Inhibition of SOX17 by MicroRNA 141 and Methylation Activates the WNT Signaling Pathway in Esophageal Cancer

Abstract

In this study, we explored the possibility of SOX17 promoter region methylation as an esophageal cancer detection marker, the regulation of SOX17 expression, and the function of SOX17 in the WNT signaling pathway in esophageal cancer. Eight esophageal cancer cell lines, 9 normal esophageal mucosa samples, 60 cases of dysplasia, and 169 cancer tissue samples were included. Methylation-specific PCR, semiquantitative reverse transcription-PCR, immunohistochemistry, luciferase reporter assay, colony formation, and Western blot analysis were used to analyze methylation and function of SOX17 in esophageal cancer. MicroRNA-related detection methods were performed to evaluate microRNA regulation of SOX17. SOX17 methylation was found in progression tendency with 0% of normal mucosa, 39% of grade 1 dysplasia, 48% of grades 2 and 3 dysplasia, and 65% of primary cancer. SOX17 methylation is related to esophageal cancer patients' history of alcohol use and may induce β-catenin expression and redistribution. Loss of SOX17 expression is correlated to promoter region hypermethylation, and re-expression was activated by 5-aza-2'-deoxycytidine treatment in esophageal cancer cell lines. Restoration of SOX17 expression suppresses TCF/β-catenin-dependent transcription and colony formation. MicroRNA 141 was also found to down-regulate SOX17 expression and activate the WNT signal pathway. SOX17 is frequently methylated in esophageal cancer and in a progression tendency during esophageal carcinogenesis. Loss of SOX17 removes the normal inhibition of WNT signaling and promotes esophageal tumorigenesis.