Xeroderma pigmentosum group G (XPG) protein is essential for the nucleotide excision repair (NER) system, and genetic variations in XPG/ERCC5 that affect DNA repair capacity may contribute to the risk of tobacco-induced cancers, including squamous cell carcinoma of the head and neck (SCCHN). We investigated the association between XPG/ERCC5 polymorphisms and risk of squamous cell carcinoma of the head and neck (SCCHN).
We genotyped 12 tagging and potentially functional single nucleotide polymorphisms (SNPs) of XPG/ERCC5 in a case-control study of 1,059 non-Hispanic white patients with SCCHN and 1,066 cancer-free age-and sex matched controls and evaluated their associations with SCCHN risk.
Multivariate logistic regression showed that only an intronic tagging SNP (rs4150351A/C) of XPG/ERCC5 was associated with a decreased risk of SCCHN (adjusted OR=0.76, 95% CI=0.62–0.92 for AC vs. AA; adjusted OR=0.81, 95% CI=0.67–0.98 for AC/CC vs. AA), but this association was nonsignificnant after corrections by the permutation test (empirical P=0.105). In the genotype-phenotype correlation analysis using peripheral lymphocytes from 44 SCCHN patients, we found that rs4150351 AC/CC was associated with a statistically significant increase in XPG/ERCC5 mRNA expression.
These findings suggest that genetic variation in XPG/ERCC5 may not affect the SCCHN risk, although rs4150351 C variant genotypes were associated with the increased expression of XPG/ERCC5 mRNA and nonsignificantly decreased risk of SCCHN. Larger population-based and additional functional studies are warranted to validate our findings.
ERCC5; polymorphism; SCCHN; risk
Inherited functional single-nucleotide polymorphisms (SNPs) in DNA repair genes may influence the capability of DNA repair and contribute to the risk of breast cancer. We therefore performed a case–control study to investigate the association of three in excision repair cross-complimentary group 1 (ERCC1) and three in xeroderma pigmentosum complementation group F (XPF) with the risk of breast cancer. Genotyping of ERCC1 (rs2298881, rs3212986, and rs11615) and XPF (rs2276465, rs6498486, and rs2276466) was performed in a 384-well plate format on the MassARRAY® platform. Odds ratios and their corresponding 95% confidence intervals were used to assess the effect of each SNP on breast cancer risk. The ERCC1 rs11615 variant A/A genotype was associated with increased breast cancer risk in codominant, dominant, and recessive models, and XPF rs6498486 variant C/C genotype carriers have a significantly increased breast cancer risk in codominant, dominant, and recessive models. Individuals with both the ERCC1 rs11615 A allele and XPF rs6498486 C allele had a heavy increased risk of breast cancer compared to double wild-type homozygotes. The present study shows that the ERCC1 rs11615 and XPF rs6498486 polymorphisms are associated with breast cancer risk in a Chinese population. Further large-scale studies are required to elucidate whether these ERCC1 and XPF SNPs interact with environmental factors in the development of breast cancer.
Non-synonymous single nucleotide polymorphisms (SNPs) within vital DNA repair genes may cause reduction of activity leaving the genome unrepaired resulting in genomic instability and cancer.
Materials and methods
The present endeavour involved study on the association of the SNP rs13181 (Lys751Gln/A18911C) in the Nucleotide Excision Repair (NER) pathway gene ERCC2 (excision repair cross-complementing rodent repair deficiency, complementation group 2) with the risks of Squamous Cell Carcinomas of the Head and Neck (SCCHN) and Breast cancer using a case-control based association study among 685 (400 controls and 285 SCCHN-affected cases) and 395 (227 normal healthy female controls and 168 breast cancer cases) ethnically-matched samples, respectively from north India using Polymerase Chain Reaction followed by Restriction Fragment Length Polymorphism (PCR-RFLP) analysis.
Results showed significant association of rs13181 homozygous mutant (CC) [Odds Ratio (OR) 4.412, 95% Confidence Interval (CI) 2.413 to 8.068], heterozygous (AC) (OR 2.086, 95% CI 1.246 to 3.492) and combined mutant (AC + CC) (OR 2.672, 95% CI 1.647 to 4.334) genotypes with predisposition to Breast cancer. Statistically significant increase in SCCHN risk was also associated with the mutant genotypes of rs13181 (ERCC2), viz. homozygous mutant (CC) (OR 1.680, 95% CI 1.014 to 2.784), heterozygous (AC) (OR 1.531, 95% CI 1.092 to 2.149) and combined mutant (AC + CC) (OR 1.560, 95% CI 1.128 to 2.158) genotypes.
The results of this case-control study indicate that the polymorphism rs13181 might be a risk factor for predisposition towards SCCHN and breast cancer among north Indian subpopulations.
Inherited functional single nucleotide polymorphisms (SNPs) in DNA repair genes may alter DNA repair capacity and thus contribute to cancer risk.
Three ERCC1 functional SNPs (rs2298881C>A, rs3212986C>A and rs11615G>A) and two XPF/ERCC4 functional SNPs (rs2276466C>G and rs6498486A>C) were genotyped for 1125 gastric adenocarcinoma cases and 1196 cancer-free controls by Taqman assays. Odds ratios (OR) and 95% confidence intervals (CI) were used to estimate risk associations, and false-positive report probabilities (FPRP) were calculated for assessing significant findings.
