Abstract Modulation of the tumor microenvironment is known to promote the growth and survival of colorectal cancer (CRC) cells. Strong epidemiological evidence links certain types of human cancer, including CRC, with obesity, and the obese pathophysiological state has been shown experimentally to stimulate CRC tumor growth. However, the mechanisms involved are not fully known: in particular, the impact of the obese tumor microenvironment on CRC tumor cellular composition, stiffness, and ECM composition is not known. Further, pathophysiologically relevant, patient-specific models for investigating obesity-linked inflammation mediated changes in the obese, tumor microenvironment do not exist for CRC. Thus, the objective of the proposed project is to examine modulation of the tumor microenvironment and obesity-related CRC disease progression using tissue-engineered patient derived xenograft (PDX) CRC models validated through comparison to patient tumors and PDX tumors. Our collaborative team will achieve this objective by leveraging their unique combined interdisciplinary expertise in CRC, tissue engineering, obesity and metabolic disease, transcriptomics, proteomics, and bioinformatics. We will use our improved models of CRC that replicate the cues found in the obese, insulin resistant/pro- inflammatory tumor microenvironment to test the hypothesis that obesity alters stromal signaling in the consensus molecular subtype 4 (CMS4) tumor microenvironment. To test our hypothesis, we have developed a tissue-engineered platform that enables long-term in vitro culture of the patient-derived CRC cells and recapitulation of the native tumor microenvironment, particularly the stromal component. The following Specific Aims will be pursued: Aim 1. Determine the extent to which 3D in vitro engineered CMS4-derived CRC tissues recapitulate patient and PDX tumors; Aim 2. Determine and compare the obesity mediated changes in the stromal component and metastatic properties of CMS4-derived 3D engineered tissues and PDX tumors; and Aim 3. Examine 3D engineered tissues, PDX tumors, and patient tumors from obese CRC patients for engineered tissue refinement and obesity model validation. This investigator-initiated research effort is in response to FOA PAR-19-113, Cancer Tissue Engineering Collaborative: Enabling Biomimetic Tissue-Engineered Technologies for Cancer Research. Overall, these efforts, which employ state-of-the-art technologies to characterize and compare our paired models and human patient tumors in an in-depth and rigorous manner, will develop a portable tissue-engineering platform with robust cross-validation so that this tool can be used to uncover CRC subtype specific mechanisms of obesity-driven tumor progression, as well as other parameters affecting CRC morbidity and mortality.

Project Narrative The tissue engineered platforms developed and validated in the proposed project will be extremely valuable to the understanding and eventual treatment of colorectal cancer (CRC) linked to obesity. The portability of these tissue engineered platforms to other obesity-linked cancers and cancer in general has the potential to inform and shift current research and clinical practice.