Associations between interleukin-6 gene -174 C/G and -572 C/G polymorphisms and the risk of gastric cancer: a meta-analysis

Investigation of the causal relationship between Interleukin-6 signaling and gastrointestinal tract cancers: A Mendelian randomization study

BACKGROUND

Observational studies indicate that interleukin-6(IL-6) has been associated with gastrointestinal tract cancers. However, the causal association is still confusing. Thus, we aimed to putative the causality between IL-6 signaling and gastrointestinal tract cancers.

METHODS

We conducted a two-sample Mendelian randomization analysis to assess the causal effects. Two groups of IL-6 signaling-related single nucleotide polymorphisms were chosen from two Genome-wide association studies. Summary-level data for gastrointestinal tract cancers including esophageal, gastric, and colorectal cancer, were obtained from the FinnGen consortium and UK Biobank study. We also performed survival analysis to explore the prognostic value of IL-6 in gastrointestinal tract cancers.

RESULTS

Genetically predicted plasma sIL6R level, which inhibits IL-6 Signaling, was associated with a reduced risk of gastric cancer in FinnGen. In the combined analysis of the two sources, genetically predicted sIL6R was associated with a decreased risk of gastric cancer (OR = 0.943, 95%CI: 0.904,0.983, p = 0.006). Survival analysis results indicated the prognostic value of IL-6 in gastric cancer.

CONCLUSIONS

These results present evidence indicating that genetically-determined reduced IL-6 signaling lowers the risk of gastric cancer, which may provide potential prevention and therapeutic strategies for gastric cancer. Additionally, IL-6 may be a prognostic biomarker for gastric cancer.

Impact of interaction between interleukin-6 gene polymorphism and Helicobacter pylori infection on susceptibility to gastric cancer

OBJECTIVE

This study aimed to evaluate the association between four single nucleotide polymorphisms (SNPs) of the interleukin-6 (IL-6) gene and gastric cancer (GC), and impact of interaction between IL-6 SNPs and Helicobacter pylori (H. pylori ) infection on susceptibility to GC.

METHODS

Logistic regression was used to test the relationships between four SNPs of IL-6 gene and GC susceptibility. A generalized multifactor dimensionality reduction (GMDR) model was employed to assess the interaction effect between IL-6 gene and H. pylori infection on GC risk.

RESULTS

Logistic regression analysis indicated that the rs1800795-C allele was associated with increased GC risk, adjusted ORs (95% CI) were 1.80 (1.21-2.41) (CC vs. GG) and 1.68 (1.09-2.30) (C vs. G), respectively. The rs10499563-C allele was associated with decreased risk of GC, and adjusted ORs (95% CI) were 0.62 (0.31-0.93) (TC vs. TT), 0.52 (0.18-0.89) (CC vs. TT) and 0.60 (0.29-0.92) (C vs. T), respectively. GMDR methods found a two-dimensional model combination (including rs1800795 and H. pylori infection) was statistically significant. The selected model had testing balanced accuracy of 59.85% and the best cross-validation consistencies of 10/10 ( P  = 0.0107). Compared with H. pylori -negative subjects with rs1800795- GG genotype, H. pylori -positive participants with GC or CC genotype had the highest risk of GC, the OR (95% CI) was 3.34 (1.78-4.97).

CONCLUSION

The rs1800795-C allele was associated with increased GC risk and the rs10499563-C allele was associated with decreased GC risk. The interaction between rs1800795 and H. pylori infection was also correlated with increased risk of GC.

