Association between GSTT-1 gene deletion and the susceptibility to oral squamous cell carcinoma in cigarette-smoking subjects.

Oral squamous cell carcinoma (OSCC) is related to tobacco use and alcohol consumption and the individual susceptibility for development of this tumor has been associated with xenobiotic-metabolizing enzymes polymorphisms. Glutathione S-transferase Theta-1 (GSTT1) is a phase II metabolic enzyme that catalyzes detoxification reactions of carcinogenic compounds. A genetic polymorphism of the GSTT1 gene is characterized by a complete gene deletion and consequent absence of the enzyme. The null genotype (gene deleted) of GSTT1 has a decreased capacity in detoxifying carcinogens present in tobacco smoke, leading the formation of DNA-adducts and DNA damage. The purpose of the present study was to evaluate the association between GSTT1 polymorphism and risk for OSCC development in a Brazilian population. We investigated the GSTT1 polymorphism in 87 patients with OSCC and 81 age-sex matched controls. The genotypes were studied by PCR-based methods. Individuals homozygous for the wild type GSTT1 (+/+) and heterozygous (+/0) were grouped together. The prevalence of GSTT1 deficiency (null) was significantly higher in the group with OSSC patients with oral cancer of the floor of the mouth. The results suggest that GSTT1 polymorphism increases the risk for OSCC development.