Association of NAT2 gene polymorphisms with susceptibility to esophageal and gastric cancers in the Kashmir Valley

Risk Factors of Esophageal Squamous Cell Carcinoma beyond Alcohol and Smoking

Esophageal squamous cell carcinoma (ESCC) is the sixth most common cause of death worldwide. Incidence rates vary internationally, with the highest rates found in Southern and Eastern Africa, and central Asia. Initial observational studies identified multiple factors associated with an increased risk of ESCC, with subsequent work then focused on developing plausible biological mechanistic associations. The aim of this review is to summarize the role of risk factors in the development of ESCC and propose future directions for further research. A systematic search of the literature was conducted by screening EMBASE, MEDLINE/PubMed, and CENTRAL for relevant publications. In total, 73 studies were included that sought to identify risk factors associated with the development of esophageal squamous cell carcinoma. Risk factors were divided into seven subcategories: genetic, dietary and nutrition, gastric atrophy, infection and microbiome, metabolic, epidemiological and environmental and other risk factors. Risk factors from each subcategory were summarized and explored with mechanistic explanations for these associations. This review highlights several current risk factors of ESCC. These risk factors were explored, and explanations dissected. Most studies focused on investigating genetic and dietary and nutritional factors, whereas this review identified other potential risk factors that have yet to be fully explored. Furthermore, there is a lack of literature on the association of these risk factors with tumor factors and disease prognosis. Further research to validate these results and their effects on tumor biology is absolutely necessary.

Gene-environment interactions in esophageal cancer

Esophageal cancer (EC) is one of the most common malignancies in low- and medium-income countries and represents a disease of public health importance because of its poor prognosis and high mortality rate in these regions. The striking variation in the prevalence of EC among different ethnic groups suggests a significant contribution of population-specific environmental and dietary factors to susceptibility to the disease. Although individuals within a demarcated geographical area are exposed to the same environment and share similar dietary habits, not all of them will develop the disease; thus genetic susceptibility to environmental risk factors may play a key role in the development of EC. A wide range of xenobiotic-metabolizing enzymes are responsible for the metabolism of carcinogens introduced via the diet or inhaled from the environment. Such dietary or environmental carcinogens can bind to DNA, resulting in mutations that may lead to carcinogenesis. Genes involved in the biosynthesis of these enzymes are all subject to genetic polymorphisms that can lead to altered expression or activity of the encoded proteins. Genetic polymorphisms may, therefore, act as molecular biomarkers that can provide important predictive information about carcinogenesis. The aim of this review is to discuss our current knowledge on the genetic risk factors associated with the development of EC in different populations; it addresses mainly the topics of genetic polymorphisms, gene-environment interactions, and carcinogenesis. We have reviewed the published data on genetic polymorphisms of enzymes involved in the metabolism of xenobiotics and discuss some of the potential gene-environment interactions underlying esophageal carcinogenesis. The main enzymes discussed in this review are the glutathione S-transferases (GSTs), N-acetyltransferases (NATs), cytochrome P450s (CYPs), sulfotransferases (SULTs), UDP-glucuronosyltransferases (UGTs), and epoxide hydrolases (EHs), all of which have key roles in the detoxification of environmental and dietary carcinogens. Finally, we discuss recent advances in the study of genetic polymorphisms associated with EC risk, specifically with regard to genome-wide association studies, and examine possible challenges of case-control studies that need to be addressed to better understand the interaction between genetic and environmental factors in esophageal carcinogenesis.

NAT1 and NAT2 genetic polymorphisms and environmental exposure as risk factors for oesophageal squamous cell carcinoma: a case-control study

Background

Tobacco smoking and red meat consumption are some of the known risk factors associated with the development of oesophageal cancer. N-acetytransferases (NAT1 and NAT2) play a key role in metabolism of carcinogenic arylamines present in tobacco smoke and overcooked red meat. We hypothesized that NAT1 and NAT2 genetic polymorphisms may influence the risk of oesophageal cancer upon exposure to environmental carcinogens.

Methods

Single nucleotide polymorphisms (SNPs) in the NAT1 and NAT2 genes were investigated by genotyping 732 cases and 768 healthy individuals from two South African populations to deduce the acetylator phenotype (slow, intermediate or rapid) from the combination of the genotyped SNPs.

