Genetic variations in the PRKAA1 and ZBTB20 genes and gastric cancer susceptibility in a Korean population

Zinc Finger and BTB Domain-Containing 20: A Newly Emerging Player in Pathogenesis and Development of Human Cancers

Zinc finger and BTB domain-containing 20 (ZBTB20), which was initially identified in human dendritic cells, belongs to a family of transcription factors (TFs) with an N-terminal BTB domain and one or more C-terminal DNA-binding zinc finger domains. Under physiological conditions, ZBTB20 acts as a transcriptional repressor in cellular development and differentiation, metabolism, and innate immunity. Interestingly, multiple lines of evidence from mice and human systems have revealed the importance of ZBTB20 in the pathogenesis and development of cancers. ZBTB20 is not only a hotspot of genetic variation or fusion in many types of human cancers, but also a key TF or intermediator involving in the dysregulation of cancer cells. Given the diverse functions of ZBTB20 in both health and disease, we herein summarize the structure and physiological roles of ZBTB20, with an emphasis on the latest findings on tumorigenesis and cancer progression.

Transcription Factor Zbtb20 as a Regulator of Malignancy and Its Practical Applications

Zbtb20 (zinc finger and BTB domain-containing protein 20) is a transcription factor with a zinc finger DNA binding domain and a BTB domain responsible for protein-protein interaction. Recently, this TF has received attention because new data showed its pivotal involvement in normal neural development and its regulatory effects on proliferation and differentiation in different tissues. Zbtb20 was shown to increase proliferation and migration and confer resistance to apoptosis in the contexts of many malignant tumors like hepatocellular carcinoma, non-small-cell lung carcinoma, gastric adenocarcinoma, glioblastoma multiforme, breast cancer, and acute myeloid leukemia. The involvement of Zbtb20 in tumor biology is best studied in hepatocellular carcinoma, where it is a promising candidate as an immunohistochemical tumor marker or may be used in patient screening. Here we review the current data connecting Zbtb20 with malignant tumors.

Ornithine decarboxylase (ODC1) gene variant (rs2302615) is associated with gastric cancer independently of Helicobacter pylori CagA serostatus

The primary cause of gastric cancer is chronic infection with Helicobacter pylori (H. pylori), particularly the high-risk genotype cagA, and risk modification by human genetic variants. We studied 94 variants in 54 genes for association with gastric cancer, including rs2302615 in ornithine decarboxylase (ODC1), which may affect response to chemoprevention with the ODC inhibitor, eflornithine (difluoromethylornithine; DFMO). Our population-based, case-control study included 1366 individuals (664 gastric cancer cases and 702 controls) from Western Honduras, a high incidence region of Latin America. CagA seropositivity was strongly associated with cancer (OR = 3.6; 95% CI: 2.6, 5.1). The ODC1 variant rs2302615 was associated with gastric cancer (OR = 1.36; p = 0.018) in a model adjusted for age, sex, and CagA serostatus. Two additional single nucleotide polymorphisms (SNPs) in CASP1 (rs530537) and TLR4 (rs1927914) genes were also associated with gastric cancer in univariate models as well as models adjusted for age, sex, and CagA serostatus. The ODC1 SNP association with gastric cancer was stronger in individuals who carried the TT genotype at the associating TLR4 polymorphism, rs1927914 (OR = 1.77; p = 1.85 × 10^-3). In conclusion, the ODC1 variant, rs2302615, is associated with gastric cancer and supports chemoprevention trials with DFMO, particularly in individuals homozygous for the T allele at rs1927914.

Helicobacter pylori infection causes both protective and deleterious effects in human health and disease

Infection with Helicobacter pylori (H. pylori) is necessary but not sufficient for the development of gastric cancer, the third leading cause of cancer death globally. H. pylori infection affects over half of people globally; however, it does not affect populations uniformly. H. pylori infection rates are declining in western industrialized countries but are plateauing in developing and newly industrialized countries where gastric cancer is most prevalent. Despite H. pylori infection being the primary causative agent for gastric cancer, H. pylori infection can also cause other effects, detrimental or beneficial, throughout an individual's life, with the beneficial effects often being seen in childhood and the deleterious effects in adulthood. H. pylori is an ancient bacterium and its likelihood of affecting disease or health is dependent on both human and bacterial genetics that have co-evolved over millennia. In this review, we focus on the impact of infection and its genetic bases in different populations and diseases throughout an individual's lifespan, highlighting the benefits of individualized treatment and argue that universal eradication of H. pylori in its host may cause more harm than good for those infected with H. pylori.

