TGFBR1 tagging SNPs and gastric cancer susceptibility: a two-stage case-control study in Chinese population.

The transforming growth factor (TGF)-ß is a potent growth inhibitor primarily responsible for cell growth, differentiation, and apoptosis, and frequently perturbed during development of tumors, including gastric cancer. TGF-ß receptor type I (TGFßR1) may be a modifier of cancer risk by constitutively decreasing the TGF-ß inhibitory signals during early tumorigenesis and increasing the TGF-ß signals in tumor progression. In this study, we hypothesized that genetic variants of TGFBR1 may influence the risk of gastric cancer. We conducted a two-stage case-control study of gastric cancer, including 650 cases and 683 controls in the first stage and 484 cases and 348 controls in the second stage, and genotyped five tagging single nucleotide polymorphisms (SNPs) to represent common variants in the whole TGFBR1 gene. In the first stage, two SNPs rs6478974 and rs10512263 were found to be potentially associated with risk of gastric cancer (P = 3.35 × 10(-3) for rs6478974 AT vs. TT and P = 0.033 for rs10512263 CT vs. TT), which were further confirmed in the second stage with similar effects (P = 0.144 and 0.049, respectively). After combining the two stages, we found that these two SNPs were associated with a significantly increased risk of gastric cancer in dominant models [adjusted odds ratio (OR) = 1.36, 95% confidence interval (CI): 1.14-1.63 for rs6478974 AT/AA vs. TT; adjusted OR = 1.26, 95% CI: 1.05-1.50 for rs10512263 CT/CC vs. TT] or additive model (adjusted OR = 1.23, 95% CI: 1.08-1.40 for rs6478974). These findings indicate that TGFBR1 polymorphisms may be implicated with the development of gastric cancer in Han-Chinese population.

Genetic variants at 5p15 are associated with risk and early onset of gastric cancer in Chinese populations.

Genetic variants at 5p15 have been associated with multiple cancers risk, suggesting pleiotropic effect on cancer. We hypothesized that genetic variants at 5p15 are important in the development of gastric cancer. To test this hypothesis, we evaluated the associations of genetic variants at 5p15 with gastric cancer based on our existing genome-wide association study (GWAS) data set of gastric cancer (1006 cases and 2273 controls), and replicated two promising loci in an independent case-control study with 1681 gastric cancer cases and 1705 controls in a Chinese population. We found that rs10052016 was consistently associated with gastric cancer risk in GWAS discovery stage (odds ratio [OR] = 0.69, 95% confidence interval [95% CI] = 0.55-0.87) and replication stage (OR = 0.80, 95% CI = 0.68-0.94). After combining these two studies, we found that the G allele of rs10052016 (at 132 kb upstream of TERT) was significantly associated with a decreased risk of gastric cancer (OR = 0.76, 95% CI = 0.67-0.87, P = 5.35 × 10(-5)). Moreover, the protective allele of rs10052016-G was also significantly associated with late onset of gastric cancer (P = 0.013). In summary, these findings indicate that genetic variants at 5p15 may contribute to gastric cancer susceptibility and may further advance our understanding of 5p15 locus in cancer development.

[An association study between transforming growth factor-ß1 receptor 2 gene polymorphisms and essential hypertension].

