Relationship of tobacco smoking, CYP1A1, GSTM1 gene polymorphism and esophageal cancer in Xi’an

Effects of Glutathione S-Transferases (GSTM1, GSTT1 and GSTP1) gene variants in combination with smoking or drinking on cancers: A meta-analysis

BACKGROUND

This meta-analysis aimed to systematically summarize the association between cancer risks and glutathione s-transferases (GSTs) among smokers and drinkers.

METHODS

Literature was searched through PubMed, Web of Science, CNKI, and WANFANG published from 2001 to 2022. Stata was used with fixed-effect model or random-effect model to calculate pooled odds ratios (ORs) and the 95% confidence interval (95% CI). Sensitivity and heterogeneity calculations were performed, and publication bias was analyzed by Begg and Egger's test. Regression analysis was performed on the correlated variables about heterogeneity, and the false-positive report probabilities (FPRP) and the Bayesian False Discovery Probability (BFDP) were calculated to assess the confidence of a statistically significant association.

RESULTS

A total of 85 studies were eligible for GSTs and cancer with smoking status (19,604 cases and 23,710 controls), including 14 articles referring to drinking status (4409 cases and 5645 controls). GSTM1-null had significant associations with cancer risks (for smokers: OR = 1.347, 95% CI: 1.196-1.516, P < .001; for nonsmokers: OR = 1.423, 95% CI: 1.270-1.594, P < .001; for drinkers: OR = 1.748, 95% CI: 1.093-2.797, P = .02). GSTT1-null had significant associations with cancer risks (for smokers: OR = 1.356, 95% CI: 1.114-1.651, P = .002; for nonsmokers: OR = 1.103, 95% CI: 1.011-1.204, P = .028; for drinkers: OR = 1.423, 95% CI: 1.042-1.942, P = .026; for nondrinkers: OR = 1.458, 95% CI: 1.014-2.098, P = .042). Negative associations were found between GSTP1rs1695(AG + GG/AA) and cancer risks among nondrinkers (OR = 0.840, 95% CI: 0.711-0.985, P = .032).

CONCLUSIONS

GSTM1-null and GSTT1-null might be related cancers in combination with smoking or drinking, and GSTP1rs1695 might be associated with cancers among drinkers.

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Alterations of DNA methylation and mRNA levels of CYP1A1, GSTP1, and GSTM1 in human bronchial epithelial cells induced by benzo[a]pyrene

Benzo[a]pyrene (B[a]P) is a known human carcinogen and plays a major function in the initiation of lung cancer at its first proximity. However, the underlying molecular mechanisms are less well understood. In this study, we investigated the impact of B[a]P treatment on the DNA methylation and mRNA levels of CYP1A1, GSTP1, and GSTM1 in human bronchial epithelial cells (16HBEs), and provide scientific evidence for the mechanism study on the carcinogenesis of B[a]P. We treated 16HBEs with DMSO or concentrations of B[a]P at 1, 2, and 5 mmol/L for 24 h, observed the morphological changes, determined the cell viability, DNA methylation, and mRNA levels of CYP1A1, GSTP1, and GSTM1. Compared to the DMSO controls, B[a]P treatment had significantly increased the neoplastic cell number and cell viability in 16HBEs at all three doses (1, 2, and 5 mmol/L), and had significantly reduced the CYP1A1 and GSTP1 DNA promoter methylation levels. Following B[a]P treatment, the GSTM1 promoter methylation level in 16HBEs was profoundly reduced at low dose group compared to the DMSO controls, yet it was significantly increased at both middle and high dose groups. The mRNA levels of CYP1A1, GSTP1, and GSTM1 were significantly decreased in 16HBEs following B[a]P treatment at all three doses. The findings demonstrate that B[a]P promoted cell proliferation in 16HBEs, which was possibly related to the altered DNA methylations and the inhibited mRNA levels in CYP1A1, GSTP1, and GSTM1.

A multinational review: Oesophageal cancer in low to middle-income countries

Oesophageal cancer (OC) is an aggressive neoplasm that manifests in the gastrointestinal tract and is the result of numerous factors that can contribute to the development of the disease. These may include old age, nutritional deficiencies, oesophageal obstruction and food ingestion difficulties. Environmental factors serve a large role in increasing the risk of developing OC. Two factors that serve an increasing risk of developing OC are the use of tobacco and the consumption of alcohol. Genetic factors also exhibit a large effect on the risk of developing OC, for example, the causative genes in Black Africans differ from other races. OC is 3–4 times more common among men than women. OC has been previously reported in >450 000 individuals worldwide, and its incidence is increasing. The current review compares OC in low to middle-income countries with developed countries. The incidence of OC, particularly squamous cell carcinoma (SCC) is high in low and middle-income countries. In developed countries, the incidence of SCC is low compared with adenocarcinoma. The majority of OC cases are diagnosed in the late stages of the disease, leading to high mortality rates. The current review aimed to discuss factors that contribute to the development of this disease in different geographical areas and genetic mechanisms governing these findings. The current review also aims to discuss the preventative treatment options for the disease, and also discusses the diagnosis and surveillance in five LMICs, including South Africa, China, Tanzania, India and Brazil.

Esophageal cancer genetics in South Africa

Esophageal cancer (EC) is an extremely aggressive cancer with one of the highest mortality rates. The cancer is generally only diagnosed at the later stages and has a poor 5-year survival rate due to the limited treatment options. China and South Africa are two countries with a very high prevalence rate of EC. EC rates in South Africa have been on the increase, and esophageal squamous cell carcinoma is the predominant subtype and a primary cause of cancer-related deaths in the black and male mixed ancestry populations in South Africa. The incidence of EC is highest in the Eastern Cape Province, especially in the rural areas such as the Transkei, where the consumption of foods contaminated with Fusarium verticillioides is thought to play a major contributing role to the incidence of EC. China is responsible for almost half of all new cases of EC globally. In China, the prevalence of EC varies greatly. However, the two main areas of high prevalence are the southern Taihang Mountain area (Linxian, Henan Province) and the north Jiangsu area. In both countries, environmental toxins play a major role in increasing the chance that an individual will develop EC. These associative factors include tobacco use, alcohol consumption, nutritional deficiencies and exposure to environmental toxins. However, genetic polymorphisms also play a role in predisposing individuals to EC. These include single-nucleotide polymorphisms that can be found in both protein-coding genes and in non-coding sequences such as miRNAs. The aim of this review is to summarize the contribution of genetic polymorphisms to EC in South Africa and to compare and contrast this to the genetic polymorphisms observed in EC in the most comprehensively studied population group, the Chinese.

Combined heavy smoking and drinking predicts overall but not disease-free survival after curative resection of locoregional esophageal squamous cell carcinoma

INTRODUCTION

The prognostic impact of smoking and drinking on esophageal squamous cell carcinoma (ESCC) was scarcely discussed. We investigated the prognostic value of smoking and drinking and their relationships with clinicopathological characteristics in a large cohort of patients with locoregional ESCC.

PATIENTS AND METHODS

We retrospectively analyzed 488 patients who underwent curative treatment at a single institution between January 2007 and December 2008. A chi-square test was used to evaluate the relationships between smoking and drinking and clinicopathological variables, the Kaplan-Meier method was used for 5-year overall survival (OS) and disease-free survival, and Cox proportional hazards models were applied for univariate and multivariate analyses of variables with respect to OS and disease-free survival.

RESULTS

Heavy smokers were more likely to have advanced Tumor-Node-Metastases (TNM) stage and higher neutrophil/lymphocyte ratio at diagnosis (P<0.05). Drinkers were more likely to have advanced TNM stage, to present with a larger tumor, and to undergo multidisciplinary treatment (P<0.05). For patients who used neither heavy tobacco nor alcohol, used either tobacco or alcohol, and used both, the 5-year OS rates and OS times were 57.4%, 46.4%, and 39.1% (P<0.05) and not reached, 55.2 months, and 41.2 months (P<0.05), respectively. On multivariate analysis, patients who both heavily smoked and drank had 1.392 times the risk of dying during follow-up compared with neither-users (95% CI =1.020-1.901, P=0.037).

