Role of NQO1 609C>T and NQO2 -3423G>A gene polymorphisms in esophageal cancer risk in Kashmir valley and meta analysis.

Esophageal cancer (EC) is a complex multifactorial disorder, where environmental and genetic factors play major role. NADPH:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2) are phase II cytosolic enzymes that catalyze metabolism of quinones, important in the detoxification of environmental carcinogens. A case-control study was performed to investigated the associations of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility to EC in a high-risk Kashmiri population of India in 135 EC patients and 195 unrelated healthy controls using PCR-RFLP. We also performed a meta analysis of nine published studies (1,224 cases and 1,740 controls) on NQO1 609C>T and evaluated the association between the NQO1 609C>T polymorphisms and esophageal cancer risk. A significant difference in NQO1 609C>T and NQO2 -3423G>A genotype distribution between EC cases and corresponding controls groups was observed (OR = 2.65; 95 % CI = 1.29-5.42 and OR = 1.88; 95 % CI = 1.02-3.49 respectively). Further, gene-gene interaction showed significantly increased risk for esophageal adenocarcinoma with variant genotypes of NQO1 609C>T and NQO2 -3423G>A polymorphisms and interaction with environmental risk factors revealed pronounced risk of EC with NQO1 609C>T TT genotype in high salted tea users of Kashmir valley (OR = 3.72, 95 % CI = 0.98-14.19). Meta analysis of NQO 609C>T polymorphism also suggested association of the polymorphism with EC in Asians as well as Europeans. In conclusion, NQO1 609C>T and NQO2 -3423G>A genetic variations modulate risk of EC in high-risk Kashmir population.