OBJECTIVE: To evaluate the association between two single nucleotide polymorphisms located in the promoter of transforming growth factor-ß1 receptor 2 (TGFBR2) gene and hypertension in Han Chinese population. METHODS: The subjects were recruited from the population of cluster sampling survey for essential hypertension (EH) in two townships of Yixing city, Jiangsu province in 2009. Overall, 2012 patients with hypertension and 2116 age (± 2 years) and sex-matched unrelated controls were selected. Epidemiological data, physical measurements results and serum glucose and lipid biomarker were collected and detected. Linkage disequilibrium (LD) analysis were applied and two tagging single nucleotide polymorphisms (tagSNP) in 5' upstream of TGFBR2 gene (rs6785358, -3779A/G; rs764522, -1444C/G) were selected for genotyping and analyzing for the association with hypertension. RESULTS: The frequencies of AA, AG, GG in case and control of rs6785358 were 1455 (72.3%), 517 (25.7%), 40 (2.0%) and 1582 (74.8%), 490 (23.2%), 43 (2.0%) respectively, and CC, CG, GG of rs764522 were 1524 (75.7%), 464 (23.1%), 24 (1.2%) and 1654 (78.2%), 436 (20.6%), 26 (1.2%) respectively. SNP rs764522 was significantly associated with EH and OR (95%CI) were 1.17 (1.01 - 1.36) (P < 0.05) in dominant model after adjustment for confounding factors such as age, sex, glucose, lipids, smoking and alcohol drinking. Further stratification analysis by age, sex, smoking and alcohol drinking indicated that individuals carrying G allele (CG/GG genotype) of SNP rs764522 had higher susceptibility to EH than CC genotype (OR = 1.21, 95%CI: 1.01 - 1.45) (P < 0.05) in ≥ 55 years group. No statistical significance was detected in the distribution of genotypes and allele frequencies for SNP rs6785358 between cases and controls (P > 0.05). Haplotype analysis showed that no significant frequency difference of haplotype structured by rs6785358 and rs764522 was found between cases and controls (P > 0.05), and no significant blood pressure change was found between genotype variations of rs6785358 and rs764522 (P > 0.05). CONCLUSION: SNP rs764522 of TGFBR2 gene is associated with increased risk of EH in elderly Han Chinese population.

Genetic variants at 1q22 and 10q23 reproducibly associated with gastric cancer susceptibility in a Chinese population.

Two recent genome-wide association studies reported significant associations of genetic variants at 1q22, 10q23 and 20p13 with gastric cancer (GC) risk in Chinese populations. However, these findings have not been confirmed in other independent studies. Here, we performed an independent case-control study in a Chinese population by genotyping three loci (rs4072037A>G at 1q22, rs2274223A>G at 10q23 and rs13042395C>T at 20p13) in 1681 GC cases and 1858 controls. We found that rs4072037 at 1q22 and rs2274223 at 10q23 were significantly associated with risk of GC with per allele odds ratio (OR) of 0.72 [95% confidence interval (CI): 0.63-0.81; P = 2.98 × 10(-7)] and 1.42 (95% CI: 1.27-1.58; P = 9.68 × 10(-10)), respectively. The association was more prominent for rs2274223 in female (OR = 1.86, 95% CI: 1.49-2.32) and gastric cardia adenocarcinoma (GCA) (OR = 1.71, 95% CI: 1.49-1.95). Furthermore, we combined the two single-nucleotide polymorphisms to evaluate the joint effect and found that the GC risk significantly increased with the number of risk allele increasing with a trend P value of 6.66 × 10(-16), and individuals with four risk alleles had a 3.28-fold (95% CI: 1.75-6.13) risk of GC compared with those having no risk alleles. However, no significant association was detected between rs13042395 at 20p13 and GC risk (OR = 1.04, 95% CI: 0.94-1.15; P = 0.452). In conclusion, our results indicate that genetic variants at 1q22 and 10q23 but not 20p13 may serve as candidate markers for GC susceptibility in the Chinese population.

Genetic variation of PSCA gene is associated with the risk of both diffuse- and intestinal-type gastric cancer in a Chinese population.

