Helicobacter pylori infection synergizes with three inflammation-related genetic variants in the GWASs to increase risk of gastric cancer in a Chinese population

Association between MUC1 rs4072037 polymorphism and Helicobacter pylori in patients with gastric cancer

Background

The MUC1 gene encodes glycoproteins attached to cell membrane that play a protective role in gastric cancer and protect epithelial surfaces against external factors such as Helicobacter pylori. H. pylori infection can induce a cascade of innate and acquired immune responses in gastric mucosa. Relationship between rs4072037G>A polymorphism of MUC1 gene and increased susceptibility to H. pylori infection aimed to investigate in patients with gastric cancer in Mazandaran, northern Iran.

Methods

A case-control study was conducted on 99 patients with gastric cancer (H. pylori positive and negative) and 98 controls (H. pylori positive and negative) without gastric cancer (confirmed by pathological biopsy samples obtained during endoscopy). H. pylori infection was diagnosed by histological examination using Giemsa staining. Genomic DNA extracted from peripheral blood was analyzed by PCR-RFLP technique.

Results

Analysis of all genetic models showed no significant relationship between rs4072037G>A polymorphism and risk of gastric cancer (GC). The relationship between H. pylori infection and rs4072037G>A polymorphism showed an increased susceptibility to gastric cancer in both positive and negative H. pylori groups (including case and control groups). The genetic model of GA/GG and H. pylori- positive versus GA/GG and H. pylori-negative showed a significantly increased susceptibility to gastric cancer (OR=0.251, CI: 0.128-0.493, P=0.000).

Conclusion

These findings indicate that rs4072037G>A polymorphism may interact with H. pylori infection to increase the risk of GC.

A Model for Gastric Cancer Risk Prediction Based on MUC1 Polymorphisms and Health-risk Behaviors in a Vietnamese Population

BACKGROUND/AIM

Although the expression of mucin 1(MUC1) and prostate stem cell antigen (PSCA) genes is correlated with gastric cancer development and progression, the utility of these two genes as biomarkers of gastric cancer prognosis still needs to be confirmed in clinical practice. This study aimed to develop a model predictive of gastric cancer that integrates several significant single nucleotide polymorphisms (SNPs) of MUC1 and PSCA genes, and some health-risk behavior factors in a Vietnamese population.

PATIENTS AND METHODS

A total of 302 patients with primary gastric carcinoma and 304 healthy persons were included in a case-control study. The generalized linear model was used with the profile of age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases, and the SNPs of MUC1 and PSCA. The prognostic value of the model was assessed by the area under a receiver operating characteristic curve (AUC) and Akaike Information Criterion (AIC) values.

RESULTS

In male participants, the final model, consisting of age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases and SNP MUC1 rs4072037, provided acceptable discrimination, with an AUC of 0.6374 and the lowest AIC value (539.53). In female participants, the predictive model including age, sex, history of smoking and using alcohol, personal and family medical history of stomach diseases, SNPs MUC1 rs4072037 and rs2070803 had an AUC of 0.6937 and AIC of 266.80. The calibration plots of the male model approximately fitted the ideal calibration line.

CONCLUSION

The predictive model based on age, sex, medical history, and genetic and health-risk behavior factors has a high potential in determining gastric cancer. Further studies that elucidate other genetic variants should be carried out to define high-risk gastric cancer groups and propose appropriate personalized prevention.

rs2671655 single nucleotide polymorphism modulates the risk for gastric cancer in Helicobacter pylori-infected individuals: a genome-wide association study in the Korean population

OBJECTIVE

To identify genetic variations which is associated with gastric cancer (GC) risk according to Helicobacter pylori infection.

METHODS

This study incorporated 527 GC patients and 441 controls from a cohort at Seoul National University Bundang Hospital. The associations between GC risk and single nucleotide polymorphisms were calculated, stratified by H. pylori status, adjusting for age, sex, and smoking. mRNA expression from non-cancerous gastric mucosae was evaluated using reverse transcription quantitative polymerase chain reaction.

RESULTS

In the entire cohort, genome-wide association study showed no significant variants reached the genome-wide significance level. In the H. pylori-positive group, rs2671655 (chr17:47,468,020;hg19, GH17J049387 enhancer region) was identified at a genome-wide significance level, which was more pronounced in diffuse type GC. There was no significant variant in the H. pylori-negative group, indicating the effect modification of rs2671655 by H. pylori. Among the target genes of GH17J049387 enhancer (PHB1, ZNF652 and SPOP), PHB1 mRNA was expressed more in cases than in controls, who were not affected by H. pylori. By contrast, an increase in ZNF652 and SPOP in GC was observed only in the H. pylori-negative group (P < 0.05). Mediation analysis showed that PHB1 (P = 0.0238) and SPOP (P = 0.0328) mediated the effect of rs2671655 on GC risk. The polygenic risk score was associated with the number of rs2671655 risk alleles only in the H. pylori-positive group (P = 0.0112).

CONCLUSION

After H. pylori infection, rs2671655 may increase GC risk, especially in diffuse-type GC, by regulating the expression of several genes that consequently modify susceptibility to GC.

Polymorphism of MUC1 Gene in Vietnamese Gastric Cancer Patients: A Multicenter Case-Control Study

Background

A few studies revealed that the polymorphisms of Mucin 1 gene have a role and significance as a susceptible factor contributing to gastric cancer. To better understand the roles of two MUC1 genotype polymorphisms of rs4072037 and rs2070803 in the development of gastric cancer in Vietnamese population, a multicenter, large-sample, case-control study was conducted to investigate the potential association of these single-nucleotide polymorphisms (SNPs) of MUC1 gene with gastric cancer risk and to evaluate the combination factors in relation with these SNPs.

