Genetic Polymorphisms of the Interleukin-18 Gene and Risk of Prostate Cancer

Investigating the Relationship of G-137C, C-607A, and A-1447G Polymorphisms in the Promoter of IL-18 and CXCL10 Inflammatory Genes with Prostate Cancer in an Iranian Population

Introduction

Genetic and environmental factors are involved in prostate cancer. The current study was conducted to study the relationship between G-137C, C-607A, and A-1447G polymorphisms in the promoter of IL-18 and CXCL10 inflammatory genes with prostate cancer.

Methods

As a genetic association study with a case-control design, the genomes of people living in Khorasan, Iran, were compared in two groups of cases and controls. The genotype of the A-1447G polymorphism present in the CXCL10 gene promoter was investigated by the PCR-RFLP method. PCR-SSP was used to study the genotype of G-137C and C-607A polymorphisms present in the IL-18 gene promoter. Odds ratio (OR) and 95% confidence interval (CI) were reported.

Results

One mutant allele in CXCL10 A-1447G polymorphism (AG) increased the chance of cancer (OR = 4.902, 95% CI = 2.70-8.87) and two mutant alleles (GG) increased more (OR = 7.174, 95% CI = 2.48-20.68). One mutant allele in IL-18 G-137C polymorphism (CG) increased the chance of cancer (OR = 5.583, 95% CI = 3.04-10.22) and two mutant alleles (CC) increased more (OR = 9.571, 95% CI = 3.10-29.46). One mutant allele in IL-18 C607A polymorphism (CA) increased the chance of cancer (OR = 5.359, 95% CI = 2.95-9.70) and two mutant alleles (AA) increased more (OR = 7.083, 95% CI = 2.61-19.15) (P < 0.001).

Conclusion

According to the results, the mutant alleles in polymorphisms CXCL10 A-1447G, IL-18 G-137C, and IL-18 C-607A alleles were associated with an increased chance of prostate cancer in this population.

Associations between single-nucleotide polymorphisms of the interleukin-18 gene and breast cancer in Iraqi women

According to long-term projections, by 2030, the world’s population is predicted to reach 7.5 billion individuals, and there will be roughly 27 million new cancer cases diagnosed. The global burden of breast cancer (BC) is expected to rise. According to the Ministry of Health-Iraqi Cancer Registry, cancer is the second largest cause of death after cardiovascular disease. This study investigated the interleukin-18 (IL18) single-nucleotide polymorphisms (SNPs) –607C/A rs1946518 and –137G/C rs187238 using the sequence-specific amplification-polymerase chain reaction approach. Regarding the position –607C/A, there was a highly significant difference between the observed and expected frequencies in patients and controls (χ² = 3.16 and χ² = 16.5), respectively. The AA and CA genotypes were associated with significantly increased BC risk (odds ratio [OR], 3.68; p = 0.004 and OR, 2.83; p = 0.04, respectively). Women with the A allele had a 5.03-fold increased susceptibility to BC. The C allele may be a protective allele against BC (OR, 0.19). Although position –137G/C showed no significant differences in the CC genotype distribution (p = 0.18), the frequency of the CC genotype was significantly higher in patients than in controls. In contrast, patients had a significantly higher frequency of GC genotypes than controls (p = 0.04), which was associated with an increased risk of developing BC (OR, 2.63). The G allele frequency was significantly lower in patients than in controls (55.0% vs. 76.2%, respectively). This SNP may be considered a common genotype in the Iraqi population, with the wild-type G allele having a protective function (OR, 0.19) and the mutant C allele having an environmental effect (OR, 2.63).

Cumulative Evidence for Association between IL-10 Polymorphisms and Kawasaki Disease Susceptibility: A Systematic Review and Meta-Analysis

BACKGROUND

This meta-analysis was carried out to evaluate the associations between IL-10 polymorphisms and Kawasaki disease (KD) risk.

METHODS

A comprehensive literature search was performed using PubMed, EMBASE, China National Knowledge Infrastructure and SciELO for all relevant studies evaluating IL-10 polymorphism and susceptibility to KD. The associations were measured by odds ratios (ORs) and its corresponding 95% confidence intervals (CIs).

RESULTS

A total of 13 studies including four studies on -1082 A > G, four studies on -819 T > C and five studies on -592 A > C polymorphism were selected. Pooled data revealed that IL-10 -592 A > C polymorphism was significantly associated with an increased risk of KD (C vs. A: OR = 0.402, 95% CI 0.194-0.832, p = 0.014). However, IL-10 -1082 A > G and -819 T > C polymorphisms were not significantly associated with risk of KD under all five genetic models.

CONCLUSIONS

Our results revealed that IL-10 -592 A > C polymorphism was associated with risk of KD, while IL-10 -1082 A > G and -819 T > C polymorphisms were not involved in the development of KD.

Polymorphisms of genes encoding cytokines predict the risk of high-grade bladder cancer and outcomes of BCG immunotherapy

Introduction

The present study investigated the association of cytokines genes polymorphisms (IL-2, IL-8 and IL-18) and polymorphisms in genes encoding molecules related to the differentiation of Th17 subpopulation (IL-17 and IL-23R) with the risk of bladder cancer (BC) and response to BCG immunotherapy.

Material and methods

Altogether, 175 BC patients treated with BCG due to high-grade non-muscle invasive tumors and 207 healthy individuals were genotyped for the following polymorphisms: IL-17A-197G>A (rs2275913); IL-17F+7488T>C (rs763780); IL-23Rc.309C>A (rs10889677);IL-23Rc.1142G>A (rs11209026); IL-2-330T>G (rs2069762), IL-8-251A>T (rs4073), and IL-18-137G>C (rs187238) using the TaqMan SNP genotyping assays.

Results

The IL-23Rc.-309C>A[A] allele was associated with the risk of BC (OR: 1.42, p = 0.03). Moreover, heterozygocities for IL-17A-197G>A[GA] and IL-18-137G>C[GC] increased the risk of BC, as compared to both homozygotes (OR: 1.67, p = 0.01 and OR: 1.84, p = 0.008, respectively). The IL-18-137G>C[GC] heterozygous patients had the highest risk of tumor recurrence and progression, and the worst recurrence-free and progression-free survival. Homozygous IL-17A-197G>A[GG] patients presented the best recurrence-free survival, while IL-17A-197G>A[AA] patients had 1.8-fold higher risk of recurrence.