Prostate stem cell antigen (PSCA), a member of the LY-6/Thy-1 family of glycosylphosphatidylinositol-anchored cell surface proteins, is considered to be involved in the cell-proliferation inhibition and/or cell-death induction activity. Two single nucleotide polymorphisms (SNPs) (rs2976392 and rs2294008) in the PSCA gene were recently identified as the susceptibility loci of gastric cancer, especially in diffuse type. Therefore, this study was to investigate whether these 2 SNPs were associated with the risk of gastric cancer in Chinese population. We genotyped rs2976392 and rs2294008 in PSCA in a case-control study including 1,053 incident gastric cancer patients and 1,100 cancer-free controls in a high-risk Chinese population. We found that variant genotypes of rs2976392 (GA/AA) were associated with a significantly 37% increased risk of gastric cancer (adjusted OR =1.37, 95% CI = 1.15-1.62), compared with variant homozygote GG, and the associations were all consistently significant in both intestinal and diffuse subtypes, and among different subgroups stratified by age, sex, drinking or smoking status. Interestingly, a significant multiplicative interaction between rs2976392 (GA/AA) and alcohol drinking was detected on the development of intestinal-type gastric cancer (p = 0.009). However, rs2294008 variant genotypes (CT/TT) were associated with a nonsignificant increased risk of gastric cancer (adjusted OR = 1.14, 95% CI = 0.96-1.36). A small meta-analysis including 5 case-control studies showed undoubtedly associations between PSCA rs2294008 and rs2976392 and gastric cancer risk (OR = 1.83, 95% CI: 1.29-2.60 and OR = 1.84, 95% CI: 1.33-2.56, respectively). These findings provide further evidence supporting that the genetic variants of PSCA gene may contribute to the gastric carcinogenesis.

A nonsynonymous polymorphism in IL23R gene is associated with risk of gastric cancer in a Chinese population.

Interleukin-23 receptor (IL-23R) is a key element in T helper (Th)17 cell-mediated inflammatory process, which plays an important role in pathogenesis of gastric cancer. Genetic variants of IL-23R have been identified as the predisposing factors for immunopathologic process. In this study, we hypothesized that the functional genetic variants of IL-23R gene may modify the risk of gastric cancer. To test this hypothesis, we conducted a case-control study including 1043 gastric cancer patients and 1089 controls in a Chinese population to assess the association between two potentially functional single nucleotide polymorphisms (SNPs) rs6682925 T>C and rs1884444 T>G of IL-23R and risk of gastric cancer. We found that the variant allele (G) of rs1884444 T>G, with amino acid His substituted by Gln at codon 3, was significantly associated with a decreased risk of gastric cancer [adjusted allelic odds ratio (OR) = 0.78, 95% confidence interval (CI) = 0.68-0.88]. In the stratified analysis, we found that this protective effect of rs1884444 G allele was mainly evident in intestinal-type gastric cancer (adjusted allelic OR = 0.75, 95% CI = 0.65-0.87) other than in diffuse-type gastric cancer (adjusted allelic OR = 0.96, 95% CI = 0.76-1.22). However, we did not find any significant association of rs6682925 T>C with gastric cancer risk. These findings indicate, for the first time, that the nonsynonymous variant rs1884444 T>G of IL-23R may contribute to gastric cancer susceptibility, especially in intestinal-type gastric cancer, in Chinese population.

Promoter polymorphisms of IL2, IL4, and risk of gastric cancer in a high-risk Chinese population.

Interleukin 2 (IL2) is a typical Th1 cytokine, and interleukin 4 (IL4) is an inducible Th2 cytokine. These cytokines are critical mediators of the Th1/Th2 balance and apoptosis potential and involved in the process of inflammation-mediated carcinogenesis in human organs, including the gastrointestinal tract. Therefore, we tested the hypothesis that functional variants in IL2 and IL4 were associated with risk of gastric cancer by genotyping two promoter polymorphisms in IL2 G-330T (rs2069762) and IL4 T-168C (rs2070874) in a case-control study of 1045 patients with incident gastric cancer and 1100 cancer-free controls in a high-risk Han Chinese population. We found that, compared with the IL4 -168TT genotype, heterozygous -168TC and combined -168TC/CC genotypes were associated with a significantly decreased gastric cancer risk [adjusted odds ratio (OR) = 0.81, 95% confidence interval (CI) = 0.67-0.98 for -168TC; OR = 0.83, 95% CI = 0.69-1.00 for -168TC/CC, respectively]. Furthermore, this significant protective effect was more evident for gastric cardia cancer patients (adjusted OR = 0.73, 95% CI = 0.56-0.95 for -168TC/CC vs. -168TT). For IL2 G-330T, subjects carrying GT/TT genotypes also had a significantly reduced risk of gastric cardia cancer (adjusted OR = 0.68, 95% CI = 0.46-0.99), compared with those carrying the GG genotype. Our results indicate that IL4 T-168C and IL2 G-330T promoter polymorphisms may contribute to the etiology of gastric cardia cancer in Chinese populations.

