Interleukin-10 and interleukin-18 promoter polymorphisms in an Italian cohort of patients with undifferentiated carcinoma of nasopharyngeal type

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.

Association of IL-8 gene promoter -251 A/T and IL-18 gene promoter -137 G/C polymorphisms with head and neck cancer risk: a comprehensive meta-analysis

Purpose

No consensus exists on the impact of polymorphisms in cytokines (such as interleukin IL-8 and IL-18) on cancer risk; moreover, there is very little evidence regarding head and neck cancer (HNC).

Methods

Thus, a meta-analysis including 22 studies with 4731 cases and 8736 controls was conducted to evaluate this association. The summary odds ratio (OR) and corresponding 95% confidence intervals (CIs) for C-X-C motif chemokine ligand 8 (CXCL8, which encodes IL-8) and IL-18 polymorphisms and HNC risk were estimated.

Results

The results showed a significantly increased risk of HNC susceptibility for IL18 −137 G/C in five genetic models, but, interestingly, no significant association was found for the CXCL8 −251 A/T polymorphism. When stratified by cancer type, an increased risk of nasopharyngeal cancer was found for both −137 G/C and −251A/T. When the studies were stratified by ethnicity and genotyping method, there were significant associations between Asian populations and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) studies for −137 G/C, and African populations for −251 A/T in some genetic models. A positive association was also found between the population-based groups in some models for −137 G/C; conversely, significantly decreased risk was found among the −251 A/T hospital-based group. Meta-regression was also conducted. The publication year, control source, and cancer type contributed to CXCL8 −251 A/T heterogeneity; however, no factors were found that contributed to IL-18 −137 G/C heterogeneity. Marginal significance was found in the recessive model for IL-18 −137 G/C by Egger’s test, whereas no publication bias was detected for CXCL8 −251 A/T.

Conclusions

The results indicate that the IL-18 −137 G/C polymorphism is associated with HNC risk, especially nasopharyngeal cancer, in Asian populations and, when using PCR-RFLP, CXCL8 −251 A/T polymorphisms play a complex role in HNC development.

The genetic polymorphism and expression profiles of NLRP3 inflammasome in patients with chronic myeloid leukemia

NLRP3 inflammasome has been recently reported as an important risk factor in the development of cancer. But the relationship between polymorphisms of NLRP3 inflammasome related genes and chronic myeloid leukemia (CML) is rarely reported. Therefore, the aim of the present study was to investigate the association of five genetic polymorphisms (NLRP3, IL-1β, IL-18, CARD8 and NF-κB) in 267 CML patients and 344 healthy controls. We found that the AT genotype of CARD8 (rs2043211) was significantly higher compared to TT genotype in high and intermediate risk CML patients. IL-1β (rs16944) polymorphism in early molecular response at 6 months was marginally different, with more GG and less AA genotype in BCR-ABL^IS >1% group. IL-18 (rs1946518) polymorphism was significantly different with more GG genotype in BCR-ABL^IS >1% group at 6 months. We also demonstrated that WBC count of newly diagnosed patients carrying AG genotype was significantly higher than that of GG or AA genotype of IL-1β (rs16944). The onset age of patients carrying ins/ins genotype of NF-κB (rs28362491) was significantly older than that of ins/del and del/del genotype. Moreover, IL-1β or NLRP3 mRNA expression was decreased and IL-18 mRNA expression was increased significantly in CML patients compared with controls. In conclusion, the genetic polymorphisms of NLRP3 inflammasome may be served as potential predictors for CML.

Genetic polymorphisms of IL-18 rs1946518 and IL-1β rs16944 are associated with prognosis and survival of acute myeloid leukemia

BACKGROUND

Though the pathogenesis of AML is still unknown, accumulating evidence revealed that immune response plays a vital part in it. NLRP3 inflammasome as a component of immune system has been found related to several cancers. The single nucleotide polymorphisms (SNPs) of NLRP3 inflammasome genes may be related to pathogenesis and prognosis of AML.

METHODS AND RESULTS

We determined polymorphisms of NLRP3 (rs35829419), CARD8 (rs2043211), IL-1β (rs16944), IL-18 (rs1946518) and NF-κB -94 ins/del ATTG in de novo AML patients to find out whether they play roles in the susceptibility and severity of AML. In our study, 383 AML cases and 300 randomly selected healthy individuals were examined for the polymorphisms and expression of NLRP3 genes. IL-1β (rs16944) polymorphism in different risk AML subgroups was found statistically different, with more GA genotype in favorable-risk cytogenetics group. We also demonstrated that the bone marrow blasts of patients carrying IL-18 (rs1946518) GG or GT genotype were higher than patients of TT genotype. IL-18 plasma level of patients with IL-18 (rs1946518) GT or TT genotype was higher than GG genotype. Moreover, the GT genotype of IL-18 (rs1946518) led to statistically poorer AML-specific survival.

CONCLUSION

IL-1β (rs16944) and IL-18 (rs1946518) may be served as potential predictors for AML.

Circulating interleukin-10 levels and human papilloma virus and Epstein-Barr virus-associated cancers: evidence from a Mendelian randomization meta-analysis based on 11,170 subjects

Recent studies have showed interleukin 10 (IL-10) is a critical cytokine that determines antiviral immune response and is related to virus-associated cancers. However, whether genetically elevated circulating IL-10 levels are associated with the risk of human papilloma virus and Epstein–Barr virus-associated cancers (HEACs) is still unclear. Mendelian randomization method was implemented to meta-analyze available observational studies by employing IL-10 three variants (−592C>A, −819C>T, and −1082A>G) as instruments. A total of 24 articles encompassing 11,170 subjects were ultimately eligible for the meta-analysis. Overall, there was a significant association between IL-10 promoter variant −1082A>G and HEACs under allelic and dominant models (both P<0.01). Subgroup analysis by cancer type indicated that the risk estimate of −1082A>G was significant for nasopharyngeal cancer under allelic, homozygous genotypic and dominant models (all P<0.001). Moreover by ethnicity, carriers of −1082G allele had a 74% increased risk for nasopharyngeal cancer in Asians under dominant model (odds ratio [OR] =1.737; 95% confidence interval [CI]: 1.280–2.358; P<0.001). In further Mendelian randomization analysis, the predicted OR for 10 pg/mL increment in IL-10 levels was 1.14 (95% CI: 1.01–16.99) in HEACs. Our findings provided strong evidence for a critical role of genetically elevated circulating IL-10 levels in the development of HEACs, especially in Asian population and for nasopharyngeal cancer.