Conclusions

The present study highlighted the importance of IL-17, IL-18, and IL-23R gene polymorphisms for BC susceptibility and BCG immunotherapy outcomes. It may help to identify appropriate candidates for early radical treatment.

Association between IL-18 -607 C/A Polymorphism and the Risk of Prostate Cancer: A Meta-Analysis of Case-Control Studies

Background: Accumulating evidence shows that cytokines play an important role in the proliferation of prostate cancer. This research is trying to determine that IL-18 -607 C/A polymorphism confers susceptibility to prostate cancer. Methods: Meta-analysis was used to collect data. The relevant studies were identified through a comprehensive search from PubMed, Excerpta Medica Database (EMBASE), Web of Science, and Chinese Biomedical Literature Database (CBM) to obtain related studies published up to December 6, 2017. The association between interleukin (IL)-18 -607 C/A polymorphism and prostate cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). Results: Nine case-control studies from 6 articles were eventually identified. In the overall population, there is a significant association between IL-18 -607 C/A polymorphism and prostate cancer risk in recessive (CC versus CA/AA: OR = 0.20, 95% CI = 0.15-0.27, P = 0.000) or dominant (CC/CA versus AA:OR = 0.42, 95% CI = 0.30–0.57, P = 0.000) models. In the sub-group analysis according to ethnicity, for Asians, IL-18 -607 C/A polymorphism was significantly associated with prostate cancer in allele contrast (C versus. A: OR=0.82, 95%CI=0.70-0.97, P=0.019), homozygote (CC versus. AA: OR=0.68, 95%CI=0.50-0.92, P=0.013), recessive (CC versus. CA/AA: OR=0.19, 95%CI=0.13-0.27, P=0.000), and dominant (CC/CA versus. AA: OR=0.37, 95%CI=0.28-0.48, P=0.000) models, for Caucasians, IL-18 -607 C/A polymorphism was significantly associated with prostate cancer risk in allele contrast (C versus. A: OR=1.27, 95%CI=1.02-1.58, P=0.033), homozygote (CC versus. AA: OR=1.86, 95%CI=1.19-2.91, P=0.007) and recessive (CC versus. CA/AA: OR=0.25, 95%CI=0.19-0.33, P=0.000) models. Conclusion: This meta-analysis has shown that IL-18 -607 C/A polymorphism contributes to a decreased risk of prostate cancer risk in the Asian population but an increased risk in the Caucasian population.

IL18 Polymorphism and Periodontitis Susceptibility, Regardless of IL12B, MMP9, and Smoking Habits

Genetic variations contribute to the susceptibility in the development of periodontitis. The aim of this study was to investigate the influence of IL18, IL12, and MMP9 polymorphisms in the chronic periodontitis. This case-control study involved 381 individuals matched by gender and age. Genotyping of IL18 (rs187238 and rs1946518) and IL12B (rs3212227) was performed by PCR-SSP and PCR-RFLP was used for MMP9 (rs3918242). IL-18 and MMP-9 were quantified in the serum by ELISA. SNPStats and OpenEpi software were used for statistical analysis and, in order to eliminate smoking as a confounding factor, the analyses were also performed in nonsmoking subjects. The IL18-137G/C genotype was associated with the risk of chronic periodontitis in nonsmokers (P_c = 0.03; OR = 1.99; overdominant inherence model). In the multivariate analyses, homozygous IL18-137G/G and IL18-607C/C were more frequent in males compared to women with these same genotypes (OR = 2.51 and OR = 3.30, respectively). The serum levels of the IL-18 in patients were higher than those in healthy controls (P = 0.005). IL12B and MMP9 polymorphisms and MMP-9 serum concentration were similar in patients and controls. In this study, IL18 was associated with chronic periodontitis susceptibility. Men had greater risk than women for developing the disease when IL18 polymorphism was considered and the susceptibility was independent of the smoking status.

Contribution of Inflammatory Cytokine Interleukin-18 Genotypes to Renal Cell Carcinoma

Interleukin-18 (IL-18) is a multi-functional immuno-mediator in the development and progression of many types of infectious and inflammatory diseases. In this study, we evaluated the contribution of IL-18 genotypes to renal cell carcinoma (RCC) in Taiwan via the genotyping of IL-18 -656 (A/C), -607 (A/C), and -137 (G/C). Moreover, we analyzed their interactions with smoking, alcohol drinking, hypertension, and diabetes status. The results showed an association of the AC and CC genotypes of IL-18 -607 with a significant decrease in the risk of RCC compared with the AA genotype (odds ratio (OR) = 0.44 and 0.35, 95% confidence interval (CI) = 0.27⁻0.72 and 0.18⁻0.66, p = 0.0008 and 0.0010, respectively). Furthermore, a significantly lower frequency of the C allele at -607 was observed in the RCC group (35.3% vs. 49.8%; OR = 0.53; 95% CI = 0.35⁻0.71, p = 0.0003). However, IL-18 -656 and -137 did not exhibit a likewise differential distribution of these genotypes between the control and case groups. Stratifying the population according to smoking, alcohol drinking, hypertension, and diabetes status revealed a different distribution of IL-18 -607 genotypes among non-smokers, non-drinkers, and patients without diabetes, but not among smokers, drinkers, or patients with diabetes. These findings suggest that IL-18 -607 genotypes may play a role in the etiology and progression of RCC in Taiwan and may serve as a useful biomarker for early detection.

Interleukin-18 promoter genotype is associated with the risk of nasopharyngeal carcinoma in Taiwan

Background

The incidence rate of nasopharyngeal carcinoma (NPC) has been documented to be high in Southeast Asia. Interleukin-18 (IL-18) is a multifunctional cytokine that augments interferon-γ production and acts as an important immunomediator in the development of several types of cancer.

Patients and methods

This case-control study evaluated the role of IL-18 in NPC at the DNA level by genotyping its promoter polymorphisms at positions -656, -607, and -137 in a Taiwanese population. A total of 176 patients with NPC and age- and gender-matched 352 noncancer controls were included in this study.

Results

The CC genotype of the IL-18-607 polymorphism was found to be associated with significantly decreased risks of NPC compared to the AA genotype (crude OR =0.50, 95% CI =0.29-0.84, P=0.0093). This significant difference persisted even in the dominant and recessive models. A significantly lower C allele frequency at position -607 was detected in the NPC group(41.8% vs 50.3%; OR =0.77; 95% CI =0.63-1.04, P=0.0089). Regarding IL-18-656 and -137 polymorphisms, there were no differential distributions of their genotypes between the NPC and control groups. After substratification of the subjects according to their smoking, alcohol consumption, and areca chewing status, the genotype distribution of the IL-18-607 polymorphism was found to be different only among nonsmokers between the NPC and control subgroups.