Potentially functional polymorphisms of the vascular endothelial growth factor gene and risk of gastric cancer.

Vascular endothelial growth factor (VEGF), the key mediator of angiogenesis, plays an important role in the development of different kind of tumors, including gastric cancer (GC). The aim of this study is to test the hypothesis that genetic variants of VEGF are associated with risk of GC. We genotyped four potentially functional polymorphisms (-2578C > A, -1498T > C, -634G > C, and +936C > T) of the VEGF gene in a population-based case-control study of 540 GC cases and 561 frequency-matched cancer-free controls in a high risk Chinese population. We found that none of the four polymorphisms or their haplotypes achieved significant difference in their distributions between GC cases and controls. Multiple logistic regression analyses revealed that GC risk was not significantly associated with the variant genotypes of the four VEGF polymorphisms as compared with their wild-type genotypes. In conclusion, our data did not support a significant association between VEGF SNPs and the risk of GC.

Polymorphisms of MTHFD, plasma homocysteine levels, and risk of gastric cancer in a high-risk Chinese population.

PURPOSE: Accumulative evidence suggests that folate has a protective effect on gastric cancer. The methylenetetrahydrofolate dehydrogenase (MTHFD) plays an important role in folate and homocysteine metabolisms, and polymorphisms of MTHFD may result in disturbance of the folate-mediated homocysteine pathway. The aim of this study is to test the hypothesis that genetic variants of MTHFD and plasma homocysteine levels are associated with risk of gastric cancer and modulated by genotypes of methylenetetrahydrofolate reductase (MTHFR). EXPERIMENTAL DESIGN: We genotyped G1958A and T401C in MTHFD and C677T in MTHFR and detected total plasma homocysteine (tHcy) levels in a case-control study of 589 gastric cancer cases and 635 cancer-free controls in a high-risk Chinese population. RESULTS: The variant genotypes of MTHFD 1958AA and 401CC were associated with a significantly increased risk of gastric cancer [adjusted odds ratio (OR), 2.05; 95% confidence interval (95% CI), 1.34-3.13 for 1958AA; adjusted OR, 1.43; 95% CI, 1.14-1.80 for 401CC] compared with 1958GG/GA and 401TT/TC genotypes, respectively. Both of the effects were more evident in the subjects carrying MTHFR 677CT/TT genotypes. The average tHcy level was significantly higher in gastric cancer cases than in controls (P < 0.01), and the upper quartile of tHcy (>13.6 micromol/L) was associated with an 82% significantly increased risk of gastric cancer, compared with the lowest quartile of tHcy (

Association study between hypertension and A/G polymorphism at codon 637 of the transporter associated with antigen processing 1 gene.

To explore the effect of A/G polymorphisms at codon 637 of the transporter associated with antigen processing 1 (TAP1) gene on the risk of hypertension. A case-control study of epidemiology was conducted. The case group included 277 community-based patients (136 males and 141 females; mean age 58.7+/-12.1 years) diagnosed with hypertension, and the control group consisted of 227 healthy subjects (95 males and 132 females; mean age 51.29+/-12.16 years) from the same community. The A/G polymorphisms at codon 637 of the TAP1 gene was examined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method with genomic DNA. The effect of A/G polymorphisms at codon 637 of the TAP1 gene on hypertension was analyzed by using multivariate unconditional logistic regression models. The contribution of TAP1 637 A/G allele frequencies of the control group was consistent with that predicted by the Hardy-Weinberg equilibrium test (x2=230, p=0.632). There was a significant difference in the frequency of the A/G polymorphisms at codon 637 of the TAP1 gene between hypertensive patients (74.4/25.6%) and controls (82.4%/17.6%), x2=9.324, p=0.002. Genotype model (AA-AG-GG) analysis showed that there was a significant difference in the frequency of the recessive genotype between cases and controls (AA/AG vs. GG: odds ratio [OR]=3.046, 95% confidence interval [CI]=1.138-8.153) after adjustment for the covariates of age, serum total cholesterol, triglycerides, body mass index (BMI) and smoking. But there were no significant differences in the frequency of the genotype for the dominant model (AA vs. AG/GG: p=0.293) or additive model (AA vs. AG vs. GG: p=0.081) after adjustment. One-way ANOVA analysis showed that the systolic blood pressure, diastolic blood pressure, and BMI levels of the GG genotype were significantly higher than those of the AA or AG genotypes. In conclusion, our findings suggest that the A/G polymorphisms at codon 637 of the TAP1 gene contributes to the risk of hypertension, possibly via the increases in blood pressure and BMI.