Methods

This case-control study included 302 gastric cancer patients and 304 controls at four national medical hospitals between 2016 and 2018. All participants were interviewed for sociodemographic characteristics, smoking and drinking status, and personal and family history of gastric diseases. Genotyping was done using polymerase chain reaction-restriction fragment length polymorphism analysis. The association of SNPs with gastric cancer was explored using logistic regression models.

Results

AA genotype for rs4072037 was significantly associated with increased gastric cancer. Those with AA genotype had higher gastric cancer risk than had patients with AG (OR: 2.09, 95% CI: 1.48-2.96) and a combination of AG+GG (OR: 1.85, 95% CI: 1.33-2.56). In rs2070803, GG genotype increased gastric cancer risk when compared with AG (OR: 1.97, 95% CI: 1.39-2.80) and AG+AA (OR: 1.71, 95% CI: 1.23-2.39). AG genotypes in both SNPs decreased gastric cancer risk when compared with homogenous genotype, more specifically AA (OR: 0.51, 95% CI: 0.35-0.72) and GG (OR: 0.58, 95% CI: 0.35-0.97). These genotypes in combination with above-60-year-old age, male gender, alcoholism, and personal history of gastric disease were also significantly elevated risk factors for gastric cancer.

Conclusions

rs4072037 and rs2070803 of Mucin 1 genes are two genotypic risk factors for gastric cancer. Those in combination with gender, family history, smoking, and drinking habits significantly increase the risk of gastric cancer.

Integrated analysis of whole genome and transcriptome sequencing in a young patient with gastric cancer provides insights for precision therapy

Gastric cancer is a leading cause of cancer-associated deaths worldwide and is considered to be an age-related disease. In younger patients, gastric cancer is biologically more aggressive, and prognosis is worse compared with that in elderly patients. In the present case report, the whole genome and transcriptome was sequenced in a 26-year-old patient with gastric cancer who presented with gastric cancer-related symptoms and was admitted to the First Affiliated Anhui Medical Hospital (Hefei, China) in December 2016. In total, 9 germline and 4 somatic mutations were identified in the patient, and there were more deleterious sites in the germline mutated genes. Genes with somatic mutations, such as MUC2, MUC4, SLC8A2, and with structural variations, including CCND3, FGFR2 and FGFR3, were found to be differentially expressed. Cancer-associated pathways, such as the 'calcium signaling pathway', 'cGMP-PKG signaling pathway' and 'transcriptional mis-regulation' were also enriched at both the genomic and transcriptomic levels. The genes found to have germline (SFRP4), somatic (MUC2, MUC4, SLC8A2) mutations, or structural variations (CCND3, FGFR2 and FGFR3) were differentially expressed in the patient and could be promising precision therapy targets.

Determination of CagA EPIYA motif in Helicobacter pylori strains isolated from patients with digestive disorder

This study was conducted to identify patterns of cagA EPIYA motifs in H. pylori strains isolated from patients with gastrointestinal diseases in Hospitals of Shahrekord, and investigate the association between these biomarkers and clinical outcomes of gastrointestinal diseases due to H. pylori. In this study, 253 patients with gastrointestinal diseases were studied within 1395–1396. Histopathological investigations and urease test showed that 207 isolates were H. pylori-positive. Then, screening using a molecular technique, PCR, confirmed that 159 isolates had cagA. Finally, the pattern and prevalence of the motifs were determined by PCR and identified a number of motifs were sequenced.

Results of this study showed that the pattern of motifs was as follows: ABC (140 isolates) (93/7%), ABCC (6 isolates) (3/77%), ABCCC (4 isolates) (2/5%), AB (7 isolates) (4/4%), AC (1 isolate) (0/6%), and BC (1 isolate) (0/6%). Sequencing results showed the presence of changed EPIYA motif in some isolates. CM motif sequence was also seen in all isolates. In this study, no significant association was seen between the prevalence rate of different patterns and clinical symptoms (p = 0.71). There is a slight association between the presence of ABC motifs and the type of digestive disorder (p = 0.056). Results indicated that ABC was the most frequently seen pattern however, in such that positive cases of ABC motifs were more common in gastritis. All isolates had kinase phosphorylation region, and the observed pattern in this region was a generally western type (ABC).

Association of MUC1 5640G>A and PSCA 5057C>T polymorphisms with the risk of gastric cancer in Northern Iran

Background

Gastric cancer is one of the four most common cancer that causing death worldwide. Genome-Wide Association Studies (GWAS) have shown that genetic diversities MUC1 (Mucin 1) and PSCA (Prostate Stem Cell Antigen) genes are involved in gastric cancer. The aim of this study was avaluating the association of rs4072037G > A polymorphism in MUC1 and rs2294008 C > T in PSCA gene with risk of gastric cancer in northern Iran.

Methods

DNA was extracted from 99 formalin fixed paraffin-embedded (FFPE) tissue samples of gastric cancer and 96 peripheral blood samples from healthy individuals (sex matched) as controls. Two desired polymorphisms, 5640G > A and 5057C > T for MUC1 and PSCA genes were genotyped using PCR-RFLP method.

Results

The G allele at rs4072037 of MUC1 gene was associated with a significant decreased gastric cancer risk (OR = 0.507, 95% CI: 0.322–0.799, p = 0.003). A significant decreased risk of gastric cancer was observed in people with either AG vs. AA, AG + AA vs. GG and AA+GG vs. AG genotypes of MUC1 polymorphism (OR = 4.296, 95% CI: 1.190–15.517, p = 0.026), (OR = 3.726, 95% CI: 2.033–6.830, p = 0.0001) and (OR = 0.223, 95% CI: 0.120–0.413, p = 0.0001) respectively. Finally, there was no significant association between the PSCA 5057C > T polymorphism and risk of gastric cancer in all genetic models.

