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 and69 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 metaanalyses 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.

Correlation between serum ANXA7, miR-211 levels and RAGE gene polymorphisms and postoperative recurrence of ESD after smoking-induced gastric cancer

Objective:To investigate the correlation between serum ANXA7,miR-211 levels and RAGE gene polymorphisms and postoperative recurrence of ESD after smoking-induced gastric cancer.Methods:A total of 400 patients with gastric cancer who underwent ESD were randomly divided into recurrent group and non-recurred group according to whether they were relapsed.According to whether smoking was classified as smoking recurrence and smoking no recurrence group.Serum ANXA7,miR-211 levels and RAGE gene polymorphisms were compared between groups.Results:The smoking rate and serum ANXA7 and miR-211 levels in the relapse group were significantly higher than those in the non-recurrent group(P<0.05).Moreover,the polymorphisms of RAGE gene rs2070600 and rs184003 may be associated with the recurrence of gastric cancer(P<0.05).The levels of serum ANXA7 and miR-211 in the smoke relapse group were significantly higher than those in the non-recurrence group(P<0.05).Moreover,the polymorphisms of RAGE gene rs2070600 and rs184003 may be associated with recurrence of ESD after smoking-induced gastric cancer(P<0.05).The polymorphisms of serum ANXA7,miR-211 and RAGE genes may be associated with recurrence of ESD after smoking-induced gastric cancer(P<0.05).Conclusion:Smoking may be one of the factors that induce recurrence of gastric cancer after ESD,and smoking may cause elevation of serum ANXA7,miR-211 and mutation of RAGE gene,which may induce recurrence of gastric cancer after ESD.

Correlation of p53 over-expression and alteration in p53 gene detected by polymerase chain reaction-single strand conformation polymorphism in adenocarcinoma of gastric cancer patients from India

AIM:To study the alterations in p53 gene among Indian gastric cancer patients and to correlate them with the various clinicopathological parameters. METHODS:A total of 103 gastric cancer patients were included in this study.The p53 alterations were studied by both immunohistochemical method as well as polymerase chain reaction(PCR)-single strand conformation polymorphism(SSCP)analysis.We only studied four(exon 5,6,7,and 8)of the 11 p53 exons.The alterations in p53 were also correlated with respect to various clinicopathological parameters. RESULTS:Among 103 cases,p53 over-expression and alteration were detected in 37(35.92%)and 19(18.44%)cases,respectively.Most of the p53 alterations were found at exon 5(31.54%),followed by exon 6(26.31%),exon 7(21.04%)and exon 8(21.04%).A significant correlation of p53 over- expression was found with p53 alteration(P=0.000). Concordance between p53 alteration(as detected by SSCP)and over-expression[as detected by immunohistochemistry(IHC)]was found in 75%cases. We found that IHC-positive/SSCP-negative cases accounted for 21%of cases and IHC-negative/SSCP- positive cases accounted for remaining 4%cases. CONCLUSION:Our results show that p53 genemutations are significantly correlated with p53 protein overxpression,with 75%concordance in overexpression and alteration in the p53 gene,but 25% disconcordance also cautions against the assumption that p53 over-expression is always associated with a gene mutation.There may be other mechanisms responsible for stabilization and accumulation of p53 protein with no evidence of gene mutation that reflect an accumulation of a non-mutated protein,or a false negative SSCP result.

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

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

Association of NOD1 and NOD2 genes polymorphisms with Helicobacter pylori related gastric cancer in a Chinese population

