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

The PSCA rs2294008 (C/T) Polymorphism Increases the Risk of Gastric and Bladder Cancer: A Meta-Analysis

Background: It has been reported that prostate stem cell antigen (PSCA) is overexpressed in certain cancer types and confers poor prognoses. The rs2294008 (C/T) polymorphism of PSCA is considered to be associated with risk for gastric, bladder, and colorectal cancers; however, these studies have produced inconsistent results, so we performed this meta-analysis to verify the association between the PSCA rs2294008 (C/T) polymorphism and cancer risk. Methods: A systematic literature search was performed using PubMed, EMBASE, and the Chinese National Knowledge Infrastructure, through October 20, 2022 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association between the PSCA rs2294008 (C/T) polymorphism and cancer risk. In addition, we explored PSCA mRNA expression in cancers through online databases. Results: In total, 45 articles met our inclusion criteria and were analyzed, including 37,586 cancer cases and 51,197 non-cancer controls. Except in the recessive model, the pooled effect indicated the PSCA rs2294008 T allele was associated with an increased overall cancer risk (T vs. C: OR = 1.120, 95% CI = 1.056-1.188, p < 0.01; TT vs. CC: OR = 1.206, 95% CI = 1.066-1.364, p = 0.03; CT vs. CC: OR = 1.249, 95% CI = 1.151-1.356, p < 0.01; [CT+TT] vs. CC: OR = 1.248, 95% CI = 1.147-1.359, p < 0.01; TT vs. [CT+CC]: OR = 1.051, 95% CI = 0.954-1.156, p = 0.314). In the subgroup analysis, there were significant associations between the rs2294008 T allele and increased risk of bladder and gastric cancer. Two different online tools were used to explore the PSCA mRNA levels in cancer and the corresponding normal adjacent tissues. We found that expression of PSCA was significantly lower in gastric cancer patients. Conclusions: The PSCA rs2294008 T polymorphism is related to increased cancer susceptibility, especially for gastric and bladder cancers. This polymorphism results in a decreased PSCA expression level in gastric cancer.

SNP rs2920280 in PSCA Is Associated with Susceptibility to Gastric Mucosal Atrophy and Is a Promising Biomarker in Japanese Individuals with Helicobacter pylori Infection

Helicobacter pylori infection results in gastric cancer (GC) with gastric mucosal atrophy (GMA). Some single-nucleotide polymorphisms (SNPs) in the prostate stem cell antigen gene (PSCA) are associated with GC and duodenal ulcers. However, the relationship of other identified SNPs in PSCA with these diseases remains unclear. Herein, the association between PSCA SNPs and GMA among 195 Japanese individuals with H. pylori infection was evaluated. The definition of GMA or non-GMA was based on serum pepsinogen levels or endoscopic findings. Five tag PSCA SNPs were analyzed using PCR high-resolution melting curve analysis with nonlabelled probes. The frequencies of alleles and the genotypes of each tag SNP were compared between the GMA and non-GMA groups. Subsequently, a genetic test was performed using associated SNPs as biomarkers to detect patients developing GMA. Two tag PSCA SNPs (rs2920280 and rs2294008) were related to GMA susceptibility. Individuals with the rs2920280 G/G genotype or the rs2294008 T/T genotype in PSCA had 3.5- and 2.1-fold susceptibility to GMA, respectively. In conclusion, SNP rs2920280 is a possible biomarker for detecting individuals developing GMA. PSCA polymorphisms may be useful biomarkers for predicting GMA linked to GC risk and a screening endoscopy strategy to detect GC related to early stage H. pylori associated GMA.

Risk Prediction for Gastric Cancer Using GWAS-Identifie Polymorphisms, Helicobacter pylori Infection and Lifestyle-Related Risk Factors in a Japanese Population

Simple Summary

Gastric cancer remains the major cancer in Japan and worldwide. It is expected that practical intervention strategies for prevention, such as personalized approaches based on genetic risk models, will be developed. Here, we developed and validated a risk prediction model for gastric cancer using genetic, biological, and lifestyle-related risk factors. Results showed that the combination of selected GWAS-identified SNP polymorphisms and other predictors provided high discriminatory accuracy and good calibration in both the derivation and validation studies; however, the contribution of genetic factors to risk prediction was limited. The greatest contributor to risk prediction was ABCD classification (Helicobacter pylori infection-related factor).

Abstract

Background: As part of our efforts to develop practical intervention applications for cancer prevention, we investigated a risk prediction model for gastric cancer based on genetic, biological, and lifestyle-related risk factors. Methods: We conducted two independent age- and sex-matched case–control studies, the first for model derivation (696 cases and 1392 controls) and the second (795 and 795) for external validation. Using the derivation study data, we developed a prediction model by fitting a conditional logistic regression model using the predictors age, ABCD classification defined by H. pylori infection and gastric atrophy, smoking, alcohol consumption, fruit and vegetable intake, and 3 GWAS-identified polymorphisms. Performance was assessed with regard to discrimination (area under the curve (AUC)) and calibration (calibration plots and Hosmer–Lemeshow test). Results: A combination of selected GWAS-identified polymorphisms and the other predictors provided high discriminatory accuracy and good calibration in both the derivation and validation studies, with AUCs of 0.77 (95% confidence intervals: 0.75–0.79) and 0.78 (0.77–0.81), respectively. The calibration plots of both studies stayed close to the ideal calibration line. In the validation study, the environmental model (nongenetic model) was significantly more discriminative than the inclusive model, with an AUC value of 0.80 (0.77–0.82). Conclusion: The contribution of genetic factors to risk prediction was limited, and the ABCD classification (H. pylori infection-related factor) contributes most to risk prediction of gastric cancer.

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.

Predictive model for risk of gastric cancer using genetic variants from genome-wide association studies and high-evidence meta-analysis

Genome-wide association studies (GWAS) have identified some single nucleotide polymorphisms (SNPs) associated with the risk of gastric cancer (GCa). However, currently, there is no published predictive model to assess the risk of GCa. In the present study, risk-associated SNPs derived from GWAS and large meta-analyses were selected to construct a predictive model to assess the risk of GCa. A total of 1115 GCa cases and 1172 controls from the eastern Chinese population were included. Logistic regression models were used to identify SNPs that correlated with the risk of GCa. A predictive model to assess the risk of GCa was established by receiver operating characteristic curve analysis. Multifactor dimensionality reduction (MDR) and classification and regression tree (CART) were applied to calculate the effect of high-order gene-environment interactions on risk of the cancer. A total of 42 SNPs were selected for further analysis. The results revealed that ASH1L rs80142782, PKLR rs3762272, PRKAA1 rs13361707, MUC1 rs4072037, PSCA rs2294008, and PLCE1 rs2274223 polymorphisms were associated with a risk of GCa. The area under curve considering both genetic factors and BMI was 3.10% higher than that of BMI alone. MDR analysis revealed that rs13361707 and rs4072307 variants and BMI had interaction effects on susceptibility to GCa, with the highest predictive accuracy (61.23%) and cross-validation consistency (100/100). CART analysis also supported this interaction model that non-overweight status and a six SNP panel could synergistically increase the susceptibility to GCa. The six SNP panel for predicting the risk of GCa may provide new tools for prevention of the cancer based on GWAS and large meta-analyses derived genetic variants.

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.

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.

Association between PSCA, TNF-α, PARP1 and TP53 Gene Polymorphisms and Gastric Cancer Susceptibility in the Brazilian Population

OBJECTIVES

To evaluate the association of allelic and genotypic frequencies of PSCA (rs2976392), TNF-α (rs1800629), PARP1 (rs1136410) and TP53 (rs368771578) SNPs with GC susceptibility in a Brazilian population.

MATERIALS AND METHODS

This is a retrospective study, which included 102 paraffin-embedded adenocarcinoma tissue samples > 5 years of obtention, with 204 alleles for each studied SNP. Other 102 healthy tissue samples were included as controls. For analysis, the genotyping method Dideoxy Single Allele-Specific - PCR was used. Statistical analysis was performed with the Bioestat software 5.3, determining Hardy-Weinberg's equilibrium for the genotypic frequencies p-values < 0.05 were considered significant.

