Annual Report 2017

Yukari Totsuka, Michihiro Mutoh, Ken-ichi Yoshioka, Gen Fujii, Haruna Sato, Nozomi Akiba, Yuya Maesako, Syouma Kamio, Shungo Saito, Akane Zenke, Takahiro Hamoya, Shuuya Tamura, Yurie Kurokawa, Maiko Takahashi, Yusuke Matsuno, Haruka Fujimori, Mai Hyodo

Introduction

 Cancer is a disease associated with aging and environmental risk factors. It is well known that chemical substances form DNA adducts, which are considered to be a 'trigger' of mutagenesis. As cancer risk elevates in association with aging, genomic destabilization frequently arises in the cells of the elderly, which is associated with the impairment of DNA repair functions. The aims of our research projects are exploration of novel cancer etiology via identification of DNA adducts that are important for human cancer development, and clarification of the mechanisms for genomic instability associated with aging. On the other hand, cancer chemoprevention is one of the preemptive approaches that is strongly expected to reduce cancer morbidity and mortality. We are working to develop novel candidates for cancer chemopreventive agents and aim for their practical application using the concept of drug repositioning.

Our team and what we do

1. Exploration of cancer etiology using whole genome/exome analysis and comprehensive DNA adduct analysis

2. Genome destabilization and the associated hypermutation induction

3. Prevention of colorectal cancer

Research activities

1. Exploration of cancer etiology using whole genome/exome analysis and comprehensive DNA adduct analysis

 A high incidence of cholangiocarcinoma among printing industry workers in Osaka, Japan

has been reported. Epidemiological data suggest

that dihaloalkanes, such as dichloromethane

(DCM) and 1,2-dichloropropane (DCP), are

responsible for occupational cholangiocarcinoma. In general, dihaloalkanes are metabolically activated by GSH S-transferase theta1 (GSTT1) to yield products such as episulfonium ions. However, it is not elucidated yet whether the GSTT1-mediated step of DCM and/or 1,2-DCP is related to occupational cholangiocarcinoma or not. We investigated the influence of GSTT1 activation on the mutagenicity of DCM and 1,2-DCP using GSTT1-expressing Salmonella typhimurium TA100 (TA100-GST). Since the mutagenicity of DCM was significantly increased in TA100-GST compared with a mock control (TA100-pCTC), GSTT1 is thought to be involved in the mutagenicity of DCM. On the other hand, 1,2-DCP did not increase the number of revertants in TA100-GSTT1. Mutation spectrum analysis revealed that C:G to A:T transversions were predominant forms observed in DCM-treated TA100-pCTC. However, C:G to T:A transitions were dramatically increased in TA100-GST. In the case of 1,2-DCP, C:G to T:A transitions were predominant in both TA100-pCTC and TA100-GSTT1. These findings suggest that GSTT1 has little involvement in DCP mutagenicity, and other mechanisms might be more important for bioactivation and consequent genotoxicity.

2. Genome destabilization and the associated hypermutation induction

 Microsatellite instability (MSI) is widely found in mismatch repair (MMR)-deficient cancer cells in association with increased levels of mutations. However, it remains elusive how MSI is induced and contributes to cancer development. Here, we showed that DNA-replication stress triggered MSI induction coupled with hypermutation, which further contributed to clonal evolution of cells mutated in cancer driver genes. MSI induction was caused by PARP-mediated repair pathway. Such MSI/hypermutation associated clonal evolution shown in MMR-deficient cells was circumvented by chromosomal instability (CIN) in MMR-proficient background. Such efficiency for the resulting clonal evolution through CIN was about 60 times lower than that through MSI/hypermutation.

3. Prevention of colorectal cancer

 Familial adenomatous polyposis (FAP) patients are a well-known high-risk group with colorectal cancer (CRC). We are evaluating the usefulness and safety of thorough endoscopic polypectomy and of cancer chemopreventive agents in FAP patients. On the basis of these findings, we are trying to clarify the underlying mechanism of colorectal carcinogenesis in a laboratory study. Moreover, we are searching for novel chemopreventive agents against CRC using animal models of FAP.

Education

 Ten undergraduate and graduate students from local universities worked as trainees in our lab and had cancer research training.

Future prospects

*Explore the novel cancer etiology using whole genome analysis and comprehensive DNA adduct analysis.

*Establish a novel cancer prevention strategy based on the exploration of cancer etiology and mechanisms.

*Develop novel candidates for cancer chemopreventive agents and aim for their practical application.