Conclusion

Results indicated that the MUC1 5640G > A polymorphism may have protective effect for gastric cancer in the Northern Iran population and could be considered as a potential molecular marker in gastric cancer.

Role of MUC1 rs4072037 polymorphism in gastric cancer: a meta-analysis

Background and objective: To further determine the association between mucin 1 (MUC1) rs4072037 polymorphism and gastric cancer risk on the basis of previously published studies. Methodology: PubMed and Embase were used to search all the available publications. The relative risk of the correlation was shown as odds ratio (OR) with 95% confidence interval (95% CI) under all the genetic comparisons. Subgroup analyses based on ethnicity, study design and HWE were also executed to detect effects of specific factors on the risk of gastric cancer. Results: MUC1 rs4072037 polymorphism was observed to reduce the risk of gastric cancer under the five genetic comparisons [(GG versus AA: OR (95% CI)=0.72 (0.61, 0.84); GG + GA versus AA: OR (95% CI)=0.82 (0.76, 0.88); GG versus AA + GA: OR (95% CI)=0.83 (0.71, 0.96); G versus A: OR (95% CI)=0.78 (0.72, 0.84); GA versus AA: OR (95% CI)=0.80 (0.74, 0.87)]. This decreased risk of gastric cancer was also detected in subgroup analyses based on ancestry (Asian and Caucasian), study design (population-based and hospital-based) and HWE (P _HWE>0.05). Conclusions: MUC1 rs4072037 polymorphism may have an important role in gastric cancer, and this protective effect may vary among different ethnic populations and control subjects.

Association between SOD2 V16A variant and urological cancer risk

Background: The correlation between superoxide dismutase 2 (SOD2) V16A variant and urological cancer susceptibility has been widely studied, however, with divergent results.

Results: Totally, 9,910 cancer patients and 11,239 control subjects were enrolled. V16A variant is associated with an increased susceptibility to urological cancer (A-allele vs. V-allele: OR = 1.06, 95% CI = 1.00 – 1.13, P = 0.047; AA+AV vs. VV: OR = 1.09, 95% CI = 1.02 – 1.16, P = 0.008), especially for prostate cancer (PCa). Serum SOD2 level of PCa patients with VV+VA genotypes was lower than in those with AA genotypes. SOD2 expression is downregulated in both prostate and bladder cancer, as compared to the control. Furthermore, SOD2 was found to be downregulated in more advanced PCa participants, as compared to the ones in early stages. PCa subjects with low SOD2 expression displayed a shorter disease-free survival (DFS) time compared to that of the high SOD2 expression counterparts.

Conclusions: The SOD2 V16A variant may be associated with increased urological cancer susceptibility, especially for prostate cancer.

Methods: A pooled analysis utilizing odds ratios (ORs), in silico tools and ELISA was adopted to demonstrate this association. We also used immunohistochemical staining (IHS) to assess SOD2 expression.

Human methionine synthase A2756G polymorphism increases susceptibility to prostate cancer

Background/Aims: Previous results on the association between MTR gene A2756G polymorphism and PCa risk are inconclusive.

Methods: We used odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) to evaluate the correlation between MTR A2756G polymorphism and risk of PCa in meta-analysis. Serum expression of MTR was detected by ELISA and in-silico tools were utilized to assess this variant.

Results: Our study included 2,921 PCa patients and 3,095 control subjects. The results indicated that the MTR A2756G polymorphism is linked with an increased risk of PCa using three genetic models (G-allele vs. A-allele: OR = 1.16, 95%CI = 1.04 - 1.30; GA vs. AA: OR = 1.17, 95%CI = 1.02 - 1.33; GG+GA vs. AA: OR = 1.18, 95%CI = 1.04 - 1.34). Stratified analysis produced similar results. A significant association was also indicated in advanced PCa from the meta-analysis. Finally, our experiments showed evidence that serum MTR levels in PCa patients with AA genotypes were statistically higher than in those with GG/GA genotypes.

Conclusions: Our present study suggests that the MTR A2756G polymorphism may contribute to the risk of developing PCa, particularly in Asian and hospital-based studies. Moreover, serum MTR might be utilized in diagnosis of PCa.

RNASEL 1623A>C variant is associated with the risk of prostate cancer in African descendants

Association between ribonuclease L (RNASEL) gene 1623A>C polymorphism and prostate cancer (PCa) susceptibility has been assessed in large quantities of studies but with controversial conclusions. We undertook a pooled analysis containing 7397 PCa cases and 6088 control subjects to assess the correlation between RNASEL 1623A>C polymorphism and PCa risk. Moreover, we used enzyme-linked immunosorbent assay to test the serum RNASEL expression among patients enrolled in our centers and in-silico tools were also utilized. The overall results of our analysis indicated a positive relationship between 1623A>C variant and PCa risk (allelic contrast, odds ratio [OR] = 1.07; 95% confidence interval [CI] = 1.02-1.12; P_{heterogeneity}  = 0.575; CC vs AA, OR = 1.14; 95% CI = 1.03-1.26; P_{heterogeneity}  = 0.217; CC + CA vs AA, OR = 1.10; 95% CI = 1.01-1.19; P_{heterogeneity}  = 0.303; and CC vs CA + AA, OR = 1.08; 95% CI = 1.00-1.17; P_{heterogeneity}  = 0.298). In ethnicity subgroup analysis, similar results were especially indicated in African descendants. In addition, serum RNASEL levels in PCa cases with CC + CA genotypes were higher than those with AA genotypes. Our present study showed evidence that RNASEL 1623A>C polymorphism is related to PCa risk, especially in African descendants.