RESULTS

PSCA (rs2976392) and TNF-α (rs1800629) SNPs were associated with GC in the analyzed samples (X2=10.3/102 and p<0.001/0.00001, respectively). TNF-α (rs1800629) SNP presented also a statistically significant relationship between its genotypes and the morphological pattern (intestinal/diffuse) (p<0.032). However, PARP1 (rs1136410) and TP53 (rs368771578) SNPs were in Hardy-Weinberg's equilibrium and, therefore, were not significantly associated with GC in these samples (X2=0.73/2.89 and p<0.39/0.08).

CONCLUSIONS

PSCA (rs2976392) and TNF-α (rs1800629) SNPs are potential molecular markers of susceptibility to GC development. PARP1 (rs1136410) and TP53 (rs368771578) SNPs were not associated with the risk of GC development.

Impact of PSCA gene polymorphisms in modulating gastric cancer risk in the Chinese population

Previous studies have identified the prostate stem cell antigen (PSCA) gene rs2294008 C > T and rs2976392 G > A polymorphisms to be associated with the risk of gastric cancer, the results of which are inconsistent. The present study aimed to evaluate the association between the two polymorphisms and the gastric cancer risk in the Chinese population. A hospital-based case-control study was conducted on 549 cases and 592 healthy controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to evaluate the association of the two polymorphisms on the gastric cancer risk. We found that both rs2294008 (CT vs. CC, OR = 1.55, 95% CI = 1.20-1.99, P<0.001 and CT+TT vs. CC, OR = 1.38, 95% CI = 1.09-1.74, P=0.008) and rs2976392 (GA vs. GG, OR = 1.61, 95% CI = 1.25-2.07, P<0.001 and GA+AA vs. GG, OR = 1.52, 95% CI = 1.20-1.92, P<0.001) were associated with an increased gastric cancer. In the combined analysis of the two polymorphisms, subjects with more than one risk genotype have a significantly increased risk of gastric cancer (OR = 1.38, 95% CI = 1.09-1.75, P=0.008) in comparison with those without any risk genotypes. In conclusion, our findings verified that the PSCA gene rs2294008 and rs2976392 polymorphisms were both significantly associated with an increased risk of gastric cancer in the Chinese population. Well-designed functional studies are to be warranted to confirm these findings.

Decrease in PSCA expression caused by Helicobacter pylori infection may promote progression to severe gastritis

SNP rs2294008 in Prostate Stem Cell Antigen (PSCA) and decreased PSCA expression are associated with gastric cancer. The objective of this study is to investigate the role of rs2294008 and PSCA expression in the gastritis-gastric cancer carcinogenic pathway. We conducted a case-control association study of H. pylori-infected gastritis and gastric cancer. rs2294008 was associated with the progression to chronic active gastritis (P = 9.4 × 10^–5; odds ratio = 3.88, TT + TC vs CC genotype), but not with H. pylori infection per se nor with the progression from active gastritis to gastric cancer. We also assessed the association of rs2294008 with PSCA mRNA expression in the gastric mucosa at various disease stages and found that rs2294008 was associated with PSCA expression (P = 1.3 × 10^–12). H. pylori infection (P = 5.1 × 10^–8) and eradication therapy (P < 1 × 10^–11) resulted in the reduced and increased PSCA expression, respectively, indicating negative regulation of PSCA expression by H. pylori infection. PSCA expression was decreased in severe gastritis compared with mild gastritis only among T allele carriers. Our findings revealed the regulation of PSCA expression by host genetic variation and bacterial infection might contribute to gastritis progression after H. pylori infection.

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.

Association between PSCA gene polymorphisms and the risk of cancer: an updated meta-analysis and trial sequential analysis

Previous studies have investigated the relationships between PSCA rs2294008 C>T and rs2976392 G>A polymorphisms and cancer susceptibility. However, the available findings remained inconsistent and even controversial. Thus, the aim of this meta-analysis was performed to clarify such associations. The online databases PubMed, EMBASE and Web of Science searched for relevant studies, covering all the papers published until September 1st, 2016. Data were pooled by odds ratios (ORs) with 95% confidence intervals (CIs) to evaluate the strength of such associations. Then, trial sequential analysis was performed to estimate whether the evidence of the results was firm. Overall, a significant increased risk of cancer was associated with PSCA rs2294008 C>T and rs2976392 G>A polymorphisms. For the PSCA rs2294008 polymorphism, when stratified by type of cancer, the results were significant especially in gastric cancer and bladder cancer. Moreover, in the subgroup analysis by ethnicity, significant results were detected in both Asian and Caucasian populations. Similarly, for the PSCA rs2976392 polymorphism, the stratification analyses by type of cancer showed that the results were significant only in gastric cancer. In addition, the stratification analyses by ethnicity detected that this polymorphism increased cancer risk only in Asian populations. Then, trial sequential analyses demonstrated that the results of the meta-analysis were based on sufficient evidence. Therefore, this meta-analysis suggested that the PSCA rs2294008 C>T and rs2976392 G>A polymorphisms might be associated with cancer susceptibility, which might act as a potential predicted biomarker for genetic susceptibility to cancer, especially in gastric cancer and bladd er cancer.

Genetic variation of the PSCA gene (rs2294008) is not associated with the risk of prostate cancer

Prostate stem cell antigen ( PSCA ) is a cell-membrane glycoprotein consisting of 123 amino acids and highly expressed in the prostate, but there have been few reports on the relationship between rs2294008 of PSCA and prostate cancer in the literature. Therefore, we evaluated the association between rs2294008 and the risk of prostate cancer. A total of 240 prostate cancer patients and 306 controls (patients with benign prostatic hyperplasia) were enrolled. Genotype analysis of rs2294008 of PSCA was performed using PCR. Logistic regression analysis was performed according to the genotype of PSCA rs2294008. We found that CT and TT genotypes were associated with an insignificant risk of prostate cancer compared with the CC genotype ( P = 0.627 and 0.397, respectively). In addition, there was no significant difference in rs2294008 according to clinicopathological parameters, such as age, Gleason score, prostate-specific antigen (PSA), stage, and metastasis in prostate cancer ( P >0.05 for each). Age, Gleason score, PSA, pathologic stage, and metastasis did not modify the association between PSCA and the risk of prostate cancer (each P >0.05 for each). Taken together, the genetic polymorphism of PSCA rs2294008 was not associated with the risk of prostate cancer. Our results suggest that rs2294008 may not play a role in prostate carcinogenesis.

Common Genetic Variants of PSCA, MUC1 and PLCE1 Genes are not Associated with Colorectal Cancer

BACKGROUND

Polymorphisms of genes encoding PSCA, PLCE1 and MUC1 have been associated with the risk of different cancers in genome wide association studies (GWAS). Up to date there are limited data on the role of these genetic alterations in colorectal cancer (CRC) development. The aim of this study was to evaluate potential associations between single nucleotide polymorphisms (SNPs) of genes encoding PSCA, PLCE1 and MUC1 and the presence of CRC in European populations.

MATERIALS AND METHODS

Gene polymorphisms were analyzed in 574 European subjects (controls: n=382; CRC: n=192). PSCA C>T (rs2294008), PSCA G>A (rs2976392), MUC1 A>G (rs4072037) and PLCE1 A>G (rs2274223) SNPs were genotyped by RT-PCR.

RESULTS

The distribution of genotypes for all four SNPs was in line with the Hardy-Weinberg equilibrium (rs2294008, P=0.153; rs2976392, P=0.269; rs4072037, P=0.609; rs2274223, P=0.858). The distribution of genotypes and alleles of PSCA C>T, PSCA G>A, MUC1 A>G and PLCE1 A>G SNPs was similar among controls and CRC patient groups (P>0.05). GG genotype of MUC1 SNP was more frequent in CRC patients (24.0%) than in controls (20.2%); however, this association failed to reach significance (OR-1.45, P=0.15). Overall, in the present study SNPs of PSCA (rs2294008, rs2976392), MUC1 (rs4072037) and PLCE1 (rs2274223) genes were not associated with the presence of CRC.