Prediction of gastric cancer risk: association between ZBTB20 genetic variance and gastric cancer risk in Chinese Han population

Background: Gastric cancer (GC) is a complex multifactorial disease. Previous studies have revealed genetic variations associated with the risk of gastric cancer. The purpose of the present study was to determine the correlation between single-nucleotide polymorphisms (SNPs) of ZBTB20 and the risk of gastric cancer in Chinese Han population.

Methods: We conducted a ‘case–control’ study involving 509 GC patients and 507 healthy individuals. We selected four SNPs of ZBTB20 (10934270 T/C, rs9288999 G/A, rs9841504 G/C and rs73230612 C/T), and used logistic regression to analyze the relationship between those SNPs and GC risk under different genetic models; multi-factor dimensionality reduction (MDR) was used to analyze the interaction of “SNP–SNP” in gastric cancer risk; ANOVA and univariate analysis were used to analyze the differences in clinical characteristics among different genotypes.

Results: Our results showed that ZBTB20 rs9288999 is a protective factor for the risk of gastric cancer in multiple genetic models, of which the homozygous model is the most significant (OR = 0.48, P=0.0003); we also found that rs9288999 showed a significant correlation with reducing the risk of gastric cancer in different subgroups (BMI; age; gender; smoking or drinking status; adenocarcinoma); rs9841504 is associated with increased GC risk in the participants with BMI>24 kg/m²; rs9841504 and rs73230612 are certainly associated with clinical characteristics of platelet and carbohydrate antigen 242, respectively.

Conclusion: Our results suggest that ZBTB20 rs9288999 may be important for reducing the risk of GC in the Chinese Han population.

Gastric cancer: epidemiology, biology, and prevention: a mini review

Gastric cancer is one of the most common causes of cancer-related mortality worldwide. The objective of this article is to review the epidemiology and biology of gastric cancer risk. This literature review explores the biological, clinical, and environmental factors that influence the rates of this disease and discuss the different intervention methods that may not only increase the awareness of gastric cancer but also increase screening in efforts to reduce the risk of gastric cancer. Helicobacter pylori infection is the primary risk factor for gastric cancer. Additional risk factors include geographical location, age, sex, smoking, socioeconomic status, dietary intake, and genetics. Primary and secondary prevention strategies such as dietary modifications and screenings are important measures for reducing the risk of gastric cancer. Interventions, such as H. pylori eradication through chemoprevention trials, have shown some potential as a preventative strategy. Although knowledge about gastric cancer risk has greatly increased, future research is warranted on the differentiation of gastric cancer epidemiology by subsite and exploring the interactions between H. pylori infection, genetics, and environmental factors. Better understanding of these relationships can help researchers determine the most effective intervention strategies for reducing the risk of this disease.

PRKAA1 rs13361707 C/T polymorphism confers decreased susceptibility to esophageal cancer: A case-control study

Background

Several studies probed into the connection between esophageal cancer (EC) risk and PRKAA1 rs13361707 C/T polymorphism, but obtained insignificant findings.

Methods

In this study, 814 EC cases and 961 controls from Eastern China were recruited to validate the relationship between this polymorphism and EC susceptibility.

Results

Data suggested rs13361707 C/T polymorphism in PRKAA1 gene was significantly related with a lower risk for EC. Such significant connection was also uncovered in subgroups of males, smokers, drinkers and individuals with age ≥ 60 years. In addition, this polymorphism was linked with the pathological grading, distant metastasis, and histology of EC.

Conclusion

In summary, PRKAA1 rs13361707 C/T polymorphism is related to the risk and clinical properties of EC patients in East China.

Tipping the Scale Toward Gastric Disease: A Host-Pathogen Genomic Mismatch?

PURPOSE OF REVIEW

Chronic infection with Helicobacter pylori infection is necessary but not sufficient to initiate development of intestinal-type gastric adenocarcinoma. It is not clear what additional factors tip the scale from commensal bacteria towards a pathogen that facilitates development of gastric cancer. Genetic variants in both the pathogen and host have been implicated, but neither alone explains a substantial portion of disease risk.

RECENT FINDINGS

In this review, we consider studies that address the important role of human and bacterial genetics, ancestry and their interactions in determining gastric disease risk. We observe gaps in the current literature that should guide future work to confirm the hypothesis of the interacting roles of host and bacterial genetics that will be necessary to translate these findings into clinically relevant information.