List of papers published in January 2017 - March 2018

Journal

 1. Onuma W, Asai D, Tomono S, Miyamoto S, Fujii G, Hamoya T, Nagano A, Takahashi S, Masumori S, Miyoshi N, Wakabayashi K, Mutoh M. Anticarcinogenic Effects of Dried Citrus Peel in Colon Carcinogenesis Due to Inhibition of Oxidative Stress. Nutr Cancer, 69:855-861, 2017

 2. Nozue M, Shimazu T, Sasazuki S, Charvat H, Mori N, Mutoh M, Sawada N, Iwasaki M, Yamaji T, Inoue M, Kokubo Y, Yamagishi K, Iso H, Tsugane S. Fermented Soy Product Intake Is Inversely Associated with the Development of High Blood Pressure: The Japan Public Health Center-Based Prospective Study. J Nutr, 147:1749-1756, 2017

 3. Terasaki M, Maeda H, Miyashita K, Tanaka T, Miyamoto S, Mutoh M. A marine bio-functional lipid, fucoxanthinol, attenuates human colorectal cancer stem-like cell tumorigenicity and sphere formation. Journal of clinical biochemistry and nutrition, 61:25-32, 2017

 4. Mori N, Shimazu T, Sasazuki S, Nozue M, Mutoh M, Sawada N, Iwasaki M, Yamaji T, Inoue M, Takachi R, Sunami A, Ishihara J, Sobue T, Tsugane S. Cruciferous Vegetable Intake Is Inversely Associated with Lung Cancer Risk among Current Nonsmoking Men in the Japan Public Health Center (JPHC) Study. J Nutr, 147:841-849, 2017

 5. Miyamoto S, Komiya M, Fujii G, Hamoya T, Nakanishi R, Fujimoto K, Tamura S, Kurokawa Y, Takahashi M, Ijichi T, Mutoh M. Preventive Effects of Heat-Killed Enterococcus faecalis Strain EC-12 on Mouse Intestinal Tumor Development. Int J Mol Sci, 18:2017

 6. Lin Y, Totsuka Y, Shan B, Wang C, Wei W, Qiao Y, Kikuchi S, Inoue M, Tanaka H, He Y. Esophageal cancer in high-risk areas of China: research progress and challenges. Ann Epidemiol, 27:215-221, 2017

 7. Noma N, Fujii G, Miyamoto S, Komiya M, Nakanishi R, Shimura M, Tanuma SI, Mutoh M. Impact of Acetazolamide, a Carbonic Anhydrase Inhibitor, on the Development of Intestinal Polyps in Min Mice. Int J Mol Sci, 18:0, 2017

 8. Shiokawa D, Sato A, Ohata H, Mutoh M, Sekine S, Kato M, Shibata T, Nakagama H, Okamoto K. The Induction of Selected Wnt Target Genes by Tcf1 Mediates Generation of Tumorigenic Colon Stem Cells. Cell Rep, 19:981-994, 2017

 9. Kato T, Toyooka T, Ibuki Y, Masuda S, Watanabe M, Totsuka Y. Effect of physicochemical character differences on the genotoxic potency of kaolin. Genes and environment, 39:12, 2017

10. Minakawa, Y., Shimizu, A., Matsuno, Y., and Yoshioka, K. Genomic Destabilization Triggered by Replication Stress during Senescence. Cancers, 9:159, 2017

11. Ishigamori R, Komiya M, Takasu S, Mutoh M, Imai T, Takahashi M. Osteopontin Deficiency Suppresses Intestinal Tumor Development in Apc-Deficient Min Mice. Int J Mol Sci, 18:2017

12. Akiba N, Shiizaki K, Matsushima Y, Endo O, Inaba K, Totsuka Y. Influence of GSH S-transferase on the mutagenicity induced by dichloromethane and 1,2-dichloropropane. Mutagenesis, 32:455-462, 2017

13. Terasaki M, Maeda H, Miyashita K, Mutoh M. Induction of Anoikis in Human Colorectal Cancer Cells by Fucoxanthinol. Nutr Cancer, 69:1043-1052, 2017

14. Hamoya T, Miyamoto S, Tomono S, Fujii G, Nakanishi R, Komiya M, Tamura S, Fujimoto K, Toshima J, Wakabayashi K, Mutoh M. Chemopreventive effects of a low-side-effect antibiotic drug, erythromycin, on mouse intestinal tumors. Journal of clinical biochemistry and nutrition, 60:199-207, 2017

15. Fukai E, Sato H, Watanabe M, Nakae D, Totsuka Y. Establishment of an in vivo simulating co-culture assay platform for genotoxicity of multi-walled carbon nanotubes. Cancer Sci, 109:1024-1031, 2018

16. Toyoda T, Totsuka Y, Matsushita K, Morikawa T, Miyoshi N, Wakabayashi K, Ogawa K. gamma-H2AX formation in the urinary bladder of rats treated with two norharman derivatives obtained from o-toluidine and aniline. J Appl Toxicol, 38:537-543, 2018

17. Matsuno Y, Torigoe H, Yoshioka K. Establishment of Cellular Quiescence Together with H2AX Downregulation and Genome Stability Maintenance. J Clin Exp Pathol, 8:335, 2018