Association of Catalase Genotype with Oxidative Stress in the Predication of Colorectal Cancer:Modification by Epidemiological Factors

Objective This paper aims to assess the interaction between common variations in catalase（CAT） polymorphic gene and environmental factors for antioxidant defense enzyme in modulating individual susceptibility to colorectal cancer（CRC）.Methods A case-control study with 880 colorectal cancer cases and 848 controls was conducted to investigate whether variations in the catalase（CAT） gene,one of the genes involved in scavenging oxidative stress,influenced susceptibility to CRC.Results The interaction between life style and genotypes as well as with their effects on colorectal cancer was deduced from the present study.Significant difference（P=0.01） was identified in the distribution of CAT genotype between the colorectal cancer cases and the controls.The CRC cases had significantly lower mean activity than the controls（P〈0.01）.Correlation analyses revealed statistically significant correlations between CAT activity and CAT genotype（P〈0.01）.Conclusion The risk of CRC was associated with smoking,low vegetable consumption,high pork and poultry consumptions,and low or high BMI.This is the first study reporting an association of polymorphism CAT-21A〉T with colorectal cancer.Low CAT activity was associated with an increased risk of CRC;however,no evidence was found to support an association between CAT-21A〉T polymorphism and CRC risk.

Oxidative Damage to DNA and Its Relationship With Diabetic Complications

Objective To detect the oxidative DNA damage in diabetic patients and to investigate the relationship of oxidative DNA damage with diabetes and diabetic nephropathy. Methods Single cell gel electrophoresis （SCGE） was used to detect the DNA strand breaks in peripheral blood lymphocytes, and oxidative DNA damage product and serum 8-OHdG were determined by a competitive ELISA in 47 cases, including 25 patients without diabetic complications, 22 patients with diabetic nephropathy and 25 normal control subjects. Results Diabetic patients showed greater oxidative damage to DNA. The percentage of comet cells and the length of DNA migration （comet tail length） of peripheral blood lymphocytes were significantly increased in patients with diabetes, and significantly higher in patients with diabetic nephropathy than in diabetic patients without vascular complications （P〈0.05）. There was a significant increase in serum 8-OHdG in diabetic patients compared with normal subjects （P〈0.05）. Moreover, serum 8-OHdG was much higher in patients with diabetic nephropathy than in diabetic patients without vascular complications （P〈0.05）. Coneluslon There is severe oxidative DNA damage in diabetic patients. Enhanced oxidative stress may be associated with diabetes, especially in patients with diabetic nephropathy.