Promoter methylation and expression changes of CDH1 and P16 genes in invasive breast cancer and adjacent normal breast tissue

We studied the promoter methylation status and expression levels of P16 and CDH1 genes in breast cancer and their adjacent normal tissues with normal control breast tissues, to correlate with their histopathological parameters. Hundred twenty four samples (tumor and adjacent nonmalignant tissues) from 62 breast cancer patients and 4 normal control breast tissues were included in the study. We used methylation specific PCR to evaluate methylation status and quantitative RTPCR to measure the gene expression levels. Methylation incidence of P16 gene and CDH1 gene in tumor tissues were 24.2 % and 33.9 %, respectively. CDH1 and P16 gene were not methylated in normal control tissues. CDH1 underexpression is found to be significant in correlation with advanced stage, histologic type, high tumor grade and lymph node involvement. P16 expression is found not to be significantly related with any histopathological parameters. But 60% of cases which overexpresses P16 were estrogen negative, and 40% of them were histologic grade 3. Both P16 and CDH1 had different expression levels in tumor tissues compared to the adjacent normal tissues and in adjacent normal tissues compared to the normal non-tumor tissues.