Increased risks between Interleukin-10 gene polymorphisms and haplotype and head and neck cancer: a meta-analysis

Molecular epidemiological research suggests that interleukin-10 (IL-10) polymorphisms may be associated with an increased risk of head and neck cancer (HNC), but results remain controversial. To derive a more precise evaluation, we performed a meta-analysis focused on genetic polymorphisms of IL-10. PubMed, Embase, CNKI and Wanfang databases were searched for studies that examined the relationship between IL-10 polymorphisms or haplotypes and HNC risk. The odds ratio (OR) and 95% confidence interval (CI) were applied to assess the relationship strength. Publication bias, sensitivity and cumulative analyses were conducted to measure the robustness of our findings. Overall, nine related studies involving 2,258 patients and 2,887 control samples were analyzed. Significant associations between the IL-10-1082A > G polymorphism and HNC risk were observed (G vs. A: OR = 1.56, 95% CI = 1.27–1.92, P < 0.01, I² = 69.4%; AG vs. AA: OR = 1.64, 95% CI = 1.32–2.05, P < 0.01, I² = 55.6%; GG vs. AA: OR = 2.24, 95% CI = 1.69–2.97, P < 0.01, I² = 38.5%; AG + GG vs. AA: OR = 1.70, 95% CI = 1.36−2.14, P = 0.02, I² = 61.8%; GG vs. AA + AG: OR = 1.89, 95% CI = 1.23−2.90, P = 0.01, I² = 46.3%) in the total population, as well as in subgroup analysis. Moreover, increased HNC risks were also associated with the IL-10 −819T > C polymorphism and the GCC haplotype. In conclusion, our meta-analyses suggest that IL-10 polymorphisms, specifically the −1082A > G polymorphism, may be associated with increased risk of HNC development.

A pooled analysis of the IL-10-1082 A/G polymorphism and the nasopharyngeal carcinoma susceptibility

It has been reported that IL-10-1082 A/G polymorphism might influence the transcription and secretion of IL10 and tumor development. While many studies have been conducted to investigate the association between IL-10-1082 A/G polymorphism and risk of nasopharyngeal carcinoma (NPC) in various populations, the results of these studies are still controversial. We aimed to explore this relationship through a cumulative meta-analysis. A search of the literature was performed using the Cochrane Library, PubMed, and EMBASE databases. The odds ratio (OR) and corresponding 95 % confidence interval (CI) were calculated to assess this possible association. Six studies were included in the study. The meta-analysis reveals a significant effect in the allelic model (G vs. A: OR 1.516, 95 % CI 1.077-2.133, P heterogeneity = 0.003), dominant model (AG + GG vs. AA: OR = 1.770, 95 % CI 1.415-2.212, P heterogeneity = 0.169), and co-dominant model (AG vs. AA: OR = 1.747, 95 % CI 1.377-2.216, P heterogeneity = 0.491). Similarly, in the stratified analyses, significant effects were reported in studies of Asian populations. Our meta-analysis results suggest that the IL-10-1082 A/G variant is associated with increased risk of NPC in Asian populations.

Association between interleukin-18 promoter variants and tacrolimus pharmacokinetics in Chinese renal transplant patients

PURPOSE

Interleukin 18 (IL-18) is a potent proinflammatory cytokine thought to down-regulate cytochrome P450 (CYP) enzyme activities. This study aimed to assess the potential influence of two functional single nucleotide polymorphisms (SNPs) in the IL-18 promoter region on the tacrolimus pharmacokinetics in Chinese renal transplant patients.

METHODS

We enrolled 96 renal allograft recipients receiving tacrolimus-based immunosuppressive regiments. Two functional SNPs in the IL-18 gene promoter region at the positions -137G/C (rs187283) and -607A/C (rs1946518) and one SNP (rs776746) of CYP3A5 were genotyped using a Mass ARRAY platform. Tacrolimus daily doses (mg/day) and trough tacrolimus concentration (ng/ml) were continuously recorded for 1 month after transplantation.

RESULTS

The tacrolimus C/D ratio was significantly associated with the IL-18 rs1946518 gene polymorphism in the first month after transplantation (P = 0.0225). We studied the influence of its polymorphism on tacrolimus C/D ratios in subjects with different CYP3A5 genotype backgrounds, and among patients with CYP3A5 expressers, the difference among the three genotypes was even more striking (P < 0.001). We did not find significant differences in tacrolimus C/D ratios between the IL-18 rs187238 genotypes, either nominally or according to the CYP3A5 genotype. In a simple linear regression model, age, hemoglobin (Hb), CYP3A5 gene polymorphisms, and IL-18 A-607C gene polymorphisms were associated with log-transformed tacrolimus C/D ratios (P < 0.05). In the final multiple linear regression model, CYP3A5 polymorphisms were the most important variant, accounting for 19.5 % of total variation involved in tacrolimus pharmacokinetics.

CONCLUSION

Our findings suggest that a combined analysis of CYP3A5 and IL-18 promoter polymorphisms may help clinicians develop individualized tacrolimus treatment, which is based on determining CYP3A5 genotype.