Conclusion

This study suggests that IL-18 plays an important role in the carcinogenesis of NPC in Taiwan and that the genotype-phenotype correlation of IL-18-607 polymorphism and its contribution to NPC need to be investigated further.

A gene-disease association study of IL18 in thyroid cancer: genotype and haplotype analyses

Thyroid cancer is the most common malignancy of the endocrine system, and genetic factors have been shown to be associated with its risk. Interleukin-18 (IL-18) is a pleiotropic pro-inflammatory cytokine that induces IFN-γ production and is involved in T helper type 1 development. To determine the role of IL-18 gene in thyroid cancer susceptibility, we conducted a case-control study, and genotyped five single nucleotide polymorphisms (SNPs) in IL-18 gene (-656 G/T (rs1946519), -607 C/A (rs1946518), and -137 G/C (rs187238) in the promoter region and +113 T/G (rs360718) and +127 C/T (rs360717) in 5'-untranslated region) in 105 patients with thyroid cancer and 148 healthy controls from Iranian population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific primer-PCR were used for genotyping. The association of different genotypes with thyroid cancer, tumor type, and the tumor stage was analyzed. Comparing all of the patient population with the controls, TT genotype at position -656 G/T was observed to be associated with a significantly increased risk of thyroid cancer [31/105 (30.1 %) vs 19/148 (13.1 %), p = 0.002, OR 2.90, CI 1.40-5.70]. No association with thyroid cancer was found at other positions (-607 C/A, -137 G/C, +113 T/G, and +127 C/T). Excluding the patients with medullary carcinoma, and including only the ones with thyroid cancer derived from the follicular epithelium, nearly the same results were observed regarding the genotypes at position -656 G/T. Furthermore, significantly decreased risk of thyroid cancer derived from the follicular epithelium was observed upon inheritance of the homozygote genotype (CC) at position +127 C/T (40/94 (42.5 %) versus 84/148 (56.8 %) in patients and controls, respectively (OR 0.56, 95 % CI for OR 0.32-0.98, p = 0.04). Haplotype analysis indicated that among 32 possible haplotypes, TAGTT haplotype frequency was significantly higher in patients than in controls [12/188 (6.4 %) vs 2/292 (0.7 %), p = 0.0008] and this difference resisted Bonferroni correction (n = 19) and significant level set at 0.003. Nearly the same results were observed after excluding the patients with medullary carcinoma. No association was found between the SNPs and the stage of tumor. Our results suggest the increased susceptibility to thyroid cancer in subjects with TT genotype at position -656 G/T of the promoter of IL-18 gene, as well as TAGTT haplotype emerged from five studied SNPs in IL-18 gene. The data also suggest that the inheritance of +127 CC genotype may protect individuals from thyroid cancer derived from follicular epithelium.

Functional genetic variability at promoters of pro-(IL-18) and anti-(IL-10) inflammatory affects their mRNA expression and survival in prostate carcinoma patients: Five year follow-up study

BACKGROUND

Inflammation is an important hallmark of all cancers. The net inflammatory response is determined by a delicate balance between pro- and anti-inflammatory cytokines, which, in turn, is determined by the genetic make-up. The present study investigates the role of variations in the promoter regions of IL-18 and IL-10 (anti-inflammatory) cytokines on mRNA expressions and survival in prostate cancer (PCa) patients.

METHODS

The study was conducted on 584 volunteer males (291 patients of PCa, between 40-80 years of age. Genetic variants were studied by using RFLP and confirmed by probe based method. Expressions of mRNA were evaluated by real-time PCR (Roche light cycler 480). Relative mRNA and fold change gene expressions were analyzed by ([1/2] (ΔCt) ) and (2(-ΔΔCt) ) methods, respectively, and 5 year follow-ups were evaluated by Log-rank (Mantel-Cox) test with Log-rank test for trends.

RESULTS

IL-18 mRNA expression was significantly elevated in GG genotypes (at -137) of PCa with relative mRNA expression of 13.95, that is, 8.48 folds higher (P < 0.05) than controls; and showed a significant median survival of 1243 days. The CC genotypes of IL-10 at both loci (-819 T/C and -592C/A) showed 3.63 and 3.52 higher relative mRNA expressions than controls, but poor survival of 984 and 1052 days than TT of 1359 days and AA of 1371 days.

CONCLUSIONS

Genetic variants of pro-inflammatory IL-18 which showed higher relative mRNA expressions have better survival. Genetic variants of anti-inflammatory IL-10 with higher relative mRNA expression showed decreased chances of survival.

Genetic variability at promoters of IL-18 (pro-) and IL-10 (anti-) inflammatory gene affects susceptibility and their circulating serum levels: An explorative study of prostate cancer patients in North Indian populations

Inflammation is an important hallmark of all types of cancers with a well-established role in carcinogenesis. The net inflammatory response is determined by the balance between pro- and anti-inflammatory cytokines, the levels of which may be affected by the genetic make-up. Interleukin (IL)-18, a pro-inflammatory cytokine expressed by various cells including those of the prostate, is a key mediator of anti-cancer immune response. IL-10, an anti-inflammatory cytokine associated with tumour malignancy, causes escape from immune surveillance. This study hypothesizes that genetic variants of IL-18 (-607 C/A and -137 G/T) and IL-10 (-819 C/T and -592 C/A) may influence the circulating levels of these interleukins, thereby generating susceptibility risk to prostate cancer. The study was conducted on 676 subjects (controls and patients of prostate cancer (PCa): 291 each; and 94 patients with benign prostate hypertrophy (BPH)). Genotyping was performed by PCR-RFLP and Real-Time PCR probe-based method. Circulating interleukin levels were obtained by ELISA. Circulating IL-18 levels were significantly elevated in cancer and BPH patients carrying GG genotypes for -137 of IL-18. The trend of circulating IL-18 levels was GG>GC>CC, observed in all groups. The -137 genetic variants of IL-18 significantly associated with PCa risk were GC, CC, and GC+CC, compared to GG (OR: 1.71, 95% CI: 1.20-2.46; OR: 3.35, 95% CI: 2.03-5.53; and OR: 2.05, 95% CI: 1.46-2.87, respectively). A significant association of AA and CA+AA against CC genotype was observed at -607 locus of IL-18 (OR: 0.46, 95%CI: 0.29-0.72; OR: 0.61, 95% CI: 0.41-0.90, respectively). Significantly elevated levels of IL-10 were observed with TT (wild) genotype at -819 of IL-10, compared to the CC (homozygous mutant) genotype in all three groups of subjects. However, no significant association was found between IL-10 promoter genotypes and PCa risk. We conclude that genetic variants of IL-18 and IL-10 promoters influence the circulating levels of these interleukins. Variations at -137 and -607 loci of IL-18 are associated with susceptibility to PCa.

