Polymorphisms in base-excision & nucleotide-excision repair genes & prostate cancer risk in north Indian population.

Background & objectives: Genetic variation in the DNA repair genes might be associated with altered DNA repair capacities (DRC). Reduced DRC due to inherited polymorphisms may increase the susceptibility to cancers. Base excision and nucleotide excision are the two major repair pathways. We investigated the association between two base excision repair (BER) genes (APE1 exon 5, OGG1 exon 7) and two nucleotide excision repair (NER) genes (XPC PAT, XPC exon 15) with risk of prostate cancer (PCa). Methods: The study was designed with 192 histopathologically confirmed PCa patients and 224 age matched healthy controls of similar ethnicity. Genotypes were determined by amplification refractory mutation specific (ARMS) and PCR-restriction fragment length polymorphism (RFLP) methods. Results: Overall, a significant association in NER gene, XPC PAT Ins/Ins (I/I) genotype with PCa risk was observed (Adjusted OR- 2.55, 95%CI-1.22-5.33, P=0.012). XPC exon 15 variant CC genotypes presented statistically significant risk of PCa (Adjusted OR- 2.15, 95% CI-1.09-4.23, P=0.026). However, no association was observed for polymorphism with BER genes. Diplotype analysis of XPC PAT and exon 15 revealed that the frequency of the D-C and I-A diplotype was statistically significant in PCa. The variant genotypes of NER genes were also associated with high Gleason grade. Interpretation & conclusions: The results indicated that there was a significant modifying effect on the association between genotype XPC PAT and exon 15 polymorphism and PCa risk which was further confirmed by diplotype analysis of XPC PAT and exon 15 in north Indian population.

Genetic variation in nucleotide excision repair pathway genes influence prostate and bladder cancer susceptibility in North Indian population.

BACKGROUND: Inherited polymorphisms of XPD and XPC genes may contribute to subtle variations in NER DNA repair capacity and genetic susceptibility to development of urological cancer such as prostate and bladder cancer. MATERIALS AND METHODS: We genotyped four Single Nucleotide Polymorphs (SNPs) of the DNA repair gene XPD and XPC in 195 prostate cancer (PCa) and 212 bladder cancer (BC) patients and 250 healthy controls from the same area. XPD Exon 10 (G>A) by amplification refractory mutation system and Exon 23 (A>C), XPC Intron 9 (Ins/Del) and Exon 15 (A>C) were genotyped by PCR-RFLP. RESULTS: Variant genotype of XPC demonstrated association with PCa as well as in BC (P, 0.013; P, 0.003). Combined genotype (GA+AA) revealed association with PCa and in BC (P, 0.012, P, 0.002). Variant allele also demonstrated risk in both the cancer. Diplotype of XPD and XPC was associated with a significant increase in PCa and BC risk. Variant (+/+) genotype of XPC intron 9 shown increased risk with PCa and in BC (P, 0.012; P, 0.032). CC genotype of XPC exon 15 revealed increase risk (P, 0.047) with PCa not in BC. In clinopathological grade variant allele of XPC intron 9 and 15 demonstrated risk with high grade of tumor and bone metastasis of PCa. In BC variant allele of XPD exon 10 and 15 also shown association with tumor grade. XPC intron 9 influences the risk of BC in former tobacco users in BC. CONCLUSIONS: Our result support that SNPs in XPD and XPC gene may reduce NER repair capacity and play a major role for PCa and BC in North India.