Results

The 341 CC genotype (rs1801280) was significantly associated with a reduced risk for oesophageal cancer in the Mixed Ancestry population (OR = 0.31; 95% CI 0.11-0.87). The NAT2 slow/intermediate acetylator status significantly increased the risk among cigarette smokers in the Black population (OR = 2.76; 95% CI 1.69-4.52), as well as among alcohol drinkers in the Mixed Ancestry population (OR = 2.77; 95% CI 1.38-5.58). Similarly, the NAT1 slow/intermediate acetylator status was a risk factor for tobacco smokers in the Black population (OR = 3.41; 95% CI 1.95-5.96) and for alcohol drinkers in the Mixed Ancestry population (OR = 3.41; 95% CI 1.70-6.81). In a case-only analysis, frequent red meat consumption was associated with a significantly increased cancer risk for NAT2 slow/intermediate acetylators in the Mixed Ancestry population (OR = 3.55; 95% CI 1.29-9.82; P = 0.019), whereas daily white meat intake was associated with an increased risk among NAT1 slow/intermediate acetylators in the Black population (OR = 1.82; 95% CI 1.09-3.04; P = 0.023).

Conclusions

Our findings indicate that N-acetylation polymorphisms may modify the association between environmental risk factors and oesophageal cancer risk and that N-acetyltransferases may play a key role in detoxification of carcinogens. Prevention strategies in lifestyle and dietary habits may reduce the incidence of oesophageal cancer in high-risk populations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1105-4) contains supplementary material, which is available to authorized users.

Different phenotypes of the NAT2 gene influences hydralazine antihypertensive response in patients with resistant hypertension

AIM

Hydralazine, a vasodilator used in resistant hypertension (RH) treatment is metabolized by an acetylation reaction mediated by N-acetyltransferase 2, the activity of which depends on NAT2 polymorphisms. Our aim was to evaluate whether different acetylation phenotypes influenced the antihypertensive effect of hydralazine in patients with RH.

PATIENTS & METHODS

DNA samples from 169 RH patients using hydralazine were genotyped by sequencing the NAT2 coding region, and acetylation phenotypes were defined.

RESULTS

Sixty-five patients (38.5%) were intermediate, 60 (35.5%) slow and 21 (12.4%) fast acetylators. Twenty-three (13.6%) patients were indeterminate. Upon association analysis, only slow acetylators had significant blood pressure reductions after hydralazine use, with mean 24-h systolic and diastolic blood pressure reductions of 9.2 and 5.5 mmHg. Four patients presented hydralazine adverse effects resulting in drug withdrawal, three of them were slow acetylators.

CONCLUSION

The slow acetylation phenotype, determined by polymorphisms within NAT2, influenced both the antihypertensive and adverse effects of hydralazine in RH.

NAT2 genetic variations among South Indian populations

The N-acetyltransferases (NATs) are xenobiotic-metabolizing enzymes involved in the metabolism of drugs, environmental toxins and the aromatic amine carcinogens present in cigarette smoke. Genetic variations in NAT2 have long been recognized as the cause of variable enzymatic activity or stability, leading to slow or rapid acetylation. In the present study, we genotyped three single-nucleotide polymorphisms (SNPs) from the NAT2 gene (rs1799929, rs1799930 and rs1799931), using TaqMan allelic discrimination, among 212 individuals from six major South Indian populations and compared the results with other available Indian and worldwide data. All three of the markers followed Hardy-Weinberg equilibrium and were highly polymorphic in the studied populations. The constructed haplotypes showed a high level of heterozygosity. All of the populations in the present study commonly shared only four haplotypes out of the eight possible three-site haplotypes. The haplotypes exhibited fairly high frequencies across multiple populations, where three haplotypes were shared by all six populations with a cumulative frequency ranging from 88.2% (Madiga) to 97.0% (Balija). We also observed a tribal-specific haplotype. A strong linkage disequilibrium (LD) between rs1799929 and rs1799930 was consistent in all of the studied populations, with the exception of the Madiga. A comparison of the genomic regions 20-kb up- and downstream of rs1799930 in a large number of worldwide samples showed a strong LD of this SNP with another NAT2 SNP, rs1112005, among the majority of the populations. Moreover, our lifestyle test (hunter-gatherer versus agriculturist) in comparison with the NAT2 variant suggested that two of the studied populations (Balija and Madiga) have likely shifted their diet more recently.