The -137G/C Polymorphism in Interleukin-18 Gene Promoter Contributes to Chronic Lymphocytic and Chronic Myelogenous Leukemia Risk in Turkish Patients

Objective:

Interleukin-18 (IL-18) is a cytokine that belongs to the IL-1 superfamily and is secreted by various immune and nonimmune cells. Evidence has shown that IL-18 has both anticancer and procancer effects. The aim of this study was to evaluate the relationship between IL-18 gene polymorphisms and susceptibility to chronic lymphocytic leukemias (CLL) and chronic myelogenous leukemias (CML) in Turkish patients.

Materials and Methods:

The frequencies of polymorphisms (rs61667799(G/T), rs5744227(C/G), rs5744228(A/G), and rs187238(G/C)) were studied in 20 CLL patients, 30 CML patients, and 30 healthy individuals. The genotyping was performed by polymerase chain reaction and DNA sequencing analysis.

Results:

Significant associations were detected between the IL-18 rs187238(G/C) polymorphism and chronic leukemia. A higher prevalence of the C allele was found in CML cases with respect to controls. The GC heterozygous and CC homozygous genotypes were associated with risk of CML when compared with controls. However, prevalence of the C allele was not significantly high in CLL cases with respect to controls. There was only a significant difference between the homozygous CC genotype of CLL patients and the control group; thus, it can be concluded that the CC genotype may be associated with the risk of CLL. Based on our data, there were no significant associations between the IL-18 rs61667799(G/T), rs5744227(C/G), or rs5744228(A/G) polymorphisms and CLL or CML.

Conclusions:

IL-18 gene promoter rs187238(G/C) polymorphism is associated with chronic leukemia in the Turkish population. However, due to the limited number of studied patients, these are preliminary results that show the association between -137G/C polymorphism and patients (CLL and CML). Further large-scale studies combined with haplotype and expression analysis are required to validate the current findings.

Intracellular distributing and interferon-γ secretion of human interleukin-18 in BxPC-3 cells

OBJECTIVE

To investigate the characteristics of interleukin-18 (IL-18) in vitro, explore IL-18, interferon-γ (IFN-γ) and interleukin-2 (IL-2) secretive activity in BxPC-3 line cells with interleukin-18 mutants.

METHODS

Human IL-18 full-length gene (hIL-18-F) and the hIL-18 presumed mature protein gene (hIL-18-M) were inserted into the expression vector pEGFP-N1, to construct recombinant plasmids as Mu0, Mu1, Mu2, Mu3, and Mu4, and the recombinant plasmids were then transferred into BxPC-3 line cells. There are significant differences between Mu1, Mu2 and the pEGFP-C1 control group (P<0.05) by 3-(4,5-dimethiazol- 2-yl)- 2,5-diphenyltetrazolium bromide (MTT) for a proliferation assay, and the fluorescence of the Mu1 and Mu 2 appeared targeted to the membranous region in the BxPC-3 cells after transfected 24h by confocal laser scanning microscope (OLSM).To characterize the intracellular distribution of hIL-18, recombinant IL-18 were each fused to the enhanced green fluorescent protein gene, and expressed in BxPC-3 cells.

RESULTS

Results showed that the Mu1 tended to the membranous region in BxPC-3 cells, this indicates that the N-terminal former amino acid peptide helped ChIL-18 target to BxPC-3 cellS membranes. ELISA results demonstrated that IFN-γ and IL-18 secreted levels of BxPC-3 cells transfecting with recombinant plasmid showed an significant difference (P<0.01); refers to IL-2 expression, the two BxPC-3 cells groups transfecting with recombinant plasmid have no significant function (P>0.05).

CONCLUSIONS

The results showed that hIL-18 and hIL-18 presumed mature protein can induce the secretion of IFN-γ in BxPC-3 cells, and increase the expression of IL-18, but they have no effects on IL-2.

Genetic variation in IL-16 miRNA target site and time to prostate cancer diagnosis in African-American men

BACKGROUND

Men with a family history of prostate cancer and African-American men are at high risk for prostate cancer and in need of personalized risk estimates to inform screening decisions. This study evaluated genetic variants in genes encoding microRNA (miRNA) binding sites for informing of time to prostate cancer diagnosis among ethnically diverse, high-risk men undergoing prostate cancer screening.

METHODS

The Prostate Cancer Risk Assessment Program (PRAP) is a longitudinal screening program for high-risk men. The eligibility includes men aged between 35 and 69 years with a family history of prostate cancer or African descent. Participants with 1 follow-up visit were included in the analyses (n=477). Genetic variants in genes encoding miRNA binding sites (ALOX15 (arachidonate 15-lipooxygenase), IL-16, IL-18 and RAF1 (v-raf-1 murine leukemia viral oncogene homolog 1)) previously implicated in prostate cancer development were evaluated. Genotyping methods included Taqman SNP Genotyping Assay or pyrosequencing. Cox models were used to assess time to prostate cancer diagnosis by risk genotype.

RESULTS

Among 256 African Americans with one follow-up visit, the TT genotype at rs1131445 in IL-16 was significantly associated with earlier time to prostate cancer diagnosis vs the CC/CT genotypes (P=0.013), with a suggestive association after correction for false discovery (P=0.065). Hazard ratio after controlling for age and PSA for TT vs CC/CT among African Americans was 3.0 (95% confidence interval: 1.26-7.12). No association with time to diagnosis was detected among Caucasians by IL-16 genotype. No association with time to prostate cancer diagnosis was found for the other miRNA target genotypes.

CONCLUSIONS

Genetic variation in IL-16 encoding miRNA target site may be informative of time to prostate cancer diagnosis among African-American men enrolled in prostate cancer risk assessment, which may inform individualized prostate cancer screening strategies in the future.

