entry. These results suggest that hzVSF has therapeutic potential for HBV infection with a novel mode of action.

DOI： 10.1016/j.heliyon.2021.e07586

Potential of HBx Gene for Hepatocarcinogenesis in Noncirrhotic Liver. Reviewed International journal

Kazuma Sekiba, Motoyuki Otsuka, Kazuhiko Koike

Seminars in liver disease 41 ( 2 ) 142 - 149 2021.5

Language：English Publishing type：Research paper (scientific journal)

Current treatments for hepatitis B virus (HBV) using nucleos(t)ide analogs cannot eliminate the risk of hepatocellular carcinoma (HCC) development. As HBV-associated HCC can develop even in the absence of liver cirrhosis, HBV is regarded to possess direct oncogenic potential. HBV regulatory protein X (HBx) has been identified as a primary mediator of HBV-mediated hepatocarcinogenesis. A fragment of the HBV genome that contains the coding region of HBx is commonly integrated into the host genome, resulting in the production of aberrant proteins and subsequent hepatocarcinogenesis. Besides, HBx interferes with the host DNA or deoxyribonucleic acid damage repair pathways, signal transduction, epigenetic regulation of gene expression, and cancer immunity, thereby promoting carcinogenesis in the noncirrhotic liver. However, numerous molecules and pathways have been implicated in the development of HBx-associated HCC, suggesting that the mechanisms underlying HBx-mediated hepatocarcinogenesis remain to be elucidated.

DOI： 10.1055/s-0041-1723033

Post-treatment cell-free DNA as a predictive biomarker in molecular-targeted therapy of hepatocellular carcinoma. Reviewed

Takuma Nakatsuka, Hayato Nakagawa, Yuki Hayata, Taijiro Wake, Tomoharu Yamada, Mizuki Nishibatake Kinoshita, Ryo Nakagomi, Masaya Sato, Tatsuya Minami, Koji Uchino, Kenichiro Enooku, Yotaro Kudo, Yasuo Tanaka, Takahiro Kishikawa, Motoyuki Otsuka, Ryosuke Tateishi, Kazuhiko Koike

Journal of gastroenterology 56 ( 5 ) 456 - 469 2021.5

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Liquid biopsies, particularly those involving circulating tumor DNA (ctDNA), are rapidly emerging as a non-invasive alternative to tumor biopsies. However, clinical applications of ctDNA analysis in hepatocellular carcinoma (HCC) have not been fully elucidated. METHODS: We measured the amount of plasma-derived cell-free DNA (cfDNA) in HCC patients before (n = 100) and a few days after treatment (n = 87), including radiofrequency ablation, transarterial chemoembolization, and molecular-targeted agents (MTAs), and prospectively analyzed their associations with clinical parameters and prognosis. TERT promoter mutations in cfDNA were analyzed using droplet digital PCR. Furthermore, we performed a comprehensive mutational analysis of post-treatment cfDNA via targeted ultra-deep sequencing (22,000× coverage) in a panel of 275 cancer-related genes in selected patients. RESULTS: Plasma cfDNA levels increased significantly according to HCC clinical stage, and a high cfDNA level was independently associated with a poor prognosis. TERT promoter mutations were detected in 45% of all cases but were not associated with any clinical characteristics. cfDNA levels increased significantly a few days after treatment, and a greater increase in post-treatment cfDNA levels was associated with a greater therapeutic response to MTAs. The detection rate of TERT mutations increased to 57% using post-treatment cfDNA, suggesting that the ctDNA was enriched. Targeted ultra-deep sequencing using post-treatment cfDNA after administering lenvatinib successfully detected various gene mutations and obtained promising results in lenvatinib-responsive cases. CONCLUSIONS: Post-treatment cfDNA analysis may facilitate the construction of biomarkers for predicting MTA treatment effects.