AIM:To investigate the association between the tag single nucleotide polymorphisms(TagSNPs) of NOD1 and NOD2 and the risk of developing gastric cancer.METHODS:We conducted a hospital-based case-control study including 296 incident gastric cancer patients and 160 gastritis controls.Eight TagSNPs in the NOD1 and NOD2 genes were selected from the Hapmap database using the haploview software and genotyped by the Sequenom MassArray system.The serum levels of anti-Helicobacter pylori(H.pylori) IgG were measured by enzyme-linked immunosorbent assay to indicate H.pylori infection.The odds ratios(OR) and 95% confidence intervals(CI) were calculated by unconditional logistic regression,including sex and age as confounding factors.RESULTS:The NOD1 rs2907749 GG genotype showed a decreased risk for gastric cancer(OR 0.50,95% CI:0.26-0.95,P = 0.04) while the rs7789045 TT genotype showed an increased risk(OR 2.14,95% CI:1.20-3.82,P = 0.01).An elevated susceptibility to gastric cancer was observed in the subjects with H.pylori infection and the NaOD1 rs7789045 TT genotype(OR 2.05,95% CI:1.07-3.94,P = 0.03) or the NOD2 rs7205423 GC genotype(OR 2.52,95% CI:1.05-6.04,P = 0.04).Haplotype analysis suggested that the distribution of AGT(rs2907749,rs2075820 and rs7789045) in NOD1 between the cases and control groups was significantly different(P corrected:0.04),and the diplotype AGT/AGT was associated with an elevated gastric cancer risk(OR 1.98,95% CI:1.04-3.79,P = 0.04).The association of the NOD1 rs7789045 TT genotype and the diplotype AGT/AGT was significant with H.pylori-related diffuse-type gastric cancer(OR 3.00,95% CI:1.38-6.53,P = 0.01;OR 4.02,95% CI:1.61-10.05,P < 0.01,respectively).CONCLUSION:Genetic polymorphisms in NOD1 and NOD2 may interact with H.pylori infection and may play important roles in promoting the development of gastric cancer in the Chinese population.

A p53 genetic polymorphism of gastric cancer: Difference between early gastric cancer and advanced gastric cancer

AIM: To investigate the role of the polymorphism of p53 codon 72 in early gastric cancer (EGC) and advanced gastric cancer (AGC) in Korean patients. METHODS: DNA was extracted from blood samples of gastric cancer patients (n = 291) and controls (n = 216). In the p53 codon 72 genotypes were determined by PCR-RFLP.RESULTS: Patients with gastric cancer had a significantly higher frequency of the homozygous proline (Pro) allele than the control (P = 0.032). Patients with AGC had a significantly higher frequency of the Arg/Arg (arginine) allele (P = 0.038) than EGC and a similar Pro/Pro allele. The signet ring cell type had a higher frequency of the Pro/Pro allele than other types (P = 0.031). The Pro/Pro genotype carries a 3.9-fold increased risk of developing gastric cancer (95% CI, 1.3-15.4, P = 0.039) when compared to Arg/Arg and Arg/Pro genotypes and to develop EGC is a 5.25 fold increased risk (95% CI, 1.8-19.6, P = 0.021). CONCLUSION: The Pro/Pro genotype of the p53 codon 72 polymorphism carries a higher risk for gastric cancer in general and is also associated with a much higher risk for EGC than AGC.

XRCC1 genetic polymorphism Arg399Gln and gastric cancer risk:A meta-analysis

AIM:TO evaluate the association between X-ray cross- complementing gene 1 (XRCC1) genetic polymorphism Arg399GIn and gastric cancer risk by means of meta- analysis. METHODS:We searched PubMed and NCBI up to June 1,2008.A total of 16 clinical trials and reports were identified,but only 8 trials qualified under our selection criteria.Statistical analysis was performed with the software program Review Manage,version 4.2.8. RESULTS:Of the 8 case-control studies selected for this meta-analysis,a total of 1334 gastric cancer cases and 2194 controls were included.For Arg399Gln,the Gln/Gln genotype carriers did not have a decreased cancer risk compared with those individuals with the Arg/Arg genotype (OR=0.92,95% CI,0.71-1.19; P=0.51).Similarly,no associations were found in the recessive and dominant modeling (Gln/Gln vs Arg/Gln +Arg/Arg:OR=0.96;95% CI,0.77-1.19;P=0.70 and Gln/Gln+Arg/Gln vs Arg/Arg:OR=0.90,95% CI,0.77-1.05;P=0.18). CONCLUSION:No association is found between the XRCC1 polymorphism Arg399Gln and gastric cancer risk.

Association between gastric cancer and -1993 polymorphism of TBX21 gene

AIM: To investigate the association between the polymorphism of TBX21 gene and the risk of gastric cancer in a Chinese population. METHODS: The -1993 polymorphism located in TBX21 gene promoter region was identified by polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) method. The risk between TBX21 gene genotype and gastric cancer was determined by multivariate logistic regression analysis in 220 gastric cancer patients and 262 cancer-free controls matched by age, sex and ethnicity. RESULTS: Compared with the TBX21 -1993TT genotype, the -1993CC genotype exhibited a significantly elevated risk for gastric cancer [Odds ratio (OR) = 3.42, 95% confidence interval (CI): 1.41-8.31]. The relation-ship between the -1993 polymorphic genotype and the invasive status such as lymph node and distant metastasis was found among the gastric cancer patients (OR = 4.02, 95% CI: 1.87-8.66; OR = 7.02, 95% CI: 3.44-14.34, respectively). CONCLUSION: TBX21 -1993 polymorphism might contribute to the risk of gastric cancer, especially to the distant metastasis.