CONCLUSION

We identified that combined heavy smoking and drinking might predict poor prognosis in ESCC patients.

Cytochrome P450 1A1 gene polymorphisms and digestive tract cancer susceptibility: a meta-analysis

Cytochrome P450 1A1 (CYP1A1) is a phase I enzyme that regulates the metabolism of environmental carcinogens and alter the susceptibility to various cancers. Many studies have investigated the association between the CYP1A1 MspI and Ile462Val polymorphisms and digestive tract cancer (DTC) risk in different groups of populations, but their results were inconsistent. The PubMed and Embase Database were searched for case–control studies published up to 30th September, 2015. Data were extracted and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the relationship. Totally, 39 case–control studies (9094 cases and 12,487 controls) were included. The G allele in Ile/Val polymorphism was significantly associated with elevated DTC risk with per‐allele OR of 1.24 (95% CI = 1.09–1.41, P = 0.001). Similar results were also detected under the other genetic models. Evidence was only found to support an association between MspI polymorphism and DTC in the subgroups of caucasian and mixed individuals, but not in the whole population (the dominant model: OR = 1.19, 95% CI = 0.94–1.91, P = 0.146). In conclusion, our results suggest that the CYP1A1 polymorphisms are potential risk factors for DTC. And large sample size and well‐designed studies with detailed clinical information are needed to more precisely evaluate our founding.

Role of household exposure, dietary habits and glutathione S-Transferases M1, T1 polymorphisms in susceptibility to lung cancer among women in Mizoram India

BACKGROUND

A case-control study was conducted to evaluate the effect of household exposure, dietary habits, smoking and Glutathione S-Transferases M1, T1 polymorphisms on lung cancer among women in Mizoram, India.

MATERIALS AND METHODS

We selected 230 newly diagnosed primary lung cases and 460 controls from women in Mizoram. Multivariate logistic regression analysis was performed to estimate adjusted odds ratio (OR).

RESULTS

Exposure of cooking oil fumes (p<0.003), wood as heating source for cooking (p=0.004), kitchen inside living room (p=0.001), improper ventilated house (p=0.003), roasting of soda in kitchen (p=0.001), current smokers of tobacco (p=0.043), intake of smoked fish (p=0.006), smoked meat (p=0.001), Soda (p<0.001) and GSTM1 null genotype (p=0.003) were significantly associated with increased risk of lung cancer among women in Mizoram. Significantly protective effect was observed for intake of bamboo shoots (p=<0.001) and egg (p<0.001). A clear increase in dose response gradient was observed for total cooking dish years. Risk for lung cancer tends to increase with collegial effect of indoor environmental sources (p=0.022). Significant correlation was also observed for interaction of GST polymorphisms with some of dietary habits.

CONCLUSIONS

We confirmed the important role of exposure of cooking oil emission and wood smoke, intake of smoked meat, smoked fish and soda (an alkali preparation used as food additives in Mizoram) and tobacco consumption for increase risk of lung cancer among Women in Mizoram.

Cytochrome P450 in Cancer Susceptibility and Treatment

Cytochrome 450 (CYP450) designates a group of enzymes abundant in smooth endoplasmic reticulum of hepatocytes and epithelial cells of small intestines. The main function of CYP450 is oxidative catalysis of various endogenous and exogenous substances. CYP450 are implicated in phase I metabolism of 80% of drugs currently in use, including anticancer drugs. They are also involved in synthesis of various hormones and influence hormone-related cancers. CYP450 genes are highly polymorphic and their variants play an important role in cancer risk and treatment. Association studies and meta-analyses have been performed to decipher the role of CYP450 polymorphisms in cancer susceptibility. Cancer treatment involves multimodal therapies and evaluation of CYP450 polymorphisms is necessary for pharmacogenetic assessment of anticancer therapy outcomes. In addition, CYP450 inhibitors are being evaluated for improved pharmacokinetics and oral formulation of several anticancer drugs.

Role and importance of polymorphisms with respect to DNA methylation for the expression of CYP2E1 enzyme

Different individuals possess slightly different genetic information and show genetically-determined differences in several enzyme activities due to genetic variability. Following an integrated approach, we studied the polymorphisms and methylation of sites contained in the 5' flanking region of the metabolizing enzyme CYP2E1 in correlation to its expression in both tumor and non-neoplastic liver cell lines, since to date little is known about the influence of these (epi)genetic elements in basal conditions and under induction by the specific inductor and a demethylating agent. In treated cells, reduced DNA methylation, assessed both at genomic and gene level, was not consistently associated with the increase of enzyme expression. Interestingly, the Rsa/Pst haplotype differentially influenced CYP2E1 enzyme expression. In addition, regarding the Variable Number of Tandem Repeats polymorphism, cells with A4/A4 genotype showed a greater expression inhibition (ranging from 20% to 30%) compared with others carrying the A2/A2 one, while those cells bringing A2/A3 genotype showed an increase of expression (of 25%, about). Finally, we demonstrated for the first time that the A2 and A3 CYP2E1 alleles play a more important role in the expression of the enzyme, compared with other (epi)genetic factors, since they are binding sites for trans-acting proteins.

Association between CYP1A1 polymorphisms and esophageal cancer: a meta-analysis

Cytochrome P4501A1 (CYP1A1) enzyme is a member of the CYP superfamily of enzymes. CYP1A1 A2455G and T3801C are two most commonly studied polymorphisms loci. Previous studies have reported that CYP1A1 polymorphisms increase esophageal cancer (EC) risk. However, the results remain controversial and ambiguous. To further investigate the association between CYP1A1 polymorphisms (A2455G and T3801C) and EC risk. A meta-analysis was performed to investigate the association between CYP1A1 polymorphisms and EC risk. A total of 13 articles (A2455G and T3801C: 2 papers, A2455G: 8 papers, T3801C: 3 papers) from the PubMed containing information on the CYP1A1 polymorphisms and EC were included in this meta-analysis, with summational sample size of 1,881 EC cases and 3,786 controls. Stratified analysis was performed to evaluate the ethnicity (Caucasians and Asian) and histopathology type (esophageal squamous cell carcinoma and esophageal adenocarcinoma) effect. No obvious publication bias in the two polymorphisms was observed. Our meta-analysis revealed a significant association between the A2455G polymorphism and EC (OR = 1.55 per A allele, 95 % CI 1.29-1.85, P < 0.001). Stratification analysis by ethnicity and histopathology type showed significant association in the population of Asian origin (OR = 1.55, 95 % CI 1.28-1.89, P < 0.001) and in histopathology type of ESCC (OR = 1.40, 95 % CI 1.19-1.65, P < 0.001). We didn't observe the significant association between CYP1A1 T3801C polymorphism and EC. We observed a difference of allele frequencies between Caucasian and Asian population in the meta-analysis. The allele frequencies in our meta-analysis were consistent with the allele frequencies in 1000 Genome Project. Our meta-analysis demonstrated distinct evidence that CYP1A1 A2455G polymorphism was associated with the risk of EC.

GSTM1 and GSTT1 polymorphism and susceptibility to esophageal cancer in high- and low-risk regions of India

Glutathione transferases, a super family of dimeric phase II metabolic enzymes play a vital role in biotransformation of many substances. This study evaluates the influence of genetic polymorphism of GSTM1 and GSTT1 gene loci on esophageal cancer risk in Assam and Delhi from India. DNA from blood samples of esophageal cancer cases (203,112) and controls (286,150) from Assam and Delhi, respectively, were extracted. GSTM1 and GSTT1 polymorphisms were analyzed by multiplex PCR procedure. Differences in proportions were tested using Pearson's chi-square test with odds ratio (OR) and 95 % confidence interval (CI). Risk of esophageal cancer was approximately twice in individuals having homozygous GSTM1 (OR-2.1, 95 % CI, 1.44-3.13) and GSTT1 null genotypes (OR-1.7,95 % CI, 0.99-2.77) in Assam, and around three times in GSTT1 null genotype (OR-2.9, 95 % CI, 1.56-5.27) in Delhi population. GSTM1 null genotype seems to play a protective role (OR-0.7, 95 % CI, 0.39-1.27) in Delhi. A significant association of GSTM1 null genotype with esophageal cancer was observed in a younger age group in Assam (OR-2.7, 95 % CI, 1.48-5.01), and in Delhi population association was observed in smokers with GSTT1 null genotype (OR-2.5, 95 % CI, 1.04-6.07), and alcoholics having GSTM1 null genotype (OR-2.6, 95 % CI, 0.99-6.77). Significant association of GSTM1 null genotype in Assam was observed between cancer cases and controls in fermented betel nut chewers only (OR-2.8, 95 % CI, 1.19-6.72), whereas, smoking and alcohol failed to show any correlation with GSTM1/GSTT1 genotypes. Cancer development is not only due to exogenous or endogenous carcinogens but depends on their interaction with genes that are involved in the detoxification of these carcinogens.