The Effect of IL-6 174G > C Gene Polymorphism on Gastrointestinal Cancer: a Systematic Review and Meta-analysis

IL-6 gene polymorphisms can play a role in the development or control of cancer by affecting cytokines. Gastrointestinal cancer is one of the most common types of cancer worldwide. The aim of this study was to investigate the effect of polymorphism of the IL-6 174G > C gene on gastrointestinal cancers based on a systematic review and meta-analysis, including gastric, colorectal, and esophageal cancer. In this study, a systematic and meta-analytical review of the study data on the effect of polymorphism of IL-6 174G > C gene on gastrointestinal cancer (gastric, colorectal, and esophageal cancer) in Scopus, EMBASE, Web of Science, PubMed, and Science Direct Databases was extracted without any time limit until April 2020. In order to perform the analysis of eligible studies, the model of random effects was used and the heterogeneity of studies was investigated with I2 index. Data analysis was performed with Comprehensive Meta-Analysis software (Version 2). The total number of surveyed studies in patients with colorectal cancer was 22 studies. Based on the results of meta-analysis, the odds ratio of GG genotype in patients with colorectal cancer was 0.88. The odds ratio of GC genotype obtained in patients with colorectal cancer was 0.88 and the odds ratio of CC genotype in patients with colorectal cancer was 0.92. The total number of surveyed studies in patients with gastric cancer was 12. Based on the meta-analysis results, the odds ratio of GG genotype in patients with gastric cancer was 0.74, the odds ratio of GC genotype in patients with gastric cancer was 1.27, and the odds ratio of CC genotype in patients with gastric cancer was 0.78. The total number of surveyed studies in esophageal cancer patients was 3 studies. Based on the results of meta-analysis, the odds ratio of GG genotype in patients with esophageal cancer was 0.57, the odds ratio of GC genotype in patients with esophageal cancer was 0.44, and the odds ratio of chance of CC genotype in patients with esophageal cancer was 0.99. In general, different genotypes of polymorphism of the IL-6 174G > C gene reduce the risk of gastric, colorectal, and esophageal cancer. However, the GC genotype of this gene was associated with a 27% increased risk of gastric cancer.

Cytokine TGF-β1, TNF-α, IFN-γ and IL-6 Gene Polymorphisms and Localization of Premalignant Gastric Lesions in Immunohistochemically H. pylori-negative Patients

Background: Cytokines and their gene variants are proven to play a role in pathogenic gastritis and carcinogenesis. The study assesses associations of the cytokine gene polymorphisms with extension of atrophic gastritis/intestinal metaplasia (AGIM) in patients without Helicobacter pylori infection on immunohistochemistry study. Methods: 224 adult consecutive patients undergoing an upper digestive endoscopy were included and grouped according to localization of AGIM: 37 patients with antrum-limited AGIM, 21 corpus-limited AGIM, 15 extended-AGIM (antrum and corpus) and 151 patients had no AGIM. Medical records of the patients were checked and a structured direct interview was applied in order to collect clinical data, including digestive symptoms. In all cases, IFN-γ +874T>A, TGF-β1 +869T>C, TNF-α-308G>A and -238G>A, and IL-6 -174C>G polymorphisms were genotyped. Results: The mean age was significantly higher in the AGIM group, while the comorbidies were similar among patients with different localization of lesions or in patients without AGIM. There were no significant differences in digestive symptoms, nor in the consumption of non-steroidal anti-inflammatory drugs or proton pump inhibitor with the different extensions of AGIM. There was a significant association between oral anticoagulant consumption and localization of AGIM (P = 0.042), frequency being higher among patients with corpus-limited AGIM than those with no AGIM (P = 0.007, adjusted P = 0.041). TGF-β1 +869T>C was less frequent among patients with corpus-limited AGIM (n=7, 33.3%) and extended AGIM (n=5, 33.3%) than in antrum-limited AGIM (n=25, 67.6%). There were no other significant differences regarding variant and wild genotype frequencies of IFN-γ +874T>A (86.5%, 81.0%, 86.7%, p=0.814), TNF-α-308G>A (35.1%, 28.6%, 53.3%, p=0.48) and IL-6 -174C>G (70.3%. 61.9%, 73.3% p=0.656) among patients with antrum-limited, corpus-limited or extended AGIM. TGF-β1 +869T>C was associated with a decreased risk for corpus-affected AGIM (adjusted odds ratio: 0.42, 95% confidence interval: 0.19-0.93, P = 0.032). The dominant inheritance models no revealed significant association for IFN-γ +874T>A, TNF-α-308G>A and IL-6 -174C>G gene polymorphism and the risk of localization of AGIM. Conclusion: TGF-β1 +869T>C gene polymorphism is associated with a decreased risk for corporeal localization of premalignant lesions, while IFN-γ +874T>A, TNF-α-308G>A and IL-6 -174C>G are not associated with the risk for AGIM in immunohistochemically H. pylori negative patients.

