Manganese superoxide dismutase and catalase geneticpolymorphisms, activity levels and lung cancer risk in Chinese in Hong Kong

Abstract

BACKGROUND: Antioxidants play an important role in counteracting the effects of potential carcinogens We aim to investigate the risk of lung cancer development with respect to manganese superoxide dismutase (MnSOD) and catalase genetic polymorphisms, and their association with erythrocyte antioxidants activities. METHODS: This is a prospective case-control study involving patients with confirmed lung cancer and healthy controls Genotyping of MnSOD and catalase in DNA extracted from peripheral white cells was performed by polymerase chain reaction based restriction fragment length polymorphism. Erythrocyte superoxide dismutase and catalase activities were measured spectrophotometrically using chemical kinetic reactions. RESULTS: We recruited 340 patients with lung cancer (67% males. 58.3±11.0 years. 55% adenocarcinoma) and 289 healthy controls. The allelic frequencies of the variant in MnSOD (Val allele) and catalase (C allele) genes are common (>85%). with similar distribution, in both lung cancer patients and controls. The homozygous variant genotypes of MnSOD and catalase were not associated with increased lung cancer risk. The erythrocyte SOD activity was significantly lower in lung cancer patients compared to controls (27±33 versus 82±30 U/g haemoglobin: p < 0 001). irrespective of different genotypes. However catalase activity was not different between patients and controls (0.036±0.061 versus 0.032±0.025U/g haemoglobin), though it was lower among those with CC genotype compared with TC and TT genotypes in lung cancer patients. CONCLUSIONS: The common Ala16Val MnSOD polymorphism and C T substitution in the promoter region of the catalase gone confer no increased risk of lung cancer of Chinese in Hong Kong.