Division of Molecular and Cellular Medicine (Ochiya Group)

Takahiro Ochiya, Yusuke Yamamoto, Ryou-u Takahashi, Takeshi Katsuda, Yusuke Yoshioka, Ayako Inoue, Kana Kurosaki, Mayuko Yamamura, Akira Yokoi, Juntaro Matsuzaki, Hiroko Tadokoro, Takumi Sonoda, Ai Hironaka, Maki Abe, Tomomi Imamura, Satoko Takizawa, Junpei Kawauchi, Kazumi Nagao, Teruko Yamaguchi, Naomi Nomura, Gailhouste Luc Nicolas, Hayato Kurata, Kurataka Otsuka, Yutaka Naito, Nao Nishida, Tsukasa Kadota, Fumihiko Urabe, Kazunori Hosaka, Masaharu Somiya, Prieto-Vila Marta, Wataru Usuba, Liew Lee Chuen, Yumi Kawamura

Introduction

The focus of the Division of Molecular and Cellular Medicine lies in the development of novel treatment and diagnosis against cancer. The specific activities are as follows:

1) Studies on microRNA (miRNA) regulation in cancer cells and development of RNA interference (RNAi)-based therapeutics;

2) An exosome as a novel diagnosis and therapeutic tool against cancer;

3) Drug discovery for targeting miRNA to regulate cancer stem cell property;

4) Development for carcinogenic model using tissue stem cell culture;

5) Chemical reprogramming of adult hepatocytes modelling for hepatocellular carcinomas.

Research activities

1.Studies on miRNA regulation in cancer cells and development of RNAi-based therapeutics

RNAi-based therapeutics is a promising approach as a novel and potentially more effective treatment for cancer, and miRNA is one of the targets involved in the regulation of tumor-related genes. Using miRNA array and mRNA-sequencing, we have identified miR-135b as a key regulator of malignancy in human myxoid liposarcoma, and also revealed that its expression levels were linked to poor prognosis in human myxoid liposarcoma (Nezu, Oncogene). Also, miR-125b and miR-100 were identified as predictive biomarkers of response to induction chemotherapy in osteosarcoma (Kubota, Sarcoma). In bladder cancer patient urine, we have found that miR-146a-5p expression was significantly increased, indicating that it could be applicable for non-invasive cancer biomarkers in bladder cancer (Sasaki, Clin Genitourin Cancer).

As microRNAs in serum have been reported to be potentially useful for detecting cancer, we have examined the expression profiles of serum miRNA in several large cohorts to identify novel miRNA that can be used to detect early stage breast cancer. As a result, a combination of five miRNA (miR-1246, miR-1307-3p, miR-4634, miR-6861-5p, and miR-6875-5p) was found to be able to detect breast cancer. With this combination, it could accurately detect early stage breast cancer (Shimomura, Cancer Science).

We previously demonstrated that silencing of RPN2 efficiently reduced resistance to docetaxel in human breast cancer cells. Since July 2015, an investigator-initiated clinical trial (first-in-human Phase I study) with intratumoral administration of RPN2-siRNA for treatment-resistant breast cancer has been ongoing at the National Cancer Center (NCC) Hospital.

2.An exosome as a novel diagnosis and therapeutic tool against cancer

We have identified "Malignant Exosomes" from highly-metastatic ovarian cancer cell line, which remarkably induce the peritoneal dissemination of ovarian cancer cells. Peritoneal mesothelial cells were a barrier of peritoneal cavity and were killed by the malignant exosome due to induced apoptotic cell death. We also found that abundant MMP1 mRNA was packaged in the exosomes and it could be a prognostic marker for early stage ovarian cancer (Yokoi, Nature Commun.).

Since the exosomes are closely related to cancer metastasis, we have tried to block circulating exosomes in blood using specific antibodies in a metastatic breast cancer mouse model (xenograft model). Administration of human specific antibodies into a mouse model significantly reduced metastatic cancer cell numbers in the lung (Nishida-Aoki, Mol. Therapy). Thus, our data clearly demonstrated that targeting the exosomes in the blood of cancer patients is a potential therapeutic strategy for cancer treatment.

In addition to these findings, we have established a rat model to trace exosome secretion using CD63-GFP transgenic rats (Yoshimura, Sci.Rep) and also tried to identify genes involved in exosome secretion, in order to develop a therapeutic method for exosome suppression in cancer cells. We have published to review articles to show the biological significance of exosome in cancer (Kosaka, JCI; Fujita, Cancer Science; Junker K, JEV; Somiya, AIMS Bioengineering; Kadota, Int J Mol Sci.; Naito, CMLS; Liew, Int Immunol).

3.Drug discovery for targeting miRNA to regulate cancer stem cell property

While cancer stem cell (CSC) properties such as tumorigenicity and drug resistance are a major focus in current cancer research, the molecular mechanisms for the regulation of CSC properties are not fully understood. MicroRNA (miRNA) is identified as the targets involved in the regulation of CSC properties. We identified microRNA-27b (miR-27b) as a key regulator for the generation of a side-population in breast cancer cells that showed CSC properties, and also found that the anti-type II diabetes (T2D) drug metformin reduced this side-population via miR-27b-mediated repression of ENPP1, which is involved in T2D development (Takahashi, Nat. Commun.). We have begun the development of a mimic (mimetic nucleic acid) delivery system for miR-27b. Using the system, we have confirmed that miR-27b mimic was successfully delivered into the tumor in tumor-bearing mice

4.Development for carcinogenic model using tissue stem cell culture

By applying stable culturing system of human epithelial stem cells (Yamamoto, Inflammation and Regeneration), we have identified stem cell population in pre-cancerous lesion such as Barrett's esophagus which is precursor of esophageal adenocarcinomas (Yamamoto, Nature Commun.). Isolated precancerous stem cells were analyzed by gene expression microarray, SNP array and whole exome-seq to show the disease progression and diversity of metaplastic stem cells. To directly demonstrate the cell-of-origin in high grade serous ovarian cancer, patient-derived fallopian epithelial stem cells were cloned and transformed by introducing oncogene combination, and we showed that transformed fallopian stem cells developed tumors in immune-deficient mice, which were like high grade serous ovarian cancer in gene expression and morphology (Yamamoto, Journal of Pathology).

5.Chemical reprogramming of adult hepatocytes modelling for hepatocellular carcinomas

We are interested in modelling hepatocellular carcinomas utilizing chemically-induced liver progenitor cells. By modifying the technique to reprogram cancer and epithelial cells (Kawamata, BBRC), we have developed a strategy that small molecular cocktail enabled mature hepatocytes to reprogram bi-potential liver progenitor cells at high efficiency. Also, we have established an orthotopic transplantation method for reprogrammed liver progenitor cells which showed remarkably high repopulation rates (Katsuda, Cell Stem Cell; Ochiya, Chin Clin Oncol.). Combining these techniques, our main focus is on the elucidation of the multi-step carcinogenesis process of normal liver cells to hepatocellular carcinomas.