No role for glutathione S-transferase genotypes in Caucasian esophageal squamous cell or adenocarcinoma etiology: an European case-control study

BACKGROUND

Identifying and monitoring high-risk patients can aid the prevention of esophageal cancer (EC). The interaction of environmental risk factor exposure and genetic susceptibility may contribute to the etiology of EC. Biotransformation enzymes such as Glutathione S-Transferases (GSTs ) detoxify mutagenic and genotoxic compounds and therefore control the rate of detoxification of carcinogens. Functional polymorphisms in the genes coding for GSTs alter their enzyme activity in vitro, and were reported to modify EC risk in Asians. We hypothesized that altered enzyme activity GST genotypes influence the susceptibility for esophageal adeno- (EAC) and squamous cell carcinoma (ESCC) in Caucasians.

METHODS

We performed a case-control study including 440 Caucasian patients with EC and 592 healthy Caucasian controls matched for age and sex. Functional polymorphisms were selected and genotypes were determined in GST classes Alpha, Mu, Theta and Pi by means of polymerase chain reaction. Genotypes were classified into predicted high, intermediate and low enzyme activity categories based on in vitro activity data. The distribution of the activity genotypes were compared between patients with EAC or ESCC, and controls. Odds ratios (OR) with 95% confidence intervals (CI) were calculated by logistic regression analyses. Gene-gene interactions were tested and for comparison purposes, the predicted low and intermediate activity genotypes were combined. Genotypes with similar risks for EAC or ESCC were combined and analyzed for multiplicative effects.

RESULTS

Our analyses includes 327 patients with EAC and 106 patients with ESCC. Low or intermediate activity enzyme genotypes for GSTM1, GSTA1, GSTP1 I105V and A114V as well as for GSTT1, did not significantly modify the risk for ESCC or EAC in our Dutch population.

CONCLUSION

Functional genotypes in GST genes are not involved in EAC or ESCC susceptibility in Caucasians, in contrast to results on ESCC from Asia or Africa.

Associations between CYP1A1 and CYP2E1 polymorphisms and susceptibility to esophageal cancer in Chaoshan and Taihang areas of China

PURPOSE

To study the causes of esophageal cancer in Chaoshan and Taihang areas.

METHODS

By using gel-based DNA microarray genotyping method, four cancer-related polymorphisms including CYP1A1 m2, CYP1A1 m4, CYP2E1 Pst I and CYP2E1 Rsa I were studied with 565 (CYP1A1) or 482 (CYP2E1) cases and 468 (CYP1A1) or 466 (CYP2E1) controls.

RESULTS

For CYP1A1 m2, the mutant allele frequencies were 21.3% (Chaoshan) and 19.6% (Taihang), and OR for AG versus AA genotype (Chaoshan) was 1.855 (95% CI [1.227-2.805]). For CYP1A1 m4, no mutant allele was detectable. For CYP2E1 Pst I, the mutant allele frequencies were 27.3% (Chaoshan) and 29.4% (Taihang), and OR for GG versus CC genotype (Taihang) was 3.263 (95% CI [1.059-10.052]). For CYP2E1 Rsa I, the mutant allele frequencies were 27.3% (Chaoshan) and 29.6% (Taihang), and OR for CC versus TT genotype (Taihang) was 3.167 (95% CI [1.026-9.776]).

CONCLUSION

The results suggest that AG genotype of CYP1A1 in Chaoshan area and GG (CC) genotype of CYP2E1 in Taihang area are significantly associated with esophageal cancer susceptibility.

Cytochrome P450 2E1 variable number tandem repeat polymorphisms and health risks: a genotype-phenotype study in cancers associated with drinking and/or smoking

Cytochrome P450 2E1 (CYP2E1) is one of the main enzymes involved in the oxidation of ethanol and in the transformation of a number of potentially dangerous compounds. It has various polymorphic sites, one of which is a variable number tandem repeat (VNTR) polymorphism previously described in the 5'-flanking region. The aim of this study was to investigate the genotype-phenotype association between CYP2E1 VNTR polymorphisms and risky health habits in healthy subjects and to analyze the associations between these polymorphisms with drinking- and/or smoking-related cancers. We analyzed 166 healthy subjects by genotyping for the CYP2E1 VNTR polymorphism associated with drinking and/or smoking habits by the more sensitive restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) method, using the NlaIV restriction enzyme. Sixty cases of pancreatic adenocarcinoma (PA) and 66 with hepatocellular carcinoma (HCC), were also genotyped. Statistical analysis was carried out to investigate the genotype-phenotype associations and to compare certain genotypes and cancer. We found 7 genotypes both in the healthy subjects and patients. The A1/A1 genotype was observed to be mainly associated with non-drinkers and -smokers (87.5 and 75.0%, respectively); moreover it was never found in the PA or HCC patients. Conversely, a weak association between A2/A3 with smokers (45.8%) and A4/A4 with drinkers (53.9%) was detected. In addition, the A4/A4 genotype was found to be significantly associated to PA [odds ratio (OR)=3.25; 95% confidence interval (CI) 1.21-7.50]. Our data demonstrate that certain CYP2E1 VNTR genotypes are associated with drinking and/or smoking habits; consequently, they may contribute either to the decreased or increased risk of developing drinking- and/or smoking-related cancers. In particular, we hypothesize that the A1/A1 VNTR genotype may have a protective role against drinking- and/or smoking-related cancers, and that A4/A4 may be a high-risk genotype during the early stages of cancer.

Glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) null polymorphisms, smoking, and their interaction in oral cancer: a HuGE review and meta-analysis

The association between glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) null polymorphisms and oral cancer is not consistent across studies, and data on their interaction with smoking in oral cancer are lacking. The authors systematically searched PubMed and SciVerse Scopus for case-control studies examining the association between null genotypes of the GSTM1 and GSTT1 genes and oral cancer. Twenty-eight case-control studies published in English were identified. Summary odds ratios were derived via random-effects models. The summary odds ratio for the GSTM1 null genotype was 1.43 in Asians (95% confidence interval (CI): 1.14, 1.78; P < 0.01, I (2) = 73%) and 0.98 in Caucasians (95% CI: 0.76, 1.28; P = 0.91, I (2) = 0%). Case-only analysis of 6 studies (552 cases) showed an inverse multiplicative interaction between GSTM1 null polymorphisms and smoking (ever/high levels of smoking vs. never/low levels) (odds ratio (OR) = 0.51, 95% CI: 0.32, 0.82; P = 0.01, I (2) = 34%). The GSTT1 null genotype was not significantly associated with oral cancer in Asians (OR = 1.07, 95% CI: 0.82, 1.38; P = 0.63, I (2) = 65%) or Caucasians (OR = 1.04, 95% CI: 0.41, 2.65; P = 0.93, I (2) = 55%). In conclusion, the GSTM1 null genotype may be associated with a higher risk of oral cancer in Asians but not in Caucasians, and this effect may be modified by smoking status. The GSTT1 null genotype may not be associated with oral cancer.

