Dietary nutrient zeaxanthin enhances anti-tumor immunity by reprogramming CD8+ T cell function

PROJECT SUMMARY/ABSTRACT While immunotherapy have benefited some cancer patients, a substantial proportion fails to respond. Lifestyle choices have been increasingly recognized as a crucial aspect influencing the effectiveness of cancer therapy. However, precise mechanisms through which lifestyle choices, especially diet, could impact patient outcomes remain unclear. This is mainly due to the diversity of the dietary components involved. To address this challenge, our lab compiled a proprietary blood nutrient library that provides a unique collection of circulating nutrients to perform high-throughput, comprehensive cell-based screenings with physiological relevance. Using our novel library, I conducted a co-culture screen to identify nutrient candidates that enhance T cell-mediated tumor cytotoxicity. My preliminary data, for the first time, indicate that dietary carotenoid zeaxanthin enhances T cell-mediated tumor cell killing in vitro and attenuates tumor growth potential in C57BL/6 mice bearing B16F10 melanoma cells in a CD8+ T cell-dependent manner. This proposal will test the central hypothesis that dietary nutrient zeaxanthin enhances anti-tumor immunity by reprogramming CD8+ T cell function. In Aim 1, I will demonstrate zeaxanthin’s translational potential with various preclinical models. I will utilize tumor-bearing mice to further assess the anti-tumor effects of zeaxanthin in immunogenic and poorly immunogenic models. I will evaluate zeaxanthin’s synergistic effect with immune checkpoint inhibitor therapy such as anti-PD-1 antibody treatment. I will also characterize the changes in immune cell populations and functional markers in tumors, spleens, and draining lymph nodes upon zeaxanthin administration. In Aim 2, I will elucidate the precise molecular mechanisms underlying zeaxanthin’s effect on CD8+ T cells using temporal, integrated mechanistic studies including kethoxal-assisted single-stranded DNA sequencing (KAS-seq), phospho-kinase antibody array, and RNA sequencing. I will determine zeaxanthin’s target in CD8+ T cells via in vitro knockdown and in vivo knockout models. The Chen lab has a proven track record of expertise in demonstrating signaling significance of blood chemicals with in-depth mechanistic studies and diverse mouse models. We foster close collaborations with Drs. Justin Kline (UChicago) and Chuan He (HHMI & UChicago), who are experts in immuno-oncology and advanced sequencing methods, respectively. Together, the support and resources available through this network provide an ideal training and research platform to conduct the proposed project. Overall, my proposal will employ cutting-edge approaches to demonstrate zeaxanthin’s impact on anti- tumor immunity in vivo and to elucidate molecular mechanisms underlying zeaxanthin-dependent changes in CD8+ T cell effector function. This proposal aims to gain insights on how lifestyle choices, particularly diet, impact T-cell based cancer immunotherapy and to propose novel strategies to improve patient outcomes.