Statistical meta-analysis to investigate the association between the Interleukin-6 (IL-6) gene polymorphisms and cancer risk

A good number of genome-wide association studies (GWAS), including meta-analyses, reported that single nucleotide polymorphisms (SNPs) of the IL-6 gene are significantly associated with various types of cancer risks, though some other studies reported insignificant association with cancers, in the literature. These contradictory results may be due to variations in sample sizes and/or deficiency of statistical modeling. Therefore, an attempt is made to provide a more comprehensive understanding of the association between the IL-6 gene SNPs (rs1800795, rs1800796, rs1800797) and different cancer risks, giving the weight on a large sample size, including different cancer types and appropriate statistical modeling with the meta-dataset. In order to attain a more reliable consensus decision about the association between the IL-6 gene polymorphisms and different cancer risks, in this study, we performed a multi-case statistical meta-analysis based on the collected information of 118 GWAS studies comprising of 50053 cases and 65204 control samples. Results from this Meta-analysis indicated a significant association (p-value < 0.05) of the IL-6 gene rs1800796 polymorphism with an overall increased cancer risk. The subgroup analysis data based on cancer types exhibited significant association (p-value < 0.05) of the rs1800795 polymorphism with an overall increased risk of cervical, liver and prostate cancers; the rs1800796 polymorphism with lung, prostate and stomach cancers; and the rs1800797 polymorphism with cervical cancer. The subgroup analysis of ethnicity data showed a significant association (p-value < 0.05) of an overall cancer risk with the rs1800795 polymorphism for the African and Asian populations, the rs1800796 polymorphism for the Asian only and the rs1800797 polymorphism in the African population. Comparative discussion showed that our multi-case meta-analyses received more support than any previously reported individual meta-analysis about the association between the IL-6 gene polymorphisms and cancer risks. Results from this study, more confidently showed that the IL-6 gene SNPs (rs1800795, rs1800796 and rs1800797) in humans are associated with increased cancer risks. Therefore, these three polymorphisms of the IL-6 gene have the potential to be evaluated as a population based rapid, low-cost PCR prognostic biomarkers for different types of cancers diagnosis and research.

Interaction of tobacco chewing and smoking habit with interleukin 6 promoter polymorphism in oral precancerous lesions and oral cancer

OBJECTIVE

Our study aims to determine the influence of smoking or tobacco chewing and the association of Interleukin 6 (IL-6) polymorphism, where G is substituted by A at the position - 596 (IL-6 - 596 G/A) and substitution of G by cytosine (C) at position - 572 (IL-6 - 572 G/C) on the susceptibility of precancerous oral lesions and oral cancer.

MATERIALS AND METHODS

The participants consisted of 250 subjects among which 75 were suffering from oral cancer, 75 subjects with precancerous oral lesions and 100 were healthy controls. Single-nucleotide polymorphism study (SNP) was done by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

RESULTS

IL-6 - 596 G/A SNP revealed genotypes, GG, and GA in subjects with precancerous oral lesions and oral cancer, and AA genotype was not found in any subject. IL-6 - 596 G/A was strongly associated with oral precancerous lesions but not with oral cancer. The present study reports that smokers carrying GA for IL-6 - 596 G/A were at several folds higher risk of developing oral precancerous lesions. Smokers with GC and CC for IL-6 - 572 G/C were at higher risk of developing oral precancerous lesions. No significant interaction was observed between these habits and IL-6 - 596 G/A and IL-6 - 572 G/C SNP with oral cancer.