ERCC1 rs2298881C and rs11615A variant genotypes were associated with increased gastric cancer risk (adjusted OR = 1.33, 95% CI = 1.05–1.67 for rs2298881 AC/CC and adjusted OR = 1.23, 95% CI = 1.05–1.46 for rs11615 AG/AA, compared with their common genotype AA and GG, respectively). Patients with 2–3 ERCC1 risk genotypes had significant increased risk (adjusted OR = 1.56, 95% CI = 1.27–1.93), compared with those with 0–1 ERCC1 risk genotypes, and this risk was more significantly in subgroups of never drinkers, non-gastric cardia adenocarcinoma (NGCA) and clinical stage I+II. All these risks were not observed for XPF SNPs.
These findings suggest that functional ERCC1 SNPs may contribute to risk of gastric cancer. Larger and well-designed studies with different ethnic populations are needed to validate our findings.
Head and neck cancers (HNC) are commonly treated with radiation and platinum-based chemotherapy, which produce bulky DNA adducts to eradicate cancerous cells. Because nucleotide excision repair (NER) enzymes remove adducts, variants in NER genes may be associated with survival among HNC cases both independently and jointly with treatment.
Cox proportional hazards models were used to estimate race-stratified (White, African American) hazard ratios (HRs) and 95 % confidence intervals for overall (OS) and disease-specific (DS) survival based on treatment (combinations of surgery, radiation, and chemotherapy) and 84 single nucleotide polymorphisms (SNPs) in 15 NER genes among 1,227 HNC cases from the Carolina Head and Neck Cancer Epidemiology Study.
None of the NER variants evaluated were associated with survival at a Bonferroni-corrected alpha of 0.0006. However, rs3136038 [OS HR = 0.79 (0.65, 0.97), DS HR = 0.69 (0.51, 0.93)] and rs3136130 [OS HR = 0.78 (0.64, 0.96), DS HR = 0.68 (0.50, 0.92)] of ERCC4 and rs50871 [OS HR = 0.80 (0.64, 1.00), DS HR = 0.67 (0.48, 0.92)] of ERCC2 among Whites, and rs2607755 [OS HR = 0.62 (0.45, 0.86), DS HR = 0.51 (0.30, 0.86)] of XPC among African Americans were suggestively associated with survival at an uncorrected alpha of 0.05. Three SNP-treatment joint effects showed possible departures from additivity among Whites.
Our study, a large and extensive evaluation of SNPs in NER genes and HNC survival, identified mostly null associations, though a few variants were suggestively associated with survival and potentially interacted additively with treatment.
Head and neck cancer DNA repair; Nucleotide excision repair; Chemotherapy; Radiation; Survival
Multimodality treatment for squamous cell carcinoma of the head and neck (SCCHN) often involves radiation (RT) and cisplatin-based therapy. Elevated activity of DNA repair mechanisms, such as the nucleotide excision repair (NER) pathway, of which ERCC1 is a rate-limiting element, are associated with cisplatin and possibly RT resistance. We have determined ERCC1 expression in HPV-negative SCCHN treated with surgery (+/− adjuvant RT/chemoradiation (CRT)).
We assessed ERCC1 protein expression in archival tumors using automated, quantitative analysis (AQUA) immunohistochemistry (IHC) and three antibodies to ERCC1 (8F1 (2009, Lab Vision), FL297 (Santa Cruz) and HPA029773 (Sigma)). Analysis with Classification and Regression Tree Methods (CART) ascertained the cut-points between high/low ERCC1 expression. Multivariable analysis adjusted for age, T and N stage. Kaplan-Meier curves determined median survival. ERCC1 expression at initial tumor presentation and in recurrent disease were compared. Performance characteristics of antibodies were assessed.
ERCC1 low/high groups were defined based on AQUA analysis with 8F1/2009, FL297 and HPA029773. Among patients treated with surgery plus adjuvant RT/CRT, longer median survival was observed in ERCC1 low tumors versus ERCC1 high (64 vs. 29 months, p=0.02 (HPA029773)). Data obtained with HPA029773 indicated no survival difference among patients treated only with surgery. Recurrent cancers had lower ERCC1 AQUA scores than tumors from initial presentation. Extensive characterization indicated optimal specificity and performance by the HPA029773 antibody.
Using AQUA, with the specific ERCC1 antibody HPA029773, we found a statistical difference in survival among high/low ERCC1 tumors from patients treated with surgery and adjuvant RT.