[Meta-analysis on the relationship between IL8-251 gene polymorphism and gastric cancer].

OBJECTIVE: To evaluate the relationship between IL8-251 gene polymorphisms and gastric cancer. METHODS: Literatures were reviewed and selected based on the criteria for inclusion. The Meta-analysis software, REVMAN 4.2, was applied to check the heterogeneity across the studies and calculating the pooled OR. RESULTS: Total of 2114 cases and 2505 controls from 8 studies for IL8-251 were included. The chi(2) value was 21.48 (P = 0.003), and the pooled OR of (AA + AT) vs. TT was 1.12 (95% CI 0.90 - 1.40). Large heterogeneity was found among the studies. After the sensitivity analysis, the pooled OR of (AA + AT) vs. TT 1.21 (95% CI 1.06 - 1.39). CONCLUSION: IL8-251-A allele might be associated with higher risk of developing gastric cancer.

Reduced folate carrier gene G80A polymorphism is associated with an increased risk of gastroesophageal cancers in a Chinese population.

Low folate intake has been associated with an increased risk of both oesophageal and gastric cancers. Reduced folate carrier (RFC1, also named SLC19A1) is an essential folate transporter and functions as a bidirectional anion exchanger, taking up folate cofactors and exporting various organic anions. A G80A polymorphism in RFC1 gene has been shown to be associated with alterations in folate and homocysteine metabolism in healthy individuals. In this study, we hypothesised that genetic variants in RFC1 may modulate risk of oesophageal cancer (EC) and gastric cancer (GC). To test this hypothesis, we evaluated the associations of the G80A polymorphism of RFC1 with EC and GC risk in a case-control study of 216 EC and 633 GC cases and 673 cancer-free controls in a Chinese population. We found that compared with the 80GG/GA genotypes in the recessive model, the variant homozygote RFC1 80AA was associated with a significantly increased risk of EC (adjusted odds ratio (OR)=1.80, 95% confidence interval (CI)=1.29-2.51), GC (adjusted OR=1.59, 95% CI=1.25-2.02) and EC and GC combined (adjusted OR=1.63, 95% CI=1.30-2.04). In the dominant model, the risk associated with RFC1 80AA was also elevated in EC (OR=1.35, 95% CI=0.91-1.99), GC (OR=1.43, 95% CI=1.07-1.91) and EC and GC combined (adjusted OR=1.40, 95% CI=1.07-1.83), compared with the 80GG genotype. The stratification analyses showed that effects of the RFC1 80AA genotype were more evident in subgroups of relatively older (60 years), female, non-smokers, and non-drinkers both in EC and GC. Although the exact biological mechanism of this association remains to be explored, our findings suggest possible involvement of RFC1 variant in the susceptibility of EC and GC. Further large and functional studies are needed to confirm our findings.

Allele 2 of the interleukin-1 receptor antagonist gene (IL1RN*2) is associated with a decreased risk of primary lung cancer.

