Involvement of methylation-associated silencing of formin 2 in colorectal carcinogenesis

摘要

AIM To investigate whether promoter methylation is responsible for the silencing of formin 2(FMN2) in colorectal cancer(CRC) and to analyze the association between FMN2 methylation and CRC. METHODS We first identified the expression levels and methylation levels of FMN2 in large-scale human CRC expression datasets, including GEO and TCGA, and analyzed the relationship between the expression and methylation levels. Then, the methylation levels in four CpG regions adjacent to the FMN2 promoter were assessed by MethylTarget? assays in CRC cells and in paired colorectal tumor samples and adjacent nontumor tissue samples. Furthermore, we inhibited DNA methylation in CRC cells with 5-Aza-2'-deoxycytidine and assessed the expression of FMN2 by q RT-PCR. Last, the association between FMN2 methylation patterns and clinical indicators was analyzed.RESULTS A statistically significant downregulation of FMN2 expression in large-scale human CRC expression datasets was found. Subsequent analysis showed that a high frequency of hypermethylation occurred in the FMN2 gene promoter in CRC tissues; operating characteristic curve analysis revealed that FMN2 gene methylation had a good capability for discriminating between CRC and nontumor tissue samples(AUC = 0.8432, P 60 years old and in colon cancer tissue. CONCLUSION FMN2 promoter hypermethylation may be an important early event in CRC, most likely playing a critical role in cancer initiation, and can serve as an ideal diagnostic biomarker in elderly patients with early-stage colon cancer.