DOI： 10.1007/s00535-021-01773-4

Mutant KRAS drives metabolic reprogramming and autophagic flux in premalignant pancreatic cells. Reviewed International journal

Tatsunori Suzuki, Takahiro Kishikawa, Tatsuyuki Sato, Norihiko Takeda, Yuki Sugiura, Takahiro Seimiya, Kazuma Sekiba, Motoko Ohno, Takuma Iwata, Rei Ishibashi, Motoyuki Otsuka, Kazuhiko Koike

Cancer gene therapy 29 ( 5 ) 505 - 518 2021.4

Language：English Publishing type：Research paper (scientific journal)

Mutational activation of the KRAS gene occurs in almost all pancreatic ductal adenocarcinoma (PDAC) and is the earliest molecular event in their carcinogenesis. Evidence has accumulated of the metabolic reprogramming in PDAC, such as amino acid homeostasis and autophagic flux. However, the biological effects of KRAS mutation on metabolic reprogramming at the earlier stages of PDAC carcinogenesis are unclear. Here we report dynamic metabolic reprogramming in immortalized human non-cancerous pancreatic ductal epithelial cells, in which a KRAS mutation was induced by gene-editing, which may mimic early pancreatic carcinogenesis. Similar to the cases of PDAC, KRAS gene mutation increased the dependency on glucose and glutamine for maintaining the intracellular redox balance. In addition, the intracellular levels of amino acids were significantly decreased because of active protein synthesis, and the cells required greater autophagic flux to maintain their viability. The lysosomal inhibitor chloroquine significantly inhibited cell proliferation. Therefore, metabolic reprogramming is an early event in carcinogenesis initiated by KRAS gene mutation, suggesting a rationale for the development of nutritional interventions that suppress or delay the development of PDAC.

DOI： 10.1038/s41417-021-00326-4

The biological role of metabolic reprogramming in pancreatic cancer International journal

Tatsunori Suzuki, Motoyuki Otsuka, Takahiro Seimiya, Takuma Iwata, Takahiro Kishikawa, Kazuhiko Koike

MedComm 1 ( 3 ) 302 - 310 2020.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease and highly resistant to all forms of therapy. PDAC cells reprogram their metabolism extensively to promote their survival and growth. Reflecting the vital role of altered metabolism, experimental and clinical trials targeting the rewired metabolism are currently underway. In this review, we summarize the vital role of metabolic reprogramming in the development of PDAC and the future of novel therapeutic applications.

DOI： 10.1002/mco2.37

The fatty-acid amide hydrolase inhibitor URB597 inhibits MICA/B shedding. Reviewed International journal

Kazuma Sekiba, Motoyuki Otsuka, Takahiro Seimiya, Eri Tanaka, Kazuyoshi Funato, Yu Miyakawa, Kazuhiko Koike

Scientific reports 10 ( 1 ) 15556 - 15556 2020.9

Language：English Publishing type：Research paper (scientific journal)

MICA/B proteins are expressed on the surface of various types of stressed cells, including cancer cells. Cytotoxic lymphocytes expressing natural killer group 2D (NKG2D) receptor recognize MICA/B and eliminate the cells. However, cancer cells evade such immune recognition by inducing proteolytic shedding of MICA/B proteins. Therefore, preventing the shedding of MICA/B proteins could enhance antitumor immunity. Here, by screening a protease inhibitor library, we found that the fatty-acid amide hydrolase (FAAH) inhibitor, URB597, suppresses the shedding of MICA/B. URB597 significantly reduced the soluble MICA level in culture medium and increased the MICA level on the surface of cancer cells. The effect was indirect, being mediated by increased expression of tissue inhibitor of metalloproteinases 3 (TIMP3). Knockdown of TIMP3 expression reversed the effect of URB597, confirming that TIMP3 is required for the MICA shedding inhibition by URB597. In contrast, FAAH overexpression reduced TIMP3 expression and the cell-surface MICA level and increased the soluble MICA level. These results suggest that inhibition of FAAH could prevent human cancer cell evasion of immune-mediated clearance.