SUMMARY

We summarize genetic risk factors for gastric disease in both H. pylori and human hosts. However, genetic variation of one or the other organism in isolation insufficiently explains gastric disease risk. The most promising models of gastric disease risk simultaneously consider the genetic variation of both the H. pylori and human host, under a co-evolution model.

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.

Genetic variations in PRKAA1 predict the risk and progression of gastric Cancer

Background

PRKAA1 encodes α-subunit of 5-AMP-activated protein kinase (AMPK), which has been implicated in the pathogenesis of carcinoma of the stomach. Previous works have suggested that polymorphisms in the PRKAA1 may be associated with the risk of non-cardiac gastric cancer (NCGC), but whether PRKAA1 polymorphisms are related to clinical pathologic characteristics of gastric cancer and its clinical outcome is largely unknown.

Methods

We carried out a case-control study including a total of 481 gastric cancer patients and 490 healthy controls. The genotypes of enrolled polymorphisms were identified with Sequenom MassARRAY platform.

Results

This study showed that rs10074991 GG genotype (adjusted OR = 1.44, 95%CI:0.99–2.09, p = 0.056) has a borderline significantly increased risk for gastric cancer, which was consistent with the result of additive model (adjusted OR = 1.21, 95%CI:1.01–1.46, p = 0.042). In similar, an increased risk of gastric cancer was also observed for rs13361707 TC genotype (adjusted OR = 1.47, 95%CI: 1.01–2.14, p = 0.043; additive model: adjusted OR = 1.22, 95%CI: 1.02–1.47, p = 0.033). Furthermore, the rs154268 and rs461404 were also found associated with increased gastric cancer risk, which may be influenced by age, tumor type and differentiation, and tumor stage. Haplotype analysis indicated A-G-C-T-C-G haplotype (rs6882903, rs10074991, rs13361707, rs3805490, rs154268 and rs461404) is associated with increased risk of gastric cancer (OR = 1.29, 95%CI: 1.02–1.62, p = 0.035). The univariate analysis for overall survival (OS) revealed that both of rs10074991 and rs13361707 variants are associated with poor OS in patients with NCGC.

Conclusion

This case-control study provided the evidence thatrs13361707CC, rs10074991GG, rs461404GG, and rs154268CC are associated with increased gastric cancer risk, especially for NCGC, and that patients with rs10074991 G or rs13361707 C allele have a poor OS.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4818-3) 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.

Differential networking meta-analysis of gastric cancer across Asian and American racial groups

Background

Gastric Carcinoma is one of the most lethal cancer around the world, and is also the most common cancers in Eastern Asia. A lot of differentially expressed genes have been detected as being associated with Gastric Carcinoma (GC) progression, however, little is known about the underlying dysfunctional regulation mechanisms. To address this problem, we previously developed a differential networking approach that is characterized by involving differential coexpression analysis (DCEA), stage-specific gene regulatory network (GRN) modelling and differential regulation networking (DRN) analysis.

Result

In order to implement differential networking meta-analysis, we developed a novel framework which integrated the following steps. Considering the complexity and diversity of gastric carcinogenesis, we first collected three datasets (GSE54129, GSE24375 and TCGA-STAD) for Chinese, Korean and American, and aimed to investigate the common dysregulation mechanisms of gastric carcinogenesis across racial groups. Then, we constructed conditional GRNs for gastric cancer corresponding to normal and carcinoma, and prioritized differentially regulated genes (DRGs) and gene links (DRLs) from three datasets separately by using our previously developed differential networking method. Based on our integrated differential regulation information from three datasets and prior knowledge (e.g., transcription factor (TF)-target regulatory relationships and known signaling pathways), we eventually generated testable hypotheses on the regulation mechanisms of two genes, XBP1 and GIF, out of 16 common cross-racial DRGs in gastric carcinogenesis.

Conclusion

The current cross-racial integrative study from the viewpoint of differential regulation networking provided useful clues for understanding the common dysfunctional regulation mechanisms of gastric cancer progression and discovering new universal drug targets or biomarkers for gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0564-z) contains supplementary material, which is available to authorized users.

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.

Is there a dose-dependent effect of genetic susceptibility loci for gastric cancer on prognosis of the patients?