ERCC1; radiation; head and neck cancer; immunohistochemistry
Single-nucleotide polymorphisms (SNPs) of TERT-rs2736098 (C > T) and CLPTM1L-rs401681(C > T) at the 5p15.33 locus are significantly associated with cancer risk as reported in genome-wide association studies (GWAS), but there are no reported studies for squamous cell carcinoma of the head and neck (SCCHN). In a case–control study of 1079 SCCHN cases and 1115 cancer-free controls of non-Hispanic whites who were frequency matched by age and sex, we genotyped for these two SNPs and assessed their associations with SCCHN risk. Compared with the CC genotypes of each polymorphism, the associations of a slightly reduced risk of SCCHN with the variant genotypes of CT + TT of both polymorphisms were approaching statistical significance [Odds ratio (OR) = 0.90, 95% confidence interval (CI) = 0.76–1.08 for TERT-rs2736098 and OR = 0.86, 95% CI = 0.71–1.04 for CLPTM1L-rs401681, respectively]. When the two SNPs were combined, the variant genotypes of the two SNPs were significantly associated a moderately reduced risk of SCCHN (OR = 0.82, 95% CI = 0.67–0.99), and the number of variant genotypes was associated with a significantly reduced risk in a dose–response manner (P = 0.028). Furthermore, the reduced risk was more pronounced in ever smokers, ever drinkers and patients with oropharyngeal cancer. Our results suggested that these two SNPs at the 5p15.33 locus may be associated with a reduced risk of SCCHN, particularly for their combined effect. Although we added additional evidence for the association of the two SNPs with cancer risk as reported in GWAS, additional studies are needed to replicate our findings.
Insulin-like growth factor binding protein 7 (IGFBP7) functions mostly independent of the IGF signaling pathway and acts as a tumor suppressor in multiple cancers, but roles of IGFBP7 genetic variants in cancer remains unknown. In a hospital-based study of 1,065 patients with squamous cell carcinoma of head and neck (SCCHN) and 1,112 cancer-free controls of non-Hispanic whites, we investigated associations between two putatively functional IGFBP7 promoter single nucleotide polymorphisms (SNPs) (−702G>C, rs11573014 and −418G>A, rs4075349) and SCCHN risk. A significantly lower SCCHN risk was observed in those subjects carrying −418AG (adjusted OR=0.82, 95% CI=0.67–0.99) and −418AG+AA (adjusted OR=0.82, 95% CI=0.69–0.99) genotypes than those carrying the −418GG genotype, but not for the −702G>C SNP. However, those subjects carrying two common homozygous genotypes of these two SNPs (−418GG and −702GG) had an increased risk (adjusted OR=1.21, 95% CI=1.00-0.1.46) than did those carrying variant genotypes (−418AG+AA and −702CG+CC). This increased risk was more evident in subgroups of never smokers and subjects with oral cancer. Further functional analysis showed that the IGFBP7 −418A allele had significantly higher promoter and DNA-protein binding activities than did the G allele, suggesting a tumor suppressor role of this allelic change in the SCCHN etiology. We conclude that the functional variant −418 G>C in the IGFBP7 promoter is associated with reduced risk of SCCHN, likely by enhancing the IGFBP7 promoter and DNA-protein binding activities. Larger studies are needed to validate our findings.
IGFBP7; case-control study; tumor suppressor gene; head and neck cancer; promoter polymorphism
Phospholipase C epsilon 1 (PLCE1) (an effector of Ras) belonging to the phospholipase family plays crucial roles in carcinogenesis and progression of several cancers, including squamous cell carcinoma of the head and neck (SCCHN). A single nucleotide polymorphism (SNP, rs2274223) in PLCE1 has been identified as a novel susceptibility locus in genome-wide association studies (GWAS) of esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) that share similar risk factors with SCCHN. Therefore, we investigated the association between potentially functional SNPs in PLCE1 and susceptibility to SCCHN.
We genotyped three potentially functional SNPs (rs2274223A/G, rs3203713A/G and rs11599672T/G) of PLCE1 in 1,098 SCCHN patients and 1,090 controls matched by age and sex in a non-Hispanic white population.
Although none of three SNPs was alone significantly associated with overall risk of SCCHN, their combined effects of risk alleles (rs2274223G, rs3203713G and rs11599672G) were found to be associated with risk of SCCHN in a locus-dose effect manner (Ptrend = 0.046), particularly for non-oropharyngeal tumors (Ptrend = 0.017); specifically, rs2274223 was associated with a significantly increased risk (AG vs. AA: adjusted OR = 1.29, 95% CI = 1.01-1.64; AG/GG vs. AA: adjusted OR = 1.30, 95% CI = 1.03-1.64), while rs11599672 was associated with a significantly decreased risk (GG vs. TT: adjusted OR = 0.54, 95% CI = 0.34-0.86; TG/GG vs. TT: adjusted OR = 0.76, 95% CI = 0.61-0.95).
Our findings suggest that PLCE1 variants may have an effect on risk of SCCHN associated with tobacco and alcohol exposure, particularly for those tumors arising at non-oropharyngeal sites. These findings, although need to be validated by larger studies, are consistent with those in esophageal and gastric cancers.
PLCE1; polymorphism; SCCHN; risk; susceptibility
Objective: We conducted a case-control study by genotyping three potential functional SNPs to assess the association of Xeroderma pigmentosum complementation group F (XPF) polymorphisms with gastric cancer susceptibility, and role of XPF polymorphisms in combination with H.pylori infection in the risk of gastric cancer.
Methodology: A hospital case-control study was conducted. A total of 331 patients with gastric cancer and 355 controls were collected. Three SNPs of XPF, XPF rs180067, rs1799801 and rs2276466, were genotyped by Taqman real-time PCR method with a 7900 HT sequence detector system.