CONCLUSION

The interaction of variant A allele of IL-6 - 596 G/A and C allele of IL-6 - 572 G/C polymorphism with smoking and increases the risk of oral precancerous lesions. Tobacco chewing was not related with IL-6 - 596 G/A or IL-6 - 572 G/C in oral precancerous lesions or oral cancer.

CLINICAL RELEVANCE

The study will help to determine the susceptibility of individuals with smoking or chewing habits to the development of oral precancerous lesion and oral cancer by monitoring the IL-6 SNPs which can be used as a biomarker for risk determination.

Polymorphisms of the Highly Expressed IL-6 Gene in the Papillary Thyroid Cancer Susceptibility Among Chinese

BACKGROUND

Papillary thyroid cancer (PTC) is the cardinal histologic type of thyroid cancer, which is the most prevalent kind of endocrine malignancy. The expression of IL-6 is found higher in thyroid carcinoma (THCA) samples than paired normal tissues based on The Cancer Genome Atlas (TCGA) and Genotype-Tissue expression (GTEx) database. In this study, we aimed to investigate the association between interleukin-6 (IL-6) polymorphisms and the PTC risk.

METHODS

A case-control study was designed using the following data: 241 PTC patients and 463 healthy controls. Five single nucleotide polymorphisms (SNPs) in IL-6 were selected and genotyped using Agena MassARRAY technology.

RESULTS

Our results revealed that SNP rs1800796 was associated with an increased PTC risk in co-dominant model (p = 0.042) and dominant model (p = 0.027). Rs1524107 was also a risk factor for PTC susceptibility in co-dominant model (p = 0.003), dominant model (p = 0.002) and log-additive model (p = 0.044). Moreover, rs2066992 significantly increased the PTC risk in co-dominant model and dominant model (p = 0.011, p = 0.009, respectively). Additionally, rs2069837 variant elevated the PTC risk based on dominant model (p = 0.041). In silico analysis, GTEx results for rs1800796, rs1524107 and rs2066992 variants are known to be associated with IL-6 gene expression. Using HaploReg, we found rs1800796, rs1524107 and rs2066992 in LD with functional importance.

CONCLUSION

Our study indicates that IL-6 variants may be a risk factor involved in the pathogenesis and development of PTC.

The Role of Host Genetic Polymorphisms in Helicobacter pylori Mediated Disease Outcome

The clinical outcome of infection with the chronic gastric pathogen Helicobacter pylori is not the same for all individuals and also differs in different ethnic groups. Infection occurs in early life (<3 years of age), and while all infected persons mount an immune response and develop gastritis, the majority of individuals are asymptomatic. However, up to 10-15% develop duodenal ulceration, up to 1% develop gastric cancer (GC) and up to 0.1% can develop gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The initial immune response fails to clear infection and H. pylori can persist for decades. H. pylori has been classified as a group one carcinogen by the WHO. Interestingly, development of duodenal ulceration protects against GC. Factors that determine the outcome of infection include the genotype of the infecting strains and the environment. Host genetic polymorphisms have also been identified as factors that play a role in mediating the clinical outcome of infection. Several studies present compelling evidence that polymorphisms in genes involved in the immune response such as pro and anti-inflammatory cytokines and pathogen recognition receptors (PRRs) play a role in modulating disease outcome. However, as the number of studies grows emerging confounding factors are small sample size and lack of appropriate controls, lack of consideration of environmental and bacterial factors and ethnicity of the population. This chapter is a review of current evidence that host genetic polymorphisms play a role in mediating persistent H. pylori infection and the consequences of the subsequent inflammatory response.

Genetic polymorphisms and gastric cancer risk: a comprehensive review synopsis from meta-analysis and genome-wide association studies

Objective

In the past few decades, more than 500 reports have been published on the relationship between single nucleotide polymorphisms (SNPs) on candidate genes and gastric cancer (GC) risk. Previous findings have been disputed and are controversial. Therefore, we performed this article to summarize and assess the credibility and strength of genetic polymorphisms on the risk of GC.