Polymorphisms of micro RNA target genes IL12B, INSR, CCND1 and IL10 in gastric cancer

AIM To evaluate associations between mi RNA target genes IL12B,INSR,CCND1 and IL10 polymorphisms and gastric cancer(GC)in European population.METHODS Gene polymorphisms were analyzed in 508 controls and474 GC patients from 3 tertiary centers in Germany,Lithuania and Latvia.Controls were patients from the out-patient departments,who were referred for upper endoscopy because of dyspeptic symptoms and had no history of previous malignancy.Gastric cancer(GC)patients had histopathological verification of gastric adenocarcinoma.Genomic DNA was extracted using salting out method from peripheral blood mononuclear cells.IL12B T>G(rs1368439),INSR T>C(rs1051690),CCND1 A>C(rs7177)and IL10 T>C(rs3024498)SNPs were genotyped by the real-time polymerase chain reaction.Associations between gene polymorphism and GC were evaluated using multiple logistic regression analysis with adjustment for sex,age and country of birth.RESULTS We observed similar distribution of genotypes and allelic frequencies of all polymorphisms between GC patients and controls except of INSR rs1051690.The frequency of the T allele of INSR gene was significantly higher in GC patients than in controls(23.26%and 19.19%respectively,P=0.028).CT genotype was also more prevalent in patients compared to control group(38.48%and 30.12%respectively,P<0.021).Logistic regression analysis revealed that only one polymorphism(rs1051690 in INSR gene)was associated with increased risk of GC.Carriers of CT genotype had higher odds of GC when compared to CC genotype(OR=1.45,95%PI:1.08-1.95,P=0.01).Similar association was observed in a dominant model for INSR gene,where comparison of TT+CT vs CC genotypes showed an increased risk of GC(OR=1.44,95%PI:1.08-1.90,P=0.01).Other analyzed SNPs were not associated with the presence of GC.CONCLUSION INSR rs1051690 SNP is associated with increased risk of GC,while polymorphisms in IL12B,CCND1 and IL10genes are not linked with the presence of GC.

Mn-SOD and CuZn-SOD polymorphisms and interactions with risk factors in gastric cancer

AIM: To investigate the effects of superoxide dismutase (SOD) polymorphisms (rs4998557 , rs4880), Helicobacter pylori (H. pylori ) infection and environmental factors in gastric cancer (GC) and malignant potential of gastric precancerous lesions (GPL). METHODS: Copper-zinc superoxide dismutase (SOD1, CuZn-SOD)-G7958A (rs4998557 ) and manganese superoxide dismutase (SOD2, Mn-SOD)-Val16Ala (rs4880 ) polymorphisms were genotyped by SNaPshot multiplex polymerase chain reaction (PCR) in 145 patients with GPL (87 cases of gastric ulcer, 33 cases of gastric polyps and 25 cases of atrophic gastritis), 140 patients with GC and 147 healthy controls. H. pylori infection was detected by immunoblotting analysis. RESULTS: The SOD1-7958A allele was associated with a higher risk of gastric cancer [odds ratio (OR) = 3.01, 95% confidence intervals (95% CI): 1.83-4.95]. SOD216Ala/Val genotype was a risk factor for malignant potential of GPL (OR = 2.04, 95% CI: 1.19-3.49). SOD216Ala/genotype increased the risk of gastric cancer (OR = 2.85, 95% CI: 1.66-4.89). SOD1-7958A/genotype, SOD2-16Ala/genotype, alcohol drinking, positive family history and type Ⅰ H. pylori infection were associated with risk of gastric cancer, and there were additive interactions between the two genotypes and the other three risk factors. SOD2-16Ala/Val genotype and positive family history were associated with malignant potential of GPL and jointly contributed to a higher risk for malignant potential of GPL (OR = 7.71, 95% CI: 2.10-28.22). SOD1-7958A/genotype and SOD2-16Ala/genotype jointly contributed to a higher risk for gastric cancer (OR = 6.43, 95% CI: 3.20-12.91). CONCLUSION: SOD1-7958A/and SOD2-16Ala/-genotypes increase the risk of gastric cancer in Chinese Han population. SOD2-16Ala/-genotype is associated with malignant potential of GPL.

