GSTM1 enzyme concentration and enzyme activity in correlation to the genotype of detoxification enzymes in squamous cell carcinoma of the oral cavity

BACKGROUND: Differences in genotype and phenotype of detoxification genes could be one reason for conflicting results in studies dealing with gene polymorphisms as susceptibility factors for tobacco associated cancer. OBJECTIVES: The objective of this study was to investigate gene polymorphisms of detoxification enzymes and to determine whether the enzyme concentration and activity of glutathione S transferase < μ1 correlates with the genotype in patients with cancer of the oral cavity. MATERIAL AND METHODS: In 73 cancer patients and 136 matched healthy controls, the polymorphisms of glutathione S-transferase μ1 and θ (GSTM/GSTT), cytochrome p450 1A1 and CYP2D6 were detected. Simultaneously, GSTM1 protein concentration and total GSTM1-activity were determined. RESULTS: Only the coincidence of GSTM1 and GSTT null genotype was associated with oral cavity cancer. GSTM1 protein concentration and enzyme activity in null-genotype patients was significantly lower than in GSTM1-allele-carrier. But the enzyme concentration did not correlate with the activity. CONCLUSION: We assume that detoxification enzymes are functionally redundant and that only the simultaneous deficiency of several detoxification enzymes increases the risk for oral cancer.