Literature suggests that genetic variants associated with increased susceptibility to gastric cancer (GCa) are mostly located in genes involved in carcinogenesis and possibly tumor progression. Therefore, we hypothesize that high genetic susceptibility is also associated with prognosis of the patients. To test this hypothesis, we selected a total of 42 common genetic variants that were reportedly associated with GCa risk with a high level of evidence obtained from either genome-wide association studies (GWASs) or meta-analyses and performed survival analysis of patients used in a case-control analysis. We first used 1115 GCa cases and 1172 cancer-free controls of ethnic Han Chinese to construct a weighted genetic risk score (GRS). Then, we included 633 GCa cases with available clinical information, fit GRS in a fractional polynomial Cox proportional hazards regression model to investigate whether there is a dose-dependent effect of GRS on risk of death in survival analysis. Dynamic predictive value of genetic risk for prognosis was also calculated. The results showed that the increase of GRS had no effect on risk of death in these GCa patients. Compared with GCa patients with the medium GRS, there was no significant difference in survival in patients with either a low (P = 0.349) or a high (P = 0.847) GRS. The results unchanged when data were stratified by tumor stage and Lauren's classification. Time-dependent predictive value for prognosis in considering both clinical factors and GRS was comparable with that in considering clinical factors alone, for either all patients (P = 0.986) or stage- and Laruen type-based subgroups (P > 0.05 for all). In conclusion, higher polygenic susceptibility loci for GCa may not indicate worse prognosis of Chinese patients. Additional variants of relevant genes modulating GCa patients' survival need to be further identified.

Genetic variants in gastric cancer: Risks and clinical implications

Cancer is a multifactorial disease that involves many molecular alterations. Gastric cancer (GC) is the third leading cause of cancer death worldwide. GC is a highly heterogeneous disease with different molecular and genetics features. Therefore, this review focuses on an overview of the genetic aspects of gastric cancer by highlighting the important impact and role of deletions and/or duplications of chromosomal segments, genomic variants, H. pylori infection and interleukin variants, as found in gene expression and newly proposed molecular classification studies. The challenge is to better understand the mechanisms and different pathways that lead to the development and progression of GC.

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.

Somatic copy number alterations in gastric adenocarcinomas among Asian and Western patients

Gastric cancer, a leading worldwide cause of cancer mortality, shows high geographic and ethnic variation in incidence rates, which are highest in East Asia. The anatomic locations and clinical behavior also differ by geography, leading to the controversial idea that Eastern and Western forms of the disease are distinct. In view of these differences, we investigated whether gastric cancers from Eastern and Western patients show distinct genomic profiles. We used high-density profiling of somatic copy-number aberrations to analyze the largest collection to date of gastric adenocarcinomas and utilized genotyping data to rigorously annotate ethnic status. The size of this collection allowed us to accurately identify regions of significant copy-number alteration and separately to evaluate tumors arising in Eastern and Western patients. Among molecular subtypes classified by The Cancer Genome Atlas, the frequency of gastric cancers showing chromosomal instability was modestly higher in Western patients. After accounting for this difference, however, gastric cancers arising in Easterners and Westerners have highly similar somatic copy-number patterns. Only one genomic event, focal deletion of the phosphatase gene PTPRD, was significantly enriched in Western cases, though also detected in Eastern cases. Thus, despite the different risk factors and clinical features, gastric cancer appears to be a fundamentally similar disease in both populations and the divergent clinical outcomes cannot be ascribed to different underlying structural somatic genetic aberrations.

Assessment of the association between ZBTB20 rs9841504 polymorphism and gastric and esophageal cancer susceptibility: a meta-analysis

BACKGROUND

The protein encoded by ZBTB20 is a member of the POK family, whose members function as transcriptional repressors through interactions mediated by their conserved C2H2 Krüppel-type zinc finger and BTB/POZ domains. Polymorphisms in ZBTB20 appeared to be associated with gastric and esophageal cancer susceptibility in biological models, but the results of these studies were inconclusive. Therefore, we conducted a meta-analysis by pooling all available data to assess the exact association between the ZBTB20 rs9841504 polymorphism and gastric and esophageal cancer susceptibility.

METHOD

The meta-analysis was performed for homozygote comparison, heterozygote comparison, and dominant and recessive models by applying a fixed- or random-effects model. The pooled odds ratios (ORs) with the corresponding confidence intervals (CIs) were calculated. Moreover, the data were analyzed using the Stata 12.0 software(StataCorp).

