Hypermethylation of MIR129-2 Regulates SOX4 Transcription and Associates with Metastasis in Patients with Colorectal Cancer.

Abstract

MicroRNA-129-2 (miR-129-2), targeting SOX4, has been shown to be involved in the pathogenesis of different cancers. Here in this study, we examined the methylation levels of the promoter region of MIR19-2 gene as well as transcription of miR-129-2 and mRNA expression of SOX4 in the tumoral tissues from colorectal cancer (CRC) patients and compared those in the normal marginal tissues. Fifty CRC patients with Iranian Azari ethnicity were recruited. Genomic DNAs were extracted from the tumoral and normal tissues and the methylation level of the promoter regions of the MIR129-2 gene was determined using methylation-specific PCR (MSP) by evaluating 100 CG sites. The RNA content of the samples was isolated and the transcript levels of miR-129-2 and SOX4 were measured using quantitative real-time PCR. Methylation level of the MIR192-2 promoter was significantly higher in the tumoral tissues compared to that in the normal marginal tissues (84% vs. 28%; P = 0.0041). The expression level of miR-192-2 was significantly downregulated (fold change = 0.34, P = 0.028) but SOX4 mRNA expression was upregulated (fold change = 2.7, P = 0.019) in the tumoral tissues compared to that in the normal marginal tissues. There was a significant correlation between the methylation level of the MIR192-2 promoter and the expression levels of miR-192-2 and SOX4 in the tumoral tissues. Associations were observed between the methylation of the MIR192-2 promoter and lymph node and liver metastasis. It seems that MIR192-2 promoter hypermethylation might regulate the expression of SOX4 and therefore modulate metastasis in CRC.