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Green Tea Extract Protects Against Diethylnitrosamine-Mediated Liver Injury and Cell Proliferation by Attenuating STAT3 and Inos

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Green Tea Extract Protects Against Diethylnitrosamine-Mediated Liver Injury and Cell Proliferation by Attenuating STAT3 and Inos Green tea extract protects against diethylnitrosamine-mediated liver injury and cell proliferation by attenuating STAT3 and iNOS expression in high fat-induced obese mice with nonalcoholic steatohepatitis THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Joshua B. Kim Graduate Program in Human Nutrition The Ohio State University 2017 Master's Examination Committee: Richard S. Bruno, Ph.D., R.D., Advisor Amanda Bird, Ph.D. Ouliana Ziouzenkova, Ph.D. Copyrighted by Joshua B. Kim 2017 Abstract Nonalcoholic steatohepatitis (NASH) increases hepatocellular carcinoma (HCC) risk by increasing inflammation and oncogenesis. Antiinflammatory activities of green tea extract (GTE) protect against dietary high-fat (HF)-induced NASH. I hypothesized that antiinflammatory and anti-oncogenic activities of GTE during NASH would also prevent diethylnitrosamine (DEN)-induced development towards HCC. Male C57BL/6J mice (4 wk old) were fed a HF diet devoid of, or supplemented with, GTE at 2% (w/w) and received once weekly intraperitoneal injections of saline vehicle or DEN (60 mg/kg; 5 and 7 wk old) until 25 wk old. Gross pathological observation indicated no tumors, as expected. GTE protected against obesity-associated parameters, histological and biochemical evidence of NASH, and hepatic TNFα and MCP-1 expression in both saline- and DEN- injected mice (P<0.05). GTE attenuated serum alanine aminotransferase (ALT) activity, hepatic malondialdehyde (MDA), hepatic iNOS and survivin mRNA expression, signal transducer and activator of transcription 3 (STAT3), and hepatocyte proliferating cell nuclear antigen (PCNA) otherwise exacerbated by DEN. Hepatic GSTP protein expression increased in mice fed GTE. Serum ALT was correlated (r = 0.71-0.83; P<0.0001) with MDA, iNOS, STAT3, survivin and PCNA. iNOS correlated with PCNA, STAT3 (r = 0.64-0.65; P<0.05) and survivin ii (r = 0.66; P<0.0001), suggesting that iNOS-induced inflammation regulates liver injury and oncogenic cell proliferation. GTE lowers NASH- and DEN-mediated HCC risk by increasing GSTP and attenuating iNOS-mediated liver injury and survivin-mediated cell proliferation. iii Acknowledgments I would like to express my sincerest gratitude towards my advisor Dr. Richard Bruno. He allowed me to enter his lab with very limited research experience and provided me many opportunities to learn not only research skills, but many life skills as well. His passion for research and passion for his students’ growth has affected me in the best of ways. He challenged me academically and always encouraged the best in me by providing mentorship and friendship. He aided me in many abstracts, posters and oral presentations during my years as a master’s student. This research could not have been done without our collaborators Dr. Jennifer Thomas-Ahner and Dr. Steven Clinton and I would like to thank them for sharing their time and extensive knowledge and expertise. I would also like to sincerely thank my other committee members, Dr. Amanda Bird and Dr. Ouliana Ziouzenkova for the time, care and advice they had given me. Dr. Bird’s passion for research, expertise and kindness was greatly encouraging especially during experiments and data analysis. During times of uncertainty, Dr. Ziouzenkova provided insight and outlook on my research and my potential future career. Both committee members truly care about students and it was a privilege to learn under their guidance. iv I would like to thank my colleagues Dr. Jinhui Li, Joshua McDonald, Geoffrey Sasaki, Dr. Priyankar Dey and Dr. Chureeporn Chitchumroonchokchai for helping me with my experiments and giving me guidance. I would especially like to thank Jinhui, Joshua, Geoff and Priyankar for their unwavering support, mentorship and friendship that was invaluable to my master’s study. I am also grateful for other professors including Dr. Martha Belury, Dr. Ahmed Yousef and Dr. En Huang for their support and suggestions through my academic career. I would like to thank the organizations that contributed financially to support my education and research: College of Education and Human Ecology (EHE) and travel awards from EHE and the Department of Human Sciences. I am also extremely grateful for the support and guidance that members of the Korean Church of Columbus and my family brought during this time. I would like to especially thank Hailey Kim, Ben Lee, Pastor Isaac Surh, Hannah Surh, Esther Yoon, Caleb Chun and Jakob Han. Each played an integral role to my growth and success. I would like to thank my father Dr. Jin-Gab Kim, my mother Yoon Kim, and my two sisters Kristen and Danielle Kim for the immense encouragement and support during both highs and lows. Lastly, I would like to give everything that I have gained from these past two years to God the Father, God the Son and God the Holy Spirit. The v opportunities they gave me and the unconditional love they showed me will forever be recorded in history that transcends time. vi Vita 2008 ....................................................... Dublin Scioto High School 2013 ....................................................... B.S. Biology, The Ohio State University 2013 to present ...................................... Graduate Teaching Associate, Department of Human sciences, The Ohio State University Publications Li J, Sapper TN, Mah E, Moller MV, Kim JB, Chitchumroonchokchai C, McDonald JK, Bruno RS. Green tea extract treatment reduces NFκB activation in mice with diet-induced nonalcoholic steatohepatitis by lowering TNFR1 and TLR4 expression and ligand availability. J Nutr Biochem. 2017 March;41:34-41 Fields of Study Major Field: Human Nutrition vii Table of Contents Abstract .................................................................................................................ii Acknowledgments ................................................................................................iv Vita ...................................................................................................................... vii Publications ......................................................................................................... vii Fields of Study ..................................................................................................... vii Table of Contents ............................................................................................... viii List of Abbreviations ............................................................................................. x List of Tables ....................................................................................................... xii List of Figures ..................................................................................................... xiii Chapter 1: INTRODUCTION ............................................................................... 1 Chapter 2: REVIEW OF LITERATURE ................................................................ 3 2.1. NAFLD is a risk factor for hepatocellular carcinoma ................................... 3 2.2. Etiology Of NASH-induced HCC ................................................................ 4 2.2.1. Metabolic imbalance and the ―two-hit‖ mechanism of NASH ............... 4 2.2.2. Fibrosis and Cirrhosis .......................................................................... 6 2.2.3. Pre-malignancy .................................................................................... 8 2.3. Signaling in Liver Cancer ........................................................................... 9 2.3.1. Pro-inflammatory Signaling in HCC ...................................................... 9 2.3.2. STAT3 pathway.................................................................................. 12 2.4. Diethylnitrosamine .................................................................................... 13 2.5. Models of HCC ......................................................................................... 16 2.5.1. Using mouse as a model system ....................................................... 16 2.5.2. DEN in mice models ........................................................................... 18 2.6. Prevention of NAFLD-induced HCC ......................................................... 20 2.7. Green Tea ................................................................................................ 20 2.7.1. Bioavailability ..................................................................................... 21 2.7.2. NAFLD prevention .............................................................................. 22 2.7.3. Anti-inflammatory and anti-cancerous effects .................................... 23 2.8. Conclusion ............................................................................................... 24 Chapter 3: MATERIALS AND METHODS .......................................................... 28 3.1. Study design ............................................................................................ 28 3.2. Hepatic lipids ............................................................................................ 29 3.3. Liver injury ................................................................................................ 31 3.4. Hepatic steatosis, fibrosis and NAS score ................................................ 31 3.5. Cell proliferation ......................................................................................
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