RESULT

A total of 8 independent case-control studies comprising 9,994 cases and 10,258 controls were included. We found a significant association between the rs9841504 polymorphism and decreased gastric cancer susceptibility in the allelic, homozygous, dominant and recessive models (B vs. A:OR = 0.797, 95% CI 0.644-0.986, p = 0.036; BB vs. AA:OR = 0.601, 95% CI 0.366-0.988, p = 0.045; BA + BB vs. AA:OR = 0.789, 95% CI 0.627-0.992, p = 0.043; BB vs. BA + AA:OR = 0.635, 95% CI 0.405-0.997, p = 0.049). Conversely, no association between the rs9841504 polymorphism and esophageal cancer susceptibility was found. In subgroup analysis by ethnicity, we observed a significantly decreased susceptibility to gastric cancer in Asian populations in the allele contrast, homozygous and recessive models (B vs. A:OR = 0.791, 95% CI 0.628-0.996, p = 0.046; BB vs. AA:OR = 0.559, 95% CI 0.323-0.966, p = 0.037; BB vs. BA + AA:OR = 0.593, 95% CI 0.361-0.972, p = 0.038).

CONCLUSIONS

In summary, our work suggests that the ZBTB20 rs9841504 polymorphism is a protective factor for gastric cancer rather than esophageal cancer.

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.

Genome-wide association study of gastric adenocarcinoma in Asia: a comparison of associations between cardia and non-cardia tumours

OBJECTIVE

Genome-wide association studies (GWAS) of gastric cancer have reported differences in single-nucleotide polymorphism (SNP) associations for tumour subtypes, particularly when divided by location into the gastric cardia versus the non-cardia.

DESIGN

Here we present results for a GWAS using 2350 East Asian gastric cancer cases divided as 1189 gastric cardia and 1027 gastric non-cardia cases and 2708 controls. We also included up to 3042 cardia cases, 4359 non-cardia cases and 7548 controls for replication from two Chinese studies and one Korean study. From the GWAS, we selected 12 top SNPs for each gastric cancer subtype, 4 top SNPs for total gastric cancer and 1 SNP in MUC1 for replication testing.

RESULTS

We observed genome-wide significant associations for rs10074991 in PRKAA1 at 5p13.1 for cardia (p=7.36×10(-12)) and non-cardia cancers (p=2.42×10(-23)) with per allele OR (95% CI) for the combined endpoint of 0.80 (0.77 to 0.83). At 6p21.1, rs2294693 near UNC5CL was significantly associated with gastric non-cardia cancer risk (p=2.50×10(-8)), with OR (95% CI) of 1.18 (1.12 to 1.26), but there was only a nominal association for cardia cancer (p=1.47×10(-2)). We also confirmed a previously reported association for rs4072037 in MUC1 with p=6.59×10(-8) for total gastric cancer and similar estimates for cardia and non-cardia cancers. Three SNPs in PSCA previously reported to be associated with gastric non-cardia cancer showed no apparent association for cardia cancer.

CONCLUSIONS

Our results suggest that associations for SNPs with gastric cancer show some different results by tumour location in the stomach.

Association of PRKAA1 gene polymorphisms with chronic hepatitis B virus infection in Chinese Han population

OBJECTIVE

Studies have indicated that AMPK play critical roles in the regulation of innate immunity and inflammatory responses. However, the role of the polymorphisms of PRKAA1 gene in immune-response to infectious organisms remains unknown. To evaluate the potential role of PRKAA1/AMPKα1 in the immune-response to HBV, we conducted this case-control study.

METHODS

We recruited 276 patients (145 men and 131 women; average age, 51.6 years) with chronic HBV infection (CHB) and 303 healthy controls (166 men and 137 women; average age, 54.2 years). All the subjects were unrelated individuals of Chinese Han Population. Three SNPs of PRKAA1gene were tested.

RESULTS

Rs1002424 polymorphism showed significant difference in the allele frequencies, but no difference in the genotype frequencies (allele: p=0.039411, OR95%CI=0.783479 [0.621067-0.988362]; genotype: p=0.104758); rs13361707 polymorphism showed significance in allele analysis, but not in genotype analysis (allele: p=0.034749, OR95%CI=1.284303 [1.017958-1.620335]; genotype: p=0.098027); rs3792822 polymorphism was demonstrated to have significant differences in both genotype and allele frequencies between cases and controls (allele: p=0.029286, OR95%CI= 0.741519 [0.566439-0.970716]; genotype: p=0.034560). The haplotype results showed that CTG and TCA in the rs13361707-rs1002424-rs3792822 block were significantly associated with the happening of HBV (CTG: p=0.036854, OR95%CI=1.281 [1.015-1.617]; p=0.030841, OR95%CI=0.743 [0.568-0.973]).

