Changes in CpG Islands Promoter Methylation Patterns during Ductal Breast Carcinoma Progression

Aberrant promoter methylation of several known or pu-tative tumor suppressor genes occurs frequently during carcinogenesis, and this epigenetic change has been con-sidered as a potential molecular marker for cancer. We examined the methylation status of nine genes (APC, CDH1, CTNNB1, TIMP3, ESR1, GSTP1, MGMT, THBS1, and TMS1), by quantitative methylation specific PCR. Synchronous preinvasive lesions (atypical ductal hyper-plasia and/or ductal carcinoma in situ) and invasive duc-tal breast carcinoma from 52 patients, together with pure lesions from 24 patients and 12 normal tissues paired to tumor and 20 normal breast distant from tumor were analyzed. Aberrant promoter methylation was detected in both preinvasive and invasive lesions for genes APC