Interleukin-8-251A/T polymorphism and Helicobacter pylori infection influence risk for the development of gastric cardiac adenocarcinoma in a high-incidence area of China

Induction and Regulation of the Innate Immune Response in Helicobacter pylori Infection

Gastric cancer (GC) is the fifth most common cancer and the fourth most common cause of cancer-related death worldwide. The intestinal type of GC progresses from acute to chronic gastritis, multifocal atrophic gastritis, intestinal metaplasia, dysplasia, and carcinoma. Infection of the stomach by Helicobacter pylori, a Gram-negative bacterium that infects approximately 50% of the world's population, is the causal determinant that initiates the gastric inflammation and then disease progression. In this context, the induction of the innate immune response of gastric epithelial cells and myeloid cells by H. pylori effectors plays a critical role in the outcome of the infection. However, only 1% to 3% of infected patients develop gastric adenocarcinoma, emphasizing that other mechanisms regulate the localized non-specific response, including the gastric microbiota and genetic factors. This review summarizes studies describing the factors that induce and regulate the mucosal innate immune response during H. pylori infection.

CDH1 gene rs1801552 C/T polymorphism increases susceptibility to esophageal squamous cell carcinoma but not to gastric cardiac adenocarcinoma

PURPOSE

The present study aimed to investigate whether the single nucleotide polymorphism (SNP) rs1801552 C/T in CDH1 gene is correlated with the risk of esophageal squamous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA), as a preliminary study.

METHODS

The rs1801552 C/T polymorphism was genotyped by the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 1316 cancer patients (810 ESCC and 506 GCA) and 1966 controls in north China. We performed two case-control studies, each of which included a population-based set and a hospital-based set.

RESULTS

The data showed that the rs1801552 C/T polymorphism was associated with the risk of ESCC. Allelotype and genotype distributions of the rs1801552 C/T polymorphism in ESCC patients of high-incidence region and hospital were significantly different from that in their respective controls (P < 0.05). Compared with C/C genotype, T/T genotype increased the risk of ESCC in high-incidence region and hospital (age, sex, smoking status and family history of UGIC adjusted odds ratio (OR) = 1.79 and 2.10, 95% confidence interval (CI) = 1.23 - 2.60 and 1.10 - 4.04, respectively). Allelotype and genotype distributions of the rs1801552 C/T polymorphism in GCA patients were not significantly different from that in their controls, respectively (P > 0.05).

CONCLUSIONS

The findings in the present pilot study suggest that the rs1801552 C/T polymorphism was associated with the risk of ESCC, but was not associated with the risk of GCA in high-incidence region and hospital.

ASSOCIATION OF IL-8 -251T>A (RS4073) POLYMORPHISM WITH SUSCEPTIBILITY TO GASTRIC CANCER: A SYSTEMATIC REVIEW AND META-ANALYSIS BASED ON 33 CASE-CONTROL STUDIES

BACKGROUND

The role of -251A>T polymorphism in the anti-inflammatory cytokine interleukin-8 (IL-8) gene in gastric cancer was intensively evaluated, but the results of these studies were inconsistent.

OBJECTIVE

Therefore, we performed a meta-analysis to provide a comprehensive data on the association of IL-8 -251T>A polymorphism with gastric cancer.

METHODS

All eligible studies were identified in PubMed, Web of Science, EMBASE, Wanfang and CNKI databases before September 01, 2019. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were derived from a fixed effect or random effect model.

RESULTS

A total of 33 case-control studies with 6,192 cases and 9,567 controls were selected. Overall, pooled data showed that IL-8 -251T>A polymorphism was significantly associated with an increased risk of gastric cancer under all five genetic models, i.e., allele (A vs T: OR=1.189, 95% CI 1.027-1.378, P=0.021), homozygote (AA vs TT: OR=1.307, 95% CI 1.111-1.536, P=0.001), heterozygote (AT vs TT: OR=1.188, 95% CI 1.061-1.330, P=0.003), dominant (AA+AT vs TT: OR=1.337, 95% CI 1.115-1.602, P=0.002) and recessive (AA vs AT+TT: OR=1.241, 95% CI 1.045-1.474, P=0.014). The stratified analysis by ethnicity revealed an increased risk of gastric cancer in Asians and mixed populations, but not in Caucasians. Moreover, stratified by country found a significant association in Chinese, Korean and Brazilian, but not among Japanese.

