Abstract
Colorectal cancer (CRC) is one of the common causes of cancer death in Iranian population. Both genetic and epigenetic changes have been implicated in CRC pathogenesis. DACT2 gene as one of the WNT signaling pathway inhibitor was shown to display tumor suppressor activity in many cancers. The aim of present study was to investigate the methylation status of DACT2 gene and its association with methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in CRC patients. Fifty formalin-fixed paraffin-embedded cancerous and adjacent healthy tissues obtained from CRC patient were investigated. Genomic DNA was isolated using a FFPE commercial DNA extraction kit. The methylation status was evaluated by methylation specific PCR. Genotyping of MTHFR C677T polymorphism was performed using PCR-RFLP technique. Statistical analysis was done by GraphPad Prism 8. Results indicated that the frequency of methylated DACT2 gene was significantly higher in cancerous tissue relative to adjacent healthy tissue (P<0.001). DACT2 gene methylation was significantly more common among carriers of MTHFR 677CC genotype (P=0.035) and significantly less common among carriers of MTHFR 677T allele (P value =0.006). In conclusion the present study identified DACT2 gene methylation as a significant risk factor for CRC development. Moreover, the low frequency of DACT2 gene methylation among carriers of MTHFR 677T allele may confer a protective role for this common polymorphism against CRC risk.