Xeroderma pigmentosum group D 751 polymorphism as a predictive factor in resected gastric cancer treated with chemo-radiotherapy

AIM: To evaluate the potential association of xeroderma pigmentosum group D (XPD) codon 751 variant with outcome after chemo-radiotherapy in patients with resected gastric cancer. METHODS: We used PCR-RFLP to evaluate the genetic XPD Lys751Gln polymorphisms in 44 patients with stage Ⅲ (48%) and Ⅳ (20%) gastric cancer treated with surgery following radiation therapy plus 5-fluorouracil/ leucovorin based chemotherapy. RESULTS: Statistical analysis showed that 75% (12 of 16) of relapse patients showed Lys/Lys genotype more frequently (P = 0.042). The Lys polymorphism was an independent predictor of high-risk relapse-free survival from Cox analysis (HR: 3.07, 95% CI: 1.07-8.78, P = 0.036) and Kaplan-Meir test (P = 0.027, log-rank test). CONCLUSION: XPD Lys751Gln polymorphism may be an important marker in the prediction of clinical outcome to chemo-radiotherapy in resected gastric cancer patients.

Stable transfection of extrinsic Smac gene enhances apoptosis-inducing effects of chemotherapeutic drugs on gastric cancer cells

AIM: TO explore the feasibility of enhancing apoptosis-inducing effects of chemotherapeutic drugs on human gastric cancer cells by stable transfection of extrinsic Smac gene. METHODS: After Smac gene was transferred into gastric cancer cell line MKN-45, subclone cells were obtained by persistent G418 selection. Cellular Smac gene expression was determined by RT-PCR and Western blotting. After treatment with mitomycin (MMC) as an apoptotic inducer, in vitro cell growth activities were investigated by trypan blue-staining method and MI-I colorimetry. Cell apoptosis and its rates were determined by electronic microscopy, annexin V-FITC and propidium iodide staining flow cytometry. Cellular caspase-3 protein expression and its activities were assayed by Western blotting and colorimetry. RESULTS: When compared with MKN-45 cells, the selected subclone cell line MKN-45/Smac had significantly higher Smac mRNA (3.12±0.21 vs0.82:1:0.14, t=7.52, P<0.01) and protein levels (4.02±0.24 vs0.98:1:0.11, t=8.32, P<0.01). After treatment with 10μg/mL MMC for 6-24 h, growth inhibition rate of MKN-45/Smac (15.8±1.2-54.8±2.9%) was significantly higher than that of MKN-45 (5.8±0.4-24.0±1.5%, t = 6.42, P<0.01). Partial MKN-45/Smac cancer cells presented characteristic morphological changes of apoptosis under the electronic microscope with an apoptosis rate of 36.4=1=2.1%, which was significantly higher than that of MKN-45 (15.2±0.8%, t = 9.25, P<0,01). Compared with MKN-45, caspase-3 expression levels in MKN-45/Smac were improved significantly (3.39±0.42 vs 0.96:1:0.14, t=8.63,P<0.01), while its activities were 3.25 times as many as those of MKN-45 (0.364±0.010 vs 0.112:1:0.007, t= 6.34, P<0.01). CONCLUSION: Stable transfection of extrinsic Smac gene and its over-expression in gasbic cancer cell line can significantly enhance cellular caspase-3 expression and activities, ameliorate apoptosis-inducing effects of mitomycin C on cancer cells, which is a novel strategy to improve chemotherapeutic effects on gastric cancer.

ERCC1 polymorphism, expression and clinical outcome of oxaliplatin-based adjuvant chemotherapy in gastric cancer

AIM: To determine the influence of excision repair cross complementing group 1 (ERCC1 ) codon 118 polymorphism and mRNA level on the clinical outcome of gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy. METHODS: Eighty-nine gastric cancer patients treated with oxalipatin-based adjuvant chemotherapy were included in this study. ERCC1 codon 118 C/T polymorphism was tested by polymerase chain reaction-ligation detection reaction (PCR-LDR) method in peripheral blood lymphocytes of those patients; and the intratumoral ERCC1 mRNA expression was measured using reverse transcription PCR in 62 patients whose tumor tissue specimens were available. RESULTS: No significant relationship was found between ERCC1 codon 118 polymorphism and ERCC1 mRNA level. The median relapse-free and overall survival period was 20.1 mo and 28.4 mo, respectively. The relapse-free and overall survivals in patients with low levels of ERCC1 mRNA were significantly longer than those in patients with high levels (P < 0.05), while there was no significant association found between ERCC1 118 genotypes and the disease prognosis. Multivariate analysis also showed that ERCC1 mRNA level was a potential predictor for relapse and survival in gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy (P < 0.05). CONCLUSION: ERCC1 codon 118 polymorphism has no signifi cant impact on ERCC1 mRNA expression, and the intratumoral ERCC1 mRNA level but not codon 118 polymorphism may be a useful predictive parameter for the relapse and survival of gastric cancer patients receiving oxaliplatin-based adjuvant chemotherapy.