CONCLUSION

This meta-analysis suggests that the IL-8 -251T>A polymorphism is associated with an increased risk of gastric cancer, especially by ethnicity (Asian and mixed populations) and country (Chinese, Korean and Brazilian).

Polymorphisms of VDR gene and risk of gastric cardiac adenocarcinoma in Chinese population

Vitamin D receptor (VDR) gene polymorphisms have been reported to increase susceptibility to some malignant tumors, yet the effect on gastric cardiac adenocarcinoma susceptibility remains unknown. Here, we conducted a hospital-based case-control study to examine the correlation of single nucleotide polymorphisms of VDR rs2107301T>C, rs2228570C>T, rs1989969C>T and rs11568820 G>A and gastric cardiac adenocarcinoma susceptibility. A total 330 cases and 608 controls were enrolled in the study. Using ligation detection reaction, we found that the variant alleles of the four polymorphisms were not associated with risk of gastric cardiac adenocarcinoma. Further stratified analyses showed that there was an increased risk associated with VDR rs1989969 polymorphism among patients who were drinking or aged <60. The haplotypes VDR T_rs2107301T_rs2228570C_rs1989969G_rs11568820 reduced the susceptibility. This study demonstrated that VDR rs1989969 polymorphism was involved in the carcinogenesis of gastric cardiac adenocarcinoma, especially increased the risk in the younger and alcohol drinking Chinese population.

IL18 rs360719 A>G, IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G polymorphisms and risk of gastric cardiac adenocarcinoma

The present study was conducted to investigate the association between gastric cardiac adenocarcinoma (GCA) and four functional single-nucleotide polymorphisms (SNPs), including interleukin 18 (IL18) rs360719 A>G, IL18 receptor 1 (IL18R1) rs13015714 G>T, IL18 receptor accessory protein (IL18RAP) rs917997 C>T and interleukin 28B (IL28B) rs8099917 T>G variants. A hospital-based case-control study was performed to evaluate the genetic effects of these SNPs. A total of 243 GCA cases and 476 controls were enrolled in this study. A custom-by-design 48-Plex SNPscan™ kit was used to determine the genotypes. When the IL18 rs360719 AA homozygote genotype was used as the reference group, the AG genotype was not associated with the risk for GCA; the GG genotype was also not associated with the risk for GCA. In the dominant model, the IL18 rs360719 AG/GG variants were not associated with the risk for GCA, compared with the IL18 rs360719 AA genotype. In the recessive model, when the IL18R1 rs13015714 AA/AG genotypes were used as the reference group, the GG homozygote genotype was not associated with risk for GCA. No association was observed between IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G polymorphisms and the risk for GCA. These results demonstrated that the functional polymorphisms IL18 rs360719 A>G, IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G do not contribute to GCA susceptibility. However, as the statistical power of our study was limited, large well-designed studies and further functional investigations are required to confirm our findings.

Human and Helicobacter pylori Interactions Determine the Outcome of Gastric Diseases

The innate immune response is a critical hallmark of Helicobacter pylori infection. Epithelial and myeloid cells produce effectors, including the chemokine CXCL8, reactive oxygen species (ROS), and nitric oxide (NO), in response to bacterial components. Mechanistic and epidemiologic studies have emphasized that dysregulated and persistent release of these products leads to the development of chronic inflammation and to the molecular and cellular events related to carcinogenesis. Moreover, investigations in H. pylori-infected patients about polymorphisms of the genes encoding CXCL8 and inducible NO synthase, and epigenetic control of the ROS-producing enzyme spermine oxidase, have further proven that overproduction of these molecules impacts the severity of gastric diseases. Lastly, the critical effect of the crosstalk between the human host and the infecting bacterium in determining the severity of H. pylori-related diseases has been supported by phylogenetic analysis of the human population and their H. pylori isolates in geographic areas with varying clinical and pathologic outcomes of the infection.