DOI： 10.1038/s41598-020-72688-y

Extracellular vesicles secreted by HBV-infected cells modulate HBV persistence in hydrodynamic HBV transfection mouse model. Reviewed International journal

Masatoshi Kakizaki, Yuichiro Yamamoto, Motoyuki Otsuka, Kouichi Kitamura, Masatoshi Ito, Hideki Derek Kawai, Masamichi Muramatsu, Tatehiro Kagawa, Ai Kotani

The Journal of biological chemistry 295 ( 35 ) 12449 - 12460 2020.8

Language：English Publishing type：Research paper (scientific journal)

Hepatitis B, a viral infection that affects the liver, is thought to affect over 257 million people worldwide, and long-term infection can lead to life-threatening issues such as cirrhosis or liver cancer. Chronic hepatitis B develops by the interaction between hepatitis B virus (HBV) and host immune response. However, questions of how HBV-infected cells thwart immune system defenses remain unanswered. Extracellular vesicles (EVs) are used for cellular communication, carrying cargoes such as RNAs, proteins, and lipids and delivering them intracellularly after being endocytosed by target cells. HBV-infected liver cells secrete several types of EVs into body fluids such as complete and incomplete virions, and exosomes. We previously demonstrated that monocytes that incorporated EVs moved to immunoregulatory phenotypes via up-regulation of PD-L1, an immunocheckpoint molecule, and down-regulation of CD69, a leukocyte activation molecule. In this study, we transfected mice with HBV using hydrodynamic injection and studied the effects of EVs secreted by HBV-infected liver cells. EVs secreted from cells with HBV replication strongly suppressed the immune response, inhibiting the eradication of HBV-replicating cells in the mice transfected with HBV. EVs were systemically incorporated in multiple organs, including liver, bone marrow (BM), and intestine. Intriguingly, the BM cells that incorporated EVs acquired intestinal tropism and the dendritic cell populations in the intestine increased. These findings suggest that the EVs secreted by HBV-infected liver cells exert immunosuppressive functions, and that an association between the liver, bone marrow, and intestinal tract exists through EVs secreted from HBV-infected cells.

DOI： 10.1074/jbc.RA120.014317

HBx increases EGFR expression by inhibiting miR129-5p function. Reviewed International journal

Masanori Ochi, Motoyuki Otsuka, Reo Maruyama, Kazuhiko Koike

Biochemical and biophysical research communications 529 ( 2 ) 198 - 203 2020.8

Language：English Publishing type：Research paper (scientific journal)

Despite the efficient suppression of hepatitis B virus (HBV) replication by nucelos(t)ide analogs, HBV RNA expression usually continues even during nucleots(t)ide analog therapy because episomal covalently closed circular DNA (ccDNA), which is the template for HBV RNA transcription, cannot be eliminated. Here, we found that the common sequences of all HBV RNAs and that encoding the X protein (HBx) have similarities with the sequences of a host cellular microRNA (miRNA), miR129-5p. HBx inhibits miR129-5p function, resulting in increased expression of ZBTB20, a target gene of miR129-5p. ZBTB20 activates transcription and increases cell-surface epidermal growth factor receptor (EGFR) levels, promoting the cell growth rate, and this effect was reversed through ZBTB20 knockdown. mir129-5p levels in Ago2-containing complexes were reduced by expression of HBx, suggesting that the viral RNA sequestered miR129-5p from Ago2-containing complexes. These results indicate the possibility that HBV RNA may maintain pathogenicity even through nucleos(t)ide analog therapy.

