Effective clinical management of colorectal cancer is still a major challenge in cancer care. MicroRNA is a set of newly-discovered, non-coding small RNA molecules that significantly contribute to a number of critical biological events including cell proliferation, apoptosis development, as well as tumorigenesis. Our group has previously identified a number of microRNA candidates associated with potential prognostic value in colorectal cancer patients. In this study, we investigated miR-200c and validated its impact on 5-FU chemosensitivity in colorectal cancer. Human colorectal cancer cell lines HCT116 and HCT15 were employed in this study. Pre-miR-200c precursor molecules and negative control (Ambion, Inc.) were transiently transfected into these cell lines and cell viability was examined using WST-1 assay (Roche, Inc.) after 5-FU treatment for 24 hours. The results indicate that miR-200c can potentially sensitize colorectal cancer cells to 5-FU up to 25% compared to controls. Also, cells over-expressing miR-200c have an approximately 50% higher apoptotic rate than controls based on flow cytometry results. Bioinformatics predicts Bcl-2 is a putative mRNA target of miR200c. Bcl-2 is an integral membrane protein located mainly on the outer membrane of mitochondria. Overexpression of Bcl-2 has been demonstrated to prevent cells from undergoing apoptosis in response to a variety of stimuli. In this study, we further experimentally validated the repressive abilities of miR-200c on Bcl-2 expression using Western Blot and Luciferase reporter assay. Our results demonstrates that miR-200c is a potential biomarker for predicting chemotherapeutic response in colorectal cancer and functions by repressing Bcl-2 expression and inducing apoptotic susceptibility to 5-FU. These results hold great promise for moving miRNAs toward future clinical application and contribute to the ultimate goal of developing or improving therapeutic intervention for patients with colorectal cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4042.