Cytochrome P450 2E1 and head and neck cancer: interaction with genetic and environmental risk factors

The present case-control study investigates the association of polymorphisms in cytochrome P450 2E1 (CYP2E1), involved in the metabolism of tobacco carcinogens and alcohol, with Head and Neck Squamous Cell Carcinoma (HNSCC). In addition, the interaction of CYP2E1 (CYP2E1*5B and CYP2E1*6) with other genetic factors (null genotype of glutathione-S-Transferase M1, GSTM1, X-Ray Repair Cross Complementing Group I, XRCC1 (Arg194Trp), and environmental risk factors such as alcohol and tobacco in modifying HNSCC risk were investigated. Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a total of 350 male cases of HNSCC and an equal number of healthy male controls. Statistical analysis showed a significant increase in HNSCC risk in cases with variant genotypes of CYP2E1*5B (RsaI) (O.R. 3.44; 95% C.I. 1.45-8.14) and CYP2E1*6 (DraI) (O.R. 1.76; 95% C.I. 1.28-2.41). Haplotype analysis revealed that haplotype T-A was associated with a greater than 10-fold increase in risk for HNSCC. Our data also revealed a several fold increase in HNSCC risk in cases carrying a combination of variant genotypes of CYP2E1 with the null genotype of GSTM1 or XRCC1 variant genotypes. Alcohol or tobacco use (both smoking and chewing) were also found to interact with variant genotypes of CYP2E1 in significantly enhancing HNSCC risk. This increase in risk associated with an interaction of CYP2E1 genotypes with GSTM1 or XRCC1 or with tobacco and alcohol use demonstrates the importance of gene-gene and gene-environment interactions in the development of HNSCC.

Association studies of CYP1A1 and GSTM1 polymorphisms with esophageal cancer risk: evidence-based meta-analyses

BACKGROUND AND AIMS

Previous studies have implicated cytochrome P450 1A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) polymorphisms as risk factors for various cancers. A number of studies have been devoted to the association of CYP1A1 or GSTM1 polymorphism with susceptibility to esophageal carcinoma and have yielded conflicting results. We undertook this study to assess possible associations of esophageal cancer risk with CYP1A1 genetic variation and GSTM1 null genotype, respectively.

METHODS

We conducted a search in MEDLINE, EMBASE and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published until May 2008. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.

RESULTS

Ultimately, 26 studies met the included criteria and thus were selected. Relevant data were extracted and further analyzed using systematic meta-analyses. Results showed that the overall OR for CYP1A1 Msp1 polymorphism was 1.24 (95% CI = 0.84-1.83). Restricting analyses to ethnic groups and histological groups, data failed to show a correlation between CYP1A1 Msp1 polymorphism and esophageal cancer risk. Overall OR for CYP1A1 exon7 polymorphism was 1.37 (95% CI = 1.06-1.77), and subgroup analyses showed that CYP1A1 exon7 polymorphism increases esophageal cancer risk in Asians but not in Caucasians. As for GSTM1 deficiency, the overall OR was 1.20 (95% CI = 0.96-1.49), and further subgroup analyses failed to show a marked association of GSTM1 deletion with esophageal cancer.

CONCLUSIONS

Results of the present study suggest that CYP1A1 exon7 polymorphisms may be a risk factor for esophageal cancer in Asians but not in Caucasians, whereas neither CYP1A1 Msp1 nor GSTM1 polymorphism was associated with increased susceptibility to esophageal cancer.

Contribution of alcohol and tobacco use in gastrointestinal cancer development

Tobacco smoke and alcohol are major risk factors for a variety of cancer sites, including those of the gastrointestinal tract. Tobacco smoke contains a great number of mutagenic and carcinogenic compounds, including polycyclic carbohydrates, nitrosamines, and nicotine, while ethanol per se has only weak carcinogenic potential, but its first metabolite, acetaldehyde, is a mutagen and carcinogen, since it forms stable adducts with DNA. The possibility of proto-oncogene mutation in gastrointestinal mucosa cells may be associated with tobacco smoking-induced cancers through the formation of unfavorable DNA adducts. Individuals with defective DNA repair mechanisms and unfavorable genetic make-up for carcinogen metabolism may be at increased risk for gastrointestinal cancers. Individuals with a high production rate of acetaldehyde from ethanol also have an increased cancer risk when they drink chronically. These include individuals with a genetically determined increased acetaldehyde production due to alcohol dehydrogenase polymorphism and those with a decreased detoxification of acetaldehyde due to acetaldehyde dehydrogenase mutation. In addition, oral bacterial overgrowth due to poor oral hygiene also increases salivary acetaldehyde. Dietary deficiencies such as a lack of folate, riboflavine, and zinc may also contribute to the increase cancer risk in the alcoholic patient. It is of considerable importance that smoking and drinking act synergistically. Smoking increases the acetaldehyde burden following alcohol consumption and drinking enhances the activation of various procarcinogens present in tobacco smoke due to increased metabolic activation by an induced cytochrome P450-2E1-dependent microsomal biotransformation system in the mucosa of the upper digestive tract and the liver.

Phase I and II enzyme polymorphisms as risk factors for Barrett's esophagus and esophageal adenocarcinoma: a systematic review and meta-analysis

Although several studies have examined the association between phase I/II enzyme polymorphisms and esophageal adenocarcinoma (EAC) and/or Barrett's esophagus (BE), their overall findings remain unclear. We performed a systematic review and meta-analysis to determine whether phase I/II polymorphisms are independent risk factors for either BE or EAC. We employed keyword searches in multiple databases to identify studies published before October 1, 2007. Single-nucleotide polymorphisms (SNPs) examined in > or =3 studies were meta-analyzed to obtain a pooled estimate of effect. Meta-analysis suggested the minor allele for GSTP1 Val(105) conveys modest excess risk (odds ratio [OR](BE)= 1.50, 95% confidence interval [CI] 1.16-1.95; OR(EAC)= 1.20, 95% CI 0.94-1.54). No excess risk was observed with GSTM1 null (OR(BE)= 0.77, 95% CI: 0.56-1.08; OR(EAC)= 1.08, 95% CI: 0.79-1.48), GSTT1 null (OR(BE)= 1.35, 95% CI: 0.91-2.01; OR(EAC)= 0.84, 95% CI: 0.48-1.49), or CYP1A Val(462) (OR(EAC)= 0.89, 95% CI: 0.40-1.97). Insufficient data existed to meta-analyze remaining SNPs. Our review identified GSTP1(Ile105Val) as a possible risk factor for BE and EAC in Caucasian males. No excess risk was observed for other phase I/II polymorphisms with sufficient data to meta-analyze. Additional studies are needed to determine if GSTP1 conveys excess risk in females or non-Caucasians and to evaluate other phase I/II polymorphisms.

Genetic polymorphisms and esophageal cancer risk

The aim of this paper is to review and evaluate, in a comprehensive manner, the published data regarding the contribution of genetic polymorphisms to risk of esophageal cancer, including squamous cell carcinoma (SCC) and adenocarcinoma, in humans. All relevant studies available in MEDLINE and published before February 2007 were identified. Studies carried out in humans and that compared esophageal cancer patients with at least 1 standard control group were considered for analysis. One-hundred studies and 3 meta-analyses were identified. Eighty (80%) studies were conducted in Asian countries, particularly China including Taiwan (60 (60%) studies). The most intensively examined genes were those encoding carcinogen metabolic enzymes. The most widely studied gene was GSTM1 (15 studies), followed by ALDH2 (11 studies). ALDH2, MTHFR C677T, CYP1A1 Ile/Val, CYP1A1MspI, CYP2E1, GSTP1, GSTM1 and GSTT1 were examined by meta-analyses and significant relations were found between ALDH2*1*2 and the CYP1A1 Val allele and increased risk of esophageal cancer. In addition, increased risk of esophageal SCC was consistently associated with the ADH2*1*2 and the p53 codon 72 Pro/Pro genotypes. Cohort studies that simultaneously consider multiple genetic and environmental factors possibly involved in esophageal carcinogenesis are needed to ascertain not only the relative contribution of these factors to tumor development but also the contributions of their putative interactions.

The NAD(P)H:quinone oxidoreductase I C609T polymorphism modifies the risk of Barrett esophagus and esophageal adenocarcinoma

PURPOSE

The role of genetic susceptibility to esophageal adenocarcinoma and its precursor lesion Barrett esophagus has not been fully elucidated. This study investigated the effect of polymorphisms in the manganese superoxide dismutase (MnSOD) and NAD(P)H:quinone oxidoreductase 1 (NQO1) genes in modulating the risk of developing Barrett esophagus or esophageal adenocarcinoma.