DOI： 10.1016/j.bbrc.2020.06.018

B型肝炎根治を目指した創薬研究宿主蛋白Smc5/6の発現回復によるHBV関連肝発癌制御の可能性

關場一磨, 大塚基之, 小池和彦

日本消化器病学会雑誌 117 ( 臨増総会 ) A93 - A93 2020.7

Emerging Roles of Exosomal Circular RNAs in Cancer. Reviewed International journal

Takahiro Seimiya, Motoyuki Otsuka, Takuma Iwata, Chikako Shibata, Eri Tanaka, Tatsunori Suzuki, Kazuhiko Koike

Frontiers in cell and developmental biology 8 568366 - 568366 2020

Language：English Publishing type：Research paper (scientific journal)

Circular RNA (circRNA) is a type of non-coding RNA that forms a covalently closed continuous loop. The expression pattern of circRNA varies among cell types and tissues, and many circRNAs are aberrantly expressed in various cancers. Aberrantly expressed circRNAs have been shown to play crucial roles in carcinogenesis, functioning as microRNA sponges or new templates for protein translation. Recent research has shown that circRNAs are enriched in exosomes. Exosomes are secretory vesicles that mediate intercellular communication through the delivery of cargo, including proteins, lipids, DNA, and RNA. Exosome-mediated crosstalk between cancer cells and the tumor microenvironment promotes the epithelial-mesenchymal transition, angiogenesis, and immune escape, and thus may contribute to cancer invasion and metastasis. In this review, we discuss the biological functions of exosomal circRNAs and their significance in cancer progression. Additionally, we discuss the potential clinical applications of exosomal circRNAs as biomarkers and in cancer therapy.

DOI： 10.3389/fcell.2020.568366

Deletion of Histone Methyltransferase G9a Suppresses Mutant Kras-driven Pancreatic Carcinogenesis

HIROYUKI KATO, KEISUKE TATEISHI, HIROAKI FUJIWARA, HIDEAKI IJICHI, KEISUKE YAMAMOTO, TAKUMA NAKATSUKA, MIWAKO KAKIUCHI, MAKOTO SANO, YOTARO KUDO, YOKU HAYAKAWA, HAYATO NAKAGAWA, YASUO TANAKA, MOTOYUKI OTSUKA, YOSHIHIRO HIRATA, MAKOTO TACHIBANA, YOICHI SHINKAI, KAZUHIKO KOIKE

Cancer Genomics - Proteomics 17 ( 6 ) 695 - 705 2020

Improved liver function in patients with cirrhosis due to chronic hepatitis C virus who achieve sustained virologic response is not accompanied by increased liver volume. Reviewed International journal

Taijiro Wake, Ryosuke Tateishi, Tsuyoshi Fukumoto, Ryo Nakagomi, Mizuki Nishibatake Kinoshita, Takuma Nakatsuka, Masaya Sato, Tatsuya Minami, Koji Uchino, Kenichiro Enooku, Hayato Nakagawa, Hidetaka Fujinaga, Yoshinari Asaoka, Yasuo Tanaka, Motoyuki Otsuka, Kazuhiko Koike

PloS one 15 ( 4 ) e0231836 2020

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Serum albumin level improves in patients with chronic hepatitis C virus (HCV) infection who achieve sustained virologic response (SVR) with antiviral therapy. However, it remains controversial whether liver volume increases along with SVR. METHODS: Patients with chronic HCV infection with a history of hepatocellular carcinoma (HCC) who achieved SVR with anti-HCV treatment from March 2003 to November 2017 were enrolled. Patients were followed up with periodic computed tomography (CT) scans to detect HCC recurrence. Patients who underwent treatment for HCC recurrence within 1 year after initiation of anti-HCV treatment were excluded. Laboratory data, including alanine aminotransferase (ALT) level, serum albumin level, and platelet count, were collected at baseline and timepoints after treatment initiation. Liver volume was evaluated at baseline and 24 and 48 weeks after treatment initiation using a CT volume analyzer. A linear mixed-effects model was applied to analyze the chronologic change in liver volume. The correlations between changes in ALT level, albumin level, and liver volume were also evaluated. RESULTS: Of 108 enrolled patients, 78 had cirrhosis. Serum albumin level continued to increase through 48 weeks after treatment initiation. A significant increase in liver volume was observed only in patients without cirrhosis (P = 0.005). There was a significant correlation between ALT level decrease and albumin level increase (P = 0.018). CONCLUSIONS: Improved liver albumin production with SVR was contributed by improved liver cell function rather than increased liver volume in patients with cirrhosis.

