Title: Obesity and Clear Cell Renal Cell Carcinoma: Unraveling the Connection Objectives: Obesity has been identified as an established risk factor in the development of clear cell renal cell carcinoma (ccRCC). Obesity can lead to chronic cellular insults which may lead to DNA injury and whether these mechanisms are critical to cancer initiation in the kidney is unclear. Understanding how free fatty acids initiate cancer is critical to understanding the role of obesity in cancer initiation and development. We hypothesize that chronic injury and repair due to excess FFA exposure could lead to ccRCC carcinogenesis and aim to define the metabolic phenotype of obesity associated ccRCC. Methods: Using publicly available data from The KIRC Cancer Genome Atlas Program (TCGA) and clinicopathologic data, we compared the RNAseq profiles of obese (BMI >= 30) to normal weight (BMI =< 25) sample origins. Of the 337, a total of 333 had BMI available for analysis. We evaluated differences in Hallmark and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Using DESeq, we adjusted for age and sex. We clustered the mRNA, miRNA, and DNA methylation data using the iClusterBayes package. In vitro, HK PCT cells were cultured in DMEM+FBS and treated with bovine serum albumin (BSA)-palmitic acid complex and we measured cell viability at 24 and 48 hours using Alamar Blue. We extracted protein and performed western blots to identify DNA damage (pATM, H2AX) and endoplasmic reticulum stress (ATF4, eFI2alpha). Results: We identified several metabolic pathways to be unregulated in the obese group, including adipogenesis, heme metabolism, fatty acid metabolism, and bile acid metabolism. Analysis of methylation levels showed that obese patients appear to present a higher number of hypermethylated genes than normal weight patients. We identified decreased viability of renal proximal tubule and embryonal cells with excess free fatty acid supplementation. We also saw decreased cell viability with supplementation of BSA alone and are exploring the possible implication of BSA in endoplasmic reticulum stress to the cells. To further evaluate fatty acid associated parthenogenesis, we are repeating studies on in vitro HK PCT and treating cells with various concentrations of ceramide extracts. Conclusions: Through the investigation of these questions, we hope to improve understanding of obesity associated ccRCC and impact oncological outcomes for patients with this cancer. Understanding changes in lipid metabolism around ccRCC initiation will help identify novel pathways for pharmacologic intervention at earlier stages of the disease.