The Interleukin-18 promoter -607C>A polymorphism contributes to nasopharyngeal carcinoma risk: evidence from a meta-analysis including 1,886 subjects

The interleukin-18 promoter -607C>A gene polymorphism may be related to nasopharyngeal carcinoma (NPC) risk but the results of individual studies remain conflicting. A meta-analysis including 1,886 subjects from five individual studies was therefore performed to provide a more accurate estimation. Pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were evaluated by fixed- or random-effects models. A significant relationship between interleukin-18 promoter -607C>A gene polymorphism and NPC was found in a dominant genetic model (OR: 1.351, 95% CI: 1.089-1.676, P=0.006, Pheterogeneity=0.904), a homozygote model (OR: 1.338, 95% CI: 1.023-1.751, P=0.034, Pheterogeneity=0.863), and a heterozygote model (OR: 1.357, 95% CI: 1.080-1.704, P=0.009, Pheterogeneity=0.824). No significant association was detected in either an allelic genetic model (OR: 1.077, 95% CI: 0.960-1.207, 0.207, Pheterogeneity=0.844) or a recessive genetic model (OR: 1.093, 95% CI: 0.878-1.361, P=0.425, Pheterogeneity=0.707). In conclusion, a significant association was found between interleukin-18 promoter -607C>A gene polymorphism and NPC risk. Individuals with the C allele of interleukin-18 promoter -607C>A gene polymorphism have a higher risk of NPC development.

IL-18 gene polymorphisms in aphthous stomatitis vs. Behçet's disease in a cohort of Egyptian patients

OBJECTIVE

A clinical investigation of the potential correlation of two single-nucleotide polymorphisms at -137 (G/C) and -607 (C/A) in the promoter region of the IL-18 gene, with the susceptibility to aphthous stomatitis and Behçet's disease.

PATIENT AND METHODS

This study included 80 aphthous stomatitis patients and 80 patients with Behçet's disease. Eighty healthy subjects were enrolled as a control group. IL-18 single-nucleotide polymorphisms at -607 and -137 regions were analyzed using polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

The genotype and allele distributions of the two regions did not differ significantly between patients with aphthous stomatitis and controls. The genotype and allele distributions at -607 were significantly different between patients with Behçet's disease [CC (P = 0.044), C allele (P = 0.043), A allele (P = 0.043)], and controls. The frequency of the GG genotype at position -137 in patients with Behçet's disease was associated only with a higher rate of ocular manifestations (OR= 1.4, CI= 0.76-2.7, P = 0.031).

CONCLUSION

IL-18 gene polymorphisms were not associated with any susceptibility to aphthous stomatitis, while a positive association was found with patients with Behçet's disease regarding -607 promoter site. Moreover, patients with Behçet's disease carrying the GG genotype at position -137 had a higher risk of developing ocular manifestations.

Prognostic importance of single-nucleotide polymorphisms in IL-6, IL-10, TGF-β1, IFN-γ, and TNF-α genes in chronic phase chronic myeloid leukemia

The aim of this study was to explore the association between polymorphisms of five cytokine genes and clinical parameters in patients with Philadelphia-positive (Ph+) chronic myeloid leukemia (CML) treated with imatinib. We analyzed five cytokine genes (interleukin [IL]-6, IL-10, gamma interferon [IFN-γ], transforming growth factor beta-1 [TGF-β1], and tumor necrosis factor-alpha [TNF-α]) in 60 cases with Ph+ CML and 74 healthy controls. Cytokine genotyping was performed by the polymerase chain reaction-sequence-specific primer. All data were analyzed using the de Finetti program and SPSS version 14.0 for Windows. No significant differences were detected between the CML group and healthy controls with respect to the distributions and numbers of genotypes and alleles in TNF-α, TGF-β1, IL-10, and IFN-γ. However, the GG genotype associated with high expression in IL-6 was found to be significantly more frequent in CML as compared to controls (p=0.010). The median follow-up time was 49.3 months (range 6.1-168.4) and the median duration of imatinib treatment was 39.5 months (range 5.2-103.4) for these patients. On multivariateanalysis, only IL-10 GCC/GCC highly produced haplotypes were significantly associated with a shorter event-free survival. The relationship between cytokine genotypes/haplotypes and clinical parameters in CML has not been investigated before. Our results suggest that IL-10 may be a useful marker for CML prognosis and theGG genotype of the IL-6 gene may be associated with susceptibility.

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.

The interleukin 10 -819C/T polymorphism and cancer risk: a HuGE review and meta-analysis of 73 studies including 15,942 cases and 22,336 controls

The aim of the present work was to perform a meta-analysis to evaluate the association between the interleukin 10 (IL-10) -819C/T (rs1800871) polymorphism and cancer risk. A total of 73 studies, including 15,942 cancer cases and 22,336 controls, were identified in this meta-analysis. The odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Overall, no significant association was identified between the IL-10 -819C/T polymorphism and cancer risk. In the subgroup analyses, the T allele and TT genotype were associated with a moderately reduced cancer risk in the Asian population (T allele vs. C allele: OR=0.93, 95%CI: 0.87, 0.99; TT vs. CC: OR=0.86, 95%CI: 0.76, 0.98; TT vs. CT/CC: OR=0.90, 95%CI: 0.82, 0.98). Individuals who were homozygous for the T allele (TT) were found to be associated with significantly reduced gastric cancer risk in the Asian population. The heterozygous variant (CT) and the dominant model (TT/CT vs. CC) were associated with an increased risk for cervical and ovarian cancer. However, the IL-10 -819C/T polymorphism was not significantly associated with breast cancer, colorectal cancer, lung cancer, hepatocellular carcinoma, prostate cancer, lymphoma, or melanoma. The depressed cancer risk of the TT genotype occurred in the studies of hospital-based case-control studies and the studies recruited less than 500 subjects, but no statistically significant results were found in the stratified analyses using genotyping method. The results suggest that the IL-10 -819TT genotype may be a protective factor for cancer in Asians, especially gastric cancer. In contrast, the CT genotype and the dominant model could be risk factors for cervical and ovarian cancer. The importance of stratifying by ethnicity, cancer type, study design, and sample size needs to be standardized in future studies, together with considering the association between the IL-10 -819C/T polymorphism and cancer risk. Furthermore, the linkage of -819C/T with other polymorphisms of the IL-10 gene may help explain the variability in findings.