METHODS

A total of 584 patients (146 esophagitis, 200 Barrett esophagus, 144 esophageal adenocarcinoma, and 94 controls) were genotyped for the MnSOD C14T and NQO1 C609T polymorphisms using polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

The NQO1 TT genotype was less common in Barrett esophagus (2.0%) and esophageal adenocarcinoma (1.4%) patients, compared with both esophagitis patients (7.6%) and controls (5.4%). After adjustment for sex, age, body mass index, reflux symptoms, and smoking status, patients with the homozygous TT genotype had a 4.5-fold decreased risk of developing Barrett esophagus (odds ratio = 0.22, 95% confidence interval = 0.07-0.76, P = 0.01) and a 6.2-fold decreased risk of esophageal adenocarcinoma (odds ratio = 0.16, 95% confidence intervals = 0.03-0.94, P = 0.04) compared with individuals with the TC and CC genotypes. No significant differences between groups were observed for the MnSOD polymorphism (P = 0.289).

CONCLUSIONS

Overall, the results of this study suggest that the NQO1 TT genotype may offer protection from reflux complications such as Barrett esophagus and esophageal adenocarcinoma.

GST, NAT1, CYP1A1 polymorphisms and risk of esophageal and gastric adenocarcinomas

BACKGROUND

Polymorphisms in glutathione-S-transferase (GST), N-acetyltransferase (NAT) 1, and CYP1A1 genes have been suggested as susceptibility factors for esophageal and gastric adenocarcinomas, but have not been consistently linked to elevated risks. In a population-based case-control study, we examined risks in relation to polymorphisms of the following genes: GSTP1; GSTM1; GSTT1; NAT1; and CYP1A1.

METHODS

Histologically confirmed incident cases, ages 30-79, were identified in three US locations. Population controls from the same catchment areas were frequency matched to expected age and sex distributions of esophageal and gastric cardia adenocarcinomas. DNA was extracted from buffy coat for PCR-based assays, with interpretable genotyping results obtained from 209 controls, 67 esophageal adenocarcinomas, 60 gastric cardia adenocarcinomas, and 56 noncardia gastric adenocarcinomas. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated among whites, adjusting for age, sex, and study center.

RESULTS

In all histologic subgroups, ORs were somewhat elevated for the GSTP1 Val/Val genotype (versus Ile/Ile), although 95% CIs included 1.00. The respective ORs for esophageal, cardia, and other gastric adenocarcinomas were 1.73 (0.75-4.02), 1.46 (0.57-3.73), and 1.22 (0.48-3.09). No consistent patterns of elevated risk were associated with the null GSTM1 or GSTT1 genotypes, one or two copies of NAT110 or 11 alleles, or CYP1A1 Val/Val or Ile/Val genotypes (versus Ile/Ile).

CONCLUSIONS

Additional research in larger samples is needed to further assess polymorphisms and their interactions with epidemiologic risk factors, particularly for esophageal adenocarcinoma, which has been increasing markedly in incidence.

Variation in genes relevant to aromatic hydrocarbon metabolism and the risk of adult brain tumors

Genes involved in phase I and phase II regulation of aromatic hydrocarbon-induced effects exhibit sequence variability that may mediate the risk of adult brain tumors. We evaluated associations between gene variants in CYP1A1, CYP1B1, GSTM3, EPHX1, and NQO1 and adult brain tumor incidence. Cases were patients with glioma (n = 489), meningioma (n = 197), or acoustic neuroma (n = 96) diagnosed from 1994 to 1998 at three U.S. hospitals. Controls were 799 patients admitted to the same hospitals for nonmalignant conditions. DNA was extracted from blood samples collected from 1277 subjects, and genotyping was conducted for CYP1A1 I462V, CYP1B1 V432L, EPHX1 Y113H, GSTM3 *A/*B (intron 6 deletion), and NQO1 P187S. The CYP1B1 V432L homozygous variant was associated with decreased risk of meningioma (odds ratio [OR] = 0.6; 95% CI, 0.3-1.0) but not the other tumor types. The GSTM3 *B/*B genotype was associated with increased risk of glioma (OR = 2.3; 95% CI, 1.0-5.2) and meningioma (OR = 3.6; 95% CI, 1.3-9.8). Increased risks associated with GSTM3 *B/*B were observed in younger subjects (age < 50) and older subjects (age > or = 50), in men and women, and within each study site. The magnitude of association for GSTM3 with glioma and meningioma was greater among ever-smokers than among those who had never smoked. None of the other genotypes showed consistent associations with any tumor type. The association with the GSTM3 *B allele, while intriguing, requires replication, and additional research is needed to clarify the function of the GSTM3 alleles studied here.

Phase I/II enzyme gene polymorphisms and esophageal cancer risk: A meta-analysis of the literature

AIM: Phase I/II enzymes metabolize environmental carcin-ogens and several functional polymorphisms have been reported in their encoding genes. Although their significance with regard to esophageal carcinogenicity has been examined epidemiologically, it remains controversial. The present systematic review of the literature was performed to clarify associations.

METHODS: Eligible studies were case-control or cohort studies published until September 2004 that were written in any language. From PubMed and a manual review of refe-rence lists in relevant review articles, we obtained 16 studies related to the CYP1A1 Ile-Val substitution in exon 7, CYP1A1 MspI polymorphisms, CYP2E1 RsaI polymorphisms, GSTM1 null type, GSTT1 null type and GSTP1 Ile104Val. All were of case-control design. Summary statistics were odds ratios (ORs) comparing heterozygous-, homozygous-non-wild type or these two in combination with the homozygous wild type, or the null type with the non-null type for GSTM1 and GSTT1. A random effect model was used to estimate the summary ORs. A meta-regression analysis was applied to explore sources of heterogeneity.

RESULTS: Individuals with the Ile-Val substitution in CYP1A1 exon 7 had increased esophageal cancer risk, with ORs (95%CI) compared with Ile/Ile of 1.37 (1.09-1.71), 2.52 (1.62-3.91) and 1.44 (1.17-1.78) for Ile-Val, Val/Val genotype and the combined group. No significant association was found between esophageal cancer risk and the other genetic parameters.

CONCLUSION: A significant association exists between the CYP1A1 Ile-Val polymorphism and risk of esophageal cancer. Polymorphisms that increase the internal exposure to activated carcinogens may increase the risk of esophageal cancer.

Polymorphic variation of Cyp1A1 is associated with the risk of gastric cardia cancer: a prospective case-cohort study of cytochrome P-450 1A1 and GST enzymes

OBJECTIVE

To determine if genetic polymorphisms of CYP1A1, GSTM1, GSTP1, or GSTT1 are associated with an increased risk of developing esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), or either in a high-risk Asian population.

METHODS

We conducted a case-cohort analysis with 5 years of prospective follow-up. The analytical cohort contained 642 individuals who participated in either the Dysplasia Trial (DT) or the General Population (GPT) of the Nutrition Intervention Trials conducted in Linxian, China, and included 131 cases of ESCC and 90 cases of GCC. Genotyping analysis was performed on DNA extracted from red blood cells using a PureGene kit (Gentra Systems, Inc., Minneapolis, MN) and real-time PCR analysis amplification (Taq-Man). Relative risks and 95% confidence intervals were estimated using the case - cohort estimator for the Cox proportional hazards models. p-values from nested models with genotyping variables came from score tests.

RESULTS

The relative risks for developing ESCC, GCC, or either cancer were calculated in the entire analytic cohort for GSTM1, P1*B (A313G), and T1 and CYP1A1*2A (T3801C) and *2C (A2455G) genotypes, and no significant associations were identified. However, because of the difference in cancer risks between the DT (9.3 cases per 1000 person years) and the GPT (5.3 cases), the analytical cohort was stratified by trial; the DT participants who were heterozygous or homozygous for the variant-allele at CYP1A1*2A had a reduced risk for developing GCC (adjusted RR (95% CI) 0.47 (0.23-1.00) p = 0.037).