Characterization and strong risk association of TLR2 del-196 to-174 polymorphism and Helicobacter pylori and their influence on mRNA expression in gastric cancer

BACKGROUND Toll-like receptor-2(TLR2) is responsible for recognizing Helicobacter pylori(H.pylori) and activating the immune response. Polymorphisms in TLR2 may modulate gastric carcinogenesis.AIM To evaluate whether the TLR2 19216 T/C(rs3804099) and TLR2-196 to-174 ins/del(rs111200466) polymorphisms contribute to gastric carcinogenesis in the Brazilian population, and to determine the influence of both polymorphisms and H. pylori infection on TLR2 mRNA expression.METHODS DNA was extracted from 854 peripheral blood leukocyte or gastric tissue samples[202 gastric cancer(GC), 269 chronic gastritis(CG), and 383 control/healthy(C)]and genotyped by allele-specific PCR or restriction fragment length polymorphism(RFLP)-PCR. Quantitative polymerase chain reaction by Taq Man■ assay was used to quantify TLR2 mRNA levels in fresh gastric tissues(48 GC, 36 CG, and 14 C).RESULTS Regarding the TLR2-196 to -174 polymorphism, the ins/del and del/del genotypes were associated with a higher risk of GC by comparison with the C in all of the analyzed inheritance models(codominant, dominant, recessive, overdominant and log-additive;P < 0.0001). Similarly, an increased risk was observed when comparing the GC and CG groups [codominant(P < 0.0001), dominant(P <0.0001), recessive(P = 0.0260), overdominant(P < 0.0001) and log-additive(P <0.0001)]. In contrast, TLR2 19216 T/C was associated with a protective effect in the GC group compared to the C group [dominant(P = 0.0420) and log-additive(P =0.0300)]. Regarding the association of polymorphisms with H. pylori infection,individuals infected with H. pylori and harboring the TLR2-196 to-174 ins/del polymorphism had an increased risk of gastric carcinogenesis [codominant(P =0.0120), dominant(P = 0.0051), overdominant(P = 0.0240) and log-additive(P =0.0030)], while TLR2 19216 T/C was associated with a protective effect[codominant(P = 0.0039), dominant(P < 0.0001), overdominant(P = 0.0097) and log-additive(P = 0.0021)]. TLR2 mRNA levels were significantly increased in the GC group(median RQ = 6.95) compared to the CG group(RQ = 0.84, P < 0.0001)and to the normal mucosa group(RQ = 1.0). In addition, both H. pylori infection(P < 0.0001) and the presence of the polymorphic TLR2-196 to -174 del(P = 0.0010)and TLR2 19216 C(P = 0.0004) alleles influenced TLR2 mRNA expression.CONCLUSION The TLR2-196 to-174 ins/del and TLR2 19216 T/C polymorphisms are strongly associated with GC. TLR2 mRNA expression levels are upregulated in neoplastic tissues and influenced by both the presence of H. pylori and variant genotypes.

Role of interleukin polymorphisms in gastric cancer: “Pros and cons”

Helicobacter pylori (H. pylori ) infection is the leading cause of gastric cancer worldwide. Infection with this bacterium causes a chronic active immune response that persists for the life of the host. The combination of bacterial factors, environmental insults, and the host immune response drives the initiation and progression of mucosal atrophy, metaplasia, and dysplasia toward GC. Among the host factors, IL-1 gene cluster polymorphisms (IL-1B encoding IL-1β and IL-1RN encoding IL-1ra, its naturally occurring receptor antagonist) play a decisive role in modulating the risk of developing hypochlorhydria, gastric atrophy and GC in the presence of H. pylori infection. In particular, one single nucleotide polymorphism in the IL-1B promoter (IL-1B-511C T), and the short allele of a 86-bp variable number of tandem repeats polymorphism in the IL-1RN second intron (IL-1RN*2) are associated with an increased risk for GC. However this hypothesis is still to be fully confirmed. This review focuses on the divergent results obtained by several epidemiological and functional in vitro and in vivo studies and show that IL-1 genotyping has still no role in the clinical management of patients with H. pylori infection.