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.

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.

Correlation between interleukin-18 promoter -607C/A polymorphism and susceptibility to ischemic stroke

Single nucleotide polymorphisms in the promoter region of interleukin-18 (IL-18), an inflammatory cytokine, have been linked to susceptibility to many diseases, including cancer and immune dysfunction. Here, we explored the potential association between the IL-18 -607C/A (rs1946518) promoter region polymorphism and susceptibility to ischemic stroke (IS). This locus was amplified from peripheral blood samples of 386 IS patients (cases) and 364 healthy individuals (controls) by the polymerase chain reaction with sequence-specific primers. Significant differences were observed by the χ² test in the -607C/A (rs1946518) genotype and allele frequencies between cases and controls (P < 0.05). Furthermore, after excluding for age, gender, smoking status, and hypertension, logistic regression indicated that IS susceptibility of -607C carriers increased 1.6 times (OR = 1.601, 95%CI = 1.148-2.233, P = 0.006) compared to -607A carriers. Additionally, similar increases in IS risk were noted for male patients or patients less than 65 years old. In conclusion, IL-18 -607C/A (rs1946518) promoter polymorphism is associated with IS susceptibility, and the C allele may confer increased IS risk.

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.

The interleukin-10 promoter polymorphism rs1800872 (-592C>A), contributes to cancer susceptibility: meta-analysis of 16,785 cases and 19,713 controls

Interleukin-10 (IL-10) is a multifunctional cytokine which participates in the development and progression of various malignant tumors. To date, a number of case–control studies were conducted to detect the association between IL-10-592C>A polymorphism and cancer risk in humans. However, the results of these studies on the association remain conflicting. In an effort to solve this controversy, we performed a meta-analysis based on 70 case–control studies from 65 articles, including 16 785 cancer cases and 19 713 controls. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall results suggested that the variant homozygote genotype AA of the IL-10-592C>A polymorphism was associated with a moderately decreased risk of all cancer types (OR = 0.90, 95% CI = 0.83–0.98 for homozygote comparison, OR = 0.92, 95% CI = 0.86–0.98 for recessive model). In the stratified analyses, the risk remained for studies of smoking-related cancer, Asian populations and hospital-based studies. These results suggested that the IL-10-592C>A polymorphism might contribute to the cancer susceptibility, especially in smoking-related cancer, Asians and hospital-based studies. Further studies are needed to confirm the relationship.

Genes of the interleukin-18 pathway are associated with susceptibility to Barrett's esophagus and esophageal adenocarcinoma

OBJECTIVES

To investigate the association of genetic polymorphisms of the interleukin-18 (IL-18) pathway to Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Most cases of EAC arise in a background of reflux-induced BE. Genetic influences in this pathway are poorly understood. IL-18 is a multifunctional cytokine implicated in anti-tumor immunity. A number of polymorphisms of the IL-18 and IL-18 receptor-accessory protein (IL-18RAP) genes have been reported to alter gene expression and have recently been linked to inflammatory processes and various tumors, but have not heretofore been studied in BE and EAC.

METHODS

Two IL-18 promoter polymorphisms -137 G/C and -607 C/A, (rs187238 and rs1946518) and one IL-18RAP polymorphism (rs917997, C/T) were analyzed. Each single-nucleotide polymorphism (SNP) was genotyped in the following groups: EAC, BE, reflux esophagitis (RE), and controls and analyzed for association with disease status.

RESULTS

The IL-18RAP rs917997C allele is strongly associated with a protective effect in BE (P = 0.0002) and EAC (P = 6 × 10(-7)), which approaches genome-wide levels of significance for allele association without incurring significant multiple testing. The CC genotype at IL-18RAP locus rs917997 was associated with a protective effect against esophageal disease (P = 6 × 10(-4), odds ratio (OR) = 0.59, and 95% confidence interval (CI) 0.43-0.80 for BE; and P = 2 × 10(-6), OR = 0.46, and 95% CI 0.34-0.64 for EAC). The genotype frequencies of IL-18-607 C/A were weakly associated with BE (P = 0.02), and this trend was also seen between controls and EAC (P = 0.07). The CC genotype was associated with an increased risk of BE (OR = 1.45, 95% CI 1.07-1.98) and approached significance for EAC (OR = 1.34, 95% CI 0.98-1.82). Allele and genotype frequencies at these loci were not significantly different between the RE group and controls. Although no significant association was observed between the disease groups at the -137 G/C locus, the -137G/-607C haplotype was associated with increased risk of BE (P = 0.006) with haplotype frequencies of 55% in controls and 65% in BE.

CONCLUSIONS

These data show a strong association of the IL-18RAP SNP rs917997 locus with BE and EAC and suggestive association of the Barrett's population with the IL-18-607 C/A promoter polymorphism. As both of these SNPs have been demonstrated as expression quantitative trait loci affecting expression of the respective genes, this strongly implicates IL-18 signaling in susceptibility to BE and EAC.

Familial and large-scale case-control studies identify genes associated with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy and has a remarkable geographic distribution, which is highly prevalent in southern China, Southeast Asia, and North Africa. Although most of the NPC are sporadic cases, the familial clustering of NPC has been demonstrated worldwide. Accumulating studies have proposed that the etiology of NPC is multi-stage and multi-factorial, involving genetic lesions, Epstein-Barr virus infection, and environmental exposure. Genetic variations result in differences in gene function, which in turn lead to different susceptibility to disease. Many studies have been carried out to dissect the genetic variants that contribute to NPC susceptibility. This article reviews the current progress of genetic studies to identify genes associated with NPC, focusing on the familial linkage and large-scale case-control study designs.