Results: The gastric cancer patients were more likely to have smoking habit, a family history of cancer and H.pylori infection. We did not find the significant difference in the genotype distributions of XPF rs180067, rs1799801 and rs2276466 between cases and controls. Multivariate logistic analysis showed a non-significant decreased risk in patients carrying rs180067 G allele, rs1799801 T allele or rs2276466 T allele genotypes. The stratification by H.pylori infection was not significantly different in polymorphisms of XPF rs180067, rs1799801 and rs2276466.
Conclusion: There was no evidence that polymorphisms in rs180067, rs1799801 and rs2276466 significantly affect the risk of gastric cancer. Further large sample size studies are strongly needed to validate their association.
Xeroderma pigmentosum complementation group F; Single Nucleotide Polymorphism; Gastric cancer; H.pylori
ERCC1 and ERCC2 play critical roles in the nucleotide excision repair pathway that effectively repairs DNA damage induced by chemotherapeutic agents. Therefore, functional single nucleotide polymorphisms (SNPs) in these genes could have an impact on clinical outcomes in cancer patients who received chemotherapy. However, few studies have simultaneously investigated the roles of ERCC1 and ERCC2 SNPs in clinical outcomes in gastric cancer patients.
We genotyped by the TaqMan assay three common, potentially functional ERCC1 (rs3212986) and ERCC2 SNPs (rs13181 and rs1799793) in 360 gastric cancer patients. We used both Kaplan-Meier tests and Cox proportional hazards models to evaluate the effects of ERCC1 and ERCC2 genotypes and haplotypes on clinical outcomes.
We found that, compared with ERCC2 rs1799793 GG+AG genotypes, the homozygous variant AA genotype was associated with significantly poorer overall survival (OS) (AA vs. GG+AG, log-rank P = 0.012) and significantly higher risk of death (AA vs. GG+AG, Adjusted hazards ratio [HR] 2.13; 95% CI, 1.28 to 3.56; P = 0.004). In combined analyses, patients with any one of the three unfavorable genotypes (i.e. ERCC1 rs3212986 TT, ERCC2 rs13181 GG and rs1799793 AA) had statistically significant hazards of poor prognosis (Adjusted HR, 1.54; 95% CI, 1.06 to 2.25; P = 0.025), compared with those without any unfavorable genotypes. Furthermore, the haplotype A-G-G (rs1799793/rs13181/rs3212986) had a significant impact on OS (Adjusted HR, 1.57; 95% CI, 1.11 to 2.21; P = 0.011), compared with the common haplotype G-T-G.
ERCC1 and ERCC2 functional SNPs may jointly affect OS in Caucasian gastric cancer patients. Additional large prospective studies are essential to confirm our findings.
Single nucleotide polymorphisms (SNPs) in microRNAs (miRNAs) may alter processing, transcription, and expression of miRNAs, and thus contribute to cancer development. We hypothesized that common polymorphisms in pre-miRNAs individually, and more likely, collectively are associated with risk of squamous cell carcinoma of the head and neck (SCCHN).
We genotyped four common polymorphisms in pre-miRNAs (hsa-mir-146a rs2910164 G>C, hsa-mir-149 rs2292832 G>T, hsa-mir-196a2 rs11614913 C>T, and hsa-mir-499 rs3746444 A>G) in 1109 SCCHN cases and 1130 cancer-free controls in a non-Hispanic white population frequency-matched by age and sex. We used univariable and multivariable logistic regression models to calculate crude and adjusted odds ratios (OR) and 95% confidence intervals (CI).
Of the four SNPs studied, hsa-mir-499 AG and GG genotypes were associated with reduced risk of SCCHN (OR, 0.83; 95% CI, 0.69–0.99). When we combined the four SNPs by putative risk genotypes, we found that the number of observed risk genotypes was associated with increased risk of SCCHN in a dose-response manner: OR=1.0, 1.20 and 1.40 for 0–1, 2–3 and 4 risk genotypes (Ptrend = 0.037). Specifically, the risk was 1.23 fold (95% CI, 0.98–1.56) for subjects with 2–4 risk genotypes and 1.40 fold (95% CI, 1.02–1.92) for subjects with 4 risk genotypes, compared with subjects with 0–1 risk genotypes. This risk was more pronounced in men and patients with oropharyngeal cancer.
The combined risk genotypes of four common SNPs in pre-mircroRNAs were significantly associated with a moderately increased risk of SCCHN. Larger studies are needed to validate our findings.
genetic susceptibility; microRNA; head and neck cancer; polymorphism; molecular epidemiology
Base excision repair and nucleotide excision repair are vital responses to multiple types of DNA damage, including damage from tobacco exposure. Single-nucleotide polymorphisms (SNP) in these pathways may affect DNA repair capacity and therefore influence risk for cancer development. We performed a clinic-based, case-control study comprising 481 consecutive patients with confirmed pancreatic adenocarcinoma and 625 healthy controls. Allele and genotype frequencies for 16 SNPs in DNA repair genes ERCC1, XPD/ERCC2, XPC, XPF/ERCC4, OGG1, and XRCC1 were compared after adjusting for age, sex, and smoking history. Subgroup analysis by sex and smoking history was performed. Carriers of one or two XPF/ERCC4 minor alleles at R415Q had decreased risk of pancreatic adenocarcinoma compared with those who had two major alleles [odds ratio (OR), 0.59; 95% confidence interval (95% CI), 0.40-0.85]. Heavy smokers (>40 pack-years) had increased risk for cancer if they were carriers of at least one minor allele for XPD/ERCC2 at D312N (OR, 2.78; 95% CI, 1.28-6.04) or D711D (OR, 2.19; 95% CI, 1.01-4.73). No other significant differences in risk were identified. Minor alleles in DNA repair genes XPF/ERCC4 and XPD/ERCC2 were associated with altered risk for pancreatic cancer.