IL-1 receptor antagonist (IL-1ra), a structural variant of IL-1, binds to the same IL-1 receptor and acts as a competitive inhibitor of IL-1 bioactivity. IL-1ra protein has been widely investigated and found to be associated with different human malignancies. In the second intron of the IL-1RN gene, there is a functional polymorphism of a variable number of tandem repeats (VNTR), which is characterized as having an importance role in regulating the serum IL-1ra levels, human immune response and cancer risk. We genotyped this VNTR of IL-1RN in a case-control study of 885 histologically confirmed lung cancer patients and 1024 cancer-free controls frequency-matched to the cases on age and sex in a Chinese population to evaluate the association of this variant and lung cancer risk. We found that the presence of the allele 2 of IL-1RN (IL-RN*2) was associated with a 32% significantly decreased risk of lung cancer (adjusted OR, 0.68; 95% CI, 0.52-0.89). Stratified analyses revealed that the reduced risks associated with the genotypes with IL-RN*2allele (I/II and II/II) were more evident in non-smokers (adjusted OR, 0.53; 95% CI, 0.35-0.79) and in subjects with squamous cell carcinoma (adjusted OR, 0.49; 95% CI, 0.31-0.76). These findings support our priori hypothesis that the IL1RN*2 allele may contribute to lung cancer risk in the Chinese population. More functional data for this IL1RN polymorphism are warranted to explore its role in lung carcinogenesis.

Prevalence of physician-diagnosed COPD and its association with smoking among urban and rural residents in regional mainland China.

OBJECTIVES: To investigate the prevalence of physician-diagnosed COPD and to explore the relationship between the total amount of cigarettes smoked (TACS) and COPD among urban and rural adults in Nanjing, China. DESIGN: Population-based, cross-sectional study conducted between October 2000 and March 2001. SETTING: Administrative villages (n = 45) randomly selected from three urban districts and two rural counties of Nanjing municipality, Jiangsu province, China, with an overall population of 5.6 million. PARTICIPANTS: All regular local residents >/= 35 years old (n = 29,319), 67.7% from urban areas and 32.3% from rural areas; 49.7% were men and 50.3% were women. RESULTS: The response rate of potential participants was 90.1%. The overall prevalence of diagnosed COPD was 5.9%. The prevalence of COPD was significantly higher among men than in women (7.2% vs 4.7%, p = 0.000), while the difference between urban and rural participants was not statistically significant (6.7% vs 4.4%, respectively; p = 0.132). The prevalence of COPD was significantly higher among smokers than nonsmokers. After adjusting for age, gender, area of residence, fuels, heating in winter, ventilation in kitchen, passive smoking, education, occupation, average family income, alcohol drinking, cooking oil, body mass index, and physical activity, a dose-response relationship between COPD and TACS was evident in this population (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.34 to 1. 92; OR, 1.39; 95% CI, 1.13 to 1.70; and OR, 1.24; 95% CI, 1.01 to 1.52 for smokers within upper, middle, and lower TACS levels compared with nonsmokers, respectively). CONCLUSIONS: The overall prevalence of diagnosed COPD (5.9%) among Chinese adults was higher than that (2.5%) estimated by World Health Organization experts, and there was a significant gradient increase in COPD prevalence from the stratum of nonsmokers to the stratum of upper TACS.

Methylenetetrahydrofolate reductase polymorphisms/haplotypes and risk of gastric cancer: a case-control analysis in China.

Studies have suggested that low dietary folate intake is associated with an increased risk of gastric cancer. Methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism and influences DNA methylation and nucleotide synthesis. MTHFR is highly polymorphic and the variant genotypes result in decreased MTHFR enzyme activity and lower plasma folate level. We hypothesized that three MTHFR common variants (i.e. C677T, A1298C and G1793A) and their haplotypes are associated with the risk of gastric cancer. To test this hypothesis, we genotyped these polymorphisms in a population-based case-control study of 320 incident gastric adenocarcinoma cases and 313 cancer-free controls in a Chinese population. Consistent with our previous observations, the 677TT genotype was associated with a significantly increased risk for gastric cancer (adjusted OR =1.79, 95% CI =1.02-3.15) compared with the 677CC genotype; the association was more evident for gastric cardia adenocarcinoma (adjusted OR =2.60, 95% CI =1.30-5.21). When we used the haplotype analyses and assumed MTHFR 677T, 1298C and 1793A as risk alleles, individuals with 6 variant alleles had a significantly (4.64-fold) increased risk for gastric cardia adenocarcinoma (OR =4.64, 95% CI =1.34-16.01) compared with those having 0-2 variants. These findings suggest that the MTHFR common variants and their haplotypes may play a role in the etiology of gastric cancer, particularly gastric cardia adenocarcinoma. Future studies using large sample sizes and incorporating detailed data on dietary folate intake and related serological measurements are warranted to confirm our findings.

