Null genotype of glutathione S-transferase T1 contributes to increased risk of gastric cancer in Asian population

GSTs genetic polymorphism, gene-environment interaction and association with gallbladder cancer risk in North Indian population: A case-controlled study

AIM

In the present case-controlled study, we explored the role of genetic polymorphism in three xenobiotic metabolizing genes, GSTM1, GSTT1 and GSTP1, and their association to gallbladder cancer (GBC) risk in a North Indian population. Its etiology is influenced by genetic, food habits, lifestyle, and environmental factors. GBC incidence is significantly higher in the Gangetic belt, India. Therefore, we explored the prognostic factors in the susceptibility of GBC through gene-gene and gene-environment interaction in this region.

MATERIAL AND METHODS

Genetic polymorphism was analyzed in 108 GBC patients from Kamala Nehru Memorial Cancer Hospital, Prayagraj and 142 matched controls. GSTM1 and GSTT1 genotypes were analyzed by multiplex PCR method, while restriction fragment length polymorphism (RFLP) was performed to analyze GSTP1 genotypes. Logistic regression analysis calculating the odds ratio (OR) and 95% confidence interval (CI) was performed to analyze the GBC risk.

RESULTS

GSTT1 (null) genotype was at a significantly higher risk and susceptible to GBC (OR = 2.044, CI = 1.225-3.411, P = 0.006), while GSTM1 and GSTP1 genotypes did not show any association to GBC risk. After sex stratification, females diagnosed with GBC had higher GSTT1 (null) genotype (OR = 2.754, CI = 1.428-5.310, P = 0.003) compared to males. GBC patients dwelling in rural areas show higher GSTT1 (null) genotype with two-fold GBC risk (OR = 2.031, CI = 1.200-3.439, P = 0.008). Further, GBC patients with histopathology of adenocarcinoma also showed higher GSTT1 (null) genotype (OR = 2.113, CI = 1.248-3.578, P = 0.005). Gene-gene interaction between GSTT1 (non-null)/GSTP1 (Ile/Val + Val/Val), enhance the GBC risk (OR = 1.840, CI = 1.135-2.982, P = 0.013).

CONCLUSIONS

The present study suggests that GSTT1 (null) genotype has higher susceptibility and risk towards GBC in North Indian population. Female patients, patients with histopathology of adenocarcinoma and rural dwelling GBC patients have higher GSTT1 (null) genotypes and may be at risk of developing GBC. The genotype combination GSTT1 (non-null)/GSTP1 (Ile/Val + Val/Val) has increased GBC susceptibility and may be considered as 'at risk' genotypes for GBC in North Indians.

N-acetyltransferase 2 status and gastric cancer risk: a meta-analysis

Case-control studies on the association between N-acetyltransferase 2 (NAT2) genotype and gastric cancer have provided either controversial or inconclusive results. In order to clarify the influence of NAT2 acetylation status on gastric cancer risk, a meta-analysis was undertaken. The primary outcome measure was the odds ratio (OR) for the risk of gastric cancer associated with the NAT2 genotype. The overall result showed that there was no statistically significant association between NAT2 status and gastric cancer risk (slow acetylation vs. rapid acetylation, OR = 1.10, 95 % confidence interval (CI) 0.97-1.25, p = 0.12). In the analysis stratified by East Asian ethnicity, a significant association was found between gastric cancer and the NAT2 genotype (slow acetylation vs. rapid acetylation, OR = 1.33, 95 % CI 1.11-1.59, p = 0.002). Our pooled data suggest that the NAT2 acetylation status has an effect on the risk of gastric cancer among East Asian populations.

Association between tumor necrosis factor β 252 A/G polymorphism and risk of gastric cancer: a meta-analysis

Tumor necrosis factor β (TNF-β) 252 A/G polymorphism has been implicated to be associated with risk of gastric cancer, but previous studies showed inconsistent and inconclusive results. Therefore, we performed a meta-analysis to assess the association between TNF-β 252 A/G polymorphism and gastric cancer risk. Relevant studies were searched from PubMed database. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate the strength of the associations between TNF-β 252 A/G polymorphism and gastric cancer risk. Overall, 11 individual case-control studies with 2,270 cases and 4,404 controls were included in the final meta-analysis. Meta-analysis of total 11 studies showed that TNF-β 252 A/G polymorphism was associated with the risk of gastric cancer (G vs. A: OR = 1.10, 95% CI 1.02-1.19, P = 0.015; GG/AG vs. AA: OR = 1.21, 95% CI 1.00-1.47, P = 0.049). Subgroup analysis by ethnicity showed that TNF-β 252 A/G polymorphism was only associated with the risk of gastric cancer in Asians, but not Caucasians. The findings from the current meta-analysis suggest that TNF-β 252 A/G polymorphism is associated with the risk of gastric cancer, especially in Asians.