The -607C/A polymorphisms in interleukin-18 gene promoter contributes to cancer risk: evidence from a meta-analysis of 22 case-control studies

BACKGROUND

Several observational studies have investigated the association between -607 C/A polymorphism of IL-18 gene and cancer risk; however, the results were inconsistent. Therefore, we performed a meta-analysis to derive a more precise estimation of the association to help us better understand the relationship between -607 C/A polymorphism of IL-18 gene promoter and risk of cancer.

METHODS

A literature search was carried out using PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI) database between January 1966 and February 2013. Fixed-effect and random-effect models were used to estimate the pooled odds ratio (OR) and the corresponding 95% confidence intervals (CIs).

RESULTS

A total of 22 case-control studies including 4100 cancer cases and 4327 controls contributed to the analysis. Significant association between -607C/A polymorphism in IL-18 gene promoter and cancer risk was observed (CA vs CC:OR =1.221, 95% CI: 1.096, 1.360; P(heterogeneity)=0.219; AA/CA vs. CC:OR =1.203, 95% CI: 1.057, 1.369; P(heterogeneity)=0.064). In the subgroup analysis by ethnicity, -607C/A polymorphism significantly increased risk of cancer among Asian population (AA/CA vs. CC:OR =1.197, 95% CI: 1.023,1.401; P(heterogeneity)=0.088); however, no significant association was found in Caucasian or African population. The -607C/A polymorphism was associated with a significantly increased risk of nasopharyngeal carcinoma (CA vs CC:OR =1.330, 95% CI: 1.029,1.719; P(heterogeneity)=0.704; AA/CA vs. CC:OR =1.323, 95% CI: 1.037,1.687; P(heterogeneity)=0.823) and esophageal cancer (AA/CA vs. CC:OR =1.289, 95% CI: 1.002,1.658; P(heterogeneity)=0.700).

CONCLUSIONS

The present meta-analysis suggests that the -607C/A polymorphisms in IL-18 gene promoter is associated with a significantly increased risk of cancer, especially for nasopharyngeal carcinoma and esophageal cancer and in Asian population. More studies with larger sample size, well controlled confounding factors are warranted to validate this association.

Association of interleukin-18 gene promoter -607 C>A and -137G>C polymorphisms with cancer risk: a meta-analysis of 26 studies

BACKGROUND

Evidence suggest that IL-18 gene polymorphisms may be risk factors for several cancers. Increasing studies investigating the association between IL-18 gene promoter polymorphisms (-607 C>A and -137G>C) and cancer risk have yielded conflicting results.

METHODOLOGY/PRINCIPAL FINDINGS

We performed a meta-analysis of 26 studies including 4096 cases and 5222 controls. We assessed the strength of the association of IL-18 gene promoter -607 C>A and -137G>C polymorphisms with cancer risk and performed sub-group analyses by cancer types, ethnicities, source of controls and sample size. The pooled results revealed a significant increased risk of cancer susceptibility for -607 C>A (CA vs. CC: OR = 1.19, 95%CI: 1.04, 1.37, Pheterogeneity = 0.033; CA/AA vs. CC: OR = 1.17, 95% CI: 1.01, 1.34, Pheterogeneity = 0.007), but no significant association for -137 G>C was observed with overall cancer risk. Sub-group analyses revealed that an increased risk of nasopharyngeal carcinoma was both found for -607 C>A (CA/AA vs. CC: OR = 1.32, 95% CI: 1.04, 1.69, Pheterogeneity = 0.823) and -137G>C (GC/CC vs. GG: OR = 1.57, 95%CI: 1.26, 1.96, Pheterogeneity = 0.373). Consistent with the results of the genotyping analyses, the -607A/-137C and -607C/-137C haplotypes were associated with a significantly increased risk of nasopharyngeal carcinoma as compared with the -607C/-137G haplotype (-607A/-137C vs. -607C/-137G: OR = 1.26, 95%CI: 1.13, 1.40; Pheterogeneity = 0.569; -607C/-137C vs. -607C/-137G: OR = 1.14, 95%CI: 1.03, 1.27; Pheterogeneity = 0.775). As for gastrointestinal cancer, we also found that -607 C>A polymorphism was significantly associated with increased cancer risk (CA/AA vs. CC: OR = 1.25, 95% CI: 1.05, 1.50, Pheterogeneity = 0.458). Further sub-group analysis revealed that -137G>C polymorphism contributed to cancer risk in Asians but not in Caucasians (GC/CC vs. GG: OR = 1.31, 95%CI: 1.05, 1.64, Pheterogeneity<0.001).

CONCLUSIONS

The meta-analysis results suggest that IL-18 gene promoter -607 C>A polymorphism is significantly associated with overall cancer risk, especially in nasopharyngeal carcinoma and gastrointestinal cancer; and the -137 G>C polymorphism is associated with increased overall cancer risk in Asian populations and also significantly increases the risk of nasopharyngeal carcinoma.

Immunotherapeutic approach for better management of cancer--role of IL-18

Interleukin-18 (IL-18) is an immune-stimulatory cytokine with antitumor activity in preclinical models. It plays pivotal roles in linking inflammatory immune responses and tumor progression and is a useful candidate in gene therapy of lymphoma or lymphoid leukemia. A phase I study of recombinant human IL-18 (rhIL-18) in patients with advanced cancer concluded that rhIL-18 can be safely given in biologically active doses to patients with advanced cancer. Some viruses can induce the secretion of IL-18 for immune evasion. The individual cytokine activity might be potentiated or inhibited by combinations of cytokines. Here we focus on combinational effects of cytokines with IL-18 in cancer progression. IL-18 is an important non-invasive marker suspected of contributing to metastasis. Serum IL-18 may a useful biological marker as independent prognostic factor of survival. In this review we cover roles of IL-18 in immune evasion, metastasis and angiogenesis, applications for chemotherapy and prognostic or diagnostic significance.

