Anvesha Srivastava

Common genetic variants in pre-microRNAs and risk of gallbladder cancer in North Indian population

MicroRNAs (miRNAs) are small, non-coding RNA molecules that function as negative regulators of gene expression. Common genetic variants (single nucleotide polymorphisms, SNPs) in miRNA genes may alter their expression or maturation resulting in varied functional consequences. Present case–control study evaluated the potential association of three SNPs (rs2910164, rs11614913 and rs3746444) in pre-miRNAs with gallbladder cancer (GBC) risk in 230 GBC cases and 230 controls in a North Indian population. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated for the association of individual SNPs and their interactions with GBC. A non-significant increased risk was observed between carriers of variant genotypes of rs2910164, rs11614913 and rs3746444 (ORs=1.3, 1.3 and 1.1, respectively). This increased risk was more profound in GBC patients with gallstones (ORs=1.4, 1.6 and 1.1, respectively). To further evaluate the cumulative effects of the variant allele, we did a combined unfavorable genotype analysis, which showed a borderline statistical significance. In comparison with the low-risk group (0–2 variant alleles), the high-risk group (>2 variant alleles) had a 1.7-fold (95% CI=1.0–2.8) increased risk for GBC (Ptrend=0.056). These findings suggest, for the first time, that common miRNA variants may not contribute to GBC susceptibility in North Indian population.

Candidate gene studies in gallbladder cancer: A systematic review and meta-analysis

Gallbladder cancer (GBC) is the most frequent biliary tract malignancy. Wide variations in GBC incidence and familial and epidemiological data suggest involvement of a genetic component in its etiopathogenesis. A systematic review of genetic association studies in GBC was performed by applying a meta-analysis approach and systematically reviewing PubMed database using appropriate terms. Odds ratios (ORs) and 95% confidence intervals (CIs) were appropriately derived for each gene-disease association using fixed and random effect models. Meta-regression with population size and genotyping method was also performed. Study quality was assessed using a 10-point scoring system designed from published guidelines. Following a review of 44 published manuscripts and one unpublished report, 80 candidate gene variants and 173 polymorphisms were analyzed among 1046 cases and 2310 controls. Majority of studies were of intermediate quality. Four polymorphisms with >3 separate studies were included in the meta-analysis [OGG1 (rs1052133), TP53 (rs1042522), CYP1A1 (rs1048943) and GSTM1 null polymorphism]. The meta-analysis demonstrated no significant associations of any of the above polymorphisms with GBC susceptibility except TP53 (rs1042522) polymorphism. To conclude, existing candidate gene studies in GBC susceptibility have so far been insufficient to confirm any association. Future research should focus on a more comprehensive approach utilizing potential gene-gene, gene-environment interactions and high-risk haplotypes.

Significant association between toll-like receptor gene polymorphisms and gallbladder cancer.

Background: Toll‐like receptors (TLRs) are evolutionarily conserved cell surface receptors of innate immune system. Various polymorphisms in TLR genes have been identified and associated with susceptibility toward various malignancies such as prostate cancer, gastric cancer and colorectal cancer. The present study was undertaken to examine the potential association of two polymorphisms in TLR2 and TLR4 genes with gallbladder cancer (GBC) susceptibility.

Polymorphisms in ERCC2, MSH2, and OGG1 DNA repair genes and gallbladder cancer risk in a population of Northern India

Genetic variants of DNA repair enzymes may lead to genetic instability and contribute to gallbladder (GB) carcinogenesis.

Cholecystokinin receptor A gene polymorphism in gallstone disease and gallbladder cancer.

Background and Aim:  Gallbladder carcinoma (GBC) usually arises in the background of gallstone disease which may be causatively related to decreased gallbladder contractility. Cholecystokinin receptor A (CCK‐AR) mediates signals resulting in gallbladder contraction. Deteriorating gallbladder contraction promotes gallstone formation. A common genetic polymorphism of CCK‐AR may be causatively associated with the risk of gallstone and GBC. This study aimed to understand the association of CCK‐AR Pst I polymorphism in gallstone disease with gallbladder cancer.