The interleukin-10-1082 promoter polymorphism and cancer risk: a meta-analysis

Interleukin-10 (IL-10) is a multifunctional cytokine with both immunosuppressive and anti-angiogenic properties and play an important role in the pathogenesis of cancer. IL-10-1082A>G polymorphism is the most extensively studied polymorphism in the IL-10 gene in cancer susceptibility. To date, a number of case-control studies were conducted to investigate the association between IL-10-1082A>G polymorphism and cancer risk in humans. However, the association between the IL-10-1082A>G polymorphism and cancer risk is still ambiguous. In an effort to solve this controversy, we performed a meta-analysis based on 61 case-control studies, including 14,499 cancer cases and 16,967 controls. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. In the stratified analyses by specific cancer type, increased risk was found in lung cancer (OR = 3.16, 95% CI = 1.16-8.63 for GA versus AA; OR = 2.07, 95% CI = 1.16-3.70 for GG versus AA; OR = 3.17, 95% CI = 1.31-7.68 for GA/GG versus AA) and non-Hodgkin's lymphoma (OR = 1.18, 95% CI = 1.02-1.36 for GA versus AA; OR = 1.17, 95% CI = 1.02-1.35 for GA/GG versus AA). The meta-analysis also indicated that the variant genotypes were associated with a moderately increased risk in Asians in all genetic models (OR = 1.80, 95% CI = 1.17-2.76 for GA versus AA; OR = 3.32, 95% CI = 1.62-6.82 for GG versus AA; OR = 1.67, 95% CI = 1.07-2.60 for GA/GG versus AA; OR= 2.93, 95% CI = 1.43-6.03 for GG versus AA/GA). The meta-analysis suggested that the IL-10-1082A>G polymorphism was associated with increased risk of cancer in Asians and lung cancer and non-Hodgkin's lymphoma. To draw comprehensive and true conclusions, more researches with larger numbers of worldwide participants are needed to examine associations between IL-10-1082A>G polymorphism and cancer risk.

Hardy-Weinberg disequilibrium of the IL-18 C-607A SNP suggesting selective advantage of heterozygotes

Interleukin-18 (IL-18) plays a key role in autoimmune, inflammatory, and infectious diseases. The IL-18 gene contains a C to A single nucleotide polymorphism (SNP) at position -607 (C-607A) within the promoter region, which was found to affect the promoter activity and subsequently the protein level of IL-18. We investigated this SNP in a group of healthy Singaporeans and found that CA was the most common genotype and the C allele was more prevalent than the A allele, which was not always the case in other ethnic groups. In addition, Singaporean Chinese were significantly different from Singaporean Indians in both allelic and genotypic distributions. Furthermore, significant deviations from Hardy-Weinberg equilibrium of this SNP were found in all three ethnic groups studied (Chinese, Indians, and Malays) and also in other published literature, suggesting that heterozygotes of this IL-18 C-607A SNP may have certain selective advantages.

IL-18 105 A>C polymorphism contributes to renal manifestations in patients with SLE

Systemic lupus erythematosus (SLE) is a multisystem autoimmune connective tissue disorder characterized by various aberrations including increased production of IL-18. As IL-18 105 A>C polymorphic variants have been linked to increased production of this cytokine, we investigated the prevalence of IL-18 105 A>C (rs549908) polymorphic variants in SLE patients (n = 111) and controls (n = 152). There were no significant differences in the distribution of IL-18 105 A>C polymorphic variants in SLE patients and controls. However, there was a significant association between the IL-18 105 AA genotype (recessive model) and renal manifestations OR = 3.360 (1.523–7.415, P = 0.0039) and the P value remained statistically significant after Bonferroni correction (P corr = 0.0351).Our findings indicate that the IL-18 105 AA genotype variant can contribute to renal manifestations in patients with SLE.

Cox-2 and IL-10 polymorphisms and association with squamous cell carcinoma of the head and neck in a Korean sample

Cyclooxygenase-2 (COX-2) is involved in inflammation and carcinogenesis. Interleukin-10 (IL-10) is also regarded as anti-inflammatory factors with the multi-functional ability to positively and negatively influence functional immunity and tumor development. Genetic polymorphisms of COX-2 and IL-10 might contribute to the development of squamous cell carcinoma of the head and neck (SCCHN). The purpose of this study was to evaluate the association of COX-2 and IL-10 single nucleotide polymorphisms (SNPs) with the risk of SCCHN in a Korean sample. We analyzed the COX-2 SNPs, -1329A>G, +1266C>T, and +6365T>C, and the IL-10 SNPs, -1082A>G, +920T>G, and +3917T>C, in 290 Korean SCCHN patients and 358 healthy controls. There was no significant association between the risk of SCCHN and the three COX-2 or three IL-10 SNPs. We analyzed three haplotypes (ht1, ht2, ht3) for COX-2 and found that COX-2 ht3+/+ was associated with a decreased risk of SCCHN in a Korean sample, compared with the COX-2 ht3 -/- genotype (P=0.03). Two haplotypes (ht1, ht2) of IL-10 were analyzed and there was no statistical significance in the distribution of haplotypes. Based on these results, the COX-2 haplotype ht3 can be used as a molecular biomarker to predict low risk groups of SCCHN in a Korean sample.

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 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).

Tumour necrosis factor gene polymorphism: a predictive factor for the development of post-transplant lymphoproliferative disease

Background:

Epstein–Barr virus-positive post-transplant lymphoproliferative disease (PTLD) is a potentially lethal complication of iatrogenic immunosupression after transplantation. Predicting the development of PTLD allowing early and effective intervention is therefore of importance. Polymorphisms within cytokine genes are implicated in susceptibility to, and progression of, disease however the published data are often conflicting. We undertook investigation of polymorphic alleles within cytokine genes in PTLD and non-PTLD transplant cohorts to determine risk factors for disease.

