Abstract 2089: Epigenetic regulation of sprouty2 in colorectal cancer

Abstract

Background: The specific role of Sprouty-2 in colorectal cancer (CRC) as either a tumor suppressor or an oncogene is unclear. This is further obscured by the fact that no known driver mutations of Sprouty-2 have been reported. Therefore, for the first time, alterations of DNA 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) were investigated to better understand the regulation of Sprouty-2 in CRC. Methods: Sprouty-2 transcript expression was evaluated in CRC patient samples and Sprouty-2 protein expression was evaluated in CRC cells. The DNA methylation status spanning Sprouty-2 gene was evaluated using combined bisulfite restriction analysis (COBRA). The 5hmC status in the Sprouty-2 gene body and promoter was analyzed using previously performed nano-hmC-seal data from colon cancers and adjacent normal colonic mucosa. Publicly available RNA-seq and methylation data from The Cancer Genome Atlas (TCGA) were extracted from tumors from CRC patients. Results: Variable Sprouty-2 mRNA expression was observed among CRC patient tumors compared to adjacent normal appearing colonocytes. For the first time, differential methylation between adjacent normal colon and CRC samples was identified in 2 CTCF binding sites and in the promoter near the Transcriptional Start Site (TSS) of Sprouty-2, where the 5mC status in 1 of the CTCF binding sites correlated with transcript abundance. In CRC, this is the first study to reveal increases of 5hmC deposition in the gene body and promoter region of Sprouty-2 compared to normal colon. In metastatic CRC, an inverse correlation of increased Sprouty-2 promoter 5mC and decreased mRNA expression was found in patients registered in TCGA. Conclusions: In terms of tumor growth, epigenetic aberrations including Sprouty-2 promoter hypomethylation and increased 5hmC may play a prominent role in positive regulation of Sprouty-2 in CRC. In metastatic stages of CRC, increases in Sprouty-2 promoter 5mC may downregulate Sprouty-2 expression, which may ultimately label Sprouty-2 as a tumor suppressor in CRC. Citation Format: Alexei Stuckel, Sharad Khare. Epigenetic regulation of sprouty2 in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2089.