Deregulated expression of most members of the E2F family has been detected in many human cancers. We examined the association of common single nucleotide polymorphisms (SNPs) of E2F1 and E2F2 with risk of squamous cell carcinoma of the head and neck (SCCHN) in 1,096 SCCHN patients and 1,090 cancer-free controls. We genotyped ten selected SNPs in E2F1 and E2F2, including those at the near 5′ UTR, miRNA binding sites at the near 3′ UTR and tagSNPs according to bioinfotmatics analysis. Although none of the selected SNPs alone was significantly associated with risk of SCCHN, there was a statistically significantly increased risk of SCCHN associated with the combined risk genotypes (i.e. rs3213182 AA, rs3213183 GG, rs3213180 GG, rs321318121 GG, rs2742976 GT+TT, rs6667575 GA+AA, rs3218203 CC, rs3218148 AA, rs3218211 CC, rs3218123 GT+TT). Compared with those with 0–4 risk genotypes, an increased risk was observed for those who carried 5–8 risk genotypes (adjusted OR = 1.04; 95% CI = 0.86–1.26) and 9–10 risk genotypes (adjusted OR = 1.62; 95% CI = 1.14–2.30) in a dose-response manner (P = 0.045). Furthermore, the joint effect was more pronounced among patients with oropharyngeal cancer, younger adults (≤57 years old), men, non-smokers, non-drinkers, and individuals with family history of cancer first-degree relatives. Additionally, we also observed that those with 5–10 risk genotypes had an earlier SCCHN onset than those with 0–4 risk genotypes, particularly for non-smokers and/or non-drinkers. We concluded that E2F1 and E2F2 genetic variants may jointly play important roles in head and neck carcinogenesis.
E2F1; E2F2; head and neck cancer; polymorphisms; age at onset
The excision repair cross-complementation group 1 (ERCC1) enzyme plays a rate-limiting role in the nucleotide excision repair pathway and is associated with resistance to platinum-based chemotherapy. The purpose of this study was to evaluate the role of ERCC1 expression as a predictive marker of survival in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) treated with cisplatin-based concurrent chemoradiotherapy (CCRT). ERCC1 expression was assessed by immunohistochemical staining. The median age of the 45 patients analysed was 56 years (range 27–75 years), and 82% were men; 73% of all specimens showed high expression of ERCC1. The overall tumour response rate after CCRT was 89%. The median follow-up was 53.6 months (95% CI, 34.5–72.7 months). The 3-year progression-free survival (PFS) and overall survival (OS) rates were 58.7 and 61.3%, respectively. Univariate analyses showed that patients with low expression of ERCC1 had a significantly higher 3-year PFS (83.3 vs 49.4%, P=0.036) and OS (91.7 vs 45.5%, P=0.013) rates. Multivariate analysis showed that low expression of ERCC1 was an independent predictor for prolonged survival (HR, 0.120; 95% CI, 0.016–0.934, P=0.043). These results suggest that ERCC1 expression might be a useful predictive marker of locally advanced SCCHN in patients treated with cisplatin-based CCRT.
ERCC1; squamous cell carcinoma; head and neck cancer; cisplatin; concurrent chemoradiation
Recent studies reported associations of the relative telomere length (RTL) and TERT variants with risk of several cancers, which has not been comprehensively investigated in squamous cell carcinoma of the head and neck (SCCHN).
We detected RTL in peripheral blood lymphocytes and genotyped six selected functional single nucleotide polymorphisms (SNPs) of the TERT gene in 888 SCCHN cases and 885 cancer-free controls of non-Hispanic whites.
Overall, we did not observe significant associations between RTL and SCCHN risk (adjusted OR, 0.97; 95% CI, 0.80–1.17 for below versus above the median; Ptrend = 0.618) nor between the six TERT SNPs and SCCHN risk. We also found no associations between RTL and TERT SNPs.
Our results suggest that RTL and TERT functional polymorphisms may not play a major role in the etiology of SCCHN. Large prospective studies are needed to validate our findings.
