Promoter Hypermethylation and Its Impact on Expression of MGMT Gene in the GIT Malignant Patients of Kashmiri Origin

ABSTRACTEpigenetic alterations, in addition to multiple gene abnormalities, are involved in the genesis and progression of human cancers. Gastrointestinal tract (GIT) cancer is a major medical and economic burden worldwide. Aberrant methylation of CpG islands within promoter regions is associated with transcriptional inactivation of various tumor suppressor genes. Although a number of cancer-associated genes have been found to be hypermethylated in GIT cancer, valuable methylation markers for early diagnosis and prognostic evaluation of this cancer remain largely unknown. O6-methyguanine DNA methyltransferase (MGMT) is a DNA-repair gene that removes mutagenic and cytotoxic adducts from the O6 position of guanine induced by alkylating agents. MGMT promoter hypermethylation and reduced expression have been found in some primary human carcinomas. We studied DNA methylation of CpG islands of the MGMT gene and its relation with MGMT protein expression in human GIT carcinomas. A total of 210 GIT tumor samples a...