Methods

We used Web of Science, PubMed, and Medline to identify meta-analyses published before July 30th, 2018 that assessed associations between variants on candidate genes and the risk of GC. Cumulative epidemiological evidence of statistical associations was assessed combining Venice criteria and a false-positive report probability (FPRP) test.

Results

Sixty-one variants demonstrated a significant association with GC risk, whereas 29 demonstrated no association. Nine variants on nine genes were rated as presenting strong cumulative epidemiological evidence for a nominally significant association with GC risk, including APE1 (rs1760944), DNMT1 (rs16999593), ERCC5 (rs751402), GSTT1 (null/presence), MDM2 (rs2278744), PPARG (rs1801282), TLR4 (rs4986790), IL-17F (rs763780), and CASP8 (rs3834129). Eleven SNPs were rated as moderate, and 33 SNPs were rated as weak. We also used the FPRP test to identify 13 noteworthy SNPs in five genome-wide association studies.

Conclusions

Sixty-one variants are significantly associated with GC risk, and 29 variants are not associated with GC risk; however, five variants on five genes presented strong evidence for an association upgraded from moderate. Further study of these variants may be needed in the future. Our study also provides referenced information for the genetic predisposition to GC.

Analysis of Polymorphism and Expression Profile of ASIC1 and IL-6 Genes in Patients with Gastric Cancer

Gastric cancer is one of the most common upper gastrointestinal malignancies. Some Iranian provinces, such as in the northern and northwestern areas, are at a high risk, whereas the central and western provinces are at a medium and the southern regions at low risk. This study was carried out to estimate the impact of the expression patterns of ASIC1 and IL-6 genes and the IL-6rs-174 and ASIC1rs 75624685 polymorphisms in the pathogenesis of gastric cancer. Materials and methods: Tetra-ARMS PCR was employed to analyze the polymorphism status of the ASIC1 and IL-6 genes with 85 paraffin-embedded tissue blocks from cases and 117 normal blood samples as controls. We also investigated mRNA expression levels of these genes in 12 cases and controls using real-time PCR. Results: Our results showed a significant association between expression of ASIC1 and elevated risk of gastric cancer (p<0.001).

Interleukin-6 Genetic Variation and Susceptibility to Gastric Cancer in an Iranian Population

Background:

Despite recent decrease in the incidence of gastric cancer, it is still a common type of cancer in the north of Iran. Many evaluations have shown that polymorphisms of cytokine genes like that for interleukin 6 (IL-6), which play important roles in regulation of the immune response, can increase the risk of gastric cancer. This study examined the role of the IL-6-174 gene polymorphism in susceptibility in an Iranian population.

Method:

Genomic DNA was extracted from peripheral whole blood of 100 patients and 361 healthy controls. Genotyping was accomplished by the sequence-specific primer-polymerase chain reaction (SSP-PCR) method and statistical analyses were carried out using Fisher’s exact test. Frequencies of the IL-6-174 G/C genotypes were determined under co-dominant, dominant, and recessive genetic models.

Results:

An association between the polymorphism of IL-6 -174 G/C and susceptibility to gastric cancer was observed. The frequency of G allele was higher in patients (78%) than in controls (70.5 %) (OR=1.48, 95% CI=1.01-2.20, P=0.04).

Conclusions:

The high G allele and G/G genotype frequency in patients compared to control subjects suggests that the IL-6 -174 G/C polymorphism may influence the susceptibility to gastric cancer. In addition, the demographic information showed that most of the subjects were male (69.0%) that gastric cancer is related to environmental factors.