Although our results suggest no association among RTL, TERT functional polymorphisms, and SCCHN risk, this study may contribute to future meta-analysis.
genetic polymorphisms; Telomere length; TERT; head and neck cancer; molecular epidemiology
Melanoma is the most highly malignant skin cancer, and nucleotide excision repair (NER) is involved in melanoma susceptibility. In this analysis of 1042 melanoma patients, we evaluated whether genetic variants of NER genes may predict survival outcome of melanoma patients. We used genotyping data of 74 tagging single nucleotide polymorphisms (tagSNPs) in eight core NER genes from our genome-wide association study (including 2 in XPA, 14 in XPC, 3 in XPE, 4 in ERCC1, 10 in ERCC2, 8 in ERCC3, 14 in ERCC4, and 19 in ERCC5) and evaluated their associations with prognosis of melanoma patients. Using the Cox proportional hazards model and Kaplan-Meier analysis, we found a predictive role of XPE rs28720291, ERCC5 rs4150314, XPC rs2470458 and ERCC2 rs50871 SNPs in prognosis of melanoma patients (rs28720291: AG vs. GG, adjusted hazard ratio [adjHR] = 11.2, 95% confidence interval [CI] 3.04–40.9, P = 0.0003; rs4150314: AG vs. GG, adjHR = 4.76, 95% CI 1.09–20.8, P = 0.038; rs2470458: AA vs. AG/GG, adjHR = 2.11, 95% CI 1.03–4.33, P = 0.040; and rs50871: AA vs. AC/CC adjHR =2.27, 95% CI 1.18–4.35, P = 0.015). Patients with an increasing number of unfavorable genotypes had dramatically increased death risk. Genetic variants of NER genes, particularly XPE rs28720291, ERCC5 rs4150314, XPC rs2470458 and ERCC2 rs50871, may independently or jointly modulate survival outcome of melanoma patients. Because our results were based on a median follow-up of 3 years without multiple test corrections, additional large prospective studies are needed to confirm our findings.
melanoma; nucleotide excision repair; survival; association
Caspase-3 plays a central role in executing cell apoptosis and thus in carcinogenesis, but little is known about the role of CASP3 variants in susceptibility to squamous cell carcinoma of the head and neck (SCCHN).
Genotype and haplotypes of the first intron (rs4647601:G>T and rs4647602:C>A) and 5′-UTR (rs4647603:G>A) regions of CASP3 (NT_022792.17) were determined for 930 SCCHN patients and 993 cancer-free controls in a US non-Hispanic white population. Odds ratio (OR) and 95% confidence interval (CI) were calculated in multivariate logistic regression analysis.
We found that the CASP3 rs4647601:TT variant genotype was associated with an increased risk of SCCHN (adjusted OR = 1.32, 95% CI = 1.00–1.73) compared with the GG genotype. This risk was more evident in the subgroups of younger (≤56 years) subjects, males, and never smokers with a significant trend for increased risk with increased number of variant T allele (P < 0.05 for all). However, these risks were not found for other two SNPs. Furthermore, individuals with two copies of haplotypes TCG or GCA were found to have a significant increased risk of SCCHN (OR = 1.31, 95% CI = 1.07–1.61), compared with the others haplotypes, and this risk was more evident in less advanced diseases (OR = 1.45, 95% CI = 1.11–1.89) than in the advanced diseases (OR = 1.22, 95% CI = 0.96–1.54).
These results suggested that genetic variation in CASP3 may contribute to SCCHN risk. Larger studies are needed to confirm our findings.
The establishment of genetic variation in CASP3 as a risk factor for SCCHN risk is an etiologically important step in predicting risk in the general population for further identification of individuals at risk for primary prevention. Indeed, this study found one of the three CASP3 SNPs to be associated with risk of SCCHN, particularly in younger, male, and never smokers with less advanced SCCHN, suggesting this SNP was a marker for susceptibility to but not disease progression of SCCHN.
Case-control study; Apoptosis; Genetic susceptibility; Molecular epidemiology; Polymorphism
Methylating agents are involved in carcinogenesis, and the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) removes methyl group from O6-methylguanine. Genetic variation in DNA repair genes has been shown to contribute to susceptibility to squamous cell carcinoma of the head and neck (SCCHN). We hypothesize that MGMT polymorphisms are associated with risk of SCCHN. In a hospital-based case-control study of 721 patients with SCCHN and 1,234 cancer-free controls frequency-matched by age, sex and ethnicity, we genotyped four MGMT polymorphisms, two in exon 3, 16196C>T and 16286C>T and two in the promoter region, 45996G>T and 46346C>A. We found that none of these polymorphisms alone had a significant effect on risk of SCCHN. However, when these four polymorphisms were evaluated together by the number of putative risk genotypes (i.e. 16195CC, 16286CC, 45996GT+TT, and 46346CA+AA), a statistically significantly increased risk of SCCHN was associated with the combined genotypes with three to four risk genotypes, compared with those with zero to two risk genotypes [adjusted odds ratio (OR) = 1.27; 95% confidence interval (CI) = 1.05-1.53]. This increased risk was also more pronounced among young subjects (OR = 1.81; 95% CI = 1.11-2.96), men (OR = 1.24; 95% CI = 1.00-1.55), ever smokers (OR = 1.25; 95% = 1.01-1.56), ever drinkers (OR = 1.29; 95% CI = 1.04-1.60), patients with oropharyngeal cancer (OR = 1.45; 95% CI = 1.12-1.87), and oropharyngeal cancer with regional lymph node metastasis (OR = 1.52; 95% CI = 1.16-2.01). In conclusion, our results suggest that any one of MGMT variants may not have a substantial effect on SCCHN risk, but a joint effect of several MGMT variants may contribute to risk and progression of SCCHN, particularly for oropharyngeal cancer, in non-Hispanic whites.