Methods:

SSP-PCR was used to analyse single nucleotide polymorphism within tumour necrosis factor (TNF)-α, interleukin- 1, -6, -10 and lymphotoxin-α genes. The TNF-α levels were measured by standard enzyme-linked immuno-absorbant assay.

Results:

We show an association between variant alleles within the TNF-α promoter (−1031C (P=0.005)); −863A (P=0.0001) and TNF receptor I promoter regions (−201T (P=0.02)); −1135C (P=0.03) with the development of PTLD. We also show an association with TNF-α promoter haplotypes with haplotype-3 significantly increased (P=0.0001) and haplotype-1 decreased (P=0.02) in PTLD patients compared to transplant controls. Furthermore, we show a significant increase (P=0.02) in the level of TNF-α in PTLD patient plasma (range 0–97.97 pg ml⁻¹) compared to transplant controls (0–8.147 pg ml⁻¹), with the highest levels found in individuals carrying the variant alleles.

Conclusion:

We suggest that genetic variation within TNF-α loci and the level of plasma cytokine could be used as a predictive risk factor for the development of PTLD.

Genetic polymorphism of interleukin-16 and risk of nasopharyngeal carcinoma

BACKGROUND

Common genetic variants in inflammatory cytokine genes can affect the risk of developing nasopharyngeal carcinoma (NPC). Interleukin-16 (IL-16), a pro-inflammatory cytokine, plays a pivotal role in inflammatory diseases as well as in the pathogenesis of tumors.

METHODS

We analyzed rs4778889 T/C, rs11556218 T/G, and rs4072111 C/T polymorphisms of IL-16 in 206 patients with NPC and 373 healthy controls in a Chinese population, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy and DNA sequencing methods.

RESULTS

The rs11556218 T/G polymorphism of IL-16 gene was significantly associated with the susceptibility to NPC. The TG genotype was associated with a significantly higher risk of NPC as compared with the TT genotype (OR=1.67; 95% CI, 1.18-2.36). Patients carrying the G allele had a significantly higher risk for developing NPC compared to individuals carrying the T allele (OR=1.36; 95% CI, 1.03-1.78).

CONCLUSIONS

This study shows an association between IL-16 gene polymorphisms and the risk of NPC, and our data suggests that IL-16 gene polymorphisms may be useful as genetic susceptibility markers for NPC.

The DLC-1 -29A/T polymorphism is not associated with nasopharyngeal carcinoma risk in Chinese population

Deleted in liver cancer-1 (DLC-1), encoding a Rho GTPase-activating protein (GAP), is considered as a promising candidate tumor suppressor gene in nasopharyngeal carcinoma (NPC). The single-nucleotide polymorphism (SNP) -29A/T upstream of ATG start codon was found when gene mutation profile of DLC-1 in NPC was analyzed. To evaluate the correlation between SNP -29A/T in the promoter region of DLC-1 gene and risk of NPC, a total of 521 samples from a Chinese population, including 320 healthy individuals and 201 NPC patients, were collected for SNP analysis by PCR-single-strand conformation polymorphism and sequencing. The differences in allele and genotype frequencies between NPC patients and controls were tested using logistic regression statistical method. No significant differences were found in allele or genotype frequencies between NPC patients and controls or among different NPC clinical stages. Hence, our data indicate that the SNP -29A/T of DLC-1 gene is not associated with NPC susceptibility.

Association of single nucleotide polymorphisms in the IL-18 gene with production of IL-18 protein by mononuclear cells from healthy donors

IL-18 has proinflammatory effects and participates in both innate and adaptive cellular and humoral immunity. A number of SNPs that influence IL-18 production are found in the gene promoter region. We investigated the association of SNPs in the IL-18 promoter at −607 and −137 with the level of IL-18 protein production by PBMC from healthy donors from Southwestern Siberia. The genetic distribution of these SNPs in the promoter site was established by PCR. IL-18 protein production was determined by ELISA. Our results showed that PBMC from donors carrying allele 137C have lower levels of both spontaneous and LPS-stimulated IL-18 production. In contrast, PBMC from donors carrying allele 607A showed significant increases in spontaneous and stimulated IL-18 production compared to wild type. Our study suggests that the SNPs −607 and −137 in the promoter region of the IL-18 gene influence the level of IL-18 protein production by PBMC from healthy donors in Southwestern Siberia.

Interleukin-10 gene polymorphism in patients with papillary thyroid cancer in Turkish population

OBJECTIVE

Interleukin-10 (IL-10) is a major anti-inflammatory cytokine that plays a crucial role in the regulation of the immune system. Chronic inflammation has been reported to be a risk factor for thyroid neoplasia. The propensity to mount an inflammatory response is modified by germ line variation in cytokine and other inflammation-related genes. We hypothesized that a proinflammatory genotype would be positively associated with thyroid cancer. We aimed to evaluate the relation between the genotypic and allelic frequencies of the IL-10(-1082 G/A), IL-10(-592 A/C), and IL-10(-819 C/T) polymorphisms, and their association with the risk of developing papillary thyroid cancer (PTC) in the Turkish population.

RESEARCH DESIGN AND METHODS

Forty-two patients with PTC and 113 healthy controls were included in this study. The diagnosis of PTC was confirmed by histopathologic examination after surgery. The evaluation of genotype for IL-10 gene polymorphism was performed using PCR-restriction fragment length polymorphism method.

RESULTS

Statistically significant difference IL-10(-1082 G/A) gene polymorphism was determined between 2 (PTC and control) groups. No difference was determined with respect to IL-10(-592 A/C) and IL-10(-819 C/T) gene polymorphisms, and IL-10(-1082 G/A), IL-10(-592 A/C), and IL-10(-819 C/T) allele frequencies of participating between the control group and the patients with PTC (p>0.05).