PLCE1 Polymorphisms and Risk of Esophageal and Gastric Cancer in a Northwestern Chinese Population

The reported risk susceptibility between phospholipase C epsilon 1 (PLCE1) polymorphisms and esophageal cancer (EC) and gastric cancer (GC) remained inconsistent and controversial, especially on variants other than rs2274223. The relationship between PLCE1 polymorphisms and gene expression is also unclear. Here we conducted a case-control study from northwest China, genotyped seven tag single nucleotide polymorphisms (SNPs) in PLCE1 with multiplexed SNP MassARRAY assay. Stratified analysis was carried out and PLCE1 expression was evaluated in specified groups with the method of qRT-PCR and immunohistochemistry. Results showed that the minor alleles of rs3765524, rs2274223, and rs10509670 were associated with increased risk of EC and GC. Linkage disequilibrium analysis revealed protective haplotypes of CCAAGTC and CCAA. By stratification, a more significant association was found in subgroups of male, age ≥ 54, tumor stages of I-II and tumor size ≤ 5 cm, EC and cardia cancer (CC) of stomach, and moderate to well differentiated squamous carcinoma. In addition, a significant association for rs3765524 with noncardia cancer (NCC) and adenocarcinoma which is predominant in China was also observed. Further expression analysis identified that PLCE1 was downregulated in NCC tissues comparing to their adjacent noncancerous tissues, and its protein expression was higher in genotype rs3765524 CT/TT than in rs3765524 CC. In summary, our study suggests that PLCE1 polymorphisms may affect its gene expression and are associated with not only EC and CC, but also, to some extent, NCC risk in this study population.

Single Nucleotide Polymorphisms in PLCE1 for Cancer Risk of Different Types: A Meta-Analysis

Background: Recent studies have investigated the relationships between PLCE1 polymorphisms and cancer susceptibility. However, some findings lack consistency.

Objectives: In the current study, we conducted a meta-analysis to more accurately evaluate the relationships between PLCE1 (rs2274223, rs3765524, rs753724, rs11187842, and rs7922612) single nucleotide polymorphisms (SNPs) and risk for different types of cancer.

Methods: We performed a comprehensive search strategy in PubMed, Web of Science, Medline, EMbase, and Scopus for articles available until 19 March 2018. A total of 54 case-control studies comprising 17,955 cases and 20,400 controls were included in the current meta-analysis, which together comprised a total of 32 publications. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate relationships between the PLCE1 polymorphisms and cancer susceptibility. All statistical analyses were performed using Stata 11 software.

Results: Results of the meta-analysis demonstrated that the rs2274223 polymorphism showed a significant correlation with increased overall cancer susceptibility (AG vs. AA: OR 1.168, 95% CI 1.084–1.259; GG vs. AA: OR 1.351, 95% CI 1.163–1.570; AG+GG vs. AA: OR 1.193, 95% CI 1.103–1.290; GG vs. AA+AG: OR 1.262, 95% CI 1.102–1.446; G vs. A: OR 1.163, 95% CI 1.089–1.242). Results of subgroup analysis showed that the rs2274223 polymorphism was associated with higher risk for esophageal cancer and gastric cancer relative to colorectal cancer and head and neck cancer. In addition, the rs2274223 polymorphism was found to be associated with increased cancer risk, especially among the subgroups comprising Asians, studies with population-based controls, studies employing the TaqMan genotyping method, and studies consistent with Hardy-Weinberg equilibrium (HWE). The association between the rs3765524 polymorphism and reduced overall cancer risk was detected in one specific genetic model (CT vs. CC: OR 0.681, 95% CI 0.523–0.886). Results of subgroup analysis showed that the rs3765524 polymorphism was associated with cancer risk in a specific genetic model among the subgroups of colorectal cancer, esophageal cancer, Asians, studies with population-based controls, and studies consistent with HWE. However, relationships among the PLCE1 rs753724, rs11187842, and rs7922612 polymorphisms and tumor risk were not identified.

Conclusions: Results of the current meta-analysis suggested that PLCE1 (rs2274223, rs3765524) polymorphisms are associated with cancer susceptibility.

Do polymorphisms in protein kinase catalytic subunit alpha-1 gene associated with cancer susceptibility? a meta-analysis and systematic review

Background

Currently, several studies have demonstrated that PRKAA1 polymorphisms conduce to the development of cancer. PRKAA1 gene encodes the AMP-activated protein kinase summit-α1, and plays an important role in cell metabolism. Thus, we performed a systematic review and meta-analysis of all enrolled eligible case-control studies to obtain a precise correlation between PRKAA1 polymorphism and cancer susceptibility.

Methods

Extensive retrieve was performed in Web of Science, Google Scholar, PubMed, EMbase, CNKI and Wanfang databases up to August 26, 2018. Odds ratios (ORs) and 95% CIs were performed to evaluate the overall strength of the associations in five models, as well as in subgroup analyses, stratified by ethnicity, cancer type or source of control. Q-test, Egger’s test and Begg’s funnel plot were applied to evaluate the heterogeneity and publication bias. In-silico analysis was performed to demonstrate the relationship of PRKAA1 expression correlated with cancer tissues and survival time.