DOI： 10.1371/journal.pone.0231836

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System. Reviewed International journal

Kazuma Sekiba, Motoyuki Otsuka, Kazuhiko Koike

Journal of visualized experiments : JoVE ( 154 ) 2019.12

Language：English Publishing type：Research paper (scientific journal)

There is an urgent need for novel therapeutic agents for hepatitis B virus (HBV) infection. Although currently available nucleos(t)ide analogs potently inhibit viral replication, they have no direct effect on the expression of viral proteins transcribed from a viral covalently closed circular DNA (cccDNA). As high viral antigen load may play a role in this chronic and HBV-related carcinogenesis, the goal of HBV treatment is to eradicate viral proteins. HBV regulatory protein X (HBx) binds to the host DNA damage-binding protein 1 (DDB1) protein to degrade structural maintenance of chromosomes 5/6 (Smc5/6), resulting in activation of viral transcription from cccDNA. Here, using a split luciferase complementation assay system, we present a comprehensive compound screening system to identify inhibitors of the HBx-DDB1 interaction. Our protocol enables easy detection of interaction dynamics in real time within living cells. This technique may become a key assay to discover novel therapeutic agents for treatment of HBV infection.

DOI： 10.3791/60652

Detection of circulating colorectal cancer cells by a custom microfluid system before and after endoscopic metallic stent placement. Reviewed International journal

Rei Ishibashi, Shuntaro Yoshida, Nariaki Odawara, Takahiro Kishikawa, Ryo Kondo, Ayako Nakada, Ryunosuke Hakuta, Naminatsu Takahara, Eri Tanaka, Kazuma Sekiba, Takahiro Seimiya, Takashi Ohnaga, Motoyuki Otsuka, Kazuhiko Koike

Oncology letters 18 ( 6 ) 6397 - 6404 2019.12

Language：English Publishing type：Research paper (scientific journal)

Although the detection of circulating tumor cells (CTCs) should be crucial for future personalized medicine, no efficient and flexible methods have been established. The current study established a polymeric custom-made chip for capturing CTCs with a high efficiency and flexibility. As an example of clinical application, the effects of self-expandable metallic stent (SEMS) placement on the release of cancer cells into the blood of patients with colorectal cancer and bowel obstruction were analyzed. This was assessed as the placement of SEMS may cause mechanical damage and physical force to malignant tissue, increasing the risk of cancer cell release into the bloodstream. The present study examined the number of CTCs using a custom-made chip, before, at 24 h after and at 4 days after SEMS placement in patients with colorectal cancer. The results revealed that, among the 13 patients examined, the number of CTCs was increased in three cases at 24 h after SEMS placement. However, this increase was temporary. The number of CTCs also decreased at 4 days after stent placement in most cases. The CTC chip of the current study detected the number of CD133-positive cancer stem-like cells, which did not change, even in the patient whose total number of CTCs temporarily increased. The results indicated that this custom-made microfluid system can efficiently and flexibly detect CTCs, demonstrating its potential for obtaining information during the management of patients with cancer.