The -137G>C polymorphism in interleukin-18 promoter region and cancer risk: evidence from a meta-analysis of 21 studies

Interleukin-18 (IL-18) is a key cytokine responsible for immune response and involved in the process of cancer development. The association of -137G>C polymorphism in the promoter region of IL-18 with cancer risk is still elusive based on current genetic association studies. We performed this meta-analysis to determine whether the -137G>C polymorphism is associated with cancer risk. A comprehensive search was conducted for databases of PubMed, EMBASE, and China National Knowledge Infrastructure. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the association strength. Publication bias was detected by Egger's and Begg's test. Twenty-one eligible studies including 3,498 cancer patients and 5,222 controls were identified and analyzed. In the overall analysis, no significant association between -137G>C polymorphism and cancer risk was observed. In the sub-group analyses of ethnicities, the -137G>C polymorphism significantly increased cancer risk in Asian population (GC/CC vs. GG: OR = 1.313, 95% CI = 1.053-1.638, heterogeneity P < 0.001) but not in Caucasian population. Further stratified analyses showed that the variant -137C allele was significantly associated with increased risk of nasopharyngeal carcinoma (C vs. G: OR = 1.484, 95% CI = 1.193-1.847, heterogeneity P = 0.213). No publication bias was detected. We provide evidence that the -137G>C polymorphism in IL-18 promoter region significantly increases cancer risk in Asian population but not in Caucasian population, and the variant -137C allele is associated with increased risk of nasopharyngeal carcinoma.

Effect of IL-18 gene promoter polymorphisms on prostate cancer occurrence and prognosis in Han Chinese population

Interleukin-18 (IL-18) has been implicated in a wide variety of cellular functions that affect the biological response to tumors. However, there is insufficient evidence to prove that IL-18 gene variants are associated with risk of prostate cancer. We examined a possible association between two promoter polymorphisms, -137G/C (rs187238) and -607C/A (rs1946518), in the IL-18 gene and prostate cancer occurrence and prognosis in Han Chinese. We used a high-resolution melting method to genotype these two polymorphisms in 375 Chinese Han patients with prostate cancer and in 400 age-matched healthy controls. A hundred and eighty-one prostate cancer patients who had been receiving androgen deprivation therapy, including operational and medical castration, were enrolled to follow-up in this study. Carriers of the GG genotype of the -137G/ C polymorphism had a 2.165-times higher risk of prostate cancer progression than carriers of GC [95% confidence interval (CI) = 1.270-3.687]. Patients with the GG genotype at clinical stages III and IV also had significantly lower rates of progression-free survival (relative risk = 2.174, 95%CI = 1.211-3.906). However, we found no significant association of genotype or allele distributions of these two polymorphisms with occurrence of prostate cancer. We conclude that there is evidence that the IL-18 gene promoter polymorphism -137G/ C influences the prognosis of prostate cancer patients in androgen deprivation therapy, although neither of the two SNPs contributes to prostate cancer development.

Association of interleukin-18 gene polymorphism with body mass index in women

BACKGROUND

Interleukin (IL)-18 is an important regulator of innate and acquired immune responses and has multiple roles in chronic inflammation and autoimmune disorders. Obesity is characterized by low- grade chronic inflammation. IL-18 has been suggested as an adipogenic cytokine that is associated with excess adiposity. The purpose of this study is to evaluate the relationship between IL-18 gene polymorphisms (-137 G/C and -607 C/A) and obesity.

METHODS

All 680 subjects were genotyped for the polymorphisms of IL-18 gene promoters (at positions -137 G/C and -607 C/A) using a polymerase chain reaction (271 cases with BMI ≥25 kg/m² and 409 controls with BMI <25 kg/m²). A chi-square test was used to compare the genotype and allele frequencies between the cases and control populations.

RESULTS

Analyses of the genotype distributions revealed that IL-18 -607 C/A polymorphism was associated with an increase in body mass index in obese women in the Korean population (chi(2) = 12.301, df = 2, p = 0.015).

CONCLUSION

Carriage of the A allele at position -607 in the promoter of the IL-18 gene may have a role in the development of obesity.

Gene variants in the angiogenesis pathway and prostate cancer

Although the causes of prostate cancer are still unknown, numerous studies support the role of genetic factors in the development and progression of this disease. Single nucleotide polymorphisms (SNPs) in key angiogenesis genes have been studied in prostate cancer. In this review, we provide an overview of the current knowledge of the role of genetic variants in the angiogenesis pathway in prostate cancer risk and progression. Of the 17 prostate cancer genome-wide association studies (GWAS) conducted to date, only one identified disease-associated SNPs in a region of an angiogenesis pathway gene. An association was observed between aggressive disease and three intergenic SNPs (rs11199874, rs10749408 and rs10788165) in a region on chromosome 10q26 that encompasses FGFR2. The majority (27/32, 84.4%) of primary candidate gene studies reviewed had a small (n < 800, 20/32, 62.5%) to medium sample size (n = 800-2000, 7/32, 21.9%), whereas only five (15.6%) had a large sample size (n ≥ 2000). Results from the large studies revealed associations with risk and aggressive disease for SNPs in NOS2A, NOS3 and MMP-2 and risk for HIF1-α. Meta-analyses have so far been conducted on FGFR2, TGF-β, TNF-α, HIF1-α and IL10 and the results reveal an association with risk for SNPs in FGFR2 and TGF-β and aggressive disease for SNPs in IL-10. Thus, existing evidence from GWAS and large candidate gene studies indicates that SNPs from a limited number of angiogenesis pathway genes are associated with prostate cancer risk and progression.

Genetic variation in Th1/Th2 pathway genes and risk of non-Hodgkin lymphoma: a pooled analysis of three population-based case-control studies

The balance between T-helper 1 (Th1) and T-helper 2 (Th2) activity is critical in lymphoid cell development and differentiation. Immune dysfunction underlies lymphomagenesis, so an alteration in the regulation of key Th1/Th2 cytokines may lead to the development of non-Hodgkin lymphoma (NHL). To study the impact of polymorphisms in Th1/Th2 cytokines on NHL risk, we analyzed 145 tag single nucleotide polymorphisms (SNPs) in 17 Th1/Th2 cytokine and related genes in three population-based case-control studies (1946 cases and 1808 controls). Logistic regression was used to compute odds ratios (OR) for NHL and four major NHL subtypes in relation to tag SNP genotypes and haplotypes. A gene-based analysis adjusting for the number of tag SNPs genotyped in each gene showed significant associations with risk of NHL combined and one or more NHL subtypes for Th1 (IL12A and IL12RB1) and Th2 (IL4, IL10RB, and IL18) genes. The strongest association was for rs485497 in IL12A, which plays a central role in bridging the cellular and humoral pathways of innate resistance and antigen-specific adaptive immune responses (allele risk OR= 1·17; P(trend)= 0·00099). This SNP was also associated specifically with risk of follicular lymphoma (allele risk OR= 1·26; P(trend)= 0·0012). These findings suggest that genetic variation in Th1/Th2 cytokine genes may contribute to lymphomagenesis.

