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Open Access Research article

Genetic polymorphisms of DNA double strand break gene Ku70 and gastric cancer in Taiwan

Mei-Due Yang1, Hwei-Chung Wang1, Wen-Shin Chang23, Chia-Wen Tsai23 and Da-Tian Bau234*

Author Affiliations

1 Department of General Surgery, China Medical University Hospital, Taichung, Taiwan, R.O.C

2 Terry Fox Cancer Research Lab, China Medical University Hospital, Taichung, Taiwan, R.O.C

3 Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, R.O.C

4 Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan, R.O.C

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BMC Cancer 2011, 11:174  doi:10.1186/1471-2407-11-174

Published: 17 May 2011

Abstract

Background and aim

The DNA repair gene Ku70, an important member of non-homologous end-joining repair system, is thought to play an important role in the repairing of DNA double strand breaks. It is known that defects in double strand break repair capacity can lead to irreversible genomic instability. However, the polymorphic variants of Ku70, have never been reported about their association with gastric cancer susceptibility.

Methods

In this hospital-based case-control study, the associations of Ku70 promoter T-991C (rs5751129), promoter G-57C (rs2267437), promoter A-31G (rs132770), and intron 3 (rs132774) polymorphisms with gastric cancer risk in a Taiwanese population were investigated. In total, 136 patients with gastric cancer and 560 age- and gender-matched healthy controls recruited from the China Medical Hospital in Taiwan were genotyped.

Results

As for Ku70 promoter T-991C, the ORs after adjusted by age and gender of the people carrying TC and CC genotypes were 2.41 (95% CI = 1.53-3.88) and 3.21 (95% CI = 0.96-9.41) respectively, compared to those carrying TT wild-type genotype. The P for trend was significant (P < 0.0001). In the dominant model (TC plus CC versus TT), the association between Ku70 promoter T-991C polymorphism and the risk for gastric cancer was also significant (adjusted OR = 2.48, 95% CI = 1.74-3.92). When stratified by age and gender, the association was restricted to those at the age of 55 or elder of age (TC vs TT: adjusted OR = 2.52, 95% CI = 1.37-4.68, P = 0.0139) and male (TC vs TT: adjusted OR = 2.58, 95% CI = 1.33-4.47, P = 0.0085). As for the other three polymorphisms, there was no difference between both groups in the distributions of their genotype frequencies.

Conclusion

In conclusion, the Ku70 promoter T-991C (rs5751129), but not the Ku70 promoter C-57G (rs2267437), promoter A-31G (rs132770) or intron 3 (rs132774), is associated with gastric cancer susceptibility. This polymorphism may be a novel useful marker for gastric carcinogenesis.

Keywords:
Ku70; Polymorphism; Gastric cancer; Carcinogenesis