CONCLUSIONS

Gene polymorphisms of PSCA, PLCE1 and MUC1 genes are not associated with the presence of CRC in European subjects.

PSCA rs2294008 polymorphism contributes to the decreased risk for cervical cancer in a Chinese population

Recently, three genome-wide association studies have identified the PSCA (prostate stem cell antigen) rs2294008 polymorphism (C > T) associated with susceptibility to gastric cancer, bladder cancer, and duodenal ulcers, highlighting its critical role in disease pathogenesis. Given PSCA is reported to be overexpressed in cervical cancer and the rs2294008 can influence PSCA transcription, we aimed to determine the role of rs2294008 in susceptibility to cervical cancer. The genotyping was performed in the 1126 cases and 1237 controls. Our results showed the rs2294008 TT genotype significantly associated with a reduced risk of cervical cancer (adjusted OR = 0.55, 95% CI = 0.38-0.79; recessive model). Stratified analyses revealed that the association was restricted to the subgroups of age > 49 years, parity ≤ 1, abortion and early-stage cervical cancer. Immunohistochemistry assay showed the individuals carrying the TT genotype having lower PSCA expression than those with CC/CT genotypes. In summary, the PSCA rs2294008 polymorphism may serve as a biomarker of cervical cancer, particularly of early-stage cervical cancer.

PSCA polymorphisms and gastric cancer susceptibility in an eastern Chinese population

The prostate stem cell antigen (PSCA) gene, which encodes a prostate-specific antigen (PSA), was identified as a gene involved in cell adhesion and proliferation. The associations between the PSCA rs2294008 and rs2976392 single nucleotide polymorphisms (SNPs) and gastric cancer (GCa) susceptibility were still controversial. To derive a more precise estimation of the associations, we conducted a case-control study of 1,124 cases and 1,192 controls in an eastern Chinese population. We found that the rs2294008T variant genotypes were associated with an increased GCa risk in this study population (CT vs CC, OR=1.59, 95% CI=1.33-1.89 and CT+TT vs CC, OR=1.38, 95% CI=1.17-1.62). For SNP rs2976392, the variant A genotypes were also associated with an increased GCa risk (AG vs GG, OR=1.61, 95% CI=1.35-1.91 and AG+AA vs GG, OR=1.47, 95% CI=1.25-1.74). The results were further validated by a meta-analysis. In conclusion, the results indicated that the PSCA rs2294008 T and rs2976392 A alleles were low-penetrate risk factors for GCa in this study population. However, large and well-designed studies are warranted to validate our findings.

Impact of DCC (rs714) and PSCA (rs2294008 and rs2976392) Gene Polymorphism in Modulating Cancer Risk in Asian Population

Multiple studies have investigated the association of gene variant of Deleted in colorectal carcinoma (DCC) and Prostate Stem cell antigen (PSCA) with various cancer susceptibility; however, the results are discrepant. Since SNPs are emerging as promising biomarker of cancer susceptibility, here, we aimed to execute a meta-analysis of DCC (rs714 A > G) and PSCA (rs2294008 C > T, rs2976392 G > A) polymorphism to demonstrate the more accurate strength of these associations. We followed a rigorous inclusion/exclusion criteria and calculated the pooled odds ratios (ORs) and 95% confidence intervals (CIs). Overall, the pooled analysis showed that the DCC rs714 conferred increased risk of cancer only in Asians (AA vs. GG: OR = 1.86, p ≤ 0.0001; AG vs. GG: OR = 1.43, p = 0.005; GA + AA vs. GG: OR = 1.66, p ≤ 0.0001; AA vs. GG + GA; OR = 1.52, p ≤ 0.004, A vs. G allele: OR = 1.41, p ≤ 0.0001). PSCA rs2294008 was associated with increased overall cancer risk (TT vs. CC: OR = 1.28, p = 0.002; CT vs. CC: OR = 1.21, p ≤ 0.0001; CT + TT vs. CC: OR = 1.24, p ≤ 0.0001; TT vs. CC + CT; OR = 1.17, p ≤ 0.005, T vs. C allele: OR = 1.16, p ≤ 0.0001); however, in stratified analysis this association was limited only to gastric and bladder cancer and the strength was more prominent in Asians. In contrast, the PSCA rs2976392 SNP did not modulate the cancer risk. Therefore, we concluded that rs714 and rs2294008 polymorphism may represent a potential genetic biomarker for cancer risk in Asians and gastric as well as bladder cancer, respectively. However, since our study is limited to Asians and cancer types, further larger studies involving other cancers and/or population, gene-environment interactions and the mechanism of DCC and PSCA gene deregulation are desired to define the role of genotype with overall cancer risk.

PSCA acts as a tumor suppressor by facilitating the nuclear translocation of RB1CC1 in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy; its mechanisms of development and progression are poorly understood. By high-throughput transcriptome sequencing (RNA-Seq) profiling of three pairs of primary ESCCs and their corresponding non-tumorous tissues, we identified that prostate stem cell antigen (PSCA), a gene that encodes a glycosylphosphatidylinositol-anchored protein, is significantly downregulated in ESCC. Here, we reported decreased expression of PSCA in 188/218 (86.2%) of primary ESCC cases and was negatively regulated by its transcription factor sex-determining region Y-box5 that was significantly associated with the poor differentiation (P = 0.003), increased lymph node metastasis (P < 0.0001), advanced stage (P = 0.007), and disease-specific survival (P < 0.0001), but not associated with the recently reported transcrible rs2294008 (C > T) polymorphism in ESCC. Functional studies showed that PSCA could arrest cell cycle progression and promote cell differentiation independent of the start codon polymorphism. Further mechanistic studies revealed that retinoblastoma 1-inducible coiled-coil 1 (RB1CC1), a key signaling node to regulate cellular proliferation and differentiation, interacted specifically with PSCA in ESCC cells. Binding of PSCA and RB1CC1 in cytoplasm resulted in stabilization and translocation of RB1CC1 into nucleus, thereby activating key factors involved in cell cycle arrest and differentiation. Collectively, our data provide a novel molecular mechanism for the tumor suppressor role of PSCA and may help design effective therapy targeting PSCA-RB1CC1 pathway to control esophageal cancer growth and differentiation.

Cholinergic Targets in Lung Cancer

Lung cancers express an autocrine cholinergic loop in which secreted acetylcholine can stimulate tumor growth through both nicotinic and muscarinic receptors. Because activation of mAChR and nAChR stimulates growth; tumor growth can be stimulated by both locally synthesized acetylcholine as well as acetylcholine from distal sources and from nicotine in the high percentage of lung cancer patients who are smokers. The stimulation of lung cancer growth by cholinergic agonists offers many potential new targets for lung cancer therapy. Cholinergic signaling can be targeted at the level of choline transport; acetylcholine synthesis, secretion and degradation; and nicotinic and muscarinic receptors. In addition, the newly describe family of ly-6 allosteric modulators of nicotinic signaling such as lynx1 and lynx2 offers yet another new approach to novel lung cancer therapeutics. Each of these targets has their potential advantages and disadvantages for the development of new lung cancer therapies which are discussed in this review.

Expression of stem cell markers nanog and PSCA in gastric cancer and its significance

The present study aimed to determine the expression of stem cell markers Nanog compared with PSCA in gastric cancer tissues and adjacent normal tissues, and to investigate the association between tumor stem cells and initiation, progression, metastasis, and prognosis of gastric cancer. One hundred chemotherapy- and radiotherapy-naive patients with pathologically confirmed gastric cancer were enrolled from the General Surgery Department and Surgical Oncology Department of the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, P.R. China), between October 2011 and June 2013. Surgically resected specimens of cancer tissues and adjacent normal tissues (>5 cm from the boundary of cancerous component) were collected. The mRNA expression levels of Nanog and PSCA in those tissues was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The correlation between the expression of stem cell markers Nanog and PSCA in gastric cancer tissues and clinicopathological factors was analyzed. The qPCR results demonstrated that the relative expression of Nanog was increased in gastric cancer tissues compared with in the adjacent tissues (P<0.05); and relative expression of PSCA was reduced in gastric cancer tissues compared with adjacent tissues (P<0.05). The expression of Nanog and PSCA in gastric cancer tissues was associated with tumor differentiation. The expression of Nanog was increased in poorly-differentiated and undifferentiated tumors compared with moderately- and well-differentiated tumors (P<0.05). The expression of PSCA was reduced in poorly differentiated and undifferentiated tumors compared with moderately- and well-differentiated tumors (P<0.05). However, the expression of Nanog and PSCA was not associated with age, gender, tumor size, TNM stage, depth of invasion, or lymph node metastasis. Therefore, Nanog and PSCA may have potential as molecular markers to reflect the differentiation status of gastric cancer.