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 of genetic variations in IL-6/IL-6R pathway genes with gastric cancer risk in a Chinese population

Interleukin-6 (IL-6) and its receptor (IL-6R) were regarded to be responsible for the occurrence of gastric cancer for their regulation roles in the inflammation. The genetic variations in these two genes (IL-6: rs6949149, rs1800796, rs10499563 and IL-6R: rs2228145) have been suggested to be associated with gastric cancer risk. However, the published results were inconsistent among subjects of different ethnicity. To evaluate such an association in Chinese population, we carried out this case-control study based on 473 patients with gastric cancer and 474 healthy controls, whose genotypes were detected by the Sequenom MassARRAY platform, and Helicobacter pylori infection was assessed by immunogold testing kit. This study showed that rs1800796 CG genotype was associated with decreased risk of gastric cancer (adjusted OR=0.75, 95% CI: 0.57-0.99, p=0.043). The stratified analysis revealed that, in the Helicobacter pylori negative infection subgroup, rs2228145 AC (adjusted OR=0.64, 95% CI: 0.42-0.97) and AC/CC (adjusted OR=0.66, 95% CI: 0.45-0.99) genotypes were associated with decreased risk of gastric cancer, respectively. In contrast, in the Helicobacter pylori positive infection subgroup, rs10499563 TC (adjusted OR=0.64, 95% CI: 0.43-0.95), CC (adjusted OR=0.35, 95% CI: 0.14-0.90), TC/CC (adjusted OR=0.59, 95% CI: 0.40-0.87) genotype were associated with decreased gastric cancer risk, respectively. Moreover, in the male subgroup, rs1800796 CG (adjusted OR=0.61, 95% CI: 0.44-0.84) and CG/GG (adjusted OR=0.67, 95% CI: 0.49-0.91) genotype were associated with decreased risk of gastric cancer, respectively. In short, this study suggested that IL-6R rs2228145 and IL-6 rs10499563 genotype were associated with decreased risk of gastric cancer for the individuals with negative and positive Helicobacter pylori infection.

Association of interleukin-6 genetic polymorphisms with risk of OSCC in Indian population

Purpose

Interleukin-6 (IL-6) encodes a cytokine protein, which causes inflammation, maintains immune homeostasis and plays an essential role in oral pathogenesis. The aim of this study was to evaluate the association between IL-6 (− 174 and − 572) G/C promoter gene polymorphisms and risk of OSCC among Indians.

Methods

Single nucleotide polymorphism in IL-6 genes was genotyped in OSCC patients and healthy controls by PCR-RFLP method. Genotype and allele frequencies were analyzed by chi-square test and strength of associations by odds ratio with 95% confidence intervals.

Results

Frequency distribution of IL-6 (− 174) G/C gene polymorphism was significantly associated with OSCC patients in comparison to healthy controls (OR: 0.541, CI: 0.356–0.822; p: 0.004. However, frequency of IL-6 (− 572) G/C gene polymorphism was not significantly associated with OSCC patients (p > 0.05).

Conclusion

The genotype GC and allele C of IL-6 (− 174) G/C gene polymorphism play a significant role in OSCC susceptibility.

•

We first demonstrate the IL-6 polymorphism in OSCC patients in Indian population.

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We obtained the SNP of IL-6 (-174) is increase the risk of OSCC.

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We also obtained the SNP of IL-6 (-572) and risk of OSCC

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We evaluate the correlation of these IL-6 polymorphisms and progression of OSCC.

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We identified the environmental factors and gene interactions with pathogenesis of OSCC.

Association between the interleukin-6 gene polymorphisms and renal cancer risk

INTRODUCTION

Interleukin-6 (IL-6), a central proinflammatory cytokine, may be involved in the host response to cancer. We therefore aimed to evaluate the association of the IL-6 gene polymorphisms at positions -174 and -572 with predisposition to renal cancer.