DOI： 10.3892/ol.2019.11047

Inhibition of HBV Transcription From cccDNA With Nitazoxanide by Targeting the HBx-DDB1 Interaction. Reviewed International journal

Kazuma Sekiba, Motoyuki Otsuka, Motoko Ohno, Mari Yamagami, Takahiro Kishikawa, Tatsunori Suzuki, Rei Ishibashi, Takahiro Seimiya, Eri Tanaka, Kazuhiko Koike

Cellular and molecular gastroenterology and hepatology 7 ( 2 ) 297 - 312 2019.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV}

BACKGROUND & AIMS: Hepatitis B virus (HBV) infection is a major health concern worldwide. Although currently used nucleos(t)ide analogs efficiently inhibit viral replication, viral proteins transcribed from the episomal viral covalently closed circular DNA (cccDNA) minichromosome continue to be expressed long-term. Because high viral RNA or antigen loads may play a biological role during this chronicity, the elimination of viral products is an ultimate goal of HBV treatment. HBV regulatory protein X (HBx) was recently found to promote transcription of cccDNA with degradation of Smc5/6 through the interaction of HBx with the host protein DDB1. Here, this protein-protein interaction was considered as a new molecular target of HBV treatment. METHODS: To identify candidate compounds that target the HBx-DDB1 interaction, a newly constructed split luciferase assay system was applied to comprehensive compound screening. The effects of the identified compounds on HBV transcription and cccDNA maintenance were determined using HBV minicircle DNA, which mimics HBV cccDNA, and the natural HBV infection model of human primary hepatocytes. RESULTS: We show that nitazoxanide (NTZ), a thiazolide anti-infective agent that has been approved by the FDA for protozoan enteritis, efficiently inhibits the HBx-DDB1 protein interaction. NTZ significantly restores Smc5 protein levels and suppresses viral transcription and viral protein production in the HBV minicircle system and in human primary hepatocytes naturally infected with HBV. CONCLUSIONS: These results indicate that NTZ, which targets an HBV-related viral-host protein interaction, may be a promising new therapeutic agent and a step toward a functional HBV cure.

DOI： 10.1016/j.jcmgh.2018.10.010

Expression of circular RNA CDR1‑AS in colon cancer cells increases cell surface PD‑L1 protein levels. Reviewed International journal

Eri Tanaka, Yu Miyakawa, Takahiro Kishikawa, Takahiro Seimiya, Takuma Iwata, Kazuyoshi Funato, Nariaki Odawara, Kazuma Sekiba, Mari Yamagami, Tatsunori Suzuki, Rei Ishibashi, Motoyuki Otsuka, Kazuhiko Koike

Oncology reports 42 ( 4 ) 1459 - 1466 2019.10

Language：English Publishing type：Research paper (scientific journal)

The expression of CDR1‑AS, a representative circular RNA, is closely linked with poor prognosis in gastrointestinal cancers, such as colon, liver, and pancreatic cancers. Although it is well known that CDR1‑AS antagonizes microRNA‑7 function through its sequence similarities in the brain, its biological function and link with the malignant potential of cancer cells remain unclear, partly due to the difficulties of ectopic expression of circular RNAs. In the present study, SW620, a colon cancer cell line that stably expresses CDR1‑AS RNA circularized, was established using the laccase 2 gene cassette, and its biological function associated with malignant behavior was determined. In contrast to previous studies, cell growth or invasion ability was not altered by CDR1‑AS expression. However, the expression levels of CMTM4 and CMTM6, which were recently recognized as critical regulators of PD‑L1 protein expression at the cell surface, were significantly increased. Accordingly, the cell surface PD‑L1 protein levels were increased in CDR1‑AS‑expressing cells. Notably, the effects were not canceled out by overexpressing microRNA‑7, indicating that the increase in cell surface PD‑L1 in CDR1‑AS‑expressing cells was not dependent on microRNA‑7 function. These results indicated that expression of this circular RNA in cancer cells may lead to poor prognosis by increasing cell surface PD‑L1 levels through microRNA‑7‑independent mechanisms.

DOI： 10.3892/or.2019.7244

Liver stiffness measurements in chronic hepatitis C: Treatment evaluation and risk assessment Reviewed

Motoyuki Otsuka

Journal of Gastroenterology and Hepatology 2019.5

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