Prostate stem cell antigen gene TT genotype and development of intestinal metaplasia in Helicobacter pylori infection

OBJECTIVES

Gastric cancer is etiologically related to interactions between Helicobacter pylori (H. pylori) infection, environmental and host factors. Gastric carcinoma is associated with a cascade of increasing atrophic gastric mucosal damage. Prostate stem cell antigen (PSCA) polymorphisms have been associated with an increased risk of gastric cancer. We aimed to examine the interaction between PSCA polymorphisms and H. pylori in the progression of H. pylori-related gastritis.

METHODS

The genotypes (TT, TC and CC) of PSCA single nucleotide polymorphism rs2294008 among H. pylori infected and uninfected Bhutanese were compared with the severity of H. pylori-related gastritis [neutrophils, monocytes, atrophy scores, H. pylori density, and the presence and extent of intestinal metaplasia (IM)] using the updated Sydney system.

RESULTS

Biopsies from 339 participants were included. The proportion of biopsies with IM was significantly (P < 0.05) greater in those with the TT genotype than in either those with the CT or CC genotype. Although no significant differences were found in inflammation or H. pylori density scores, the scores for IM at both gastric corpus and antrum among participants infected by H. pylori with the TT genotype was significantly (P < 0.05) greater than in the C allele carriers.

CONCLUSION

PSCA TT genotype is associated with a more than a threefold increase in the prevalence and the extent of gastric mucosal IM compared to C allele carriers among H. pylori-infected Bhutanese.

PSCA rs2294008 Polymorphism with Increased Risk of Cancer

Background

Published data on the association between PSCA rs2294008 polymorphism and cancer risk have implicated inconclusive results. To determine the relationship and to precisely assess the effect size estimate of the association, we performed a meta-analysis.

Methods

We searched published literature in Embase and PubMed databases using the search terms “PSCA”, “prostate stem cell antigen”, “variants”, “polymorphism”, “polymorphisms”, and “cancer”. A total of 21 eligible articles were retrieved, with 27, 197 cancer cases and 48, 237 controls.

Results

On the whole, we found the association between PSCA rs2294008 polymorphism and cancer risk was statistically significant: TT vs CC: OR = 1.18, 95% CI, 1.10 to 1.27; TT + CT vs CC: OR = 1.08, 95% CI, 1.05 to 1.10; TT vs CT + CC: OR = 1.14, 95% CI, 1.07 to 1.21; T vs C: OR = 1.10, 95% CI, 1.06 to 1.14; CT vs CC: OR = 1.10, 95% CI, 1.06 to 1.13. Stratified analyses in cancer type and ethnicity showed similar results.

Conclusions

Based on the statistical evidence, we can draw a conclusion that the rs2294008 polymorphism of PSCA gene is likely to play a role in cancer carcinogenesis, especially in gastric cancer and bladder cancer.

PSCA s2294008 C>T and rs2976392 G>A polymorphisms contribute to cancer susceptibility: evidence from published studies

PSCA gene plays an important role in cell adhesion, proliferation and survival. Increasing studies have focused on the association of PSCA gene rs2294008 C>T and rs2976392 G>A with cancer risk. However, the conclusions were inconsistent. Therefore, we performed a meta-analysis to elucidate whether there is a true association, or artifact. We systematically searched eligible studies from MEDLINE, EMBASE and CBM database. Odds ratios and 95% confidence intervals were used to evaluate the strength of the association. The final analysis included 32 studies consisting of 30028 cases and 38765 controls for the rs2294008 C>T polymorphism, and 14 studies with 8190 cases and 7176 controls for the rs2976392 G>A polymorphism. Consequently, the PSCA rs2294008 C>T polymorphism was significantly associated with increased overall cancer risk. Further stratifications indicated the increased risk was more pronounced for gastric (diffused type and non-gastric cardia adenocarcinoma) and bladder cancer. A similar association was observed for the rs2976392 G>A polymorphism. This meta-analysis demonstrated that both of the PSCA rs2294008 C>T and rs2976392 G>A polymorphisms are associated with increased cancer risk, especially for gastric cancer and bladder cancer. Further large-scale studies with different ethnicities and subtypes of gastric cancer are required to confirm the results from this meta-analysis.

Role of Lynx1 and related Ly6 proteins as modulators of cholinergic signaling in normal and neoplastic bronchial epithelium

The ly-6 proteins are a large family of proteins that resemble the snake three finger alpha toxins such as α-bungarotoxin and are defined by their multiple cysteine residues. Multiple members of the ly-6 protein family can modulate nicotinic signaling including lynx1, lynx2, slurp-1, slurp-2 and prostate stem cell antigen (PSCA). Consistent with the expression of multiple nicotinic receptors in bronchial epithelium, multiple members of the nicotinic-modulatory ly-6 proteins are expressed in lung including lynx1 and lynx2. We studied the role of lynx1 as an exemplar of the role of ly-6 proteins in lung. Our data demonstrates that lynx1 acts as a negative modulator of nicotinic signaling in normal and neoplastic lung. In normal lung lynx1 serves to limit the ability of chronic nicotine exposure to increase levels of nicotinic receptors and also serves to limit the ability of nicotine to upregulate levels of GABAA receptors in lung. In turn this allows lynx1 to limit the ability of nicotine to upregulate levels of mucin which is mediated by GABAergic signaling. This suggests that lynx1-mimetics may have potential for treatment of asthma and COPD. In that most lung cancer cells also express nicotinic receptor and lynx1 we examined the role of lynx-1 in lung cancer. Lynx1 levels are decreased in lung cancers compared to adjacent normal lung. Knockdown of lynx1 by siRNAs increased growth of lung cancer cells while expression of lynx1 in lung cancer cell decreased cell proliferation. This suggests that lynx1 is an endogenous regulator of lung cancer growth. Given that multiple small molecule negative and positive allosteric modulators of nicotinic receptors have already been developed, this suggests that lynx1 is a highly druggable target both for development of drugs that may limit lung cancer growth as well as for drugs that may be effective for asthma or COPD treatment.

Influence of prostate stem cell antigen gene polymorphisms on susceptibility to Helicobacter pylori-associated diseases: a case-control study

BACKGROUND

Patients with duodenal ulcer have a reduced risk of developing gastric cancer compared to those without. Recently, the prostate stem cell antigen (PSCA) rs2294008 C>T polymorphism was found to be associated with different pathogenesis of duodenal ulcer and gastric cancer developments. However, whether PSCA rs2294008 C>T polymorphism is associated with severity of gastric mucosal atrophy is unclear. We examined the influence of the PSCA rs2294008 C>T polymorphism on susceptibility to H. pylori-related diseases and the relationships between PSCA polymorphism and gastric mucosal atrophy.

METHODS

PSCA rs2294008 C>T polymorphism was assessed in H. pylori-positive Japanese patients (n = 488) with noncardia gastric cancer (n = 193), gastric ulcer (n = 84), duodenal ulcer (n = 61), and atrophic gastritis (n = 150), as well as in H. pylori-negatives (n = 266).

RESULTS

Frequency of PSCA rs2294008 C/C genotype in duodenal ulcer was 36.1%, which was significantly higher than those with gastric cancer (12.4%), gastric ulcer (19.0%), gastritis (10.7%), and H. pylori-negatives (19.5%) (p < .001). Compared with duodenal ulcer, having the T allele significantly increased the risk of gastric cancer (OR: 3.97, 95% CI: 2.02-7.80; p < .001), gastric ulcer (2.40, 1.13-5.10; p = .023), and gastritis (4.72, 2.26-9.86; p < .001). Mean pepsinogen (PG) I/PG II ratio in T allele carriers (2.17 ± 0.75) was significantly lower than that in C/C genotype (3.39 ± 1.27, p < .001).

