Loss expression of O6-methylguanine DNA methyltransferase by promoter hypermethylation and its relationship to betel quid chewing in oral squamous cell carcinoma.

Objective: O(6)-methylguanine-DNA methyltransferase (MGMT) ameliorates mutagenic, carcinogenic, and cytotoxic adducts from O(6)-methylguanine in DNA through a direct reversal mechanism. Decreased expression of MGMT has been reported in a variety of human malignant tumors. The purpose of this study was to clarify the correlation of MGMT expression levels in oral squamous cell carcinoma (OSCC) with promoter hypermethylation and with betel quid chewing and cigarette smoking.

O6-methylguanine-DNA methyltransferase gene coding region polymorphisms and oral cancer risk.

Background: O (6) -methylguanine-DNA methyltransferase (MGMT) is a specific DNA direct reversal repair protein which ameliorates mutagenic, carcinogenic and cytotoxic adducts from O(6) -methylguanine in DNA. The aim of this study was to investigate the potential association between six polymorphisms in the coding region of the MGMT gene and oral cancer risk in Taiwanese population.

Methods: In this hospital-based case-control study, the MGMT genotypes were determined by using DNA sequencing in 176 patients with oral squamous cell carcinoma (OSCC), 77 patients with oral premalignant lesions and 110 normal individuals.