MATERIALS AND METHODS

We conducted a hospital-based case-control study. A total of 432 subjects, including 216 pathologically-proven renal cancer cases and 216 age- and gender-matched healthy controls, were recruited in this study. Polymorphism for the IL-6 gene was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Patients with renal cancer had a significantly higher frequency of IL-6 -174 CC genotype [odds ratio (OR)=2.08, 95% confidence interval (CI)=1.05, 4.13; P=0.04] than healthy controls. When stratifying by the grade, patients with higher grade (grade 3 or 4) renal cancer had a significantly higher frequency of IL-6 -174 CC genotype (OR=2.33, 95% CI=1.04, 5.23; P=0.04).

CONCLUSION

This study is, to our knowledge, the first to examine prospectively an increased risk role of IL-6 -174 CC genotype in renal cancer susceptibility.

Lack of association between a functional polymorphism (rs1800796) in the interleukin-6 gene promoter and lung cancer

Background

A number of studies have examined the association between interleukin-6 (IL-6) rs1800796 polymorphism and risk of lung cancer but revealed inconsistent results. The aim of this study was to clarify the association between IL-6 rs1800796 polymorphism and risk of lung cancer.

Methods

Literature databases including PubMed, Embase and CNKI were searched up to January 2014. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) under co-dominant model, dominant model and recessive model were estimated using random-effects model.

Results

A total of seven studies, including 2691 lung cancer cases and 3067 controls, were included in the meta-analysis. The results suggested that IL-6 rs1800796 polymorphism was not associated with risk of lung cancer under homogeneous co-dominant model (OR = 1.06, 95%CI = 0.73-1.54), heterogeneous co-dominant model (OR = 1.24, 95%CI = 0.96-1.60), dominant model (OR = 1.23, 95%CI = 0.95-1.58) and recessive model (OR = 0.96, 95%CI = 0.70-1.32). The association was still not significant in either never-smokers (OR = 1.19, 95%CI = 0.95-1.48) or ever-smokers (OR = 1.73, 95%CI = 0.89-3.36).

Conclusion

The present meta-analysis suggested that there was no association between IL-6 rs1800796 polymorphism and lung cancer, which was independent of smoking status.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1060061508127855

Interleukin 6 -174G>C polymorphism and cancer risk: meta-analysis reveals a site dependent differential influence in Ancestral North Indians

In our earlier studies, single nucleotide polymorphisms (SNPs) associated with anti-inflammatory cytokines were found to influence risk for breast cancer in western Indian women. Analysis of Interleukin 6 (IL-6) -174G>C polymorphism in this cohort (patients = 182; controls = 236) suggested a protective role for IL-6 -174C allele associated with the lower expression of the cytokine (OR = 0.54; 95% CI 0.32-0.89, dominant model). Together these observations suggested that in comparison to Caucasians, inflammation associated-cytokine gene polymorphisms may have higher influence on risk for cancer in this population. To examine this possibility we analyzed data assessing influence of Interleukin 6 (IL-6) -174G>C polymorphism on risk for various cancers. Overall, there was a marginally higher risk for rare allele homozygotes compared to wild type homozygotes (OR = 1.07; 95% CI 1.00-1.15). Increased risks for genitourinary cancers and for skin cancer were also indicated. The ethnicity based analysis indicated a protective effect of the minor allele in Ancestral North Indians (OR = 0.73; 95% CI 0.55-0.97). Site by ethnicity analysis once again revealed a significant protection against breast cancer (OR = 0.51; 95% CI = 0.37-0.70; dominant model) but an opposite influence on the risk of genitourinary malignancies (OR = 2.51; 95% CI 1.59-3.96; recessive model) in this population alone. The observations imply that contribution of IL-6 to inflammation or effector immunity may depend on the site of malignancy. Assessment of available data in relation to prognosis in breast cancer patients also revealed trends that are compatible with the observations of the meta-analysis. Thus, IL-6 -174G>C polymorphism clearly represents a potential modulator of risk for malignant disorders with ethnicity and site dependent trends. The results also support the possibility of higher influence of inflammation related cytokine gene polymorphisms on the risk for cancers in Ancestral North Indians.