oral cancer; DNA repair; methylation; genetic susceptibility; molecular epidemiology
Exposure to ionizing radiation has been consistently associated with increased risk of female breast cancer. Although the majority of DNA damage caused by ionizing radiation is corrected by the base-excision repair pathway, certain types of multiple-base damage can only be repaired through the nucleotide excision repair pathway. In a nested case–control study of breast cancer in US radiologic technologists exposed to low levels of ionizing radiation (858 cases, 1,083 controls), we examined whether risk of breast cancer conferred by radiation was modified by nucleotide excision gene polymorphisms ERCC2 (XPD) rs13181, ERCC4 (XPF) rs1800067 and rs1800124, ERCC5 (XPG) rs1047769 and rs17655; and ERCC6 rs2228526. Of the 6 ERCC variants examined, only ERCC5 rs17655 showed a borderline main effect association with breast cancer risk (ORGC = 1.1, ORCC = 1.3; p-trend = 0.08), with some indication that individuals carrying the C allele variant were more susceptible to the effects of occupational radiation (EOR/GyGG = 1.0, 95% CI = <0, 6.0; EOR/GyGC/CC = 5.9, 95% CI = 0.9, 14.4; phet = 0.10). ERCC2 rs13181, although not associated with breast cancer risk overall, statistically significantly modified the effect of occupational radiation dose on risk of breast cancer (EOR/GyAA = 9.1, 95% CI = 2.1–21.3; EOR/GyAC/CC = 0.6, 95% CI = <0, 4.6; phet = 0.01). These results suggest that common variants in nucleotide excision repair genes may modify the association between occupational radiation exposure and breast cancer risk.
Although the role of TNFAIP2 is still unclear, it is an important gene involved in apoptosis, and there are single-nucleotide polymorphisms (SNPs) at its microRNA (miRNA)-binding sites that could modulate miRNA target gene function. In this study, we evaluated associations of four selected SNPs (rs8126 T > C, rs710100 G > A, rs1052912 G > A and rs1052823 G > T) in the miRNA-binding sites of the 3′ untranslated region (UTR) with squamous cell carcinoma of the head and neck (SCCHN) risk in 1077 patients with SCCHN and 1073 cancer-free controls in a non-Hispanic White population. We found that, compared with the rs8126 TT genotype, the variant C allele were associated with increased SCCHN risk in an allele dose–response manner (adjusted odds ratio = 1.48 and 95% confidence interval = 1.06–2.05 for CC, respectively; Ptrend = 0.009). No significant associations were seen for the other three SNPs (rs710100 G > A, rs1052912 G > A and rs1052823 G > T). Additionally, we identified that the rs8126 T > C SNP is within the miR-184 seed binding region in the 3′ UTR of TNFAIP2. Further functional analyses showed that the rs8126 variant C allele led to significantly lower luciferase activity, compared with the T allele. In the genotype–phenotype correlation analysis of peripheral blood mononuclear cells from 64 SCCHN patients, the rs8126 CC genotype was associated with reduced expression of TNFAIP2 messenger RNA. Taken together, these findings indicate that the miR-184 binding site SNP (rs8126 T > C) in the 3′ UTR of TNFAIP2 is functional by modulating TNFAIP2 expression and contributes to SCCHN susceptibility. Larger replication studies are needed to confirm our findings.
DNA-methyltransferase-3B (DNMT3B) may play an oncogenic role during tumorigenesis, and its genetic variants have been reportedly to be associated with risk of several cancers, but few studies have investigated their roles in head and neck cancer. Here we report a hospital-based case-control study with 832 SCCHN patients and 843 cancer-free controls of non-Hispanic whites that evaluated the association between two DNMT3B single nucleotide polymorphisms (SNPs) DNMT3B-149C>T (rs2424913) and DNMT3B-579G>T (rs2424909) in the promoter region and risk of squamous cell carcinoma of the head and neck (SCCHN). We found that compared with C-allele carriers, the DNMT3B-149 TT genotype was statistically significantly associated with increased risk of SCCHN (adjusted OR, 1.35, 95% CI, 1.01-1.80, P = 0.043), whereas the DNMT3B-579 TT genotype showed only a non-statistically significant risk compared with G-allele carriers. Further analysis of the effects of combined genotypes suggested that subjects with either DNMT3B-149 TT or DNMT3B-579 TT homozygous genotypes had statistically significantly increased risk of SCCHN (adjusted OR = 1.36, 95% CI = 1.07-1.73, P = 0.013). Stratification analysis showed a more profound risk in the subgroups of the young (≤57 years, the median age of the controls), males, current smokers, current drinkers, and patients with primary tumor sites of pharynx and larynx. This large study provides reliable risk estimates for associations between DNMT3B variants and SCCHN risk in non-Hispanic whites, and our findings are consistent with that of previously reported cancer case-control studies of other cancers. Further mechanistic studies are needed to unravel the underlying molecular mechanisms.