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.

N-acetyltransferase 2 polymorphisms and risk of esophageal cancer in a Chinese population

Esophageal cancer was the fifth most commonly diagnosed cancer and the fourth leading cause of cancer-related death in China in 2009. Genetic factors might play an important role in the carcinogenesis of esophageal squamous cell carcinoma (ESCC). We conducted a hospital-based case-control study to evaluate ten NAT2 tagging single nucleotide polymorphisms (SNPs) on the risk of ESCC. Six hundred and twenty-nine ESCC cases and 686 controls were recruited. Their genotypes were determined using the ligation detection reaction method. In the single locus analyses, there was a borderline statistically significant difference in genotype frequencies of NAT2 rs1565684 T>C SNP between the cases and the controls (p = 0.057). The NAT2 rs1565684 CC genotype was associated with a borderline significantly increased risk for ESCC (CC vs. TT: adjusted OR = 1.77, 95% CI = 0.97–3.21, p = 0.063 and CC vs. TT/TC: adjusted OR = 1.68, 95% CI = 0.93–3.04, p = 0.085). The association was evident among older patients and patients who never drunk. After the Bonferroni correction, in all comparison models, NAT2 rs1565684 T>C SNP was not associated with ESCC risk (p>0.05). For the other nine NAT2 SNPs, after Bonferroni correction, in all comparison models, the nine SNPs were also not associated with ESCC risk (p>0.05). Thus, nine NAT2 tagging SNPs were not associated with risk of ESCC. NAT2 rs1565684 T>C SNP might play a slight role in ESCC etiology. Additional, larger studies and tissue-specific biological characterization are required to confirm the current findings.

Full-gene-sequencing analysis of N-acetyltransferase-2 in an adult Indian population

AIMS

Drug-metabolizing enzymes play a major role in determining the outcome of drug therapy. N-acetyltransferase-2 (NAT2) is one of the main enzymes involved in metabolism of isoniazid used in treatment of tuberculosis (TB). Several variations in the NAT2 gene give rise to multiple haplotypes that phenotypically code for different acetylator status. The objective was to generate a more unambiguous picture of the NAT2 scenario in India as compared to that obtained from polymerase chain reaction-restriction fragment length polymorphism methods.

METHODS

Full-gene-sequencing analysis of NAT2 was carried out in 181 healthy Indian subjects from different regional groups.

RESULTS

A total of 33 diplotypes were recorded from six known single-nucleotide polymorphisms. The overall frequency of the slow acetylator haplotypes detected in this study was 65%, followed by 26% and 9% intermediate and rapid acetylators, respectively. Of the slow acetylator alleles, the NAT2*5B/*6A occurred in 25% of the study subjects.

CONCLUSIONS

The study indicates that the frequency of slow acetylator alleles is high in the adult Indian population. Since the prevalence of TB is high in this population, pharmacogenetic testing for NAT2 alleles may be advisable before start of therapy with isoniazid to prevent drug toxicity.

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.

An unlikely role for the NAT2 genotypes and haplotypes in the oral cancer of south Indians

The arylamine N-acetyltransferase 2 (NAT2) enzyme detoxifies a wide spectrum of naturally occurring xenobiotics including carcinogens and drugs. Acetylation catalysed by the NAT2 is an important process in metabolic activation of arylamines to electrophilic intermediates that initiate carcinogenesis. Polymorphism in N-acetyltransferase 2 gene was reported to be associated with the susceptibility of various cancers.

OBJECTIVE

The aim of our study was to determine whether there is any association between the susceptibility to oral cancer amongst the variations of NAT2 genotypes.

DESIGN

This study was carried out in 157 patients with oral cancer. The control group consisted of 132 healthy volunteers. The most common polymorphisms rs1799929, rs1799930 and rs1799931 on the NAT2 gene were screened for the genotypes using TaqMan allelic discrimination.