Genetic variation in Th1/Th2 pathway genes and risk of non-Hodgkin lymphoma: a pooled analysis of three population-based case-control studies

The balance between T-helper 1 (Th1) and T-helper 2 (Th2) activity is critical in lymphoid cell development and differentiation. Immune dysfunction underlies lymphomagenesis, so an alteration in the regulation of key Th1/Th2 cytokines may lead to the development of non-Hodgkin lymphoma (NHL). To study the impact of polymorphisms in Th1/Th2 cytokines on NHL risk, we analyzed 145 tag single nucleotide polymorphisms (SNPs) in 17 Th1/Th2 cytokine and related genes in three population-based case-control studies (1946 cases and 1808 controls). Logistic regression was used to compute odds ratios (OR) for NHL and four major NHL subtypes in relation to tag SNP genotypes and haplotypes. A gene-based analysis adjusting for the number of tag SNPs genotyped in each gene showed significant associations with risk of NHL combined and one or more NHL subtypes for Th1 (IL12A and IL12RB1) and Th2 (IL4, IL10RB, and IL18) genes. The strongest association was for rs485497 in IL12A, which plays a central role in bridging the cellular and humoral pathways of innate resistance and antigen-specific adaptive immune responses (allele risk OR= 1·17; P(trend)= 0·00099). This SNP was also associated specifically with risk of follicular lymphoma (allele risk OR= 1·26; P(trend)= 0·0012). These findings suggest that genetic variation in Th1/Th2 cytokine genes may contribute to lymphomagenesis.

Gene expression correlation analysis predicts involvement of high- and low-confidence risk genes in different stages of prostate carcinogenesis

BACKGROUND

Whole genome association studies have identified many loci associated with the risk of prostate cancer (PC). However, very few of the genes associated with these loci have been related to specific processes of prostate carcinogenesis. Therefore I inferred biological functions associated with these risk genes using gene expression correlation analysis.

METHODS

PC risk genes reported in the literature were classified as having high (P<10(-6)), medium (P<10(-4)), or low (P<10(-2)) statistical confidence. Correlation coefficients of the expression levels between the risk genes and other genes in cancerous prostates samples were compared against those in normal prostates using a microarray dataset from Gene Expression Omnibus.

RESULTS

Overall, significant decrease of correlations in PC was observed between the levels of expression of the high-confidence genes and other genes in the microarray dataset, whereas correlation between low-confidence genes and other genes in PC showed smaller decrease. Genes involved in developmental processes were significantly correlated with all risk gene categories. Ectoderm development genes, which may be related to squamous metaplasia, and genes enriched in fetal prostate stem cells (PSCs) showed strong association with the high-confidence genes. The association between the PSC genes and the low-confidence genes was weak, but genes related to neural system genes showed strong association with low-confidence genes.

CONCLUSIONS

The high-confidence risk genes may be associated with an early stage of prostate carcinogenesis, possibly involving PSCs and squamous metaplasia. The low-confidence genes may be involved in a later stage of carcinogenesis.

Inflammatory genetic markers of prostate cancer risk

Prostate cancer is the most common cancer in Western society males, with incidence rates predicted to rise with global aging. Etiology of prostate cancer is however poorly understood, while current diagnostic tools can be invasive (digital rectal exam or biopsy) and/or lack specificity for the disease (prostate-specific antigen (PSA) testing). Substantial histological, epidemiological and molecular genetic evidence indicates that inflammation is important in prostate cancer pathogenesis. In this review, we summarize the current status of inflammatory genetic markers influencing susceptibility to prostate cancer. The focus will be on inflammatory cytokines regulating T-helper cell and chemokine homeostasis, together with the Toll-like receptors as key players in the host innate immune system. Although association studies indicating a genetic basis for prostate cancer are presently limited mainly due to lack of replication, larger and more ethnically and clinically defined study populations may help elucidate the true contribution of inflammatory gene variants to prostate cancer risk.

Review and pooled analysis of studies on -607(C/A) and -137(G/C) polymorphisms in IL-18 and cancer risk

Interleukin-18 (IL-18) is a pleiotropic, pro-inflammatory cytokine with dual effects on tumor development and progression. The -607(C/A) and -137(G/C) polymorphisms in IL-18 gene region have been implicated in cancer risk; however, data from published studies with individually low statistical power are conflicting. To clarify the role of IL-18 -607(C/A) and -137(G/C) genotype in global cancer, we examined all the available published studies through a pooled analysis approach. Overall, IL-18 -607A allele was associated with increased total cancer risk when compared with -607C allele (OR=1.14, 95% CI=1.01-1.28, P=0.010), as well as in the heterozygote comparison (OR=1.10, 95% CI=1.04-1.15, P=0.256) and the dominant model (OR=1.07, 95% CI=1.03-1.11, P=0.124). Furthermore, IL-18 -137(G/C) polymorphism was associated with increased nasopharyngeal carcinoma risk. In the stratified analysis for -607(C/A) polymorphism, a significantly increased cancer risk in Asian population was found, as well as subgroup in source of control. Similar results were found in the stratified analysis for -137(G/C) polymorphism. Our pooled analysis supported that IL-18 is a good candidate for large-scale epidemiological case-control studies that may be a low-penetrance susceptibility biomarker for cancer.

Interleukin-18 promoter polymorphism is associated with lung cancer: a case-control study

BACKGROUND

Interleukin-18 (IL-18) is a multifunctional cytokine that augments IFN-gamma production and affects tumor immune response. In the present case-control study, we tested whether IL-18 promoter polymorphism contributes to lung cancer susceptibility in Iranian patients.

MATERIAL AND METHODS

The study groups were 73 patients with lung cancer, including 53 with squamous carcinoma (SC) and 20 with small cell lung carcinoma (SCLC), and 97 healthy regional aged-matched individuals. The frequency of IL-18 promoter single nucleotide polymorphisms (SNPs) at positions -656 (G/T), -607 (C/A), and -137 (G/C) was determined by polymerase chain reaction analyses.