Association of the IL-1RN variable number of tandem repeat polymorphism and Helicobacter pylori infection: A meta-analysis

The aim of this study was to clarify the association of IL-1RN variable number of tandem repeat (VNTR) polymorphism and H. pylori infection. We performed a meta-analysis of studies retrieved by systematic searches of Pubmed, Embase and the Cochrane Library. Data were analyzed with STATA 13.1 using pooled odds ratios (ORs) with 95% confidence intervals (CIs). A total of 18 studies were included in our meta-analysis, and IL-1RN VNTR was found to be significantly associated with H. pylori infection in the comparisons of 22+2L vs. LL (OR = 1.17, 95% CI = 1.02-1.33) and 2 allele vs. L allele (OR = 1.18, 95% CI = 1.00-1.40). Stratified analyses on study designs and ethnicities were also conducted. IL-1RN VNTR was positively correlated with H. pylori infection in Asian subgroup and Hospital-Based subgroup (i.e., study samples obtained from hospital inpatients). In conclusion, our study demonstrated that IL-1RN VNTR polymorphism might increase the risk of H. pylori infection, especially in Asians.

Tagging polymorphisms of methyl-CpG binding domain 4 and gastric cardiac adenocarcinoma risk in a Chinese population

Potential effects of genetic factors on carcinogenesis of gastric cardiac adenocarcinoma (GCA) may exist. The present experiment specifically evaluated the genetic influence of single nucleotide in methyl-CpG binding domain 4 (MBD4) on GCA tumorigenesis. A case-control experiment based on hospital recruited 330 GCA patients and 608 non-cancer patients was carried out. We employed ligation detection reaction method to detect the genotypes. The results revealed that MBD4 rs3138373, rs2005618, and rs3138355 mutations had no significant association with the risk of GCA. However, a lower risk of GCA presented in male patients who carried the MBD4 rs3138355 G>A polymorphic loci by the stratified analyses. In general, The MBD4 gene polymorphism could not influence GCA hereditary predisposition. Nevertheless, whether the finding learned from our experiment could apply to other ethnic groups will remain vague until future multicenter studies further test and verify our conclusions.

Variant TP53BP1 rs560191 G>C is associated with risk of gastric cardia adenocarcinoma in a Chinese Han population

OBJECTIVE

To investigate the association between gastric cardia adenocarcinoma (GCA) and ten functional single nucleotide polymorphisms (SNPs), including TP53BP1 rs560191 G>C, CASP8 rs1035142 G>T, CASP7 rs3127075 G>C, CASP7 rs7907519 C>A, and six C1orf10/CRNN variants. We performed a hospital-based case-control study to evaluate the genetic effects of these SNPs.

METHODS

Two hundred and forty-three GCA cases and 476 controls were enrolled in this study. A custom-by-design 48-Plex SNPscan(TM) Kit was used to determine their genotypes.

RESULTS

When the TP53BP1 rs560191 GG homozygote genotype was used as the reference group, the GC genotype was associated with a significantly increased risk of GCA. The CC genotype was not associated with the risk of GCA compared with the GG genotype. None of the CASP8 rs1035142 G>T, CASP7 rs3127075 G>C, CASP7 rs7907519 C>A or the six C1orf10/CRNN polymorphisms showed a significant difference in genotype distributions between the cases and the controls.

CONCLUSIONS

The results demonstrated that the functional polymorphism TP53BP1 rs560191 G>C might contribute to GCA susceptibility. However, the statistical power of our study was limited. Large, well-designed studies and further functional investigations are needed to confirm our findings.

Effect of eradication of Helicobacter pylori on expression levels of FHIT, IL-8 and P73 in gastric mucosa of first-degree relatives of gastric cancer patients

Objectives

Helicobacter pylori (H. pylori) infection plays an important role in the carcinogenesis and development of gastric cancer. Eradication of H. pylori can effectively reduce the risk of gastric cancer, but the underlying mechanisms are not fully understood. This study aimed to investigate the effect of eradication of H. pylori on the expression levels of FHIT, IL-8 and P73 in the gastric mucosa of first-degree relatives of gastric cancer patients.

Methods

One hundred and thirty-two patients with functional dyspepsia having first-degree relatives with gastric cancer were prospectively recruited in this study. Nine patients presented with H. pylori infection and family histories of gastric cancer, 61 with H. pylori infection and without family histories of gastric cancer, 6 without H. pylori infection and with family histories of gastric cancer, and 56 without H. pylori infection and family histories of gastric cancer. The protein and mRNA expression levels of FHIT, IL-8 and P73 in gastric mucosa of the subjects were detected by immunohistochemical staining and polymerase chain reaction, respectively.