CONCLUSIONS

The polymorphism of IL-10(-1082 G/A) gene was significantly associated with the occurrence of PTC. Such studies will contribute significantly to our understanding of the biological role of IL-10(-1082 G/A) gene polymorphism in PTC development. In conclusion, IL-10(-1082 G/A) gene polymorphism may affect the survival of papillary thyroid carcinoma.

Genetic association of cytokine DNA polymorphisms with head and neck cancer

Mutations in oncogenes or tumor suppressor genes, as well as environmental factors such as tobacco chewing or smoking, poor oral hygiene, ill-fitting dental appliances, infection by certain HPV types, or alcohol abuse, seem to be involved in the multifactorial process of carcinogenesis in head and neck. Recently, several genetic association studies have indicated that common DNA polymorphisms in low penetrance genes may affect the susceptibility of an individual to malignancy. Cytokines are an important group of proteins that regulate and mediate inflammation and angiogenesis. Tumor growth, invasion and metastasis are facilitated when there is a deregulation in their production. Cytokines include interleukins (ILs), tumor necrosis factors (TNFs) and certain growth factors (GFs). A number of genetic association studies have recently investigated the putative correlation between functional DNA polymorphisms in cytokine genes and head and neck carcinomas. This review discusses the findings of such studies in oral, nasopharyngeal and esophageal squamous cell carcinomas. Extensive research has indicated that functional polymorphisms affecting gene expression of IL-4,-6,-8,-10 as well as TNF-alpha are strongly associated with increased risk for oral cancer. Gene expression of TNF-alpha seems to be associated also with esophageal carcinomas, while for nasopharyngeal cancer the picture is yet unclear. It is generally believed that such genetic association studies will gradually increase our knowledge regarding the predisposed manifestation and advancement of these malignancies in the head and neck region.

Interleukin-18 gene promoter polymorphisms and the risk of esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is multifactorial, and the genetic background may be a crucial etiologic factor. Interleukin-18 (IL-18) is a multifunctional cytokine that induces interferon (IFN)-gamma secretion and plays an important role in antitumor immunity. Variations in the DNA sequence in the IL-18 gene promoter may lead to altered IL-18 production and/or activity, and so this can modulate an individual's susceptibility to ESCC. To test this hypothesis, we investigated the relationship of IL-18 gene promoter -137 G/C and -607 C/A polymorphisms and their haplotypes with the risk of ESCC in a Chinese population.

METHODS

Two hundred and thirty five patients with ESCC and 250 age- and sex-matched controls, using sequence specific primers-polymerase chain reaction (PCR-SSP).

RESULTS

Two polymorphisms, -137 G/C and -607 C/A were in strong linkage disequilibrium (LD). There were significantly 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 ESCC as compared with the -137 GG genotypes (OR = 1.91, 95% CI, 1.29-2.82, p = 0.001 and OR = 2.95, 95% CI, 1.23-7.04, p = 0.012, respectively). Consistent with the results of the genotyping analyses, the -137 C/ -607 A haplotype was associated with a significantly increased risk of ESCC as compared with the -137G/-607 C haplotype (OR = 1.61; 95% CI, 1.16-2.23; p = 0.004).

CONCLUSION

This study shows for the first time an association between IL-18 gene promoter -137 G/C polymorphism may contribute represent a genetic risk factor for ESCC in a Chinese population.

Interleukin-10 and interferon-gamma gene polymorphisms in patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a multifactorial disease. Cytokines driving the immune response seem to be disturbed in NPC patients. Since interleukin-10 (IL-10) is known to reduce the production of interferon-gamma (IFN-gamma), we supposed that genetic differences in IL-10 and IFN-gamma expression could be a mechanism by which NPC cells escape antitumour immune response. As the production of each cytokine is affected by the genetic background, we investigated the possible association between single nucleotide polymorphisms in genes of IL-10 and IFN-gamma with NPC. Different IL-10 -1082 G/A and IFN-gamma+874 Tau/Alpha genotypes were determined in 160 patients with nasopharyngeal carcinoma and 197 healthy controls. No association was found either for each SNP studied alone or for the combined analysis for both IL-10 and IFN-gamma polymorphisms among NPC patients in comparison with controls. Compared with individuals from high incidence countries, we noted huge significant differences in genotype distribution between individuals from low and intermediate NPC incidence countries. Polymorphisms of the IL-10 and IFN-gamma do not appear to be associated with NPC risk in the Tunisian population. Nevertheless, we strongly believe that the relationship between cytokines polymorphisms and NPC susceptibility deeply depends on the ethnicity.

Interleukin (IL)-18 polymorphism 133C/G is associated with severe respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of bronchiolitis in infants. During the course of RSV infection, predominant T helper cell (TH) 2 response is associated with disease progression, whereas predominant TH1 reaction provides convalescence. Interleukin (IL)-18 plays an important role in adjusting the TH1/TH2 immune response to viral infections. Thus, we tested the hypothesis that polymorphisms in IL-18 were associated with severe RSV-associated diseases.

METHODS

We chose to study the promotor polymorphisms -607A/C (rs1946518) and -137G/C (rs187238), the 2 exon polymorphisms 113T/G (rs360718) and 127C/T (rs360717), and 2 intron polymorphisms 5304A/G (rs795467) and 133G/C (rs360721) within the IL-18 gene. Genotyping was performed on 154 children with severe RSV infection as defined by strict clinical criteria and on 270 controls. Statistical analyses of single polymorphisms made use of the Armitage's trend test, haplotypes were calculated with FASTEHPLUS and FAMHAP.

RESULTS

-133G/C showed association with severe RSV infection (P = 0.043). The association was further supported by haplotype analyses with all 6 polymorphisms (P < 0.00001 for association with RSV).