Interaction models of CYP1A1, GSTM1 polymorphisms and tobacco smoking in intestinal gastric cancer.

AIM: To explore the interaction models of the cytochrome P-450 (CYP) 1A1 Val variant and glutathione S-transferase (GST) M1 null polymorphisms with tobacco smoking in the occurrence of intestinal gastric cancer. METHODS: A community-based case-control study was conducted in Yangzhong. Subjects included 114 intestinal types of gastric cancer with endoscopic and pathological diagnosis during January 1997 and December 1998, and 693 controls selected from their spouse, siblings or siblings-in-law who had no history of digestive system cancer. Logistic regression was used to estimate the interaction models. RESULTS: The frequency of the CYP1A1 Val variant allele in cases did not differ from that in controls. The OR of GSTM1 null genotype was 2.0 (95% confidence interval (95%CI): 1.2-3.1, P<0.01). It showed a significant type 2 form of interaction model when both CYP1A1 Val variant allele and former tobacco smoking existed (i.e., among the multiplicative effects, the disease risk is increased by the tobacco exposure alone but not by the CYP1A1 variant alone). The interaction index gamma was 2.8, and OR(eg) (95%CI) was 5.0 (1.9-13.4). GSTM1 null genotype and former tobacco smoking were significant in a type 4 interaction model (i.e., the disease risk is increased by GSTM1 null genotype or tobacco exposure alone among the multiplicative effects). The interaction index gamma and OR(eg) (95%CI) were 3.4 and 8.4 (3.4-20.9), respectively. CONCLUSION: Different interaction models of CYP1A1 Val variant allele and GSTM1 null genotype with tobacco smoking will contribute to understanding carcinogenic mechanism, but there is a need to further investigate in larger scale studies.

Human leukocyte antigen class II DQB1*0301, DRB1*1101 alleles and spontaneous clearance of hepatitis C virus infection: a meta-analysis.

AIM: To assess the associations of human leukocyte antigen (HLA) class II DQB1*0301 and/or DRB1*1101 allele with spontaneous hepatitis C virus (HCV) clearance by meta-analysis of individual dataset from all studies published till date. METHODS: To clarify the impact of HLA class II polymorphisms on viral clearance, we performed a meta-analysis of the published data from 11 studies comparing the frequencies of DQB1*0301 and DRB1*1101 alleles in individuals with spontaneous resolution to those with persistent infection. As we identified the heterogeneity between studies, summary statistical data were calculated based on a random-effect model. RESULTS: Meta-analyses yielded summary estimates-odds ratio (OR) of 2.36 [95%CI (1.62, 3.43), P<0.00001] and 2.02 [95%CI (1.56, 2.62), P<0.00001] for the effects of DQB1*0301 and DRB1*1101 alleles on spontaneous clearance of HCV, respectively. CONCLUSION: These results support the hypothesis that specific HLA class II alleles might influence the susceptibility or resistance to persistent HCV infection. Both DQB1*0301 and DRB1*1101 are protective alleles and present HCV epitopes more effectively to CD4(+)T lymphocytes than others, and subjects with these two alleles are at a lower risk of developing chronic HCV infection. Large, multi-ethnic confirmatory and well-designed studies are needed to determine the host genetic determinants of HCV infection.

E-cadherin gene C-160A promoter polymorphism and risk of non-cardia gastric cancer in a Chinese population.