Results

Compared with the patients without H. pylori infection and family histories of gastric cancer, both the protein and mRNA levels of FIHT significantly decreased in patients with H. pylori infection and/or family histories of gastric cancer, and both the protein and mRNA levels of IL-8 significantly increased. After eradication of H. pylori, both the protein and mRNA levels of FHIT were significantly higher, and both the protein and mRNA levels of IL-8 were significantly lower. However, H. pylori infection and family histories of gastric cancer had no major effect on P73 expression.

Conclusions

Down-regulation of FHIT and up-regulation of IL-8 may be involved in the pathogenesis of H. pylori infection in the first-degree relatives of gastric cancer patients.

Polymorphisms of the IL-6, IL-8 and IL-10 genes and the risk of gastric pathology in patients infected with Helicobacter pylori

BACKGROUND/PURPOSE

Helicobacter pylori-induced gastric mucosal inflammation is mediated by proinflammatory and anti-inflammatory cytokines. Polymorphisms in genes that code cytokines influence cytokine secretion levels and appear to contribute to the risk of gastric diseases. In this sense, we performed this study to identify the polymorphisms in the IL-6, IL-8, and IL-10 genes and their associations with H. pylori infection and gastric pathologies.

METHODS

Gastric biopsy samples of 151 patients infected with H. pylori and 76 uninfected individuals were used. Helicobacter pylori infection was diagnosed by histological examination and the detection of the ureA and glmM genes. The polymorphisms in the IL-6 (at position -174), IL-8 (at position -251), and IL-10 (at position -819) were detected by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Among the genetic polymorphisms studied, we observed that only the presence of the A allele at position -251 of the IL-8 gene was significantly associated with H. pylori infection. In addition, patient carriers of the A/A genotype at position -251 of the IL-8 gene and carriers of the T allele at position -819 of the IL-10 gene had an increased risk of peptic ulcer disease in the presence of H. pylori infection. We did not find a correlation between polymorphisms in the IL-6, IL-8, and IL-10 genes and a higher risk of gastric carcinoma.

CONCLUSION

We demonstrated that polymorphisms in the IL-8 gene was significantly associated with H. pylori infection. Furthermore, polymorphisms in the IL-8 and IL-10 genes were associated with an enhanced risk of peptic ulcer disease in H. pylori-positive patients.

p21, p53, TP53BP1 and p73 polymorphisms and the risk of gastric cardia adenocarcinoma in a Chinese population

Gastric cardia adenocarcinoma (GCA) is one of the most common malignant tumors and among the leading causes of cancer-related death. Genetic factors might play an important role in GCA carcinogenesis. Here, we performed a hospital-based case-control study to evaluate the effect of functional p21, p53, TP53BP1 and p73 single nucleotide polymorphisms (SNPs) on the risk of GCA. The study included 330 GCA cases and 608 controls. Genotypes were determined using the ligation detection reaction (LDR) method. The p21 rs1059234 TT, p21 rs3176352 GC/CC, p21 rs762623 GA and TP53BP1 rs560191 CC genotypes were associated with the risk of GCA, and a genotype combination effect was observed. After Bonferroni correction, the association remained significant for TP53BP1 rs560191 G > C, whereas the remaining four SNPs showed no association between the polymorphisms and GCA risk in all comparison models. Further large replication studies are needed to confirm the present findings.

Interleukin 17A rs3819024 A>G polymorphism is associated with an increased risk of gastric cardia adenocarcinoma in a Chinese population

Gastric cardia adenocarcinoma (GCA) is one of the most common malignant tumors. In addition to environmental risk factors, genetic factors might play an important role in GCA carcinogenesis. To evaluate the association between polymorphisms in the interleukin 17A (IL17A) gene on the development of GCA, we conducted a hospital-based case-control study. A total of 243 GCA cases and 476 controls were recruited and their genotypes were determined using a custom-by-design 48-Plex SNPscan™ Kit. IL17A rs3819024 A > G polymorphism was found to be associated with the increased risk of GCA. When the IL17A rs3819024 AA homozygote genotype was used as the reference group, the AG genotype was associated with a significantly increased risk of GCA (AG versus AA: adjusted OR = 1.53, 95% CI = 1.05-2.23, p = 0.026). However, there was no significant association between five other SNPs and GCA. Stratified analyses indicated that a significantly increased risk of GCA associated with the IL17A rs3819024 A > G polymorphism was evident among male patients, patients who drank alcohol or those who never smoked. These findings indicated that functional polymorphism IL17A rs3819024 A > G might contribute to GCA susceptibility. Future larger studies with more rigorous study designs are required to confirm the current findings.