CONCLUSIONS

This study indicates possible involvement of IL-18 in the determination of severe RSV-associated diseases. Defining the genetic basis of RSV bronchiolitis might help us in identifying new drug targets for a more specific therapy. In addition, it might enable an early identification of children at risk for RSV bronchiolitis and thus make a selective prevention feasible.

Genetic variation in interleukin-10 gene and risk of oral cancer

BACKGROUND

Common genetic variants in immune and inflammatory response genes can affect the risk of developing oral cancer. Interleukin-10 (IL-10) is an immunosuppressive cytokine which may facilitate development of cancer by supporting tumor escape from the immune response. Inter-individual variations in IL-10 production were genetically contributed to polymorphisms within IL-10 promoter region. We determined whether single nucleotide polymorphisms (SNPs) at positions -1082 A/G (rs1800870), -819 T/C (rs1800871) and -592 A/C (rs1800872) in the IL-10 gene promoter were involved in predisposing an individual to oral cancer.

METHODS

We analyzed 3 SNPS of IL-10 gene promoter in 280 patients with oral cancer and 300 age and sex matched controls in a Chinese population, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy.

RESULTS

There were significant differences in the genotype and allele distribution of -1082 A/G (rs1800870) polymorphism of the IL-10 gene among cases and controls. The -1082 G alleles carriers were associated with a significantly increased risk of oral cancer compared with the non-carriers (OR=1.821, 95% CI, 1.329-2.496, P<0.001). Haplotype analysis revealed that the GCC haplotype (defined by SNPs at positions -1082, -819 and -592) of IL-10 gene conveys the highest risk for oral cancer compared with the ATA haplotype (OR=1.716; 95% CI, 1.230-2.395; P=0.001).

CONCLUSION

IL-10 gene promoter -1082 A/G (rs1800870) polymorphism, and its haplotype are significantly associated with the risk of oral cancer. Our data suggests that IL-10 gene plays an important role in the development of oral cancer.

Association of IL-8 (−251)T/A polymorphism with susceptibility to and aggressiveness of nasopharyngeal carcinoma

Interleukin-8 (IL-8) is an angiogenic chemokine that plays a potent role in both development and progression of many human malignancies including nasopharyngeal carcinoma (NPC). In the present study, we evaluated the susceptibility and prognostic implications of the (-251) T/A genetic variation in IL-8 in NPC. We used the allele-specific polymerase chain reaction to characterize the variation of the IL-8 promoter region for 160 unrelated Tunisian patients with NPC and 169 healthy control subjects. There was a significant association between the homozygotes IL-8 (-251) AA genotype and nasopharyngeal carcinoma (OR = 2.46; P = 0.004). The presence of the IL-8 (-251) AA genotype was highly associated with elevated NPC risk for male patients. A significant association was demonstrated between the IL-8 (-251) AA genotype and the aggressive forms of NPC as defined by large tumor size, lymph node metastasis, and advanced stages. Moreover, the presence of the IL-8 (-251) AA genotype indicated a significant association with decreased overall survival. Our findings suggest that the IL-8 promoter polymorphism is associated with increased nasopharyngeal carcinoma risk, particularly in males, as well as disease progress, supporting our hypothesis for IL-8 involvement in NPC pathogenesis.

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

Genetic factors are known to be important in the development of prostate cancer. 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 in the IL-18 gene promoter may lead to altered IL-18 production and/or activity, and so this can modulate an individual's susceptibility to prostate cancer. To test this hypothesis, we investigated the relationship of IL-18 gene promoter -137 G/C and -607 C/A polymorphisms and their haplotypes with the risk of prostate cancer. We analyzed two single nucleotide polymorphisms of IL-18 gene promoter -137 G/C and -607 C/A in 265 patients with prostate cancer and 280 age- and sex-matched controls, using sequence-specific primers-polymerase chain reaction strategy. 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 prostate cancer as compared with the -137 GG genotypes [odds ratio (OR) = 1.721; 95% confidence interval (CI): 1.187-2.496; p = 0.004, and OR = 2.181; 95% CI: 1.034-4.603; p = 0.037, for GC and CC, respectively]. Consistent with the results of the genotyping analyses, the -137C/-607A haplotype was associated with a significantly increased risk of prostate cancer as compared with the -137G/-607C haplotype (OR = 1.544; 95% CI, 1.137-2.096; p = 0.005). This study shows for the first time an association between IL-18 gene promoter -137 G/C polymorphism and prostate cancer in a Chinese population.

Clinical and experimental approaches to the pathophysiology of interleukin-18 in cancer progression

Interleukin-18 (IL-18, interferon [IFN]-gamma-inducing factor) is a proinflammatory cytokine converted to a biologically active molecule by interleukin (IL)-1beta converting enzyme (caspase-1). A wide range of normal and cancer cell types can produce and respond to IL-18 through a specific receptor (IL-18R) belonging to the toll-like receptor family. The activity of IL-18 is regulated by IL-18-binding protein (IL-18bp), a secreted protein possessing the ability to neutralize IL-18 and whose blood level is affected by renal function and is induced by IFNgamma. IL-18 plays a central role in inflammation and immune response, contributing to the pathogenesis and pathophysiology of infectious and inflammatory diseases. Because immune-stimulating effects of IL-18 have antineoplastic properties, IL-18 has been proposed as a novel adjuvant therapy against cancer. However, IL-18 increases in the blood of the majority of cancer patients and has been associated with disease progression and, in some cancer types, with metastatic recurrence risk and poor clinical outcome and survival. Under experimental conditions, cancer cells can also escape immune recognition, increase their adherence to the microvascular wall and even induce production of angiogenic and tumor growth-stimulating factors via IL-18-dependent mechanism. This is particularly visible in melanoma cells. Thus, the role of IL-18 in cancer progression and metastasis remains controversial. This review examines the clinical correlations and biological effects of IL-18 during cancer development and highlights recent experimental insights into prometastatic and proangiogenic effects of IL-18 and the use of IL-18bp against cancer progression.