CONCLUSIONS

This study found an association for the CYP1A1*2A variant allele and a reduced risk of GCC in people at high risk for development of this disease. This finding is consistent with previous studies suggesting that substrates for the cytochrome P-450 1A1 metabolic pathway, such as polycyclic aromatic hydrocarbons, may be etiologically significant in this high-risk region.

Genetic polymorphisms in three Iranian populations with different risks of esophageal cancer, an ecologic comparison

The age-standardized incidence of esophageal cancer (EC) varies from 3 to >100/100,000 per year in different provinces of Iran. This striking variation of incidence is associated with differences in ethnic backgrounds, raising the possibility that genetic factors are involved in the pathogenesis of EC. We compared the frequencies of polymorphisms in ten genes that have been hypothesized to have a role in risk of EC (CYP1A1, CYP2A6, CYP2E1, GSTM1, GSTP1, GSTT1, ADH2, ADH3, ALDH2, and O6-MGMT) among three Iranian ethnic groups with highly varying rates of EC. These three groups included high-risk Turkomans, medium-risk Turks, and low-risk Zoroastrian Persians. Compared to Zoroastrians, Turkomans had higher frequency of four alleles that are speculated to favor carcinogenesis (CYP1A1 m1, CYP1A1 m2, CYP2A6*9, and ADH2*1); these results are consistent with an influence of these allele variants on the population risk of EC. However, none of these four alleles had a high enough prevalence in Turkomans to explain the high rates of EC in this group. Three of these four alleles (CYP1A1 m1, CYP1A1 m2, CYP2A6*9) were less frequent among Turkomans than in some Asian populations with lower risks of EC. We conclude that it is unlikely that variations in these polymorphic genes are major contributors to the high incidence of EC among Turkomans in Iran.

Genotoxicity of tobacco smoke and tobacco smoke condensate: a review

This report reviews the literature on the genotoxicity of mainstream tobacco smoke and cigarette smoke condensate (CSC) published since 1985. CSC is genotoxic in nearly all systems in which it has been tested, with the base/neutral fractions being the most mutagenic. In rodents, cigarette smoke induces sister chromatid exchanges (SCEs) and micronuclei in bone marrow and lung cells. In humans, newborns of smoking mothers have elevated frequencies of HPRT mutants, translocations, and DNA strand breaks. Sperm of smokers have elevated frequencies of aneuploidy, DNA adducts, strand breaks, and oxidative damage. Smoking also produces mutagenic cervical mucus, micronuclei in cervical epithelial cells, and genotoxic amniotic fluid. These data suggest that tobacco smoke may be a human germ-cell mutagen. Tobacco smoke produces mutagenic urine, and it is a human somatic-cell mutagen, producing HPRT mutations, SCEs, microsatellite instability, and DNA damage in a variety of tissues. Of the 11 organ sites at which smoking causes cancer in humans, smoking-associated genotoxic effects have been found in all eight that have been examined thus far: oral/nasal, esophagus, pharynx/larynx, lung, pancreas, myeoloid organs, bladder/ureter, uterine cervix. Lung tumors of smokers contain a high frequency and unique spectrum of TP53 and KRAS mutations, reflective of the PAH (and possibly other) compounds in the smoke. Further studies are needed to clarify the modulation of the genotoxicity of tobacco smoke by various genetic polymorphisms. These data support a model of tobacco smoke carcinogenesis in which the components of tobacco smoke induce mutations that accumulate in a field of tissue that, through selection, drive the carcinogenic process. Most of the data reviewed here are from studies of human smokers. Thus, their relevance to humans cannot be denied, and their explanatory powers not easily dismissed. Tobacco smoke is now the most extreme example of a systemic human mutagen.

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An evolutionary perspective on single-nucleotide polymorphism screening in molecular cancer epidemiology

Given that there are millions of single-nucleotide polymorphisms (SNPs) in the entire human genome, a major difficulty faced by scientists in planning costly population-based genotyping is to choose target SNPs that are most likely to affect phenotypic functions and ultimately contribute to disease development. Although it is widely accepted that sequences with important functionality tend to be less variable across species because of selective pressure, to what extent evolutionary conservation is mirrored by epidemiological outcome has never been demonstrated. In this study, we surveyed odds ratios detected for 46 SNPs in 39 different cancer-related genes from 166 molecular epidemiological studies. The conservation levels of amino acid that these SNPs affected were calculated as a tolerance index by comparing sequences from different species. Our results provide evidence of a significant relationship between the detected odds ratios associated with cancer risk and the conservation levels of the SNP-affected amino acids (P = 0.002; R(2) = 0.06). Tolerance indices were further calculated for 355 nonsynonymous SNPs identified in 90 human DNA repair genes, of which 103 caused amino acid changes in very conserved positions. Our findings support the concept that SNPs altering the conserved amino acids are more likely to be associated with cancer susceptibility. Using such a molecular evolutionary approach may hold great promise for prioritizing SNPs to be genotyped in future molecular epidemiological studies.

Expression properties of recombinant pEgr-P16 plasmid in esophageal squamous cell carcinoma induced by ionizing irradiation

AIM: To construct the recombinant pEgr-P16 plasmid for the investigation of its expression properties in esophageal squamous cell carcinoma induced by ionizing irradiation and the feasibility of gene-radiotherapy for esophageal carcinoma.

METHODS: The recombinant pEgr-P16 plasmid was constructed and transfected into EC9706 cells with lipofectamine. Western blot, quantitative RT-PCR and flow cytometry were performed to study the expression of pEgr-P16 in EC9706 cells and the biological characteristics of EC9706 cell line after transfection induced by ionizing irradiation.

RESULTS: The eukaryotic expression vector pEgr-P16 was successfully constructed and transfected into EC9706 cells. The expression of P16 was significantly increased in the transfected cells after irradiation while the transfected cells were not induced by ionizing irradiation. The induction of apoptosis in transfection plus irradiation group was higher than that in plasmid alone or irradiation alone.

CONCLUSION: The combination of pEgr-P16 and irradiation could significantly enhance the P16 expression property and markedly induce apoptosis in EC9706 cells. These results may lay an important experimental basis for gene radiotherapy for esophageal carcinoma.

Separation and identification of differentially expressed nuclear matrix proteins between human esophageal immortalized and carcinomatous cell lines

AIM: To separate and identify differentially expressed nuclear matrix proteins (NMPs) between the immortalized human esophageal epithelial cell line (SHEE) and the malignantly transformed esophageal carcinoma cell line (SHEEC), and to provide new ways for finding specific markers and the pathogenesis of esophageal carcinoma.

METHODS: SHEE and SHEEC cell lines were used to extract NMPs. The quality of NMPs was monitored by Western blot analysis including DNA topoisomerase IIα, proliferation cell nuclear antigen (PCNA) and histone. NMPs of SHEE and SHEEC were analyzed by two-dimensional electrophoresis (2-DE), silver staining and PDQuest6.2 image analysis software. Three spots in which the differentially expressed NMPs were more obvious, were selected and analyzed with matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS) and database search.

RESULTS: Western blot analysis revealed that DNA topoisomerase IIα and PCNA were detected, and the majority of histones were deleted in NMPs of SHEE and SHEEC. After 2-DE image analysis by PDQuest6.2 software, the 2-DE maps were detected with an average of 106 ± 7.1 spots in SHEE and 132 ± 5.0 spots in SHEEC. Most of them were matched one another (r = 0.72), only 16 protein spots were found differing in intensity. Three NMPs including cytoskeletal tropomyosin, FK506-binding protein 6, similar to retinoblastoma binding protein 8 were preliminarily identified by MALDI- TOF-MS.

CONCLUSION: These differentially expressed NMPs may play an important role during malignant transformation from SHEE to SHEEC. Their separation and identification will contribute to searching for specific markers and probing into the pathogenesis of esophageal carcinoma.

FT-IR spectroscopic analysis of normal and cancerous tissues of esophagus

AIM: To investigate the special Fourier transform infrared spectroscopy (FT-IR) spectra in normal and cancerous tissues of esophagus.

