Abstract 5131: Dysregulated cholesterol metabolism facilitates epithelial-to-mesenchymal transition and tumor progression in colorectal cancer

Introduction: Colorectal cancer (CRC) is a leading cause of cancer-related death in the United States, and its development is closely correlated with lifestyle factors, including a high cholesterol “Western” diet. In our novel study, we investigated the etiology of dysregulated cholesterol homeostasis in CRC and characterized its systemic effects on tumor progression. Methods: Expression of DHCR7, the rate-limiting enzyme of cholesterol biosynthesis, in CRC was analyzed in silico using TCGA-COAD data. A human tissue microarray (n=208 cores) with samples from normal colon, local colon tumors, and lymph node metastases was stained for DHCR7 using IHC. Stained tissue cores were scored blindly by a clinical pathologist based on our histological scoring system, which accounted for the percentage of positive cells and the intensity of staining. We generated an APCCDX-CreER CRC mouse model and collected colonic tissue samples for analysis. Tissues were stained for DHCR7 and scored. To assess the impacts of high diet cholesterol on epithelial-to-mesenchymal transition (EMT) in vivo, we developed an APC model which was divided into three diet groups of equal size: a control group (fed a 0 ppm cholesterol diet), a low cholesterol group (186 ppm), and a high cholesterol group (880 ppm). Colonic tissue samples were stained for claudin-1, a classical marker of epithelial barrier integrity. MTT assays were used to measure the in vitro proliferation of SW620 human CRC cells incubated in 0, 5, 10, 15, 20, and 25 μM cholesterol. Results: In silico data analysis indicated that DHCR7 is broadly overexpressed in CRC patients. Histological scoring of human patient samples showed upregulation of DHCR7 in local and metastatic CRC tumors compared to normal colonic tissue. Surprisingly, DHCR7 expression was significantly higher in lymph node metastases than in the primary tumor. DHCR7 overexpression was also observed in tumor-bearing APC mice relative to tumor-free controls. Claudin-1 expression was found to be significantly downregulated in mice fed a high cholesterol diet compared to mice fed a low cholesterol or control diet. Finally, SW620 cells grown in cholesterol proliferated at a faster rate over 96 hours than control cells incubated in 0 μM cholesterol media, although a dose-dependent effect was not observed. Conclusions: DHCR7 is systemically overexpressed in CRC primary tumors, and expression is even further elevated in metastatic disease. Therefore, de novo cholesterol synthesis is dysregulated in tumor cells, causing a profound disruption to cholesterol homeostasis which may potentiate EMT and metastasis. High cholesterol uptake also promotes a mesenchymal phenotype in tumor cells and stimulates proliferation. Our findings indicate that dysregulation of cholesterol homeostasis increases the tumorigenicity and metastatic potential of CRC cells and may be a target for therapy. Citation Format: Blake M. Arciga, Van Nguyen, Jussuf T. Kaifi, Satyanarayana Rachagani. Dysregulated cholesterol metabolism facilitates epithelial-to-mesenchymal transition and tumor progression in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5131.