Abstract 1125: FOXM1 and FOXQ1 are novel oncogenes in colorectal cancer and can be therapeutically targeted through miRNA-based therapeutics

OBJECTIVES: The development of colorectal cancer (CRC) is a highly complex process which needs coordinated regulation in the gene regulatory network. Forkhead box (FOX) proteins constitute a large family of transcriptional regulators. Accumulating evidence indicates that several FOX family members are critical regulators of tumor progression. However, the role of FOX proteins in CRC remains vastly unknown. miRNAs are single stranded small non-coding RNAs which can regulate a variety of biological processes in various human diseases including cancer. AIMS: Herein, we aimed to identify the expression patterns of FOX family members in CRC, followed by extensive characterization for their functional and mechanistic role in this malignancy. In addition, we sought to identify specific miRNAs that are responsible for dysregulated expression of FOX proteins in CRC. METHODS: The web-based database ONCOMINE was used to identify most highly expressed FOX family members in CRC. A cohort of 178 frozen tissues including 134 primary CRC tissues, and 44 matched normal mucosa tissues were collected to analyze the expression levels of FOX genes. For functional analysis, cell proliferation, migration and invasion assays were performed following siRNA knockdown of specific FOX proteins in CRC cells. The potential FOX-targeting miRNAs were initially identified using in-silico approaches, followed by luciferase reporter assays to validate their binding to downstream target genes. RESULTS: We systematically analyzed the expression profiles of FOX family members across 24 studies in cancer and normal tissues, and identified FOXM1, FOXQ1 and FOXA2 as the most highly expressed FOX genes in CRC. The over-expression of FOXM1 and FOXQ1 in CRC was confirmed in a cohort of CRC and matched adjacent normal tissues. Furthermore, the analysis of 134 CRC samples revealed that high FOXM1 and FOXQ1 expression resulted in worse overall survival. We next identified miR-342 as a potential regulator of both FOXM1 and FOXQ1, and subsequently validated its direct binding to the 3’UTR regions of both genes. Furthermore, the expression of miR-342 in CRC tissues inversely correlated with both FOXM1 and FOXQ1 expression. In-vitro functional analysis revealed that suppression of FOXM1 or overexpression of miR-342 inhibited CRC cell proliferation, while FOXM1 and FOXQ1 knockdown or miR-342 overexpression suppressed migration and invasion capacity of CRC cell lines. The stable overexpression of miR-342 reduced FOXM1 and FOXQ1 expression and significantly inhibited tumor growth in CRC xenografts in nude mice. CONCLUSIONS: FOXM1 and FOXQ1 promote cancer progression and act as potential prognostic factors in colon cancer. The downregulation of miR-342 in tumor tissues may contribute to the CRC development through inhibition of FOXM1 and FOXQ1 expression, suggesting that miR-342 could be used as a therapeutic target in colorectal cancer. Citation Format: Wenhao Weng, Yoshinaga Okugawa, Shusuke Toden, Ajay Goel. FOXM1 and FOXQ1 are novel oncogenes in colorectal cancer and can be therapeutically targeted through miRNA-based therapeutics. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1125.