AIM: To test the hypothesis that E-cadherin gene (CDH1) C-160A promoter variant genotype is associated with an increased risk for developing gastric cancer. METHODS: In this population-based case-control study of gastric cancer in Jiangsu Province, China, we performed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to genotype the C-160A polymorphism of CDH1 promoter in 206 non-cardia gastric cancer patients and 261 age- and sex-matched but unrelated cancer-free controls. RESULTS: The frequencies of genotypes CC, CA and AA were 57.8%, 36.4% and 5.8% in gastric cancer cases, respectively, and 58.2%, 34.9% and 6.9% in controls respectively. The distributions of CDH1 genotypes were not significantly different between gastric cancer cases and controls (P = 0.87 for genotype frequency and P = 0.92 for allele frequency). Compared with the CC genotype, the CA and AA genotypes were not associated with an increased risk for non-cardia gastric cancer (adjusted odds ratios (OR) = 1.15, and 95% confidence interval (95% CI) = 0.78-1.72 for CA genotype, and OR = 0.90 and 95% CI = 0.42-2.01 for AA genotype). CONCLUSION: E-cadherin gene C-160A promoter polymorphism may not play a major role in the etiology of non-cardia gastric cancer in Chinese population.

Polymorphisms of DNA repair gene XRCC3 Thr241Met and risk of gastric cancer in a Chinese population.

Mammalian cells are constantly exposed to a wide variety of genotoxic agents from both endogenous and exogenous sources. Genetic variability in DNA repair may contribute to human cancer risk. In this population-based case-control study in China, we tested the hypothesis that a C to T variant (Thr241Met) of DNA repair gene XRCC3 (X-ray repair cross-complementing group 3) is associated with risk of developing gastric cancer. We genotyped for this variant using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) in 188 histologically confirmed gastric cancer patients and 166 frequency-matched cancer-free controls. The XRCC3 genotype and allele frequencies were not significantly different between cases and controls (P = 0.99 for genotype; P = 0.76 for allele). The XRCC3 241Met allele frequency (4.8%) was significantly lower in healthy Chinese controls than previously reported healthy US Caucasian controls (38.9%). Compared with the XRCC3 241Thr/Thr genotype, the variant XRCC3241Thr/Met and Met/Met genotypes were not associated with an increased risk of gastric cancer (adjusted odds ratio (OR(a)), 1.06; 95% confidence interval (CI), 0.52-2.16). These findings suggest that polymorphisms of XRCC3 Thr241Met may not play a role in the etiology of gastric cancer. Further studies with a larger number of subjects and simultaneous measurement of different polymorphisms in DNA repair genes in the same pathway are needed to confirm these findings.

Interleukin-1B gene promoter variants are associated with an increased risk of gastric cancer in a Chinese population.

Studies suggest that IL-1beta (encoded by IL-1B gene) is a pro-inflammatory cytokine and potent inhibitor of gastric acid secretion, which is proposed as a key determinant in gastric carcinogenesis. Two potentially functional polymorphisms (C-31T and T-511C) in the IL-1B promoter were suggested to be correlated with alteration of Helicobacter pylori infection and IL-1beta expression and therefore may be associated with risk of gastric cancer. To test the hypothesis that these two polymorphisms are associated with gastric cancer risk, we performed a case-control study of 280 histologically confirmed gastric cancer patients and 258 age, sex frequency-matched cancer-free controls in a Chinese population. Multivariate logistic regression analyses revealed that the risks (adjusted odds ratio [OR] and 95% confidence interval [CI]) associated with the IL-1B variant genotypes were 1.64 (95% CI, 1.01-2.66) for -31TT and 1.52 (95% CI, 0.91-2.54) for -511CC, respectively, compared with their wild-type homozygotes. The risks were significantly more evident in individuals with H. pylori infection (adjusted OR, 2.14; 95% CI, 1.13-4.06 for -31TT; adjusted OR, 2.00; 95% CI, 1.02-3.89 for -511CC), which was consistent with the biological effects of IL-1beta. When we used the haplotype analyses and assumed the IL-1B -31T and -511C as risk alleles, no synergistic effect was found between these two loci. These findings indicate that these two IL-1B promoter variants may contribute to the risk of developing gastric cancer in the Chinese population, especially in individuals with H. pylori infection.