RESULTS

All the three SNPs were polymorphic with minor allele frequency of 0.339, 0.372 and 0.061 for rs1799929, rs1799930 and rs1799931, respectively. None of the polymorphic site deviated from HWE in controls. There were no significant differences in genotype or allele frequencies of three SNPs between controls and cases with oral cancer. Risk of oral cancer development for the carriers of the individual deduced phenotypes was also not statistically significant. Of the 3 studied polymorphisms, 2 were in strong LD and form one haplotype block. None of the haplotype had shown significant association with the oral cancer.

CONCLUSIONS

Our study concludes that the NAT2 genotypes, phenotypes and haplotypes are not involved in the susceptibility to oral cancer in South Indian subjects.

Poorly differentiated oesophageal squamous cell carcinoma in Western Kenya: A case report

Poorly differentiated oesophageal squamous cell carcinoma in Western Kenya: A case report

Role of NQO1 609C>T and NQO2-3423G>A polymorphisms in susceptibility to gastric cancer in Kashmir valley

NADPH: quinone oxidoreductase 1 (NQO1) and dihydronicotinamide riboside: quinone oxidoreductase 2 (NQO2) are cytosolic enzymes that catalyze reductive activation of carcinogens from cigarette smoke, such as nitrosamines and heterocyclic amines. These enzymes also protect cells against oxidative damage from reactive oxygen species. The present study investigated the associations of genetic variants of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility to gastric cancer (GC) as well as their interactions with known risk factors in Kashmir valley. A case control study was performed in 303 subjects (108 GC and 195 healthy controls). All subjects were genotyped using polymerase chain reaction-restriction fragment length polymorphism method. Data were statistically analyzed by chi-square test and logistic regression model. The NQO1 609C>T TT genotype and T allele were significantly associated with increased risk for GC, whereas NQO2 -3423G>A polymorphism did not show any association with GC. Also, NQO1 609C>T TT genotype showed significant association with gastric adenocarcinoma. The interaction of NQO1/NQO2 genotypes with high consumption of salted tea, a known risk factor, did not further modulate the risk of GC. In conclusion, NQO1 609C>T polymorphism shows association with GC risk in Kashmir valley.

Factors that impact susceptibility to fiber-induced health effects

Asbestos and related fibers are associated with a number of adverse health effects, including malignant mesothelioma (MM), an aggressive cancer that generally develops in the surface serosal cells of the pleural, pericardial, and peritoneal cavities. Although approximately 80% of individuals with MM are exposed to asbestos, fewer than 5% of asbestos workers develop MM. In addition to asbestos, other mineralogical, environmental, genetic, and possibly viral factors might contribute to MM susceptibility. Given this complex etiology of MM, understanding susceptibility to MM needs to be a priority for investigators in order to reduce exposure of those most at risk to known environmental carcinogens. In this review, the current body of literature related to fiber-associated disease susceptibility including age, sex, nutrition, genetics, asbestos, and other mineral exposure is addressed with a focus on MM, and critical areas for further study are recommended.

Association of matrix metalloproteinase-7 (-181A>G) polymorphism with risk of esophageal squamous cell carcinoma in Kashmir Valley

BACKGROUND/AIM

Degradation of the basement membrane and extracellular matrix by matrix metalloproteinases (MMPs) is believed to be an essential step in the complicated process of hematogenous metastasis. Matrix metalloproteinase-7 (MMP-7) is a small secreted proteolytic enzyme with a broad substrate specificity, and its expression has been shown to be associated with tumor invasion and metastasis for various cancers.

PATIENTS AND METHODS

To document the role of MMP-7 polymorphism in esophageal carcinogenesis, a case-control study was performed comprising 135 patients with esophageal cancer (EC) and 195 healthy controls. Genotyping was done by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Data were statistically analyzed using χ2 - test and logistic regression models.

