Polymorphisms of Human 8-Oxoguanine Glycosylase1 (hOGG1) in Bladder Tumor

Kim, Eun Jung; Jeong, Pildu; Jung, Choon Goo; Kim, Wun Jae

Abstract

Purpose
Repairing damaged DNA has been shown to be involved in an increased susceptibility to cancer development and prevention. Therefore, the genetic polymorphisms of the hOGG1 gene associated with the gene repair mechanism were investigated. In this study, the possible association of genetic polymorphisms in hOGG1 with bladder tumor risk was examined.
MATERIALS AND METHODS
The hospital based, case-control investigation was carried out in 168 primary bladder tumor patients and 672 controls. The DNA extracted from the blood and tissue samples was analyzed by SSCP, PCR-based restriction fragment length polymorphism (RFLP) and direct DNA sequencing in order to characterize the genetic polymorphism of hOGG1.
RESULTS
Two polymorphic sites in hOGG1 were found. A polymorphism at codon 326 (1a type) in exon 7 was associated with an amino acid exchange. Another polymorphic site at codon 324 (1b type) in exon 6 was silent. The association between the polymorphism at codon 326 and the risk of the bladder tumor was examined by age-sex adjusted analysis. The distribution of the hOGG1 codon 326 genotypes in the controls (Ser/Ser, 18.9%; Ser/Cys, 54.0%; Cys/Cys, 27.1%) was significantly different from that in the bladder tumor patients (26.2%, 51.8% and 22.0%, respectively) (p=0.034, adjusted OR=0.652, 95% CI=0.44-0.97). In particular, bladder tumor risk in Korean males under 40 years old was approximately 6 times higher than in males over 40 years old (p=0.015, adjusted OR=0.165, 95% CI=0.04-0.75). Furthermore, frequent mutations of codon 326 in the hOGG1 gene in tumor tissues (23.6%) might occur during tumorigenesis.
CONCLUSIONS
The data suggests that polymorphism at codon 326 of hOGG1 gene might affect tumorigenesis of a bladder tumor.