Results

Twenty-two case-control studies from 14 publications were enrolled, with 17,068 cases and 20,871 controls for rs13361707, and 2514 cases and 3193 controls for rs10074991. Overall, we identified that the PRKAA1 rs13361707 polymorphism is not significantly associated with cancer susceptibility under all five genetic models. For rs10074991, we revealed a significant decrease risk in allelic comparison model (B vs. A: OR = 0.774, 95% CI = 0.642–0.931, P_Adjust = 3.376*10^− 2), heterozygote comparison model (BA vs. AA: OR = 0.779 95%CI = 0.691–0.877, P_Adjust = 9.86*10^− 10;), and dominant genetic model (BB + BA vs. AA: OR = 0.697 95%CI = 0.533–0.912, P_Adjust = 4.211*10^− 2;). Evidence from TCGA database and GTEx projects indicated that the expression of PRKAA1 in gastric cancer tissue is higher, compared to normal stomach tissue, as well as it in breast cancer and esophageal squamous cell carcinoma. However, the Kaplan-Meier estimate showed that there is no significant difference of OS and RFS between the low and high PRKAA1 TPM groups in gastric cancer, breast cancer, and esophageal carcinoma.

Conclusions

To sum up, PRKAA1 rs13361707 polymorphism is not participant with the increased risk of cancer, while the A allele of PRKAA1 rs10074991 revealed a significant decrease risk.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0704-8) contains supplementary material, which is available to authorized users.

Evidence for PTGER4, PSCA, and MBOAT7 as risk genes for gastric cancer on the genome and transcriptome level

Genetic associations between variants on chromosome 5p13 and 8q24 and gastric cancer (GC) have been previously reported in the Asian population. We aimed to replicate these findings and to characterize the associations at the genome and transcriptome level. We performed a fine‐mapping association study in 1926 GC patients and 2012 controls of European descent using high dense SNP marker sets on both chromosomal regions. Next, we performed expression quantitative trait locus (eQTL) analyses using gastric transcriptome data from 143 individuals focusing on the GC associated variants. On chromosome 5p13 the strongest association was observed at rs6872282 (P = 2.53 × 10⁻⁰⁴) and on chromosome 8q24 at rs2585176 (P = 1.09 × 10⁻⁰⁹). On chromosome 5p13 we found cis‐eQTL effects with an upregulation of PTGER4 expression in GC risk allele carrier (P = 9.27 × 10⁻¹¹). On chromosome 8q24 we observed cis‐eQTL effects with an upregulation of PSCA expression in GC risk allele carrier (P = 2.17 × 10⁻⁴⁷). In addition, we found trans‐eQTL effects for the same variants on 8q24 with a downregulation of MBOAT7 expression in GC risk allele carrier (P = 3.11 × 10⁻⁰⁹). In summary, we confirmed and refined the previously reported GC associations at both chromosomal regions. Our data point to shared etiological factors between Asians and Europeans. Furthermore, our data imply an upregulated expression of PTGER4 and PSCA as well as a downregulated expression of MBOAT7 in gastric tissue as risk‐conferring GC pathomechanisms.

Association between PRKAA1 rs13361707 T>C polymorphism and gastric cancer risk: Evidence based on a meta-analysis

BACKGROUND

Recently, several published studies investigating the relationship between protein kinase catalytic subunit alpha-1 gene (PRKAA1) rs13361707 T>C polymorphism and gastric cancer (GC) susceptibility reported controversial results. The purpose of this meta-analysis was to estimate the strength of the relationship.

METHODS

Qualified studies were identified form a comprehensive search conducted in the Embase, Pubmed, Wangfang, and China National Knowledge Infrastructure (CNKI) databases for studies published before February 12, 2018. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the relationship between the PRKAA1 rs13361707 T>C polymorphism and GC risk.

RESULTS

Fifteen independent case-control studies, which included 14,615 GC patients and 18,143 control subjects, were included in this present meta-analysis. The overall analysis of the 15 studies indicated that the PRKAA1 rs13361707 T>C polymorphism significantly increased susceptibility for GC in all genetic models. When stratified analysis was carried out by country and source of controls, similar results were found in each subgroup, except for the Hispanic Americans. There was no publication bias in our study. Omitting each study 1 at a time in the sensitivity analysis of the PRKAA1 rs13361707 T>C polymorphism and GC risk had no noticeable influence on the pooled OR, which identified the reliability of the meta-analysis. False-positive report probability analysis and trial sequential analysis demonstrated that such relationship was confirmed in the present study.

CONCLUSIONS

The meta-analysis reveals that the PRKAA1 rs13361707 T>C polymorphism has a significant relationship with increased GC risk. To confirm the risk identified in the present meta-analysis, well-designed and large-scale case-control studies are warranted to investigate the relationship, especially among non-Asian ethnicity.

MUC1 rs4072037 polymorphism is associated with decreased risk of gastric cancer: a meta-analysis

BACKGROUND

Several studies have recently investigated the association between mucin 1 (MUC1) rs4072037 polymorphism and gastric cancer (GC) risk, but with conflicting results. The aim of this meta-analysis was to evaluate the association between MUC1 rs4072037 polymorphism and GC risk.

METHODS

A comprehensive database search of PubMed, Elsevier, Embase and China National Knowledge Infrastructure (CNKI) databases was performed to identify relevant studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of any association.

RESULTS

A total of 12 papers containing 18 studies were included in this meta-analysis, involving 12,373 cases and 15,008 controls. Our data suggested that rs4072037 polymorphism was associated with a decreased risk of GC. Stratification analyses of ethnicity indicated that rs4072037 decreased the risk of GC among white populations, but no significant relationship was observed among Asian populations. No significant associations were observed in subgroups of Lauren classification (intestinal or diffuse) and anatomical classification (cardia or non-cardia).

CONCLUSIONS

In conclusion, this meta-analysis suggested that rs4245739 polymorphism in the MUC1 gene may play a pivotal role in the pathogenesis of GC, especially for white populations.

