A study on promoter methylation of PTEN in sporadic breast cancer patients from North India.

Abstract

Epigenetic silencing of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) through DNA methylation has been implicated in the pathogenesis of breast cancer. Present study investigates the contribution of PTEN promoter methylation and its associated protein expression in sporadic breast cancer patients from North India. A total of 360 paired breast carcinoma and adjacent normal tissue samples from 180 sporadic breast cancer patients were included in the present study and examined for PTEN promoter methylation status by methylation-specific polymerase chain reaction. Immunohistochemistry method was used for determining PTEN protein expression. Molecular findings were statistically correlated with various clinicopathological parameters to identify associations of clinical relevance. Presence of PTEN promoter methylation (39.44%) significantly correlated with its expression downregulation (45.56%) in breast tumors (P=0.0001). Furthermore, their interaction with various clinical parameters was evidenced in stratified analysis. Correlation of PTEN promoter methylation with histologically more malignant grade and PTEN expression loss with triple negative tumor status remained significant even after Bonferroni correction (P<0.003). Results implicate promoter methylation to be a mechanism partially responsible for PTEN silencing in sporadic breast cancer for North Indian women. Besides, methylation and expression loss of PTEN exhibited promising potential as candidate biomarkers of risk assessment in subcategorized breast tumors with critical pathologic parameters.