CONCLUSION

These findings suggest that PRKAA1 polymorphisms may contribute to the susceptibility of chronic HBV infection in Chinese Han origin.

Epigenetic and genetic variation in GATA5 is associated with gastric disease risk

Gastric cancer incidence varies considerably among populations, even those with comparable rates of Helicobacter pylori infection. To test the hypothesis that genetic variation plays a role in gastric disease, we assessed the relationship between genotypes and gastric histopathology in a Colombian study population, using a genotyping array of immune-related single nucleotide polymorphisms (SNPs). Two synonymous SNPs (rs6061243 and rs6587239) were associated with progression of premalignant gastric lesions in a dominant-effects model after correction for multiple comparisons (p = 2.63E-07 and p = 7.97E-07, respectively); effect sizes were β = -0.863 and β = -0.815, respectively, where β is an estimate of effect on histopathology scores, which ranged from 1 (normal) to 5 (dysplasia). In our replication cohort, a second Colombian population, both SNPs were associated with histopathology when additively modeled (β = -0.256, 95 % CI = -0.47, -0.039; and β = -0.239, 95 % CI = -0.45, -0.024), and rs6587239 was significantly associated in a dominant-effects model (β = -0.330, 95 % CI = -0.66, 0.00). Because promoter methylation of GATA5 has previously been associated with gastric cancer, we also tested for the association of methylation status with more advanced histopathology scores in our samples and found a significant relationship (p = 0.001). A multivariate regression model revealed that the effects of both the promoter methylation and the exonic SNPs in GATA5 were independent. A SNP-by-methylation interaction term was also significant. This interaction between GATA5 variants and GATA5 promoter methylation indicates that the association of either factor with gastric disease progression is modified by the other.

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.

Genetic variation and gastric cancer risk: a field synopsis and meta-analysis

BACKGROUND

Data on genetic susceptibility to sporadic gastric carcinoma have been published at a growing pace, but to date no comprehensive overview and quantitative summary has been available.

METHODS

We conducted a systematic review and meta-analysis of the evidence on the association between DNA variation and risk of developing stomach cancer. To assess result credibility, summary evidence was graded according to the Venice criteria and false positive report probability (FPRP) was calculated to further validate result noteworthiness. Meta-analysis was also conducted for subgroups, which were defined by ethnicity (Asian vs Caucasian), tumour histology (intestinal vs diffuse), tumour site (cardia vs non-cardia) and Helicobacter pylori infection status (positive vs negative).

RESULTS

Literature search identified 824 eligible studies comprising 2 530 706 subjects (cases: 261 386 (10.3%)) and investigating 2841 polymorphisms involving 952 distinct genes. Overall, we performed 456 primary and subgroup meta-analyses on 156 variants involving 101 genes. We identified 11 variants significantly associated with disease risk and assessed to have a high level of summary evidence: MUC1 rs2070803 at 1q22 (diffuse carcinoma subgroup), MTX1 rs2075570 at 1q22 (diffuse), PSCA rs2294008 at 8q24.2 (non-cardia), PRKAA1 rs13361707 5p13 (non-cardia), PLCE1 rs2274223 10q23 (cardia), TGFBR2 rs3087465 3p22 (Asian), PKLR rs3762272 1q22 (diffuse), PSCA rs2976392 (intestinal), GSTP1 rs1695 11q13 (Asian), CASP8 rs3834129 2q33 (mixed) and TNF rs1799724 6p21.3 (mixed), with the first nine variants characterised by a low FPRP. We also identified polymorphisms with lower quality significant associations (n=110).

CONCLUSIONS

We have identified several high-quality biomarkers of gastric cancer susceptibility. These data will form the backbone of an annually updated online resource that will be integral to the study of gastric carcinoma genetics and may inform future screening programmes.

Synergistic effect of smoking with genetic variants in the AMPKα1 gene on the risk of coronary artery disease in type 2 diabetes

BACKGROUND

Increasing evidence suggests that adenosine monophosphate-activated protein kinase (AMPK) plays a critical physiological role in the cardiovascular system. The objective of this study was to assess the possible correlation between the genetic variability of the AMPKα1 (PRKAA1) gene and the risk of cardiovascular disease, as well as the interactive effects of the genetic variations and environmental factors, on the risk in Chinese patients with type 2 diabetes.