Genetic polymorphism of the phospholipase C epsilon 1 gene and risk of gastric cancer

Background The pathogenesis of gastric cancer （GC） involves environmental and genetic factors.Recently,two genome-wide association studies found that phospholipase C epsilon 1 （PLCE1） polymorphisms might be related to GC risk,and several studies further validated this finding.However,these studies yielded inconsistent results.Methods A comprehensive database search was performed to identify eligible studies.Odds ratios with 95％ confidence intervals were calculated to assess the strength of the association between PLCE1 rs2274223,rs753724,and rs11187842 and risk of GC.Subgroup analyses,publication bias,and sensitivity analyses were also conducted.Results Eleven studies （12 cohorts） were included in the meta-analysis.Based on 13 676 cases and 23 569 controls,a significant association between PLCE1 rs2274223 and GC risk was detected under various genotypic models.In the subgroup analyses,the association was significant for cardia GC,but weak for non-cardia GC.The association under the heterozygote model was detected for PLCE1 rs753724 and rs11187842 based on three studies involving 2768 cases and 3890 controls.Conclusions Our findings demonstrate that the presence of the G allele at rs2274223 of the PLCE1 gene may contribute to susceptibility to GC,especially cardia GC.PLCE1 rs753724 and rs11187842 are associated with GC risk under the heterozygote model.Further well-designed large studies are warranted to validate these findings.

Role of polymorphisms in genes that encode cytokines and Helicobacter pylori virulence factors in gastric carcinogenesis

The Helicobacter pylori(H. pylori) infection is a determinant factor in gastric cancer(GC) development. However, the infection outcomes are variable and depend on both host and bacterial characteristics. Some host cytokines such as interleukin(IL)-1β, IL-1 Ra, IL-8, IL-10 and tumor necrosis factor-α play important roles in the host immune system response to the pathogen, in the development of gastric mucosal lesions and in cell malignant transformation. Therefore, these host factors are crucial in neoplastic processes. Certain polymorphisms in genes that encode these cytokines have been associated with an increased risk of GC. On the other hand, various virulence factors found in distinct H. pylori bacterial strains, including cytotoxinassociated antigen A, vacuolating cytotoxin, duodenal ulcer promoting gene A protein, outer inflammatory protein and blood group antigen binding adhesin, have been associated with the pathogenesis of different gastric diseases. The virulent factors mentioned above allow the successful infection by the bacterium and play crucial roles in gastric mucosa lesions, including malignant transformation. Moreover, the role of host polymorphisms and bacterial virulence factors in gastric carcinogenesis seems to vary among different countries and populations. The identification of host and bacterium factors that are associated with an increased risk of GC development may be useful in determining the prognosis of infection in patients, what could help in clinical decision-making and in providing of an optimized clinical approach.

Toll-like receptor 9 polymorphisms and Helicobacter pylori influence gene expression and risk of gastric carcinogenesis in the Brazilian population

