Lack of association between -174G>C and -634C>G polymorphisms in interleukin-6 promoter region and lung cancer risk: a meta-analysis

Genetic polymorphisms and lung cancer risk: Evidence from meta-analyses and genome-wide association studies

A growing number of studies investigating the association between Single Nucleotide Polymorphisms (SNPs) and lung cancer risk have been published since over a decade ago. An updated integrative assessment on the credibility and strength of the associations is required. We searched PubMed, Medline, and Web of Science on or before August 29^th, 2016. A total of 198 articles were deemed eligible for inclusion, which addressed the associations between 108 variants and lung cancer. Among the 108 variants, 63 were reported to be significantly associated with lung cancer while the remaining 45 were reported non-significant. Further evaluation integrating the Venice Criteria and false-positive report probability (FPRP) was performed to determine the strength of cumulative epidemiological evidence for the 63 significant associations. As a result, 15 SNPs on or near 12 genes and one miRNA with strong evidence of association with lung cancer risk were identified, including TERT (rs2736098), CHRNA3 (rs1051730), AGPHD1 (rs8034191), CLPTM1L (rs401681 and rs402710), BAT3 (rs3117582), TRNAA (rs4324798), ERCC2 (Lys751Gln), miR-146a2 (rs2910164), CYP1B1 (Arg48Gly), GSTM1 (null/present), SOD2 (C47T), IL-10 (-592C/A and -819C/T), and TP53 (intron 6). 19 SNPs were given moderate rating and 17 SNPs were rated as having weak evidence. In addition, all of the 29 SNPs identified in 12 genome-wide association studies (GWAS) were proved to be noteworthy based on FPRP value. This review summarizes and evaluates the cumulative evidence of genetic polymorphisms and lung cancer risk, which can serve as a general and useful reference for further genetic studies.

IL6-174 G>C Polymorphism (rs1800795) Association with Late Effects of Low Dose Radiation Exposure in the Portuguese Tinea Capitis Cohort

Head and neck cancers, and cardiovascular disease have been described as late effects of low dose radiation (LDR) exposure, namely in tinea capitis cohorts. In addition to radiation dose, gender and younger age at exposure, the genetic background might be involved in the susceptibility to LDR late effects. The -174 G>C (rs1800795) SNP in IL6 has been associated with cancer and cardiovascular disease, nevertheless this association is still controversial. We assessed the association of the IL6-174 G>C SNP with LDR effects such as thyroid carcinoma, basal cell carcinoma and carotid atherosclerosis in the Portuguese tinea capitis cohort. The IL6-174 G>C SNP was genotyped in 1269 individuals formerly irradiated for tinea capitis. This sampling group included thyroid cancer (n = 36), basal cell carcinoma (n = 113) and cases without thyroid or basal cell carcinoma (1120). A subgroup was assessed for atherosclerosis by ultrasonography (n = 379) and included matched controls (n = 222). Genotypes were discriminated by real-time PCR using a TaqMan SNP genotyping assay. In the irradiated group, we observed that the CC genotype was significantly associated with carotid plaque risk, both in the genotypic (OR = 3.57, CI = 1.60–7.95, p-value = 0.002) and in the recessive (OR = 3.02, CI = 1.42–6.42, p-value = 0.004) models. Irradiation alone was not a risk factor for carotid atherosclerosis. We did not find a significant association of the IL6-174 C allele with thyroid carcinoma or basal cell carcinoma risk. The IL6-174 CC genotype confers a three-fold risk for carotid atherosclerotic disease suggesting it may represent a genetic susceptibility factor in the LDR context.

Association between interleukin-6 polymorphisms and urinary system cancer risk: evidence from a meta-analysis

Background

Interleukin-6 (IL-6) is a multifunctional proinflammatory cytokine involved in cancer initiation and progression. Numerous studies have investigated the associations between IL-6 polymorphisms (IL-6 −174G>C, −592G>C, −597G>A) and risk of urinary system cancers, including prostate cancer, bladder cancer, and renal cell cancer. However, conclusions from these studies were controversial. Thus, we conducted the current meta-analysis to obtain the comprehensive profile regarding the association between IL-6 polymorphisms and urinary system cancer risk.

Methods

According to inclusion and exclusion criteria, the associations of IL-6 polymorphisms with urinary system cancer were searched from database and analyzed using STATA 12.0 statistical software. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the associations.

Results

A total of 20 previous publications consisting of 15,033 cases and 17,655 controls were involved in this meta-analysis. Significant association was observed in overall population regarding IL-6 −592G>C polymorphisms (G vs C: OR =0.1.30, 95% CI =1.13−2.52; GG vs CC: OR =1.81, 95% CI =1.31−2.52; GG vs GC + CC: OR =1.33, 95% CI =1.02−1.75; GG + GC vs CC: OR =1.41, 95% CI =1.09−1.83). In the stratified analyses by ethnicity, the significant associations were found among Asian (GG vs CC: OR =1.89, 95% CI =1.34−2.66; GG + GC vs CC: OR =1.43, 95% CI =1.09−1.87) and Black population (GC vs CC: OR =0.20, 95% CI =0.05−0.82) rather than Caucasian men. Likewise, there were noticeable associations in almost all the other subanalyses such as cancer types, control sources, genotyped methods, and sample sizes. However, no significant associations were identified between any of IL-6 −174G>C polymorphisms with urinary system cancer, except for Asian population (G vs C: OR =0.81, 95% CI =0.70−0.95; GG vs CC: OR =0.51, 95% CI =0.35−0.74; GC vs CC: OR =0.49, 95% CI =0.33−0.72; GG + GC vs CC: OR =0.50, 95% CI =0.35−0.72; respectively). In addition, no significant associations were detected between IL-6 −597G>A polymorphism and urinary system cancer, regardless of whole or subgroups.

Conclusion

This meta-analysis presents a relatively comprehensive view of the associations between IL-6 polymorphism and urinary system cancer risk to explore the carcinogenic mechanisms, which will help shed light on the clinical diagnosis and therapy for urinary system cancer. However, further detailed studies are needed to verify our conclusion.