Role of genetic variant A-204C of cholesterol 7α-hydroxylase (CYP7A1) in susceptibility to gallbladder cancer

Gallbladder carcinoma (GBC) usually arises in the background of gallstone disease. Cholesterol 7alpha-hydroxylase (CYP7A1) is a rate-limiting enzyme for cholesterol catabolism and bile acid synthesis. A-204C genetic polymorphism in CYP7A1 may influence gene expression and thus affect the risk of gallstone disease and GBC. We aimed to study the association of A-204C variation of CYP7A1 gene promoter polymorphism in GBC patients, gallstone patients and healthy subjects. The study included 141 histopathologically proven GBC patients, ultrasonographically proven 185 symptomatic gallstone patients and 200 gallstone-free healthy subjects. Genotyping was done by PCR-RFLP method. CYP7A1 A-204C genotypes in control population were in Hardy-Weinberg equilibrium. The CC genotype conferred marginally significant risk for gallstone disease (p=0.051; OR=1.54; 95% CI=0.9-3.4). In GBC patients, the CYP7A1 A-204C polymorphism conferred high risk for GBC at genotype (p=0.005; OR=2.78; 95% CI: 1.3-5.6) as well as allele levels (p=0.008; OR=1.58 and 95% CI: 1.1-2.2). After stratification of GBC patients on the basis of presence or absence of gallstones, CC genotype imparted higher risk for GBC without stones (p=0.002; OR=4.44: 95% CI=1.7-11.3). The association of the polymorphism with GBC was more pronounced in female GBC patients, and also in cancer patients who developed GBC at advanced age. The CC genotype of CYP7A1 is an independent genetic risk factor for GBC but plays a modest role in susceptibility to gallstone disease. The GBC pathogenesis by CYP7A1 polymorphism appears to be independent of gallstone pathway and probably involves genotoxicity due to lipid peroxidation mechanisms.

Gallbladder Cancer Predisposition: A Multigenic Approach to DNA-Repair, Apoptotic and Inflammatory Pathway Genes

Gallbladder cancer (GBC) is a multifactorial disease with complex interplay between multiple genetic variants. We performed Classification and Regression Tree Analysis (CART) and Grade of Membership (GoM) analysis to identify combinations of alleles among the DNA repair, inflammatory and apoptotic pathway genetic variants in modifying the risk for GBC. We analyzed 16 polymorphisms in 8 genes involved in DNA repair, apoptotic and inflammatory pathways to find out combinations of genetic variants contributing to GBC risk. The genes included in the study were XRCC1, OGG1, ERCC2, MSH2, CASP8, TLR2, TLR4 and PTGS2. Single locus analysis by logistic regression showed association of MSH2 IVS1+9G>C (rs2303426), ERCC2 Asp312Asn (rs1799793), OGG1 Ser326Cys (rs1052133), OGG1 IVS4-15C>G (rs2072668), CASP8 -652 6N ins/del (rs3834129), PTGS2 -1195G>A (rs689466), PTGS2 -765G>C (rs20417), TLR4 Ex4+936C>T (rs4986791) and TLR2 –196 to –174del polymorphisms with GBC risk. The CART analysis revealed OGG1 Ser326Cys, and OGG1 IVS4-15C>G polymorphisms as the best polymorphic signature for discriminating between cases and controls. In the GoM analysis, the data was categorized into six sets representing risk for GBC with respect to the investigated polymorphisms. Sets I, II and III described low intrinsic risk (controls) characterized by multiple protective alleles while sets IV, V and VI represented high intrinsic risk groups (GBC cases) characterized by the presence of multiple risk alleles. The CART and GoM analyses also showed the importance of PTGS2 -1195G>A polymorphism in susceptibility to GBC risk. In conclusion, the present multigenic approach can be used to define individual risk profiles for gallbladder cancer in North Indian population.

Single nucleotide polymorphism in the ABCG8 transporter gene is associated with gallbladder cancer susceptibility

Background: Gallbladder cancer (GBC) usually arises against the background of gallstone disease, which may be causatively related to supersaturation of cholesterol in bile. An imbalance in cholesterol homeostasis because of oversecretion of cholesterol in the gallbladder promotes gallstone formation. The excretion of cholesterol from the liver is regulated by adenosine triphosphate‐binding cassette transporter ABCG8. A common genetic polymorphism D19H of ABCG8 associated with gallstone disease may be causatively related to the genetic predisposition of GBC.

Role of ABCG8 D19H (rs11887534) variant in gallstone susceptibility in northern India

Background and Aim:  The excretion of cholesterol from the liver is regulated by the ATP‐binding cassette transporter ABCG8. A common genetic polymorphism D19H of ABCG8 might be related to the genetic predisposition of gallstone disease, which is causatively related to supersaturation of cholesterol in bile. We aimed to examine the role of the ABCG8 D19H (rs11887534) polymorphism in susceptibility to gallstone disease in the northern Indian population.

Haplotype analysis of signal peptide (insertion/deletion) and XbaI polymorphisms of the APOB gene in gallbladder cancer.

Purpose: The incidence of gallbladder cancer (GBC) is usually paralleled by the prevalence of gallstone disease, and genes of cholesterol metabolism have been implicated in gallstone disease. The XbaI and insertion/deletion (ins/del) polymorphism of Apolipoprotein B (APOB) appears to influence cholesterol homoeostasis and possibly risk for gallstone disease. We examined the effect of these polymorphisms individually as well as their haplotypes on GBC and gallstone patients in North Indian population.