CONCLUSIONS

The PSCA rs2294008 C>T polymorphism is associated with differing susceptibilities to H. pylori-associated diseases. The PSCA rs2294008 C>T polymorphism may be acting through induction of gastric mucosal atrophy, finally leading to development of gastric ulcer and gastric cancer in PSCA rs2294008 T allele carriers, but not duodenal ulcer.

rs2294008T, a risk allele for gastric and gallbladder cancers, suppresses the PSCA promoter by recruiting the transcription factor YY1

Previous genomewide association studies identified prostate stem cell antigen (PSCA) as a gastric cancer (GC) susceptibility gene and showed an association between GC and the T allele of the single nucleotide polymorphism rs2294008 (C/T) in this gene. The protein product of this gene inhibits cell growth, and the T allele significantly suppresses the transcriptional activity of the -3.2 kb PSCA upstream region. However, the mechanism remains unknown. In this study, we conducted reporter assays using the PSCA upstream region containing the C allele and identified the region from -200 to +38 bp of the transcription initiation site of the gene as a critical region of the -3.2 kb PSCA upstream region. We found that introducing the T allele at rs2294008 generated a consensus binding sequence for the Polycomb group transcription factor Yin Yang 1 (YY1) and that disruption of the consensus sequence restored the transcriptional activity to the -3.2 kb PSCA upstream region. These findings imply that the T allele significantly suppresses PSCA expression in vivo by recruiting YY1 to its promoter, which eventually predisposes gastric epithelial cells to GC development.

PSCA rs2294008 C > T polymorphism contributes to gastric and bladder cancer risk

Background

Previous studies suggested genetic variations in PSCA (prostate stem cell antigen) may confer the susceptibility of cancer. Many case–control studies have reported the relationship between PSCA rs2294008 C > T polymorphism and cancer, especially gastric cancer and bladder cancer. However, the results are inconsistent. This meta-analysis is aimed at evaluating the association of rs2294008 polymorphism with cancer risk.

Methods

The databases of PubMed, ISI Web of Knowledge, EMBASE, and Chinese National Knowledge Infrastructure (CNKI) were searched for related publications. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of the associations. Fixed models were used when heterogeneity among studies was not detected, otherwise the random model was used.

Results

Twenty-six studies from 24 articles with 30,050 multiple cancer cases and 51,670 controls were pooled into this meta-analysis. The results showed that the rs2294008 polymorphism was associated with increased cancer risk in any genetic model (T vs C, OR: 1.18, 95% CI: 1.08–1.28; TT vs CC, OR: 1.36, 95% CI: 1.14–1.62; TC vs CC, OR: 1.29, 95% CI: 1.17–1.44; TT + TC vs CC, OR: 1.32, 95% CI: 1.18–1.49; TT vs TC + CC, OR: 1.15, 95% CI: 1.02–1.30). In stratified analysis by cancer type, we found that the T allele had a significant high risk of gastric and bladder cancer, but not in other cancers. In subgroup analysis by ethnicity, increased cancer risk was found in both Asians and Caucasians.

Conclusion

Our study suggested that the PSCA rs2294008 C > T polymorphism is a risk factor for cancer, especially in gastric and bladder cancer.

Associations of genetic variants in the PSCA, MUC1 and PLCE1 genes with stomach cancer susceptibility in a Chinese population

BACKGROUND

Several genetic variants including PSCA rs2294008 C>T and rs2976392 G>A, MUC1 rs4072037 T>C, and PLCE1 rs2274223 A>G have shown significant association with stomach cancer risk in the previous genome-wide association studies (GWASs).

METHODS

To evaluate associations of these SNPs in the Han Chinese, an independent hospital based case-control study was performed by genotyping these four polymorphisms in a total of 692 stomach cancer cases and 774 healthy controls acquired by using frequency matching for age and gender. False-positive report probability (FPRP) analysis was also performed to validate all statistically significant findings.

RESULTS

In the current study, significant association with stomach cancer susceptibility was observed for all the four polymorphisms of interest. Specifically, a significant increased stomach cancer risk was associated with PSCA rs2294008 (CT vs. CC: adjusted OR = 1.37, 95% CI = 1.07-1.74, and CT/TT vs.CC: adjusted OR = 1.30, 95% CI = 1.03-1.63), PSCA rs2976392 (AG vs. GG: adjusted OR = 1.30, 95% CI = 1.02-1.65, and AG/AA vs. GG: adjusted OR = 1.26, 95% CI = 1.00-1.59), or PLCE1 rs2274223 (AG vs. AA: adjusted OR = 1.48, 95% CI = 1.15-1.90, and AG/GG vs. AA: adjusted OR = 1.45, 95% CI = 1.14-1.84), respectively. In contrast, MUC1 rs4072037 was shown to decrease the cancer risk (CT vs. TT: adjusted OR = 0.77, 95% CI = 0.60-0.98). Patients with more than one risk genotypes had significant increased risk to develop stomach cancer (adjusted OR = 1.30, 95% CI = 1.03-1.64), when compared with those having 0-1 risk genotypes. Stratified analysis indicated that the increased risk was more pronounced in younger subjects, men, ever smokers, smokers with pack years ≤ 27, patients with high BMI, or non-cardia stomach cancer.

CONCLUSIONS

This study substantiated the associations between four previous reported genetic variants and stomach cancer susceptibility in an independent Han Chinese population. Further studies with larger sample size and different ethnicities are warranted to validate our findings.

Genetics of gastric cancer

Gastric cancer remains highly prevalent and accounts for a notable proportion of global cancer mortality. This cancer is also associated with poor survival rates. Understanding the genetic basis of gastric cancer will offer insights into its pathogenesis, help identify new biomarkers and novel treatment targets, aid prognostication and could be central to developing individualized treatment strategies in the future. An inherited component contributes to <3% of gastric cancers; the majority of genetic changes associated with gastric cancer are acquired. Over the past few decades, advances in technology and high-throughput analysis have improved understanding of the molecular aspects of the pathogenesis of gastric cancer. These aspects are multifaceted and heterogeneous and represent a wide spectrum of several key genetic influences, such as chromosomal instability, microsatellite instability, changes in microRNA profile, somatic gene mutations or functional single nucleotide polymorphisms. These genetic aspects of the pathogenesis of gastric cancer will be addressed in this Review.

Association of a common genetic variant in prostate stem cell antigen with cancer risk

INTRODUCTION

Polymorphisms in the prostate stem cell antigen (PSCA) gene have been hypothesized to increase the genetic susceptibility to cancers. The common sequence variation in PSCA rs2294008 (C>T) has been implicated in cancer risk. However, results of the relevant published studies were somewhat underpowered and controversial in general.

MATERIAL AND METHODS

To evaluate the role of PSCA rs2294008 (C>T) genotype in global cancer, we performed a pooled analysis of all the available published studies involving 22,817 cancer patients and 27,753 control subjects.

RESULTS

The results showed evidence that PSCA rs2294008 (C>T) was associated with increased total cancer risk in the overall comparisons. Stratified analysis by cancer type indicated that PSCA rs2294008 T is associated with increased risk of gastric cancer (OR = 1.24, 95% CI = 1.09-1.42, p heterogeneity < 0.001, I (2) = 88.0%) and bladder cancer (OR = 1.07, 95% CI = 1.04-1.11, p heterogeneity = 0.108, I (2) = 55.0%) by allelic contrast. Furthermore, in stratified analysis by histological types of gastric cancer, this PSCA variant showed significant associations with diffuse type (OR = 1.81, 95% CI = 1.16-2.81, p heterogeneity < 0.001, I (2) = 88.9%) but not intestinal type (OR = 1.29, 95% CI = 0.95-1.74, p heterogeneity < 0.001, I (2) = 85.2%) in a dominant genetic model. Similar results were found in Asian and European descendents and population-based studies.