The polymorphism interleukin-8 -251A/T is associated with a significantly increased risk of cancers from a meta-analysis

Emerging evidences show that interleukin-8 (IL-8) has important regulatory functions in tumorigenesis. IL-8 -251A/T is a single nucleotide polymorphism in the promoter region of the IL-8 gene and affects IL-8 production. Analysis of previous studies on the association of -251A/T polymorphism with different cancer types remained to be illustrated. To further assess the effect of -251A/T polymorphism on cancer risks, we performed this meta-analysis, up to November 2013, of 12,917 cases with different cancer types and 17,689 controls from 47 published case-control designed studies. Statistical analyses were performed using STATA 11.0 software. Crude odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of associations. ORs with 95 % CIs for IL-8 -251A/T polymorphism and cancer were estimated using fixed- and random-effects models when appropriate. Significantly increased risks were found in overall under the models of A allele vs. T allele, AA vs. TT, and AA vs. AT/TT. Significantly elevated risks were observed in breast cancer under the models of A allele vs. T allele, AT vs. TT, AA/AT vs. TT, and AA vs. AT/TT, and in nasopharyngeal carcinoma under the models of AT vs. TT, AA/AT vs. TT, and AA vs. AT/TT. We found that significantly elevated risks were observed in the Asian population and hospital-based studies in all comparison models. Thus, this meta-analysis indicates that IL-8 -251A/T polymorphism is associated with a significantly increased risk of cancers and may provide evidence-based medical certificate to study the cancer susceptibility.

Interleukin 15 receptor alpha rs2228059 A > C polymorphism decreased risk of gastric cardiac adenocarcinoma in a Chinese population

Gastric cardiac adenocarcinoma (GCA) is one of the common malignant tumors in the world and has a high incidence in China. Both environmental risk factors and genetic factors might play an essential role in the GCA carcinogenesis. We performed a hospital-based case-control study to evaluate the genetic effects of interleukin 15 (IL15) and IL15 receptor alpha (IL15RA) functional single nucleotide polymorphisms (SNPs) on the pathogenesis of GCA. A total of 243 GCA cases and 476 controls were enrolled in this study. The genotypes were determined using a custom-by-design 48-Plex SNPscan(TM) Kit. When the IL15RA rs2228059 AA homozygote genotype was used as the reference group, the CC genotype was correlated with a significantly decreased risk for GCA (CC vs. AA: adjusted OR = 0.61, 95 % CI = 0.37-0.98, p = 0.042). Our results revealed that functional variant IL15RA rs2228059 A > C might attenuate individual's risk of GCA. However, there was no significant association between the other five IL15 SNPs and GCA susceptibility. This present study demonstrated that IL15RA rs2228059 A > C polymorphism might modify GCA susceptibility. The results were based on a limited sample size; future larger studies with more rigorous designs are warranted to validate our findings.

Positive association between Interleukin-8 -251A > T polymorphism and susceptibility to gastric carcinogenesis: a meta-analysis

Backgrounds

The associations between the polymorphisms of interleukin-8 (IL-8) gene and gastric carcinogenesis have been extensively investigated in recent years. However, the results remain conflicting rather than conclusive.

Methods

A meta-analysis of 18 eligible studies was performed to evaluate the association of IL-8 -251A > T polymorphism with risk of gastric carcinogenesis. A systematic literature search of MEDLINE, Embase, and Web of Science, CNKI databases was conducted. Statistical analysis was performed by using the Revman 5.1 software and the Stata 12.0 software.

