PROJECT ABSTRACT Hepatocellular carcinoma (HCC) is a deadly disease with limited treatment options. Therefore, there is an urgent need to develop alternative treatments for liver cancer, which is the primary goal of this application under the existing research program (1R01 CA222490). An effective cancer treatment strategy should target the pathways by which cancer arises in the first place. Emerging evidence also reveals that gut microbiota- derived signaling is not only implicated in colon cancer but also affects hepatic inflammation and liver carcinogenesis. Thus, to develop targeted strategies for liver cancer treatment, it is important to uncover the mechanism of gut-derived signaling in the liver. The Research Specialist (Dr. Ying Hu) and Unit Director (Dr. Yu-Jui Yvonne Wan) have worked together for the past 8 years, starting in 2011, and have generated 11 peer- reviewed publications in cancer research. Dr. Wan's research programs have been sponsored by a long-term, continuously funded R01 grant, NCI R01 CA053596 (1991-2016), and a cooperative U grant NCI U01 CA179582 (2014-2019, lead PI), NCI R01 CA222490 (2018-2023), and NIDDK R01 DK092100 (2011-2017). Dr. Hu has participated in all of these above-mentioned projects and has a thorough understanding of how Dr. Wan's cancer research program evolved. Dr. Hu has unique expertise in the gut-liver axis as well as in orthotopic liver and colon cancer animal models. She has conducted extensive research using both liver and colon cancer cells and mouse models to study the pathways controlled by natural compounds present in the gut and liver, including bile acids (BAs), retinoic acid (RA), and short-chain fatty acids (SCFAs). Our research program (1R01 CA222490) focuses on these natural chemicals, which are directly or indirectly produced by gut microbes and are able to induce the tumor suppressor miR-22 in the liver and colon. Thus, miR-22 and its inducers can not only induce cancer cell apoptosis and arrest, but also provide a preventive means to stop cancer reoccurrence, leading to an effective treatment strategy. The applicant, Ying Hu, has worked closely with Dr. Wan in developing plans to achieve the following goals: Aim 1 studies the mechanism by which miR- 22 has an anti-cancer effect by studying the downstream targets of miR-22. Aim 2 examines the role of miR-22 in liver cancer treatment using orthotopic liver cancer mouse models. Aim 3 analyzes the role of miR-22 inducers in liver cancer treatment. Successful completion of the proposed studies will lead to novel strategies to treat liver cancer as well as colon cancer via miR-22 targeted pathways. The funds freed-up due to funding of the current application will allow us to develop other collaborative programs that will lead to submission of an SBIR grant application to advance Dr. Hu's career goals. Dr. Wan is the primary support Unit Director who will continue to work with Dr. Hu to plan, direct, and execute the proposed research.