Correlation between protein kinase catalytic subunit alpha-1 gene rs13361707 polymorphism and gastric cancer susceptibility in asian populations

A single nucleotide polymorphism (SNP) of the protein kinase catalytic subunit alpha-1 gene (PRKAA1) that confers susceptibility to gastric cancer (GC) was identified by genome-wide association in several case-control studies. However, the results remained controversial and ambiguous. Therefore, we performed a larger meta-analysis to confirm this association. We searched the PubMed, Embase, WanFang, and CNKI databases, without any restriction on language, covering all papers published until Feb 22, 2017. Overall, 14 case-control studies with 14,485 cases and 14,792 controls were retrieved based on the search criteria. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to quantify the strength of the association. Publication bias was assessed by Egger’s and Begg’s tests. We found that the PRKAA1 rs13361707 C/T polymorphism had no association with GC risk in any of the pooled genetic models (for example, the T-allele vs. C-allele allelic contrast model yielded the following estimates: OR = 0.87, 95% CI = 0.73–1.05, P_{heterogeneity} = 0.000). Furthermore, in analyses stratified by either source of control or geographical origin of subjects, a statistically significant inverse relationship was detected between PRKAA1 rs13361707 C/T polymorphism and GC risk. No obvious evidence of publication bias was detected in the pooled meta-analysis. Furthermore, we observed that individuals carrying T-allele (TT or TC) genotypes had a lower expression of PRKAA1. Our present study indicated that PRKAA1 rs13361707 C/T was not significantly associated with GC risk, despite few positive results in the subgroups.

Gastrin and Gastric Cancer

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Despite progress in understanding its development, challenges with treatment remain. Gastrin, a peptide hormone, is trophic for normal gastrointestinal epithelium. Gastrin also has been shown to play an important role in the stimulation of growth of several gastrointestinal cancers including gastric cancer. We sought to review the role of gastrin and its pathway in gastric cancer and its potential as a therapeutic target in the management of gastric cancer. In the normal adult stomach, gastrin is synthesized in the G cells of the antrum; however, gastrin expression also is found in many gastric adenocarcinomas of the stomach corpus. Gastrin's actions are mediated through the G-protein-coupled receptor cholecystokinin-B (CCK-B) on parietal and enterochromaffin cells of the gastric body. Gastrin blood levels are increased in subjects with type A atrophic gastritis and in those taking high doses of daily proton pump inhibitors for acid reflux disease. In experimental models, proton pump inhibitor-induced hypergastrinemia and infection with Helicobacter pylori increase the risk of gastric cancer. Understanding the gastrin:CCK-B signaling pathway has led to therapeutic strategies to treat gastric cancer by either targeting the CCK-B receptor with small-molecule antagonists or targeting the peptide with immune-based therapies. In this review, we discuss the role of gastrin in gastric adenocarcinoma, and strategies to block its effects to treat those with unresectable gastric cancer.

Environmental factors, seven GWAS-identified susceptibility loci, and risk of gastric cancer and its precursors in a Chinese population

Gene–environment interactions may increase gastric cancer (GC) risk. Seven susceptibility loci identified by genome‐wide association studies (GWASs) suggest that genetic factors play a role in gastric carcinogenesis. Meanwhile, Helicobacter pylori (H. pylori) infection, smoking, and alcohol drinking are also important environmental factors for gastric cancer. However, studies to explore the role of gene–environment interactions in gastric carcinogenesis, and particularly the relationship between the seven susceptibility loci and their potential interactions with H. pylori infection, smoking, and alcohol drinking in risk of GC, and severe intestinal metaplasia (IM)/dysplasia, have been inconclusive. A total of 1273 subjects in a Chinese population were recruited, and genotyping was carried out using the competitive allele‐specific PCR (KASP) method. Unconditional logistic regression was applied to model the associations between genetic polymorphisms and the disease risk. Effect modifications by H. pylori infection, smoking and alcohol drinking were evaluated. PSCA rs2294008/rs2976392 showed a significant, multiplicative interaction with H. pylori infection in risk of GC. Meanwhile, PRKAA1 rs13361707 had an additive interaction with H. pylori infection. SLC52A3 rs13042395 showed an interaction with alcohol drinking in risk of GC. Moreover, three SNPs, MUC1 rs4072037, ZBTB20 rs9841504 and PRKAA1 rs13361707, were associated with precancerous gastric lesions (severe IM/dysplasia). Our data suggest that genetic predisposition factors identified by GWAS may interact with environmental risk factors, Particularly for H. pylori infection and alcohol consumption, to increase the risk of GC.

Additive interactions between PRKAA1 polymorphisms and Helicobacter pylori CagA infection associated with gastric cancer risk in Koreans

Although several studies reported genetic polymorphisms in protein kinase AMP‐activated alpha 1 catalytic subunit (PRKAA1) and their associations with gastric cancer risk, few have evaluated associations between Helicobacter pylori infection and PRKAA1 gene‐environment interactions. Here, we evaluated the effects of interactions between H. pylori infection and PRKAA1 polymorphisms on gastric cancer risk in Koreans. In this hospital‐based case–control study, PRKAA1 genotypes were analyzed and H. pylori infection and CagA status were examined using a serologic method in 846 pairs of gastric cancer patients and controls matched for age and sex. H. pylori seropositivity was associated with a 1.43‐fold [95% confidence interval: 1.12–1.81] increase in the risk of gastric cancer, and CagA low‐positive titers during H. pylori infection increased the risk by 1.85‐fold (95% confidence interval, 1.38–2.48). Significant positive interaction between the PRKAA1 rs13361707 genotype and H. pylori infection was verified on an additive scale [relative excess risk due to interaction, 0.55; 95% confidence interval, 0.05–1.04; P = 0.030], and the gene‐environment interaction between PRKAA1 rs13361707 and CagA status was also statistically significant (relative excess risk due to interaction, 0.50; 95% confidence interval, 0.30–0.70; P < 0.001). Our results indicated that H. pylori infection, CagA status, and PRKAA1 polymorphisms were risk factors for gastric cancer in Koreans, and that the combination of two of these factors rather than their independent effects synergistically increased the risk.