Results

Of the 293 unique studies identified using our search criteria, 18 studies fulfilled our inclusion criteria and were included in the meta-analysis. These studies cumulatively reported 5,321 cases and 6,465 controls. The combined results based on all studies showed that the IL-8 -251A > T polymorphism was associated with the risk of gastric carciongenesis (A vs. T: OR: 1.14 [1.02, 1.26], P = 0.02), especially gastric cancer (A vs. T: OR: 1.15 [1.03, 1.29], P = 0.02), but not associated with the risk of precancerous lesion (A vs. T: OR: 1.09 [0.99, 1.20], P = 0.08). Analysis stratified by ethnicity may seem that IL-8 -251A > T polymorphism was susceptible to gastric cancer in Asian population, but not in Caucasian population.

Conclusions

Our meta-analysis results provide evidence that IL-8 -251A > T polymorphism is significantly associated with increased risk of gastric carcinogenesis in Asian population, particularly in gastric cancer. Further large and well-designed studies are required to confirm this conclusion.

Genotyping of IL-8-251 T > A yields prognostic information in patients with gastric carcinoma

This study was designed to investigate the association of the IL-8-251 T > A gene polymorphism with clinicopathological features and the prognostic role of the gene polymorphism in patients with gastric adenocarcinoma. The gene polymorphism was detected by the polymerase chain reaction-restriction fragment length polymorphism method, followed by univariate and multivariate analyses to elicit its prognostic role. The frequency of IL-8-251 A/A, A/T and T/T genotypes were 11.0% (23/210), 43.8% (92/210) and 45.2% (95/210), respectively. The IL-8-251 gene polymorphism was closely correlated with depth of invasion (p = 0.007), grade of differentiation (p = 0.002) and TNM stage (p = 0.009). A/A genotype carriers showed more frequency of serosa involvement, low grade of differentiation and advanced stage of gastric carcinoma. IL-8-251 T > A gene polymorphism have no significant correlation with other clinicopathological features. The 5-year overall survival of IL-8-251 A/A genotype and T allele carriers were 30.8% and 59.2%, respectively. There is a significant discrepancy among the different genotype carriers. Multivariate analysis with the Cox regression model revealed that the IL-8-251 A/A genotype is an independent prognostic indicator (HR = 2.285, 95% Confidence Interval = 1.06-4.93, p = 0.035). We conclude that the IL-8-251 A/A genotype may indicate a poor prognosis for gastric adenocarcinoma patients.

AA genotype of IL-8 -251A/T is associated with low PaO(2)/FiO(2) in critically ill patients and with increased IL-8 expression

BACKGROUND AND OBJECTIVE

Interleukin-8 (IL-8) is a central chemokine in acute respiratory distress syndrome (ARDS), and the IL-8 gene contains a functional single nucleotide polymorphism (SNP) -251A/T in its promoter region. We hypothesized that IL-8 -251A/T SNP is associated with PaO(2)/FiO(2) in critically ill patients.

METHODS

We conducted genetic-association studies in intensive care units at academic teaching centres using a derivation septic shock cohort (vasopressin and septic shock trial (VASST), n = 467) and a validation post-cardiopulmonary bypass surgery cohort (CPB, n = 739) of Caucasian patients. Patients in both cohorts were genotyped for IL-8 -251A/T. The primary outcome variable in both cohorts was the fraction of patients who had a PaO(2) /FiO(2) < 200. IL-8 mRNA expression was measured in genotyped lymphoblastoid cells in vitro.

RESULTS

The frequency of the patients with PaO(2)/FiO(2) <200 was significantly greater in patients who had the AA genotype of -251A/T than in patients who had the AT or TT genotypes in both VASST (AA = 60.8% vs AT and TT = 53.8% and 48.0%, P = 0.038) and the CPB cohort (AA = 37.0% vs AT and TT = 27.0% and 26.0%, P = 0.039). Patients having the AA genotype had a higher probability to remain on mechanical ventilation (P = 0.047) in the first 14 days. Lymphoblastoid cells having the AA genotype had significantly higher IL-8 mRNA expression than cells having the AT or TT genotype (P = 0.022).

CONCLUSIONS

Critically ill Caucasian patients who had the AA genotype of IL-8 -251A/T had an increased risk of PaO(2)/FiO(2) <200. The AA genotype was associated with greater IL-8 mRNA expression than the AT or TT genotypes.

