Adipose tissue-colorectal tumor cross-talk: new targets for breaking the obesity-cancer link

SUMMARY The pandemic rise of obesity worldwide is alarming, with the highest increases occurring in the United States. Obesity is a major risk factor for many cancer types, including colon cancer (CC). To date, the biologic mechanisms underlying this relationship, specifically the potential signaling between dysregulated adipose tissue and adjacent tumor, are incompletely understood. Given the rising rates of obesity and the challenges for many people to lose excess adipose tissue, an integrated, multilevel approach to efficiently identify crosstalk and validate key molecular targets is needed to develop effective mechanism-based strategies for prevention and control of obesity-driven CC. We hypothesize that the metabolic and inflammatory perturbations induced by obesity increase CC risk through altered signaling between adipocytes and colon epithelial/tumor cells, and that inhibition of this crosstalk will disrupt the obesity-CC link. We will test this hypothesis through the integration of: 1) a unique, prospective, multicenter epidemiologic cohort of normoweight to obese CC patients, from whom paired serum, tumor, and tumor-adjacent adipose tissue samples will be used to discover and validate lead targets; and 2) complementary in vivo models of lean and diet-induced obese mice with CC, together with in vitro/in vivo organoid models in which potential targets underlying the effects of obesity on CC will be tested mechanistically. This unique transdisciplinary approach utilizes innovative clinical/epidemiological and preclinical studies of biochemical, transcriptomic, and metabolomics analyses in rigorous study designs to identify and validate new targets for disrupting the reciprocal crosstalk between adipocytes and colonic epithelial cells. We propose three synergistic aims: 1a) to discover and validate targets underlying the adipose tissue-CC link, using 400 CC patients; b) to identify and validate metabolic and transcriptomic signatures of adipocyte-colonocyte crosstalk; 2) to characterize the adipocyte-colonocyte crosstalk underlying the obesity-CC link, using two rigorous mouse models of CC; 3) to determine the causal role of candidate epithelial target genes in obesity-associated CC progression using murine in vitro and in vivo organoid CC models. This paradigm-shifting transdisciplinary collaboration builds on extensive preliminary data and generates maximum synergy through complementary human and murine studies, using identical state-of-the-art biomarker panels and platforms across clinical and preclinical studies. We anticipate that findings from these proposed studies will address the clinical challenges associated with obesity and CC by establishing causal links of the most promising targets for intercepting and disrupting adipocyte-epithelial cell crosstalk.