Genetic variant rs4072037 of MUC1 and gastric cancer risk in an Eastern Chinese population

Published data on the association between the MUC1 rs4072037A > G polymorphism and gastric cancer (GCa) risk were inconclusive. To derive a more precise estimation of the association, we conducted a large GCa study of 1,124 cases and 1,192 controls to confirm this association in an Eastern Chinese population. Our results showed that the G allele was strongly associated with a decreased GCa risk in the study population [GG vs. AA, odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.31-0.73; AG/GG vs. AA, OR = 0.82, 95% CI = 0.68-0.99; GG vs. AA/AG, OR = 0.48, 95% CI = 0.32-0.74]. These associations remained significant in subgroups of age, tumor site, drinking and smoking status. Moreover, this association was supported by an additional meta-analysis of published studies. In summary, these results suggest that the MUC1 rs4072037G allele may be a low-penetrating protection factor for GCa risk in Chinese populations.

Genetic variant of PRKAA1 and gastric cancer risk in an eastern Chinese population

Published data on the association between PRKAA1 rs13361707 T > C polymorphism and gastric cancer (GCa) susceptibility were inconclusive. To derive a more precise estimation of the association, we conducted a large-scale GCa study of 1,124 cases and 1,194 controls to confirm this association in an eastern Chinese population. Our results showed that the C allele of PRKAA1 rs13361707 increased the GC risk in the study population [CT vs. TT, odds ratio (OR) = 1.72, 95% confidence interval (CI) = 1.40-2.12; CC vs. TT, OR = 2.15, 95%CI = 1.70-2.71; CT/CC vs. TT, OR = 1.86, 95%CI = 1.53-2.26; CC vs.TT/CT, OR = 1.49, 95%CI = 1.24-1.79]. In addition, the association of C allele with an increased GCa risk was still significant in subgroups, when stratified by age, sex, tumor site, drinking and smoking status. Moreover, the findings in the present study were validated by our further meta-analysis. In summary, these results indicated that the C allele of PRKAA1 rs13361707 was a low-penetrate risk factor for GCa.

Association of risk of gastric cancer and consumption of tobacco, alcohol and tea in the Chinese population

This study aimed at summarizing epidemiological research findings on associations between tobacco, alcohol and tea consumption and risk of gastric cancer (GC) in the Chinese population. The review searched PubMed, Embase, China National Knowledge Infrastructure (CNKI) and China Biology Medicine (CBM) databases and reference lists of review papers for all studies published in English or Chinese languages. Information extracted, via two independent researchers, from retrieved articles included first author, year of publication, study design, sample size, source of controls and adjusted odds ratio (OR) or relative risk (RR) with the corresponding 95% confidence intervals (CIs) for each category. Statistical analyses used software STATA version 12.0. The systematic search found 89 articles containing 25,821 GC cases and 135,298 non-cases. The overall random effects in terms of pooled OR and 95%CI for tobacco, alcohol and tea consumption were 1.62 (95%CI: 1.50-1.74), 1.57 (95%CI: 1.41-1.76) and 0.67 (95%CI: 0.59-0.76) respectively; while the heterogeneity among included studies ranged from 80.1% to 87.5%. The majority of subgroup analyses revealed consistent results with the overall analyses. All three behavioral factors showed statistically significant dose-dependent effects on GC (P<0.05). The study revealed that tobacco smoking and alcohol drinking were associated with over 1/2 added risk of GC, while tea drinking conferred about 1/3 lower risk of GC in the Chinese population. However, these results should be interpreted with caution given the fact that most of the included studies were based on a retrospective design and heterogeneity among studies was relatively high.

Medical management of gastric cancer: a 2014 update

Gastric cancer represents a serious health problem on a global scale. It is the second leading cause of cancer-related death worldwide. Novel therapeutic targets are desperately needed because the meager improvement in the cure rate of about 10% realized by adjunctive treatments to surgery is unacceptable as > 50% patients with localized gastric cancer succumb to their disease. Either postoperative chemoradiotherapy (United States), pre-and post-operative chemotherapy (Europe), and adjuvant chemotherapy after a D2 resection (Asia) can all be regarded as standards of care in the localized gastric cancer management. In metastatic disease the addition of trastuzumab to chemotherapy is standard of care in Her2 positive disease. In the HER2 negative population, the treatments remain limited. In the first line setting, the standard of care is a combination of fluoropyrimidine and platinum containing chemotherapy, with or without epirubicin or docetaxel. The results of targeted therapy trials have by and large been disappointing, but none of these trials looked at an appropriately enriched population. Finally there is a meager overall survival benefit in treating patients with metastatic disease in the second line setting, with either irinotecan, docetaxel or ramucirumab however none of these drugs have been compared head to head in a well-powered randomized controlled trial.

MUC1 gene polymorphism rs4072037 and susceptibility to gastric cancer: a meta-analysis

The association between MUC1 polymorphism rs4072037 and the risk of gastric cancer has been described in several studies. However, these studies yielded inconsistent results, especially in different pathological type of gastric cancer. Therefore, we performed this meta-analysis to evaluate the relationship between MUC1 gene polymorphism and gastric cancer susceptibility. A comprehensive database search was performed to identify eligible studies. Odds ratios with 95% confidence intervals were calculated to assess the strength of the association between MUC1 rs4072037 and risk of gastric cancer. Subgroup analyses, publication bias, and sensitivity analyses were also conducted. PubMed, EMBASE, Web of Science and CNKI databases were systematically searched to identify relevant studies. A total of 9 studies (12 datasets) were included in the meta-analysis including 10,410 cases and 11,437 controls. Overall, the G allele at rs4072037 of MUC1 gene was associated with a significant decreased gastric cancer risk (OR=0.70, 95% CI: 0.64-0.76). The association was significant in both anatomic location and pathological subtype subgroup analyses. However, the association was detected in Asian rather than Caucasian. Our findings demonstrate that the presence of the G allele at rs4072037 of the MUC1 gene may contribute to protection against gastric cancer in Asian. Further large studies of multiethnic groups are needed to validate these findings.