Three common polymorphisms in the IL-4 gene and cancer risk: a meta-analysis involving 5,392 cases and 6,930 controls

Interleukin-4 (IL-4) is a typical pleiotropic T helper 2 (Th2) cytokine. This cytokine is a critical mediator of the Th1/Th2 balance and apoptosis potential and involved in the process of inflammation-mediated carcinogenesis in human organs. IL-4 gene polymorphisms influence IL-4 transcription and have been implicated in cancer risks. However, current published data show conflicts among of them. To assess the relationship between IL-4 polymorphisms and cancer risks, we performed a meta-analysis which includes 14 studies involving 3,562 cancer cases for IL-4 rs2243250 polymorphism, 6 studies involving 2,052 subjects for IL-4 rs2070874 polymorphism, and 5 studies involving 791 subjects for IL-4 intron-3 polymorphism. As for rs2243250 polymorphism, no significant association of cancer risk was found in the overall analysis. When stratified by cancer type, we observed that the IL-4 rs2243250 polymorphism was significantly associated with decreased oral cancer risk and increased renal cell cancer risk (for oral cancer, TT vs. CC: odds ratio (OR) = 0.40, 95 % confidence interval (95 % CI) 0.19-0.84, P heterogeneity = 0.662, P = 0.016; TT/CT vs. CC: OR = 0.45, 95 % CI 0.22-0.94, P heterogeneity = 0.407, P = 0.033; and for renal cell cancer, TT vs. CC: OR = 1.98, 95 % CI 1.06-3.69, P heterogeneity = 0.535, P = 0.031; TT vs.

CC/CT

OR = 1.43, 95 % CI 1.05-1.95, P heterogeneity = 0.959, P = 0.022). For rs2070874 and intron-3 polymorphisms, no significant association of cancer risk was found in the overall analysis. However, in the subgroup analysis by source of controls and ethnicities, a significant association between cancer risk and rs2070874 polymorphism was found in population-based studies (A allele vs. G allele: OR = 1.18, 95 % CI 1.03-1.35, P heterogeneity = 0.621, P = 0.0172; AA vs.

AG/GG

OR = 1.23, 95 % CI 1.03-1.47, P heterogeneity = 0.196, P = 0.024) and Caucasian populations (A allele vs. G allele: OR = 1.24, 95 % CI 1.03-1.48, P heterogeneity = 0.925, P = 0.022), but not in Asian populations. Taken together, our results indicated that IL-4 rs2243250 polymorphism was associated with decreased oral cancer risk in both the homozygote contrasts and the dominant genetic model, as well as increased renal cell cancer risk in both the homozygote contrasts and the recessive genetic model. The A allele of rs2070874 polymorphism in the IL-4 gene may be a risk factor for cancer development among Caucasians. Further larger, preferably prospective studies are needed to confirm these results.

A meta-analysis of interleukin-8 -251 promoter polymorphism associated with gastric cancer risk

Background

Potential functional allele A/T single nucleotide polymorphism (SNP) of Interleukin 8 (IL-8) promoter -251has been implicated in gastric cancer risk.

Methods

We aimed to explore the role of A/T SNP of IL-8 -251 in the susceptibility to gastric cancer through a systematic review and meta-analysis. Each initially included article was scored for quality appraisal. Desirable data were extracted and registered into databases. Eighteen studies were ultimately eligible for the meta-analysis of IL-8 - 251 A/T SNP. We adopted the most probably appropriate genetic model (codominant model). Potential sources of heterogeneity were sought out via stratification and sensitivity analyses, and publication biases were estimated.

Results

Between IL-8 -251 AA genotype with gastric cancer risk, statistically significant association could be noted with overall gastric cancer, evidently noted in Asians, witnessed in high quality subgroup, and apparently noted in intestinal-type gastric cancer.

Conclusions

Our meta-analysis indicates that IL-8 -251 AA genotype is associated with the overall risk of developing gastric cancer and may seem to be more susceptible to overall gastric cancer in Asian populations. IL-8 -251 AA genotype is more associated with the intestinal-type gastric cancer. IL-8 -251 AA genotype is not associated with Helicobacter Pylori infection status in our meta-analysis.

Impact

The analyses suggest that IL-8 -251 AA genotype may be an important biomarker of gastric cancer susceptibility for Asians, especially for Chinese Han population, the assumption that needs to be further confirmed in future well-designed studies in China.