Polymorphism; Methylation; DNMT3B; Molecular epidemiology; Cancer risk
Benzo[a]pyrene diol epoxide (BPDE)-induced DNA adducts are a risk factor for tobacco-related cancers. Excision repair cross-complementing complementation group 1 (ERCC1) and excision repair cross-complementing complementation group 2/xeroderma pigmentosum D (ERCC2/XPD) participate in the nucleotide excision repair (NER) pathway that removes BPDE–DNA adducts; however, few studies have provided population-based evidence for this association. Therefore, we assayed for levels of in vitro BPDE-induced DNA adducts and genotypes of single-nucleotide polymorphisms (SNPs) of the NER genes ERCC1 (rs3212986 and rs11615) and ERCC2/XPD (rs13181, rs1799793 and rs238406) in 707 healthy non-Hispanic whites. The linear trend test of increased adduct values in never to former to current smokers was statistically significant (Ptrend = 0.0107). The median DNA adduct levels for the ERCC2 rs1799793 GG, GA and AA genotypes were 23, 29 and 30, respectively (Ptrend = 0.057), but this trend was not observed for other SNPs. After adjustment for covariates, adduct values larger than the median value were significantly associated with the genotypes ERCC1 rs3212986TT [odds ratio (OR) = 1.89, 95% confidence interval (CI) = 1.03–3.48] and ERCC2/XPD rs238406AA (OR = 0.64, 95% CI = 0.41–0.99) and rs238406CA (OR = 0.63, 95% CI = 0.45–0.89) compared with their corresponding wild-type homozygous genotypes. The results of haplotype analysis further suggested that haplotypes CAC and CGA of ERCC2/XPD, TC of ERCC1 and CACTC of ERCC2/XPD and ERCC1 were significantly associated with high levels of DNA adducts compared with their most common haplotypes. Our findings suggest that the genotypes and haplotypes of ERCC1 and ERCC2/XPD may have an effect on in vitro BPDE-induced DNA adduct levels.
Single nucleotide polymorphisms (SNPs) in alcohol metabolism genes are associated with squamous cell carcinoma of the head and neck (SCCHN), and may influence cancer risk in conjunction with alcohol. Genetic variation in the oxidative stress pathway may impact the carcinogenic effect of reactive oxygen species produced by ethanol metabolism. We hypothesized that alcohol interacts with these pathways to affect SCCHN incidence.
Interview and genotyping data for 64 SNPs were obtained from 2552 European- and African-American subjects (1227 cases, 1325 controls) from the Carolina Head and Neck Cancer Epidemiology study, a population-based case-control study of SCCHN conducted in North Carolina from 2002–2006. We estimated odds ratios and 95% confidence intervals for SNPs and haplotypes, adjusting for age, sex, race, and duration of cigarette smoking. P-values were adjusted for multiple testing using Bonferroni correction.
Two SNPs were associated with SCCHN risk: ADH1B rs1229984 A allele (OR=0.7, 95%CI=0.6–0.9) and ALDH2 rs2238151 C allele (OR=1.2, 95%CI=1.1–1.4). Three were associated with sub-site tumors: ADH1B rs17028834 C allele (larynx, OR=1.5, 95%CI=1.1–2.0), SOD2 rs4342445 A allele (oral cavity, OR=1.3, 95%CI=1.1–1.6), and SOD2 rs5746134 T allele (hypopharynx, OR=2.1, 95%CI=1.2–3.7). Four SNPs in alcohol metabolism genes interacted additively with alcohol consumption: ALDH2 rs2238151, ADH1B rs1159918, ADH7 rs1154460, and CYP2E1 rs2249695. No alcohol interactions were found for oxidative stress SNPs.
Conclusions and Impact
Previously unreported associations of SNPs in ALDH2, CYP2E1, GPX2, SOD1, and SOD2 with SCCHN and sub-site tumors provide evidence that alterations in alcohol and oxidative stress pathways influence SCCHN carcinogenesis, and warrant further investigation.
Head and Neck Neoplasms; Head and Neck Neoplasms/epidemiology; Gene-environment interaction; Alcohol Drinking/metabolism; Oxidative Stress
The nucleotide excision repair (NER) pathway is central in response to damage induced by environmental carcinogens. Efficiency of this pathway, probably genetically determined, may modulate individual risk of developing squamous cell carcinoma of the head and neck (SCCHN) as well as second primary malignancy (SPM) after the index tumor. We hypothesized that common non-synonymous and regulatory single-nucleotide polymorphisms (SNPs) in the NER core genes individually, and more probably collectively, associated with the risk of SPM. We genotyped for seven selected SNPs in 1376 incident SCCHN patients who were prospectively recruited between 1995 and 2006 and followed for SPM development. We found that 110 patients (8%) developed SPM: 43 (39%) second SCCHN; 38 (35%) other tobacco-associated sites and 29 (26%) other non-tobacco-associated sites. The associations of these SNPs with SPM risk were assessed assuming a recessive genetic model. We did not find any significant associations of each or in combination of the seven SNPs with SPM risk in the recessive models. However, when we explored the combined effect based on an alternatively dominant genetic model, we found that the number of observed risk genotypes was associated with a significantly increased SPM risk in a dose-response manner (P = 0.005) and patients with five to seven risk genotypes had a significantly 2.4-fold increased SPM risk compared with patients with zero to two risk genotypes. These findings suggest that a profile of NER core gene polymorphisms might collectively contribute to risk of SPM not in a recessive model but in a dominant model among patients with an index primary SCCHN. These findings need to be validated in future studies with larger sample sizes and longer follow-up time.