BACKGROUND Toll-like receptors(TLRs)are the first line of host defense,and are involved in Helicobacter pylori(H.pylori)recognition and activation of both inflammatory and carcinogenic processes.The presence of single nucleotide polymorphisms(SNPs)in genes that activate the immune response may modulate the risk of precancerous lesions and gastric cancer(GC).Among them,Toll-like receptor 9(TLR9)polymorphisms have emerged with a risk factor of infectious diseases and cancer,however the studies are still inconclusive.AIM To evaluate whether TLR9 rs5743836 and rs187084 SNPs contribute to the risk of gastric carcinogenesis,and its influence on mRNA expression.METHODS A case-control study was conducted to evaluate two TLR9 SNPs(TLR9-1237 TCrs5743836 and TLR9-1486 CT-rs187084)in chronic gastritis(CG)and GC patients.A total of 609 DNA samples of peripheral blood[248 CG,161 GC,and 200 samples from healthy individuals(C)]were genotyped by polymerase chain reaction-restriction fragment length polymorphism.All samples were tested for the H.pylori infection using Hpx1 and Hpx2 primers.Quantitative polymerase chain reaction by TaqMan?assay was used to quantify TLR9 mRNA from fresh gastric tissues(48 GC,26 CG,and 14 C).RESULTS For TLR9-1237,the TC+CC or CC genotypes were associated with a higher risk of GC than C[recessive model odds ratio(OR)=5.01,95%confidence interval(CI):2.52-9.94,P<0.0001],and the CG(recessive model OR=4.63;95%CI:2.44-8.79,P<0.0001)groups.For TLR9-1486,an association between the CT+TT genotypes and increased risk of both GC(dominant model OR=2.72,95%CI:1.57-4.72,P<0.0001)and CG(dominant model OR=1.79,95%CI:1.15-2.79,P=0.0094)was observed when compared to the C group.Moreover,the presence of TLR9-1237 TC/CC+TLR9-1486 CC genotypes potentiate the risk for this neoplasm(OR=18.57;95%CI:5.06-68.15,P<0.0001).The TLR9 mRNA level was significantly higher in the GC group(RQ=9.24,P<0.0001)in relation to the CG group(RQ=1.55,P=0.0010)and normal mucosa(RQ=1.0).When the samples were grouped according to the polymorphic genotypes and the presence of H.pylori infection,an influence of TLR9-1237 TC+CC polymorphic genotypes(P=0.0083)and H.pylori infection(P<0.0001)was observed on the upregulation of mRNA expression.CONCLUSION Our findings show that TLR9 rs5743836 and rs187084 polymorphisms are associated with a higher risk of carcinogenesis gastric,and that TLR9 mRNA levels can be modulated by TLR9-1237 TC+CC variant genotypes and H.pylori infection.

Association of hypoxia-inducible factor-1α (HIF1α) 1772C/T genepolymorphism with susceptibility to renal cell carcinoma/prostatecancer

In this study,we used a meta-analysis method to evaluate the relationship between hypoxia-inducible factor-1α(HIF1α)1772C/T gene polymorphism(rs 11549465)and renal cell carcinoma(RCC)/prostate cancer risk.We searched for relevant studies(before March 1,2019)on Cochrane Library,Embase,and PubMed.Studies meeting the inclusion criteria were recruited into this meta-analysis.The outcome of dichotomous data was showed in the way of odds ratios(OR),and 95%confidence intervals(CI)were also counted.In this investigation,there was no association between HIF1α1772C/T gene polymorphism and susceptibility to RCC in Caucasians,Asians as well as overall populations.In addition,HIF1α1772C/T gene polymorphism was not found to be relevant to the survival in RCC.Interestingly,the T allele was relevant to prostate cancer risk in all populations,but not in Caucasians and Asians.However,the TT genotype and the CC genotype were not related to prostate cancer susceptibility in Asian,Caucasian,and all populations.In conclusion,the T allele of the HIF1α1772C/T gene polymorphism was related to prostate cancer risk in the overall populations.

XbaⅠpolymorphisms of apolipoprotein B gene:Another risk factor of gallstone formation after radical gastrectomy

AIM:To prospectively investigate the association between the XbaⅠpolymorphisms of apolipoprotein B (APOB)gene and gallstone formation following gastrectomy.METHODS:The study was conducted between January 2005 and December 2006.A total of 186 gastric cancer patients who had undergone radical gastrectomy were grouped according to XbaⅠpolymorphisms of APOB gene(X+X-group,n=24 and X-X-group,n =162)and compared.The XbaⅠpolymorphisms of APOB gene were detected by polymerase chain reaction-restriction fragment length polymorphism(PCRRFLP).RESULTS:The incidence of gallstone was significantly higher in the X + X-group than in the X-X-group[54.2% vs 9.3%,RR=5.85(2.23-15.32),P<0.001].The serum levels of total cholesterol(TC)and low-density lipoprotein(LDL)were higher in the X + X-than in the X-X-group(4.02±1.12 vs 3.48±0.88,P=0.004 before surgery and 3.88±1.09 vs 3.40±0.86,P=0.008 after surgery).LDL was 2.21±0.96 vs 1.89±0.84(P =0.042)before surgery and 2.09±0.95 vs 1.72±0.85 (P=0.029)after surgery in the two groups.No relationship was found between XbaⅠpolymorphisms and gallbladder motility.CONCLUSION:In Chinese patients after radical gastrectomy,X + allele of APOB gene is another risk factor for the development of gallstone besides the gallbladder motility disorder after surgery.