Polymorphisms of NRF2 and NRF2 target genes in urinary bladder cancer patients

PURPOSE: NRF2 transcription factor is involved in modulation of various antioxidant and metabolic genes and, therefore, may modulate anti-carcinogenic potential. Association between polymorphisms of NRF2 and five NRF2-regulated genes and urinary bladder cancer (BC) risk was analyzed. METHODS: The study group included 244 BC patients, while the control group comprised 365 individuals with no evidence of malignancy. Genotyping of GSTM1 (deletion), GSTT1 (deletion), GSTA1 −69C/T (rs3957357), GSTP1 Ile105Val (rs1695), SOD2 Ala16Val (rs4880) and NRF2 −617C/A (rs6721961) in blood genomic DNA was performed by means of real-time PCR assays. The associations between gene polymorphism and BC risk were computed by logistic regression. RESULTS: The frequency of GSTA1, GSTP1, SOD2 and NRF2 genotypes did not differ in both groups. A significantly higher BC risk was associated with GSTM1 null genotype after adjusting to age, sex and smoking habit (OR 1.85, 95 % CI 1.30–2.62; P = 0.001). GSTT1 null (OR 0.50, 95 % CI 0.31–0.81; P = 0.005) and GSTP1 Val105Val (OR 0.52, 95 % CI 0.27–0.98; P = 0.04) genotypes were associated with reduced BC risk separately or in combination (OR 0.24, 95 % CI 0.11–0.51; P < 0.0001) (P heterogeneity = 0.01). Combined GSTT1 null and SOD2 with at least one 16Val allele among never smokers encompass reduced BC risk (OR 0.14, 95 % CI 0.03–0.63; P = 0.01) (P heterogeneity = 0.04). CONCLUSIONS: This study supports hypothesis that GSTM1 null genotype may be a moderate BC risk factor. The gene–gene and gene–environment interactions associated with combined GSTP1/GSTT1 and combined GSTT1/SOD2 genetic polymorphisms along with cigarette smoking habit may play a significant role in BC risk modulation.