Promoter epigenetics of APC gene and its implication in sporadic breast cancer patients from South Indian population

Abstract

BackgroundThe adenomatous polyposis coli (APC) gene is a tumor suppressor gene associated with both familial and sporadic cancer, whose protein plays an important role in the WNT signal transduction pathway. WNT signaling is a key developmental pathway involved in embryonic development, cell differentiation, cell proliferation and tissue maintenance in adults. APC protein acts as an antagonist of the WNT signaling pathway by binding and regulating the β-catenin protein. Impaired APC gene function usually leads to a lack of degradation of β-catenin, which could cause uncontrolled cell growth and lead to tumorigenic transformation. APC gene may be inactivated by aberrant DNA methylation of CpG islands in their promoter regions. ObjectiveHence the present study was designed to determine the role of promoter methylation of APC genes in sporadic breast cancer patients from South Indian population. MethodsDNA methylation analyses of APC gene was performed by methylation-specific polymerase chain reaction (MSP).·Fifty biopsy samples of breast tumor and their corresponding non-malignant portions as controls were studied comparatively. APC mRNA expression analysis was also done using real time PCR. ResultsThirty eight percent (38%) cancerous tissue samples (19/50) showed promoter hypermethylation in APC gene; however, none of normal tissues showed promoter hypermethylation. The difference in methylation frequency between cancerous and normal tissue was statistically significant (p = 0.0001). APC promoter methylation was positively associated with lymph node involvement (p = 0.048), APC Promote hyper methylation and decreased mRNA expression was significantly associated (p = 0.0034). Lower APC-mRNA expression was associated with patient's age above 50 years (p = 0.044). ConclusionIn conclusion, our data showed that promoter hypermethylation of APC gene was a prognostic factor in breast cancer patients from South Indian population. The loss of APC gene function usually leads to an accumulation of β-catenin, which may promote tumorigenesis.