CONCLUSIONS

In all, our meta-analysis suggests that PSCA rs2294008 (C>T) may play allele-specific roles in cancer development. Further prospective studies with larger numbers of participants worldwide should be performed in different kinds of cancer and other descendents in more detail.

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.

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.

Genetic variants at 8q24 are associated with risk of esophageal squamous cell carcinoma in a Chinese population

Esophageal cancer and gastric cancer have shared risk factors and inherited susceptibility. Recent genome-wide association studies have identified multiple genetic loci associated with gastric cancer risk, which may also involve in the development of esophageal cancer. Herein, we evaluated the relationship of gastric cancer risk-related variants at 1q22, 3q13.3, 5p13.1, and 8q24 with the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese population with a case–control study (2139 cases and 2273 controls). We found that the T allele of rs2294008, an intronic variant of the PSCA gene at 8q24 that was previously associated with an increased risk of gastric cancer, was inversely associated with a decreased risk of ESCC (odds ratio = 0.90; 95% confidence interval, 0.81–0.99; P = 0.034). Of interest, the association of rs2294008 with ESCC was consistent with that observed in esophageal adenocarcinoma and ESCC in Caucasian populations. However, no significant associations were observed for the other three variants at 1q22 (rs4072037), 3q13.31 (rs9841504), and 5p13.1 (rs13361707). Our findings suggest that the susceptibility locus of PSCA at 8q24 may be a double-edged sword, as modulator between the carcinogenesis processes of stomach and esophagus.

Prostate stem cell antigen and cancer risk, mechanisms and therapeutic implications

Prostate stem cell antigen (PSCA) was originally identified as a tumor antigen in prostate cancer. Recent studies indicated that PSCA was correlated with many cancer types. In this review, we will consider the origin of PSCA, discuss the expression of PSCA in normal and cancer tissue, describe PSCA polymorphisms and cancer risk, summarize potential mechanisms for PSCA involvement in cancer; and look into the therapeutic implications of PSCA. PSCA is upregulated in prostate cancer, pancreatic cancer and bladder cancer, as well as a number of others, making it an ideal clinical target for both diagnosis and therapy. Future studies will be required to explore its mechanisms on various cancer types, and to confirm its clinical utility for diagnosis and immunotherapy strategies. The study of PSCA regulation and expression may also provide information on normal prostate development and prostate carcinogenesis.

Quantitative assessment of the influence of prostate stem cell antigen polymorphisms on gastric cancer risk

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored 123-amino acid protein related to the cell proliferation inhibition and/or cell death induction activity which has attracted considerable attention as a candidate gene for gastric cancer (GC) since it was first identified through genome-wide association approach. Since then, the relationship between PSCA polymorphisms (rs2294008, rs2976392) and GC has been reported in various ethnic groups; however, these studies have yielded inconsistent results. To investigate this inconsistency, we performed a meta-analysis of 16 studies involving a total of 18,820 cases and 35,756 controls for the two widely studied polymorphisms of PSCA on genetic susceptibility for GC. Overall, the summary odds ratio for GC was 1.46 (95% CI 1.30-1.69, P < 10(-5)) and 1.49 (95% CI 1.22-1.82, P < 10(-4)) for PSCA rs2294008 and rs2976392 polymorphisms, respectively. Meanwhile, haplotype analyses of the two polymorphisms revealed a significant association between the combination of these alleles and GC risk. When stratifying for ethnicity, significantly increased risks were found for rs2294008 and rs2976392 polymorphism among East Asians in all genetic models, while no significant associations were observed for the rs2294008 polymorphism in Caucasians. In the stratified analyses according to histological type, and source of controls, evidence of gene-disease association was still obtained. In addition, our data indicate that rs2294008 of PSCA is involved in GC susceptibility and confer its effect primarily in noncardia tumors (OR = 1.30, 95% CI 1.12-1.53, P < 10(-4)). Our findings demonstrated that rs2294008 and rs2976392 polymorphism of PSCA is a risk-conferring factor associated with increased GC susceptibility, especially in East Asians.

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

A recent genome-wide association study (GWAS) identified new susceptibility single-nucleotide polymorphisms (SNPs) rs13361707 (PRKAA1 and PTGER4 gene on 5p13.1) and rs9841504 (ZBTB20 gene on 3q13.31) that were significantly associated with non-cardia gastric cancer. The aim of this study was to determine whether rs13361707 and rs9841504 polymorphisms are associated with the risk of gastric cancer in a Korean population. We conducted a large-scale case-control study of 3245 gastric cancer patients and 1700 controls. The allele frequencies for rs13361707 C and rs9841504 G were 53.5% and 18.3% among gastric cancer cases, compared with 47.1% and 17.2% among controls, respectively. We found that rs13361707 TC and CC genotypes were associated with increased risk for gastric cancer (odds ratios [OR] = 1.29; 95% confidence interval [CI] = 1.11-1.51 for TC vs. TT and 1.68; 1.41-2.01 for CC vs. TT). However, we found no significant association between rs9841504 and gastric cancer risk (OR = 1.11; 0.97-1.28 for CG vs. CC; OR = 1.09; 0.77-1.53 for GG vs. CC). We observed no significant interactions between rs13361707 and rs9841504 polymorphisms and age, gender, smoking habit, alcohol consumption, and clinicopathologic characteristics such as anatomical tumor location and histological type. Our study showed that the rs13361707 polymorphism was associated with increased risk of gastric cancer in a Korean population. This finding provides further evidence that genetic variant of PRKAA1 and PTGER4 genes may contribute to the gastric carcinogenesis. However, we found no association between rs9841504 and gastric cancer risk.

Prostate stem cell antigen rs2294008 polymorphism differentially contributes to Helicobacter pylori-negative gastric cancer among various populations in China

Gastric cancer is a lethal disease with a high mortality rate. Studies have suggested that prostate stem cell antigen (PSCA) rs2294008 polymorphism is associated with gastric cancer (GC). In this case-control study, we investigated rs2294008 polymorphism in the Tibet, Hui and Han nationalities in the Qinghai area of China. Genomic DNA was extracted from the peripheral blood of 286, 315 and 350 healthy volunteers and from 219, 233 and 265 Helicobacter pylori-negative non-cardia GC patients from the Tibet, Hui and Han populations, respectively. The rs2294008 polymorphism was analyzed by denaturing high-performance liquid chromatography. rs2294008 CT and TT genotypes were associated with GC both in the Tibet and Han populations (adjusted OR=1.51, 1.47, 2.01, 1.85; 95% CI, 1.04-2.19, 1.05-2.06, 1.04-3.88, 1.03-3.34; P=0.030, 0.025, 0.039, 0.040, respectively). rs2294008 TT genotype was associated with GC in the Hui population (adjusted OR=2.14; 95% CI, 1.29-3.55; P=0.003). Furthermore, when stratified by histopathology, the rs2294008 CT and TT genotypes were associated with diffuse GC in the Tibet and Han nationalities (adjusted OR=1.93, 1.73, 2.69, 2.86; 95% CI, 1.09-3.44, 1.01-2.95, 1.06-6.84, 1.27-6.46; P=0.025, 0.045, 0.038, 0.011, respectively). However, the rs2294008 TT genotype was associated with both intestinal and diffuse types of GC (adjusted OR=2.10, 2.21; 95% CI, 1.17-3.75, 1.12-4.38; P=0.012, 0.023, respectively) and the rs2294008 CT genotype was only associated with intestinal-type GC in the Hui nationalitiy group (adjusted OR=1.60; 95% CI, 1.04-2.47; P=0.034). The results therefore showed that rs2294008 may differentially contribute to GC among different nationalities in one area and its role is independent from Helicobacter pylori-infection.

Missense allele of a single nucleotide polymorphism rs2294008 attenuated antitumor effects of prostate stem cell antigen in gallbladder cancer cells

Background:

Prostate stem cell antigen (PSCA), an organ-dependent tumor suppressor, is down regulated in gallbladder cancer (GBC). It is anticipated that the missense allele C of the single nucleotide polymorphism (SNP) rs2294008 (T/C) in the translation initiation codon of the gene affects the gene's biological function and has some influence on GBC susceptibility. We examined the biological effect of the C allele on the function of the gene and the relation between the C allele and GBC susceptibility.