At the bedside: Helicobacter pylori, dysregulated host responses, DNA damage, and gastric cancer

Clinical trials performed in populations at high GC risk have demonstrated that eradication of Helicobacter pylori from the stomach with a course of combination antimicrobials helps prevent gastric carcinogenesis when they are administered before precancerous lesions have yet developed. In this review, we consider the insights into H. pylori-associated gastric carcinogenesis that have been gained from these and many other clinical studies in the field to highlight priority areas for basic research and clinical investigation. Among these are defining the magnitude of the risk reduction that may be achieved in clinical practice and at a population level by H. pylori eradication and investigating when, during the slow multistep progression to GC, intervention will be of the most benefit. Additional strategies to prevent GC induced by H. pylori, including chemoprevention, dietary modification, and close endoscopic surveillance, may also have value in augmenting the risk reduction. Why only a small subpopulation of those infected by H. pylori go on to develop GC may be partially explained by genetic susceptibility related to SNPs in several genes regulating the intensity of the gastric inflammatory response to H. pylori. Investigation of the basic mechanisms underlying the promotion of GC by H. pylori and the associated inflammatory response will likely continue to improve clinical strategies for the prevention of one of the most common causes of cancer death globally. See related review, At the Bench: H. pylori, dysregulated host responses, DNA damage, and gastric cancer.

The therapeutic value of targeting inflammation in gastrointestinal cancers

Inflammation has been implicated in the initiation and progression of gastrointestinal (GI) cancers. Inflammation also plays important roles in subverting immune tolerance, escape from immune surveillance, and conferring resistance to chemotherapeutic agents. Targeting key regulators and mediators of inflammation represents an attractive strategy for GI cancer prevention and treatment. However, the targeting of inflammation in GI cancer is not straightforward and sometimes inflammation may contribute to tumor regression. We discuss the origins and effects of inflammation in GI cancer and how to target it successfully.

Mucin 1 gene (MUC1) and gastric-cancer susceptibility

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia. It is classified into intestinal and diffuse types. While the intestinal-type GC (IGC) is almost certainly caused by Helicobacter pylori (HP) infection, its role in the diffuse-type GC (DGC) appears limited. Recently, genome-wide association studies (GWAS) on Japanese and Chinese populations identified chromosome 1q22 as a GC susceptibility locus which harbors mucin 1 gene (MUC1) encoding a cell membrane-bound mucin protein. MUC1 has been known as an oncogene with an anti-apoptotic function in cancer cells; however, in normal gastric mucosa, it is anticipated that the mucin 1 protein has a role in protecting gastric epithelial cells from a variety of external insults which cause inflammation and carcinogenesis. HP infection is the most definite insult leading to GC, and a protective function of mucin 1 protein has been suggested by studies on Muc1 knocked-out mice.

The effect of MUC1 rs4072037 functional polymorphism on cancer susceptibility: evidence from published studies

Genome-wide association studies have identified a susceptibility variation MUC1 rs4072037 for gastric cancer in Chinese population. Subsequent case-control studies have reported this association in other populations. However, the results remain controversial and ambiguous. The aim of this study is to provide a precise quantification for the association between MUC1 rs4072037 variation and the risk of cancer. We performed pooled analysis of 10 case-control designed studies including 4,220 cases and 6,384 controls. Odds ratios (OR) and 95% confidence interval (95%CI) were calculated to assess strength of association in overall studies and in subgroup analysis stratified by ethnicity and cancer types. All statistical analyses were performed by Manager 5.0 and Stata 12.0 software. Overall, the MUC1 rs4072037 polymorphism was associated with risk of cancer in all genetic models (G vs A: OR = 0.71, 95%CI: 0.63-0.80, p<0.01; GA vs AA: OR = 0.61, 95%CI:0.55-0.67, p<0.01; GG vs AA: OR = 0.58, 95%CI: 0.47-0.71, p<0.01; AG+AA vs GG: OR = 0.60, 95%CI: 0.55-0.60, p<0.01; GG vs AG+AA: OR = 0.70, 95%CI: 0.58-0.85, p<0.01). Further, subgroup analysis based on ethnicity suggested MUC1 rs4072037 polymorphism had a subtly reduced cancer risk among Asian population, and stratified analysis by cancer types showed significantly decreased risk of gastric cancer in all genetic models. In conclusion, MUC1 rs4072037 polymorphism may be used as potential biomarker for cancer susceptibility particularly for gastric cancer and for Asian population.

The importance of student initiative both in and out of the lab: the second immunobiology student symposium

In September 2013, graduate students from the Yale Immunobiology Department hosted the second Yale Immunobiology Student Symposium. It was an eclectic and thought-provoking event that encouraged scientists to think outside the box both in their research and in their endeavors outside of the laboratory. The speakers ranged from a government representative to a New York Times science journalist and included four research scientists at the cutting-edge in their field. Speakers discussed their current research, from the role of our gut microbiota in causing colorectal cancers to the biochemical modifications in histone tails that give rise to our unique human biology. The overarching message was to let scientists, especially those of the younger generation, know how to approach, think, and talk about science.