RESULTS

Carriers for the MMP-7 (-181A>G) GG were associated with an increased risk for EC [odds ratio (OR = 2.17; 95% confidence interval (CI) = 1.21-3.92; P = 0.010; P-trend = 0.04]. Also, in a recessive model, our results showed that MMP-7 (-181A>G) GG allele conferred significantly higher risk for EC (OR =2.16; 95% CI = 1.31-3.54; P = 0.003). The high risk due to MMP-7 (-181GG) genotype was limited to squamous cell histology of EC (OR = 2.41; 95% CI = 1.27-4.56; P = 0.007). Although smoking (Hukka) and high consumption of salted tea are independent risk factors for EC, the interaction of MMP-7 (-181A>G) genotypes with these factors did not further modulate the risk of EC.

CONCLUSIONS

In conclusion, our results show that MMP-7 (-181A>G) GG carriers are at a higher risk of esophageal squamous cell carcinoma in Kashmir valley.

Epidemiological review of gastric cancer in India

Stomach cancer is the one of the leading cause of cancer in southern region of India. Its incidence is decreasing worldwide yet on global scale stomach cancer remains one of the most common causes of cancer death. Etiology of gastric cancer includes Helicobacter pylori infection, diet and lifestyle, tobacco, alcohol and genetic susceptibility. In this review, we tried to find the contribution of Indian scientist in understanding the descriptive and observational epidemiology of stomach cancer. PubMed was used as a search platform using key words such as "stomach cancer, treatment, clinical characteristics, stomach cancer outcome, epidemiology, etiological factor and their corresponding Mesh terms were used in combination with Boolean operators OR, AND". Most of the reported studies on gastric cancer from India are case report or case series and few are case-control studies. Indian studies on this topic are limited and have observed H. pylori infection, salted tea, pickled food, rice intake, spicy food, soda (additive of food), tobacco and alcohol as risk factors for gastric cancer. More research is required to understand the etiology, develop suitable screening test, to demarcate high-risk population and to develop and evaluate the effect of primary prevention programs.

NAT2 polymorphism and gastric cancer susceptibility: a meta-analysis

BACKGROUND AND AIMS

N-acetyltransferase 2 (NAT2) is a polymorphic enzyme that plays an important role in the metabolism of various potential carcinogens. NAT2 can be subdivided into rapid and slow acetylation phenotype according to the different genotypes. Studies investigating the association between NAT2 polymorphisms and gastric cancer risk in humans showed conflicting results. The aim of this study was to conduct a meta-analysis assessing the association of NAT2 acetylation phenotype with risk of gastric cancer.

METHODS

Relevant studies were identified through a search of Embase, ISI Web of Knowledge, Medline and Chinese Biomedicine Database until January 2010. A meta-analysis was conducted to quantitatively summarize association of NAT2 acetylation phenotype with GC susceptibility.

RESULTS

Thirteen studies were included in the present meta-analysis, which described a total of 2,391 gastric cancer cases and 3,237 controls. The combined ORs for NAT2 slow or rapid acetylator and gastric cancer risk were 1.05 (95% CI 0.810-1.35) and 0.96 (95% CI 0.74-1.23), respectively. When stratifying for race and Lauren's classification, results also showed no significant association in genotype distribution between gastric cancer and control.

CONCLUSIONS

No association is found between NAT2 acetylation status and gastric cancer risk in this meta-analysis.

OGG1 Ser326Cys polymorphism and susceptibility to esophageal cancer in low and high at-risk populations of northern India

BACKGROUND

Esophageal cancer has diverse incidence worldwide, and genetic/environmental risk factors are supposed to be responsible for it. OGG1 Ser326Cys gene polymorphism (rs1052133) has been found to be associated with different cancer susceptibilities and interaction with different environmental factors.

AIM OF THE STUDY

The aim of this study is to detect the role of OGG1 Ser326Cys polymorphism in susceptibility to esophageal cancer in two Northern Indian populations having different incidence rates.

METHODS

A total of 737 cases and controls from two high and low at-risk populations were selected for the study. All the subjects were genotyped by PCR with confronting two-pair primers.

RESULTS

No significant association was found between OGG1 Ser326Cys genotypes and esophageal cancer risk in both of the populations. Gene-environment analysis revealed no significant interaction between OGG1 Ser326Cys genotypes and smoking/high-salted tea intake habits.

CONCLUSION

OGG1 Ser326Cys polymorphism does not have a role in determining susceptibility to esophageal cancer either in high or in low at-risk populations of Northern India.