Materials and Methods:

Functional analysis of the SNP was conducted by introducing PSCA cDNA harboring the allele to a GBC cell line TGBC- 1TKB and performing colony formation assays in vitro and tumor formation assays in mice. The effect on transcriptional regulation was assessed by reporter assays. The association study was conducted on 44 Japanese GBC cases and 173 controls.

Results:

The PSCA cDNA harboring the C allele showed lower cell growth inhibition activity (20% reduction) than that with the T allele. Concordantly, when injected into subcutaneous tissues of mice, the GBC cell line stably expressing the cDNA with the C allele formed tumors of almost the same size as that of the control cells, but the cell line expressing the cDNA with the T allele showed slower growth. The upstream DNA fragment harboring the C allele had more transcriptional activity than that with the T allele. The C allele showed positive correlation to GBC but no statistical significant odds ratio (OR = 1.77, 95% confidence interval 0.85-3.70, P value = 0.127 in dominant model).

Conclusions:

The missense allele was shown to have a biological effect, attenuating antitumor activities of PSCA, and consequently it may be a potential risk for GBC development. An association study in a larger sample size may reveal a significant association between the allele and GBC.

Case-control study of single nucleotide polymorphisms of PSCA and MUC1 genes with gastric cancer in a Chinese

AIMS

A case-control study of 300 gastric cancer patients and 300 controls was conducted to investigate whether the polymorphisms rs2294008 in PSCA and rs2070803 in MUC1 might be associated with risk of gastric cancer in a Chinese population.

METHODS

Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY platform.

RESULTS

The data showed that the rs2294008 TT genotype increased gastric cancer risk to an adjusted odds ratio (OR) of 2.26 (95%CI 1.25-4.07), TC to 1.72 (95%CI 1.23-2.42) and TC/TT to 1.81 (95% CI 1.31-2.50), while the rs2070803 GA genotype was associated with a decrease in risk to an adjusted OR of 0.42 (95% CI 0.28-0.62) and rs2070803 GA / AA to 0.46 (95% CI 0.32-0.67). Further stratification analysis revealed that rs2294008 in PSCA consistently increased risk of both intestinal and diffuse-type gastric cancers. The effect of rs2070803 in MUC1 was noteworthily also consistent with both subtypes.

CONCLUSIONS

Our study suggested rs2294008 in the PSCA gene to be associated with increased risk of gastric cancer and rs2070803 in MUC1 to play a protective role in a Chinese population.

Genetic factors related to gastric cancer susceptibility identified using a genome-wide association study

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia, where Japan and Korea have the highest incidence in the world. Gastric cancer is classified into intestinal and diffuse types. While the former is almost absolutely caused by Helicobacter pylori infection as the initial insult, the latter seems to include cases in which the role of infection is limited, if any, and a contribution of genetic factors is anticipated. Previously, we performed a genome-wide association study (GWAS) on diffuse-type GC by using single nucleotide polymorphisms (SNP) catalogued for Japanese population (JSNP), and identified a prostate stem cell antigen (PSCA) gene encoding a glycosylphosphatidylinositol-anchored cell surface antigen as a GC susceptibility gene. From the second candidate locus identified using the GWAS, 1q22, we found the Mucin 1 (MUC1) gene encoding a cell membrane-bound mucin protein as another gene related to diffuse-type GC. A two-allele analysis based on risk genotypes of the two genes revealed approximately 95% of Japanese population have at least one of the two risk genotypes, and approximately 56% of the population have both risk genotypes. The two-SNP genotype might offer ample room to further stratify a high GC risk subpopulation in Japan and Asia by adding another genetic and/or non-genetic factor. Recently, a GWAS on the Chinese population disclosed an additional three GC susceptibility loci: 3q13.31, 5p13.1 and 10q23.

Genetic variant as a selection marker for anti-prostate stem cell antigen immunotherapy of bladder cancer

A monoclonal antibody against prostate stem cell antigen (PSCA) has emerged as a novel cancer therapy currently being tested in clinical trials for prostate and pancreatic cancers, but this treatment is likely to be efficient only in patients with PSCA-expressing tumors. The present study demonstrates that a genetic variant (rs2294008) discovered by bladder cancer genome-wide association studies is a strong predictor of PSCA protein expression in bladder tumors, as measured by two-sided multivariable linear regression (P = 6.46×10⁻¹¹; n = 278). The association pattern is similar in non-muscle-invasive tumors, stages Ta (P = 3.10×10⁻⁵; n = 173) and T1 (P = 2.64×10⁻⁵; n = 60), and muscle-invasive tumors, stages T2 (P =.01; n = 23) and T3/4 (P =.03; n = 22). The study suggests that anti-PSCA immunotherapy might be beneficial for bladder cancer patients with high tumor PSCA expression, which is statistically significantly associated with the presence of CT and TT genotypes of a common genetic variant, rs2294008. Future clinical studies will be needed to validate PSCA as a therapeutic target for bladder cancer.

Global gene expression and functional network analysis of gastric cancer identify extended pathway maps and GPRC5A as a potential biomarker

To get more understanding of the molecular mechanisms underlying gastric cancer, 25 paired samples were applied to gene expression microarray analysis. Here, expression microarray, quantitative reverse transcription-PCR (qRT-PCR) and immunohistochemical analysis indicated that GPRC5A was significantly elevated in gastric cancer tissues. The integrative network analysis of deregulated genes generated eight subnetworks. We also mapped copy number variations (CNVs) and associated mRNA expression changes into pathways and identified WNT, RTK-Ras-PI3K-AKT, NF-κB, and PLAU-JAK-STAT pathways involved in proliferation, evading apoptosis and sustained angiogenesis, respectively. Taken together, our results reveal several interesting genes including GPRC5A as potential biomarkers for gastric cancer, and highlight more systematical insight of deregulated genes in genetic pathways of gastric carcinogenesis.

Polymorphisms of tumor-related genes IL-10, PSCA, MTRR and NOC3L are associated with the risk of gastric cancer in the Chinese Han population

BACKGROUND

Gastric cancer is the fourth most common cancer in the world. Environmental and genetic factors both play critical roles in the etiology of gastric cancer. Hundreds of SNPs have been identified to have association with the risk of gastric cancer in many races. In this study, 25 SNPs in genes for IL-10, IL-1B, MTRR, TNF-а, PSCA, PLCE1 and NOC3L were analyzed to further evaluate their associations with gastric cancer susceptibility in the Chinese Han population.

METHODS

Two hundred and seventy nine gastric cancer patients and 296 healthy controls were recruited in this study. SNP genotyping was conducted using Sequenom MassARRAY RS1000. Data management and statistical analyses were conducted by Sequenom Typer 4.0 Software and Pearson's χ(2) test.

RESULTS

One protective allele and three risk alleles for gastric cancer patients were found in this study. The allele "G" of rs1801394 in MTRR showed an association with a decreased risk of gastric cancer: odds ratio (OR) = 0.74, 95% confidence interval (95% CI) = 0.57-0.97, P = 0.030 in the additive model; OR = 0.495, 95% CI = 0.26-0.95, P = 0.034 in the recessive model. The other three SNPs, the allele "C" of rs1800871 in IL10 (OR = 1.33, 95% CI = 1.04-1.90; P = 0.026 in the additive model; OR = 1.46, 95% CI = 1.04-2.06; P = 0.030 in the recessive model), the allele "A" of rs2976391 in PSCA (OR = 1.30, 95% CI = 1.01-1.66; P = 0.041 in the additive model and OR = 1.48, 95% CI = 1.04-2.11, P = 0.028 in the recessive model), and the allele "G" of rs17109928 in NOC3L gene (OR = 1.34, 95% CI = 1.01-1.78; P = 0.042 by additive model analysis; OR = 1.47, 95% CI = 1.04-2.07, P = 0.028 by dominant model analysis), showed an association with an increased risk of gastric cancer.

CONCLUSIONS

These results indicate the importance of four gastric cancer susceptibility polymorphisms of IL-10, NOC3L, PSCA and MTRR in the Chinese Han population, which could be used in the determination of gastric cancer risk in clinical practice.

