Abstract 173: SOX4 interacts with EZH2 and HDAC3 to suppress microRNA-31 in invasive esophageal cancer cells

Abstract

Abstract Tumor metastasis is responsible for 90% of cancer-related deaths. A strong link between microRNA dysregulation and human cancers has recently been established. However, the molecular mechanisms through which microRNAs regulate metastasis and cancer progression remain unclear. We analyzed the reciprocal expression regulation of miR-31 and SOX4 in esophageal squamous and adenocarcinoma cell lines by qRT-PCR and Western Blotting using overexpression and shRNA knock-down approaches. Here we report that SOX4 promotes esophageal tumor cell proliferation and invasion by silencing miR-31 via activation and stabilization of a co-repressor complex with EZH2 and HDAC3. We demonstrate that miR-31 is significantly decreased in invasive esophageal cancer cells compared to non-invasive cell lines, while upregulation of miR-31 inhibits growth, migration and invasion of esophageal adenocarcinoma (EAC) and squamous cell carcinoma (ESCC) cell lines. miR-31, in turn, targets SOX4 for degradation by directly binding to its 3′-UTR. Additionally, miR-31 regulates EZH2 and HDAC3 indirectly. SOX4, EZH2 and HDAC3 levels inversely correlate with miR-31 expression in ESCC cell lines. Ectopic expression of miR-31 in ESCC and EAC cell lines leads to down regulation of SOX4, EZH2 and HDAC3. Conversely, pharmacologic and genetic inhibition of SOX4 and EZH2 restore miR-31 expression. We show that SOX4, EZH2 and HDAC3 form a co-repressor complex that binds to the miR-31 promoter, repressing miR-31 through an epigenetic mark by H3K27me3 and by histone acetylation. Clinically, when compared to normal adjacent tissues, esophageal tumor samples show upregulation of SOX4, EZH2, and HDAC3, and EZH2 expression is significantly increased in metastatic ESCC tissues. Thus, we identified a novel molecular mechanism by which the SOX4, EZH2 and miR-31 circuit promotes tumor progression and potential therapeutic targets for invasive esophageal carcinomas. Citation Format: Rainelli B. Koumangoye, Thomas Andl, Kenneth J. Taubenslag, Steven T. Zilberman, Chase Taylor, Claudia D. Andl. SOX4 interacts with EZH2 and HDAC3 to suppress microRNA-31 in invasive esophageal cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 173. doi:10.1158/1538-7445.AM2015-173