METHODS: Twenty-seven pairs of normal and cancerous tissues of esophagus were studied by using FT-IR and the special spectra characteristics were analyzed in different tissues.

RESULTS: Different spectra were found in normal and cancerous tissues. The peak at 1550/cm was weak and wide in cancerous tissues but strong and high in normal tissues.The ratio of I 1647/I 1550 was 2.0 in normal tissues and 2.36 in cancerous tissues (P < 0.05). The ratio of I 1550/I 1080 was 4.5 in normal tissues and 3.4 in cancerous tissues (P < 0.01). The peak at 1453/cm was higher than at 1402/cm in normal tissue and lower than at 1402/cm in cancerous tissues.

CONCLUSION: The results indicate that FTIR may be used in clinical diagnosis.

DNA polymerase ζ: new insight into eukaryotic mutagenesis and mammalian embryonic development

Information about the mechanisms that generate mutations in eukaryotes is likely to be useful for understanding human health concerns, such as genotoxicity and cancer. Eukaryotic mutagenesis is largely the outcome of attacks by endogenous and environmental agents. Except for DNA repair, cell cycle checkpoints and DNA damage avoidance, cells have also evolved DNA damage tolerance mechanism, by which lesion-targeted mutation might occur in the genome during replication by specific DNA polymerases to bypass the lesions (translesion DNA synthesis, TLS), or mutation on undamaged DNA templates (untargeted mutation) might be induced. DNA polymerase ζ (pol ζ), which was found firstly in budding yeast Saccharomyces cerevisiae and consists of catalytic subunit scRev3 and stimulating subunit scRev7, has received more attention in recent years. Pol ζ is a member of DNA polymerase δ subfamily, which belongs to DNA polymerase B family, and exists in almost all eukaryotes. Human homolog of the scRev3 gene is located in chromosome region 6q21, and the mouse equivalent maps to chromosome 10, distal to the c-myb gene and close to the Macs gene. Alternative splicing, upstream out-of frame ATG can be found in yeast scRev3, mouse and human homologs. Furthermore, the sequence from 253-323 immediate upstream of the AUG initiator codon has the potential to form a stem-loop hairpin secondary structure in REV3 mRNA, suggesting that human REV3 protein may be expressed at low levels in human cells under normal growth conditions. The functional domain analysis showed that yeast Rev3-980 tyrosine in conserved region II is at the polymerase active site. Human REV3 amino acid residues 1776-2195 provide a REV7 binding domain, and REV7 amino acid residues 1-211 provide a bind domain for REV1, REV3 and REV7 itself. More interestingly, REV7 interacts with hMAD2 and therefore might function in the cell cycle control by affecting the activation of APC (anaphase promoting complex). Currently it has been known that pol ζ is involved in most spontaneous mutation, lesion-targeted mutation via TLS, chemical carcinogen induced untargeted mutation and somatic hypermutation of antibody genes in mammalian. In TLS pathway, pol ζ acts as a "mismatch extender" with combination of other DNA polymerases, such as pol ι. Unlike in yeast, it was found that pol ζ also functioned in mouse embryonic development more recently. It was hypothesized that the roles of pol ζ in TLS and cell cycle control might contribute to mouse embryonic lethality.

Response of human REV3 gene to gastric cancer inducing carcinogen N-methyl-N’-nitro-N-nitrosoguanidine and its role in mutagenesis

AIM: To understand the response of human REV3 gene to gastric cancer inducing carcinogen N-methyl-N’-nitro-N-nitrosoguanidine (MNNG) and its role in human mutagenesis.

METHODS: The response of the human REV3 gene to MNNG was measured in human 293 cells and FL cells by RT-PCR. By using antisense technology, mutation analysis at HPRT locus (on which lesion-targeted mutation usually occurs) was conducted in human transgenic cell line FL-REV3^- by 8-azaguanine screening, and mutation occurred on undamaged DNA template was detected by using a shuttle plasmid pZ189 as the probe in human transgenic cell lines 293-REV3^- and FL-REV3^-. The blockage effect of REV3 was measured by combination of reverse transcription-polymerase chain reaction to detect the expression of antisense REV3 RNA and Western blotting to detect the REV3 protein level.

RESULTS: The human REV3 gene was significantly activated by MNNG treatment, as indicated by the upregulation of REV3 gene expression at the transcriptional level in MNNG-treated human cells, with significant increase of REV3 expression level by 0.38 fold, 0.33 fold and 0.27 fold respectively at 6 h, 12 h and 24 h in MNNG-treated 293 cells (P < 0.05); and to 0.77 fold and 0.65 fold at 12 h and 24 h respectively in MNNG-treated FL cells (P < 0.05). In transgenic cell line (in which REV3 was blocked by antisense REV3 RNA), high level of antisense REV3 RNA was detected, with a decreased level of REV3 protein. MNNG treatment significantly increased the mutation frequencies on undamaged DNA template (untargeted mutation), and also at HPRT locus (lesion-targeted mutation). However, when REV3 gene was blocked by antisense REV3 RNA, the MNNG-induced mutation frequency on undamaged DNA templates was significantly decreased by 3.8 fold (P < 0.05) and 5.8 fold (P < 0.01) respectively both in MNNG-pretreated transgenic 293 cells and FL cells in which REV3 was blocked by antisense RNA, and almost recovered to their spontaneous mutation levels. The spontaneous HPRT mutation was disappeared in REV3-disrupted cells, and induced mutation frequency at HPRT locus significantly decreased from 8.66 × 10^-6 in FL cells to 0.14 × 10^-6 in transgenic cells as well (P < 0.01).

CONCLUSION: The expression of the human REV3 can be upregulated at the transcriptional level in response to MNNG. The human REV3 gene plays a role not only in lesion-targeted DNA mutagenesis, but also in mutagenesis on undamaged DNA templates that is called untargeted mutation.

Inhibitory effect of p27kip1 mediated by adenovirus on model of esophageal carcinoma in nude mice

AIM

To investigate the inhibitory effect of p27kip1 mediated by adenovirus vector on esophageal carcinoma in vivo.

METHODS

Eca109 cells were injected into the subcutaneous tissue of nude mice to establish tumors. The transplanted tumors were reproduced among the nude mice contionually after original grafts grew well. The model of esophageal carcinoma in nude mice was established by transplanting the tumor tissue mass into the subcutaneous tissue of nude mice .The successful constructed recombinant adenoviral vector carrying p27kip1 gene and LacZ recombinant adenovirus were directly injected into the esophageal tumors in nude mice respectively. Compared with control group, the growth curves of tumor were drawed and the growth inhibition rates of tumor were calculated.

RESULTS

The growth of tumors in gene therapy group with p27kip1 was obviously suppressed, which had a significant difference compared with control group (P < 0.001). The growth inhibition rate of tumor reached 64.1%.

CONCLUSION

p27kip1 gene therapy mediated by adenovirus vector has significant inhibitory effect on esophageal carcinoma in vivo.

Association of GSTM1, CYP1A1 and CYP2E1 genetic polymorphisms with susceptibility to lung adenocarcinoma: a case-control study in Chinese population

A case-control study of 164 lung adenocarcinoma (AC) patients with 181 age- and gender-matched healthy controls was conducted in order to assess any associations between glutathione-S-transferase M1 (GSTM1), cytochrome P4501A1 (CYP1A1) and cytochrome P4502E1 (CYP2E1) polymorphisms and susceptibility to lung AC in Chinese. The presence of CYP2E1 variant allele was significantly less frequent in cases than in controls, while the distribution of GSTM1 null genotype and variant CYP1A1 Msp1 allele did not vary between cases and controls. After adjustment for age, gender, smoking and all other genotypes, the CYP2E1 Rsa1 variant allele was significantly associated with decreased risk of lung AC [odds ratio 0.534 (95% confidence interval, 0.340-0.837)]. Furthermore, 3.0-fold increased risk was found in individuals with combined GSTM1 null genotype and CYP2E1 Rsa1 wild type versus those with combined GSTM1 non-null type and CYP2E1 variant allele. Our results suggest that CYP2E1 Rsa1 variant allele is associated with a decreased risk of lung AC, and combined GSTM1 null genotype and CYP2E1 Rsa1 wild type has a promoting effect on susceptibility to lung AC.