The role of CXC chemokines in the transition of chronic inflammation to esophageal and gastric cancer

Chronic inflammation may increase the risk to develop cancer, for instance esophagitis or gastritis may lead to development of esophageal or gastric cancer, respectively. The key molecules attracting leukocytes to local inflammatory sites are chemokines. We here provide a systematic review on the impact of CXC chemokines (binding the receptors CXCR1, CXCR2, CXCR3 and CXCR4) on the transition of chronic inflammation in the upper gastrointestinal tract to neoplasia. CXCR2 ligands, including GRO-α,β,γ/CXCL1,2,3, ENA-78/CXCL5 and IL-8/CXCL8 chemoattract pro-tumoral neutrophils. In addition, angiogenic CXCR2 ligands stimulate the formation of new blood vessels, facilitating tumor progression. The CXCR4 ligand SDF-1/CXCL12 also promotes tumor development by stimulating angiogenesis and by favoring metastasis of CXCR4-positive tumor cells to distant organs producing SDF-1/CXCL12. Furthermore, these angiogenic chemokines also directly enhance tumor cell survival and proliferation. In contrast, the CXCR3 ligands Mig/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11 are angiostatic and attract anti-tumoral T lymphocytes and may therefore mediate tumor growth retardation and regression. Thus, chemokines exert diverging, sometimes dual roles in tumor biology as described for esophageal and gastric cancer. Therefore extensive research is needed to completely unravel the complex chemokine code in specific cancers. Possibly, chemokine-targeted cancer therapy will have to be adapted to the individual's chemokine profile.

-251 T/A polymorphism of the interleukin-8 gene and cancer risk: a HuGE review and meta-analysis based on 42 case-control studies

The -251T/A (rs4073), a single nucleotide polymorphism, has been identified in the promoter region of the interleukin-8 (IL-8) gene. It's presence could influence the production of IL-8 protein by regulating the transcriptional activity of the gene. A large number of studies have been performed to evaluate the role of -251T/A polymorphism on various cancers, with inconsistent results being reported. In this paper, we summarized 13,189 cases and 16,828 controls from 42 case-control studies and attempted to assess the susceptibility of -251T/A polymorphism to cancers by a comprehensive meta-analysis. Pooled odds ratios and 95% confidence intervals were calculated by using the random-effects model. Publication bias, subgroup, and sensitivity analysis were also performed. Results showed that the carriers of the -251A allele had about a 12-21% increased risk for the reviewed cancer, in total. The carriers of -251A had an elevated risk to breast cancer, gastric cancer and nasopharyngeal cancer and a reduced risk to prostate cancer, but no evidence was found to indicate that the -251A allele predisposed its carriers to colorectal and lung cancers. When stratified separately by 'racial descent' and 'study design', it was found that the carriers of the -251A allele among the African group, Asian group and hospital-based case-control study group were at a higher risk for cancer, but not in European group and population-based case-control study. These results show that -251A allele is susceptible in the development of low-penetrance cancers.

IL-6 -174G>C polymorphism and cancer risk: a meta-analysis involving 29,377 cases and 37,739 controls

Interleukin-6 (IL-6) is a multifunctional cytokine involved in different physiologic and pathophysiologic processes and plays important roles in the etiology of cancer. The -174G>C polymorphism of the IL-6 gene influences IL-6 transcription and has been implicated in cancer risk. However, published data have been conflicting. To derive a more precise estimation of the relationship, a meta-analysis of 29,377 cancer cases and 37,739 controls from 50 published case-control studies was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between -174G>C polymorphism and cancer risk. Overall meta-analysis indicated that no association was found between -174G>C genotypes and cancer risk. However, the positive association was found in bladder cancer (OR=4.33, 95% CI: 1.93-9.71 for CC vs. GC, OR=2.81, 95% CI: 1.39-5.68 for CC vs. GG, and OR=2.19, 95% CI: 1.32-3.64 for CC vs. GG/GC), and among Asians (OR=2.08, 95% CI: 1.07-4.06 for CC vs. GG, and OR=2.20, 95% CI: 1.02-4.74 for CC vs. GG/GC) and Africans (OR=1.61, 95% CI: 1.07-2.42 for GC vs. GG). This meta-analysis showed the evidence that the -174G>C of the IL-6 gene was a low-penetrance susceptibility gene for bladder cancer. Further larger, preferably prospective studies are needed to confirm this relationship.