Abstract 4368: MicroRNAs miR-503 and -182 regulate FBXW7 contributing to the malignant transformation to colon adenocarcinoma

Progression from adenoma to colon cancer is a multi-step process and the role of microRNAs in this transformation is not completely understood. We used both in vitro and in vivo approaches to demonstrate the role of miRNAs in the transformation of adenoma to adenocarcinoma. Reporter assays were used to show the direct interaction of miRNAs to target gene. A Tet-inducible TripZ system and miRzips constructs were used in the in vitro function and xenograft studies. Kaplan-Meier survival curves and Cox regression were used to analyze the survival data in colon cancer patients. Here, we show that the combination of miR-503 and miR-182 contributes to the transformation of colon adenoma to adenocarcinoma by cooperatively regulating the tumor suppressor gene, FBXW7. We found that miR-182 was upregulated in both colon adenoma and adenocarcinoma, whereas miR-503 was upregulated only in adenocarcinoma, indicating a potential hierarchical and stepwise expression of these miRNAs in the regulation of FBXW7. Furthermore, we showed that colon adenoma derived non-tumorigenic AAC1 cells were transformative and tumorigenic in mice when expressing Tet-inducible miR-503. Finally, the combination of miR-503 and miR-182 transcript levels was predictive of poor outcome in colon cancer patients. We conclude that a step-wise expression of miR-182 and miR-503 in benign adenoma synergistically regulates the driver gene FBXW7, thus contributing to the progression of colon adenoma to adenocarcinoma. Citation Format: Lihua Li, Aaron Sarver, Rohini Khatri, Praveensingh Hajeri, Iris Kamenev, Stephen Thibodeau, Clifford J. Steer, Subbaya Subramanian. MicroRNAs miR-503 and -182 regulate FBXW7 contributing to the malignant transformation to colon adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4368. doi:10.1158/1538-7445.AM2014-4368