Multifactorial etiology of gastric cancer

The prevalence of gastric cancer is associated with several factors including geographical location, diet, and genetic background of the host. However, it is evident that infection with Helicobacter pylori (H. pylori) is crucial for the development of the disease. Virulence of the bacteria is also important in modulating the risk of the disease. After infection, H. pylori gains access to the gastric mucosa and triggers the production of cytokines that promote recruitment of inflammatory cells, probably involved in tissue damage. Once the infection is established, a cascade of inflammatory steps associated with changes in the gastric epithelia that may lead to cancer is triggered. H. pylori-induced gastritis and H. pylori-associated gastric cancer have been the focus of extensive research aiming to discover the underlying mechanisms of gastric tissue damage. This research has led to the association of host genetic components with the risk of the disease. Among these is the presence of single nucleotide polymorphisms (SNPs) in several genes, including cytokine genes, which are able to differentially modulate the production of inflammatory cytokines and then modulate the risk of gastric cancer. Interestingly, the frequency of some of these SNPs is different among populations and may serve as a predictive factor for gastric cancer risk within that specific population. However, the role played by other genetic modifications should not be minimized. Methylation of gene promoters has been recognized as a major mechanism of gene expression regulation without changing the primary structure of the DNA. Most DNA methylation occurs in cytosine residues in CpG dinucleotide, but it can also be found in other DNA bases. DNA methyltransferases add methyl groups to the CpG dinucleotide, and when this methylation level is too high, the gene expression is turned off. In H. pylori infection as well as in gastric cancer, hypermethylation of promoters of genes involved in cell cycle control, metabolism of essential nutrients, and production of inflammatory mediators, among others, has been described. Interestingly, DNA changes like SNPs or mutations can create CpG sites in sequences where transcription factors normally sit, affecting transcription.In this chapter, we review the literature about the role of SNPs and methylation on H. pylori infection and gastric cancer, with big emphasis to the H. pylori role in the development of the disease due to the strong association between both.

Effect of PSCA gene polymorphisms on gastric cancer risk and survival prediction: A meta-analysis

Previous studies have shown that two single-nucleotide polymorphisms (SNPs) in PSCA (rs2976392 and rs2294008) are associated with gastric cancer (GC), but the results are conflicting. Additionally, the prognostic value of PSCA gene polymorphisms for GC patients is unknown. We performed a meta-analysis using 9 eligible case-control studies to investigate the association between PSCA polymorphisms and GC risk, and additionally investigated the prognostic value of PSCA polymorphisms for GC patients with two eligible studies. The association was measured using random-effect or fixed-effect odds ratios (ORs) combined with 95% confidence intervals (CIs) according to the heterogeneity of the studies. We found that rs2294008 (dominant model: OR, 1.44; 95% CI, 1.16-1.79) and rs2976392 (dominant model: OR, 1.41; 95% CI, 0.98-2.04) polymorphisms were associated with increased risk of GC, although the association of rs2976392 was not statistically significant. For rs2294008, the associations were all consistently significant among the different subgroups stratified by ethnicity and tumor location, but not significant in intestinal or diffuse subtypes. For rs2976392, the associations were consistently significant for the intestinal, diffuse and non-cardia subtypes, but not significant for the cardia subtype. Furthermore, two eligible studies reported inverse results of PCSA in predicting the survival of GC patients (HR, 0.75; 95% CI, 0.59-0.96; and HR, 2.12; 95% CI, 1.22-3.69, respectively). In conclusion, PSCA gene polymorphisms are associated with increased risk of GC and are correlated with the prognosis of GC patients. Future studies are required to evaluate the molecular mechanisms of PSCA polymorphisms in GC and validate the prognostic value in a larger number of patients.

The PSCA polymorphisms derived from genome-wide association study are associated with risk of gastric cancer: a meta-analysis

PURPOSE

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored 123-aa protein related to the cell-proliferation inhibition and/or cell-death induction activity. Many studies had reported the role of PSCA rs2294008 C > T and rs2976392 G > A polymorphisms on gastric cancer risk.

METHODS

To investigate a more precise estimation of the relationships, we performed a meta-analysis on 9 case-control studies included 10,746 cases and 9,158 controls. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of the association.

RESULTS

For PSCA rs2294008 C > T polymorphism, there was a significantly increased risk of gastric cancer in all genetic models (TT/TC vs. CC: OR = 1.61, 95 % CI = 1.35-1.91; TT vs.

TC/CC

OR = 1.33, 95 % CI = 1.24-1.42). Similar results were also observed for PSCA rs2976392 G > A polymorphism (AA/AG vs. GG: OR = 1.69, 95 % CI = 1.24-2.31; AA vs.

AG/GG

OR = 1.36, 95 % CI = 1.24-1.50). In the stratified analysis by ethnicity of rs2294008, an increased gastric cancer risk was found in both Asians (TT vs.

TC/CC

OR = 1.31, 95 % CI = 1.22-1.42) and Europeans (TT/TC vs. CC: OR = 1.42, 95 % CI = 1.18-1.71). Furthermore, when stratified by clinicopathologic characteristics of tumor location and histology, a higher risk on non-cardia compared with cardia gastric cancer (TT vs.

TC/CC

OR = 1.43, 95 % CI = 1.12-1.83) as same as diffused compared with intestinal gastric cancer (TT vs.

TC/CC

OR = 1.29, 95 % CI = 1.13-1.49) was observed.

CONCLUSION

These findings supported that PSCA rs2294008 C > T and rs2976392 G > A polymorphisms may contribute to the susceptibility to gastric cancer, particular in non-cardia or diffused gastric cancer.

A germline variant N375S in MET and gastric cancer susceptibility in a Chinese population

MET tyrosine kinase and its ligand, hepatocyte growth factor (HGF), play a pivotal role in the activties of tumor cells. A germline missense variant in exon 2 of the MET gene, N375S (rs33917957 A>G), may alter the binding affinity of MET for HGF and thus modify the risk of tumorigenesis. In this study, we performed a case-control study to assess the association between N375S and gastric cancer risk in 1,681 gastric cancer cases and 1,858 cancer-free controls. Logistic regression analysis was applied to estimate crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between genotypes and gastric cancer risk. We found that MET N375S variant genotypes (NS/SS) were associated with a significantly decreased risk of gastric cancer (OR = 0.78, 95% CI = 0.63-0.96, P = 0.021) compared with the wildtype homozygote (NN). The finding indicates that this germline variant in MET may decrease gastric cancer susceptibility in Han Chinese.

Prostate stem cell antigen polymorphisms and susceptibility to gastric cancer: a systematic review and meta-analysis

BACKGROUND

Many studies have reported that prostate stem cell antigen (PSCA) polymorphisms (rs2294008 and/or 2976392) are significantly associated with gastric cancer (GC) risk, although the published results are inconsistent. We conducted a systematic review and meta-analysis for relevant literatures to quantitatively evaluate the relationship between PSCA polymorphisms and GC susceptibility.

METHODS

Extensive searches were conducted in three databases up to November 1, 2011. ORs and 95% CIs were used to assess the strength of the associations. The data were further stratified by ethnicity, histopathology, subsite, and study design. All of the associations were evaluated with dominant model and recessive model, respectively. Heterogeneity and publication bias were also assessed by Q test, I(2), and funnel plot accordingly.

RESULTS

Nine articles including 11 case-control data sets were included, with 10,746 GC cases and 9,158 controls for rs2294008 and 6,060 cases and 4,824 controls for rs2976392. The results showed that risk allele carriers were significantly associated with GC risk compared with nonrisk allele homozygotes. In stratification analyses, these associations remained significant for majority of subgroups except for Caucasians and noncardia tumor in dominant model, and cardia tumor in both dominant and recessive model. Random model was used when heterogeneity among studies was detected. No publication bias was observed.

CONCLUSIONS

The two loci of PSCA (rs2294008 and rs2976392) were both significantly associated with GC susceptibility and in linkage disequilibrium.

IMPACT

More prospective studies on PSCA polymorphisms at multicenters with sufficient sample size and less heterogeneity will be needed for further validations.