RESULTS

There were significant differences in the IL-18 -607 allele and genotype distributions between the 73 lung cancer patients and controls. A significantly higher A allele frequency at position -607, which is associated with lower IL-18 production, was observed in lung cancer patients (48.6% vs. 35%; OR = 1.75; 95% CI 1.13-2.72). Also, patients with the -607 CA and the AA genotypes had a 2.60-fold (95% CI 1.26-5.36) and 3.15-fold (95% CI 1.16-8.55) increase in risk of lung cancer. Subdivision of the patients according to histological type revealed that SC was significantly associated with IL-18 -607 SNPs. Although the percentages of -607 alleles and genotypes in SCLC patients were similar to the results in SC patients, the differences compared to control individuals did not reach statistical significance. Analysis with Arlequin software identified eight haplotypes from three SNPs analyzed here. The distributions of IL-18 gene haplotypes were not significantly different between patients and controls after Bonferroni correction.

DISCUSSION

This is the first report to investigate the association between IL-18 polymorphism and lung cancer. Our results suggest that IL-18 polymorphism contributes to the lung cancer risk, particularly among SC patients. Further studies with larger numbers of patients are required to determine the possible association between IL-18 polymorphisms and different histological types of lung cancer.

Polymorphisms of pro-inflammatory genes and prostate cancer risk: a pharmacogenomic approach

In this paper, we consider the role of the genetics of inflammation in the pathophysiology of prostate cancer (PCa). This paper is not an extensive review of the literature, rather it is an expert opinion based on data from authors' laboratories on age-related diseases and inflammation. The aim is the detection of a risk profile that potentially allows both the early identification of individuals at risk for disease and the possible discovery of potential targets for medication. In fact, a major goal of clinical research is to improve early detection of age-related diseases, cancer included, by developing tools to move diagnosis backward in disease temporal course, i.e., before the clinical manifestation of the malady, where treatment might play a decisive role in preventing or significantly retarding the manifestation of the disease. The better understanding of the function and the regulation of inflammatory pathway in PCa may help to know the mechanisms of its formation and progression, as well as to identify new targets for the refinement of new treatment such as the pharmacogenomics approach.

Interleukin-18 gene promoter polymorphism and the risk of nasopharyngeal carcinoma in a Chinese population

Nasopharyngeal carcinoma (NPC) is one of the most common cancers in southern China. In addition to environmental factors such as Epstein-Barr virus infection and chemical carcinogen exposure, genetic susceptibility has been reported to play a key role in the development of this disease. Interleukin-18 (IL-18) is a multifunctional cytokine that induces interferon-gamma secretion and plays an important role in antitumor immunity. Variations in the DNA sequence of the IL-18 gene promoter may lead to altered IL-18 production and/or activity, so this can modulate an individual's susceptibility to NPC. To test this hypothesis, we analyzed two single-nucleotide polymorphisms of IL-18 gene promoter, -137 G/C and -607 C/A, in 250 patients with NPC and 270 age- and sex-matched controls, using polymerase chain reaction-restriction fragment length polymorphism. Two polymorphisms, -137 G/C and -607 C/A, were in strong linkage disequilibrium. There were significant differences in the genotype and allele distribution of -137 G/C polymorphism of the IL-18 gene among cases and controls. The -137 GC and CC genotypes were associated with a significantly increased risk of NPC as compared with the -137 GG genotypes (odds ratio [OR] = 1.697; 95% confidence interval [CI], 1.158-2.488; p = 0.007, and OR = 2.700; 95% CI, 1.268-5.751; p = 0.008, respectively). Consistent with the results of the genotyping analyses, the -137 C/-607 A haplotype was associated with a significantly increased risk of NPC as compared with the -137 G/-607 C haplotype (OR = 1.721; 95% CI, 1.262-2.349; p = 0.001).

IL-18 serum level and IL-18 promoter gene polymorphism in Iranian patients with gastrointestinal cancers

BACKGROUND AND AIM

Interleukin (IL)-18 level and association of its two promoter gene polymorphisms at -607 C/A and -137 G/C positions were investigated in Iranian patients with gastrointestinal (GI) cancers.

METHODS

232 cases of GI cancers and 312 healthy controls were enrolled. Serum level of IL-18 was measured by enzyme linked immunosorbent assay (ELISA) and genotyping of IL-18 gene polymorphisms were assessed by allele-specific polymerase chain reaction (PCR).

RESULTS

There was a significant difference in the frequency of -137 G/C genotype between patients with stomach or colorectal cancers and control group. In patients with colorectal cancer, the frequency of the -607 AA/-137 GC genotype combination in unwell-differentiated cases was more than those with well-differentiated cancer. Haplotype analysis showed that in patients with stomach cancer -607 C/-137 C and -607 A/-137 G and in patients with colorectal cancer -607 C/-137 C were decreased compared with control group, and this difference reached statistical significance. Serum analysis revealed that the mean IL-18 serum level in stomach and colorectal cancer before and after surgical operation was significantly higher than healthy volunteers. Postoperative IL-18 level for all patients with colorectal cancer was significantly decreased compared with the levels before surgery.

CONCLUSION

Results of this investigation suggests that Single Nucleotide Polymorphism (SNP) at position -137 G/C and haplotype frequency may play a role in predisposition of Iranian patients to stomach and colorectal cancers. In addition, increasing serum IL-18 level may have clinical importance as a diagnostic marker in patients with stomach and colorectal cancer.

Head and neck squamous cell carcinoma is not associated with interleukin-18 promoter gene polymorphisms: a case–control study

Objective:

To investigate the association of two functional single nucleotide polymorphisms in the promoter region of the interleukin-18 gene, at positions −607 and −137, with head and neck squamous cell carcinoma.

Design:

Genomic deoxyribonucleic acid was extracted, by the salting-out method, from peripheral blood leukocytes. Single nucleotide polymorphisms of the interleukin-18 gene at positions −607 (cytosine/adenine) and −137 (guanine/cytosine) were analysed by sequence-specific polymerase chain reaction.

Subjects:

One hundred and eleven patients (86 men and 25 women; mean age 56.7±13.7 years) and 212 regional controls (165 men and 47 women; mean age 53.3±12.2 years) were studied. Control subjects comprised healthy volunteers or cancer-free individuals presenting with otolaryngological disease. The diagnosis of squamous cell carcinoma was confirmed histopathologically. Various clinical parameters were collected at diagnosis, including tumour site, tumour size, lymph node involvement, distant metastasis and stage.

Results:

There was no significant association between the allele, genotype or haplotype frequencies of the two single nucleotide polymorphisms of the interleukin-18 promoter and the head and neck squamous cell carcinoma susceptibility or clinical parameters at diagnosis.

Conclusion:

Interleukin-18 polymorphisms at positions −607 and −137 did not confer susceptibility to head and neck squamous cell carcinoma in southern Iranian patients.