HLA-DRB1 allele polymorphisms in genetic susceptibility to esophageal carcinoma

AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal carcinoma in Han Chinese in Hubei Province.

METHODS: HLA-DRB1 allele polymorphisms were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP) in 42 unrelated patients with esophageal cancer and 136 unrelated normal control subjects and the associated HLA-DRB1 allele was measured by nucleotide sequence analysis with PCR.SAS software was used in statistics.

RESULTS: Allele frequency (AF) of HLA-DRB1*0901 was significantly higher in esophageal carcinoma patients than that in the normal controls (0.2500 vs 0.1397, P = 0.028, the odds ratio 2.053, etiologic fraction 0.1282). After analyzed the allele nucleotide sequence of HLA-DRB1*0901 which approachs to the corresponded exon 2 sequence of the allele in genebank. There was no association between patients and controls in the rested HLA-DRB1 alleles.

CONCLUSION: HLA-DRB1*0901 allele is more common in the patients with esophageal carcinoma than in the healthy controls, which is positively associated with the patients of Hubei Han Chinese. Individuals carrying HLA-DRB1*0901 may be susceptible to esophageal carcinoma.

Expression of e-cadherin and β-catenin in human esophageal squamous cell carcinoma: relationships with prognosis

AIM: To elucidate the expression of E-cadherin and β-catenin correlating with its clinical outcome in patients with esophageal squamous cell carcinoma (ESCC), by analyzing their interrelationship with clinicopathological variables and their effects on progress and prognosis.

METHODS: Expression of E-cadherin and β-catenin was determined by SP immunohistochemical technique in patients with ESCC consecutively, their correlation with clinical characteristics was evaluated and analyzed by multivariate analysis.

RESULTS: The rate of expression of E-cadherin decreased to 66.03% (70/106) in ESCC and the protein level was negative correlated with histologic grade, tumor size, clinical staging, lymph node metastasis and venous invasion. Whereas the expression rate of β-catenin was reduced to 69.8% (74/106) and the level of protein expression correlated only with histologic grade. There obviously existed inverse correlation between level of E-cadherin protein and survival, especially in stage I, IIa, IIb (P = 0.0033), Patients with low-expressing tumors for β-catenin and non-expressing tumors for E-cadherin/β-catenin had lower survival period than those with normal-expressing ones (P = 0.0501 and P = 0.0080, respectively). Patients with diminished expression of E-cadherin as grade II or III had shorter survival period than those with normally expressing and grade I, no significance existed between grade I and grade II or III with respect to different status of E-cadherin expression. Furthermore, Correlation analysis showed level of E-cadherin correlated with that of β-catenin (P = 0.005). Cox proportional hazards model analysis suggested downregulation of E-cadherin was an important factor indicating poor prognosis.

CONCLUSION: As a probable independent prognostic factor, it correlates with overall and disease free survival period, expression of E-cadherin but not β-catenin may predict prognosis in patients with ESCC.

An analysis of esophageal cancer incidence in Cixian county from 1974 to 1996

AIM: To describe the incidence of esophageal cancer (EC) in Cixian, a county of Hebei province during 1974-1996. We analyzed the sex and age characteristics as well as the geographic distribution of EC, in order to determine the impact so that methods of preventing and controlling EC in Cixian can be put in place.

METHODS: Since the early 1970s, the cancer registry system has been established, which collects the cancer incidence in Cixian county. The malignant tumors were coded according to International Classification of Disease IX (ICD-9). All the data were checked and analyzed using EPIINFO.

RESULTS: The trend of the incidence rate of EC from 1974 to 1996 had declined, (229.9/100000 vs 178.5/100000, Odds ratio = 1.47, 95% CI:1.32~1.63, χ² = 52.89. trend χ² = 26.54, P < 0.001). The incidence rate of males declined significantly (281.81/100000 vs 157.96/100000, Odds ratio = 1.61, 95% CI: 1.41~1.84, χ² = 47.85. Trend χ² = 44.86, P < 0.001), whereas, the females remained steady (157.96/100000 vs 133.41/100000, odds ratio = 1.28, 95% CI:1.17~1.49, χ² = 9.26. trend χ² = 2.69, P > 0.05). Male average annual incidence rate was 142.80/100000 and the female's was 95.18/100000. The sex ratio (males to females) was 1.50:1. The incidence rate was increasing along with the age. As to the geographic distribution, the incidence rate in mountainous areas and hilly areas showed a significantly declining trend (mountainous areas, trend χ² = 149.93, P < 0.001; hilly areas, trend χ² = 42.70, P < 0.001). The incidence rate of EC in plain areas had increased (trend χ² = 22.39, P < 0.001).

CONCLUSION: The incidence rate of EC in Cixian county shows a trend and has declined after two decades, especially in mountainous area. But compared to other regions in the world, Cixian county still had a high incidence rate of EC.

Preoperative TN staging of esophageal cancer: Comparison of miniprobe ultrasonography, spiral CT and MRI

AIM: To evaluate the value of miniprobe sonography (MPS), spiral CT and MR imaging (MRI) in the tumor and regional lymph node staging of esophageal cancer.

METHODS: Eight-six patients (56 men and 30 women; age range of 39-73 years, mean 62 years) with esophageal carcinoma were staged preoperatively with imaging modalities. Of them, 81 (94%) had squamous cell carcinoma, 4 (5%) adenocarcinoma, and 1 (1%) adenoacanthoma. Eleven patients (12%) had malignancy of the upper one third, 41 (48%) of the mid-esophagus and 34 (40%) of the distal one third. Forty-one were examined by spiral CT in whom 13 were co-examined by MPS, and forty-five by MRI in whom 18 were also co-examined by MPS. These imaging results were compared with the findings of the histopathologic examination for resected specimens.

RESULTS: In staging the depth of tumor growth, MPS was significantly more accurate (84%) than spiral CT and MRI (68% and 60%, respectively, P < 0.05). The specificity and sensitivity were 82% and 85% for MPS; 60% and 69% for spiral CT; and 40% and 63% for MRI, respectively. In staging regional lymph nodes, spiral CT was more accurate (78%) than MPS and MRI (71% and 64%, respectively), but the difference was not statistically significant. The specificity and sensitivity were 79% and 77% for spiral CT; 75% and 68% for MPS; and 68% and 62% for MRI, respectively.

CONCLUSION: MPS is superior to spiral CT or MRI for T staging, especially in early esophageal cancer. However, the three modalities have the similar accuracy in N staging. Spiral CT or MRI is helpful for the detection of far-distance metastasis in esophageal cancer.

Genetic polymorphisms of cytochrome P4501A1 and oesophageal squamous-cell carcinoma in Taiwan

Several in vitro studies have demonstrated that genetic polymorphisms result in functionally significant changes in cytochrome p4501A1 (either CYP1A1 MspI or exon 7) but the few epidemiologic studies of these polymorphisms in oesophageal squamous-cell carcinoma have been inconclusive. These inconclusive results motivated us to further examine the relationship between CYP1A1 MspI and exon 7 polymorphisms and risk of oesophageal cancer. In total, 146 cases of oesophageal squamous-cell-carcinoma and 324 control cases (a total of 470 cases) were genotyped from records at three Taiwan hospitals. No significant association was noted for the CYP1A1 MspI polymorphism variable between carcinoma and control cases. In contrast, the frequency of Ile/Ile, Ile/Val, and Val/Val in exon 7 was 68 (46.6%), 62 (42.5%), and 16 (11.0%) in carcinoma cases and 179 (55.3%), 127 (39.2%), and 18 (5.6%) in control cases, respectively. After factoring out other potential contributing factors, patients with Val/Val showed a 2.48 (95% CT=1.15-5.34) greater risk of developing oesophageal cancer than those with Ile/Ile. A slightly (albeit not significantly) greater risk was identified in subjects with Ile/Val (OR=1.34; 95% CI=0.86-2.07). These findings suggest that an exon 7 polymorphism, not a MspI polymorphism, in CYP1A1 may be pivotal in the development of oesophageal cancer.