METHODS

Five haplotype-tagging single nucleotide polymorphisms (SNPs) at the AMPKα1 locus and 404 unrelated Chinese Han subjects with type 2 diabetes were studied; 260 individuals with coronary artery disease and 144 non-coronary artery disease controls were genotyped using the polymerase chain reaction-restriction fragment length polymorphism assay.

RESULTS

Minor allele C at rs3805489 was protective from coronary artery disease in type 2 diabetic subjects compared with allele A (OR 0.67, 95% CI 0.48-0.92, p = 0.015). There was no significant correlation between the genotypes at five SNPs and the risk of coronary artery disease. In addition, a significant interaction was identified between smoking status and rs3805489 (p = 0.018 for interaction). The smokers with genotype AA at the SNP had a three-fold higher risk of coronary artery disease compared with non-smokers with genotypes AC or CC (OR' 3.02, 95% CI' 1.39-6.57, p' = 0.005, after adjustment for other known coronary artery disease risk factors).

CONCLUSIONS

The genetic variability at the AMPKα1 locus has synergetic effects with smoking to increase the risk of coronary artery disease in the Chinese Han population with type 2 diabetes.

Gene-diet interactions in gastric cancer risk: A systematic review

AIM: To conduct a systematic review of the published epidemiological studies investigating the association of the interactions between gene variants and dietary intake with gastric cancer risk.

METHODS: A literature search was conducted in PubMed, EMBASE, and MEDLINE for articles published between January 2000 and July 2013, and 38 studies were identified. Previous studies included various dietary factors (e.g., fruits and vegetables, soybean products, salt, meat, and alcohol) and genetic variants that are involved in various metabolic pathways.

RESULTS: Studies suggest that individuals who carry high-risk genetic variants and demonstrate particular dietary habits may have an increased risk of gastric cancer compared with those who do not carry high-risk genetic variants. Distinctive dietary patterns and variations in the frequency of genetic variants may explain the higher incidence of gastric cancer in a particular region. However, most previous studies have limitations, such as a small sample size and a retrospective case-control design. In addition, past studies have been unable to elucidate the specific mechanism in gene-diet interaction associated with gastric carcinogenesis.

CONCLUSION: Additional large prospective epidemiological and experimental studies are required to identify the gene-diet metabolic pathways related to gastric cancer susceptibility.

Genetic and intermediate phenotypic susceptibility markers of gastric cancer in Hispanic Americans: a case-control study

BACKGROUND

Hispanics are the largest nonwhite ethnic group in the US population, and they have higher incidence and mortality rates for gastric cancer (GC) than whites and Asians. Studies have identified several genetic susceptibility loci and intermediate phenotypic biomarkers for GC in whites and Asians. No studies have evaluated genetic susceptibility and intermediate phenotypic biomarkers in Hispanics.

METHODS

In a case-control study of 132 Hispanic patients with GC (cases) and a control group of 125 Hispanics (controls), the authors evaluated the association of 5 single nucleotide polymorphisms (SNPs) that predispose whites and/or Asians to GC and of 2 intermediate phenotypic markers in peripheral blood leukocytes, ie, telomere length and mitochondrial DNA (mtDNA) copy number, with the GC risk.

RESULTS

The variant C allele of the reference SNP rs2294008 in the PSCA gene was associated with a significantly reduced risk of GC (per allele-adjusted odds ratio [aOR], 0.51; 95% confidence interval [CI], 0.33-0.77; P = .002). Leukocyte mtDNA copy numbers were significantly lower in GC cases (mean ± standard deviation, 0.91 ± 0.28) than in controls (1.29 ± 0.42; P < .001). When individuals were dichotomized into high and low mtDNA copy number groups based on the median mtDNA copy number value in the controls, those who had a low mtDNA copy number had a significantly increased risk of GC (aOR, 11.00; 95% CI, 4.79-25.23; P < .001) compared with those who had a high mtDNA copy number. Telomere length was not associated significantly with the risk of GC (aOR, 1.21; 95% CI, 0.65-2.27; P = .551).

CONCLUSIONS

Hispanics share certain genetic susceptibility loci and intermediate phenotypic GC biomarkers with whites and Asians and may also have distinct genetic susceptibility factors.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.