Genetic susceptibility and gastric cancer risk: the importance of meta-analyses as a statistical tool

Gastric cancer (GC) is a complex disease and a worldwide health burden due to its high prevalence and poor prognosis. A deeper knowledge of the factors involved in the development and progression of GC could help to identify subpopulations at risk that therefore require surveillance or early treatment strategies. Current research is based on the study of genetic variants that confer a higher risk of GC and their interactions with environmental exposure. Recently, meta-analysis has emerged as an important statistical method involving pooling of data from individual association studies to increase statistical power and obtain more conclusive results. Given the importance of chronic inflammation in the process of gastric carcinogenesis, the present article reviews the most recent meta-analyses of the contribution of cytokine gene polymorphisms to GC risk.

Gastric cancer susceptibility genes

Genetic susceptibility results from genetic factors or some genetic defects, and endows the offspring with some physiological and metabolic features prone to certain diseases. At present, gastric cancer susceptibility genes have become a hot research topic in China, and the identification and characterization of gastric cancer susceptibility genes can help develop methods for exploring gastric cancer etiology and provide a scientific basis for the prevention and control of this malignancy. In this paper, we will review the current progress in research of gastric cancer susceptibility genes.

Interleukin 6 gene polymorphism -174 is associated with the diffuse type gastric carcinoma

The aim of this study was to assess the significance of the interleukin 6 gene polymorphism -174 in gastric cancer risk. The interleukin 6 -174 G/C (rs1800795) gene polymorphisms was analyzed in gastric cancer, peptic ulcer, and nonulcer dyspepsia patients and in healthy control subjects and the data were correlated with the histopathological features of the patients' biopsies. The interleukin 6 -174 GG and GC genotypes have been previously associated with high interleukin 6 serum levels. We discovered that the interleukin 6 -174 GG and GC genotypes are associated with an increased risk of the diffuse histologic subtype of gastric carcinomas (OR: 6.809, P = 0.034), but absent in the intestinal type carcinomas (OR: 1.109, P = 0.908). No significant associations with peptic ulcer, gastric atrophy, or intestinal metaplasia were seen. Our results demonstrate that the interleukin 6 -174 GG and GC genotypes increase the risk of the diffuse type gastric carcinoma, but not the intestinal type gastric carcinoma or its precursor conditions, including atrophy or intestinal metaplasia. Thus, interleukin 6 seems to be an important carcinogenetic factor in the diffuse type gastric adenocarcinoma and its carcinogenetic effect could be noninflammatory.

Relationship between gene polymorphisms of two cytokine genes (TNF-α and IL-6) and occurring of lung cancers in the ethnic group Han of China

Tumor necrosis factor (TNF) is a cytokine involved in inflammation and TNF-α might be synthesized ectopically in malignant tumors. Interleukin-6 (IL-6) is an interleukin that acts as both a pro-inflammatory and anti-inflammatory cytokine. The present study is to investigate the relationship between genetic polymorphisms of the TNF-α and IL-6 genes and susceptibility to lung cancers in the ethnic group Han of North China. The genotypes in the -238G locus of TNF-α gene and the -572C locus of the IL-6 gene were determined by PCR-RFLP method in 138 patients with lung cancers and 138 healthy individuals. Software PHASE 1.0 was used to analyze the experimental data. The non-conditional logistic regression model was used to analyze the statistical association of genotypes and susceptibility in two groups adjusted by multiple factors. We found that the TNF-α and IL-6 polymorphisms may be a critical risk for the genetic susceptibility to lung cancers in the ethnic group Han of North China. SNP polymorphisms at the -238G locus of TNF-α gene and the -572C locus of the IL-6 gene were detected by the RFLP-PCR method. We found that high rates of single-base G-to-A alteration at the -238G locus of both alleles and high rates of single-base C-to-G alteration at the -572C locus of both alleles correlated with occurring of lung cancers. It is possible that the SNP markers at the -238G locus of TNF-α gene and the -572C locus of the IL-6 gene serve as biological markers of lung cancers upon further study in the future.