Distribution and haplotype associations of XPD Lys751Gln, XRCC1 Arg280His and XRCC1 Arg399Gln polymorphisms with nasopharyngeal carcinoma in the Malaysian population

Association between superoxide dismutase 2, glutathione peroxidase 1, xeroderma pigmentosum group d gene variations, and head and neck squamous cell cancer susceptibility

As oxidative stress is implicated in the pathogenesis of head and neck squamous cell cancer (HNSCC), the functions of antioxidant enzyme systems and DNA repair proteins are critical in the development of cancer. To investigate the role of genetic polymorphisms of the antioxidant superoxide dismutase 2 (SOD2) Val16Ala, glutathione peroxidase 1 (GPX1) Pro198Leu, and the DNA repair Xeroderma Pigmentosum Group D (XPD) Lys751Gln genes under exogenous risk factors, including smoking and alcohol consumption, in HNSCC carcinogenesis, we conducted a case-control study on 139 unrelated cases and 265 non-cancer controls. Polymorphisms were analyzed in additive, dominant and recessive genetic models, individually and in an interaction model. Carriers of the T allele of SOD2 were associated with an increased risk for HNSCC in the overall subgroups of males and smokers; similarly, the T allele of GPX1 was associated with elevated risk in the overall and smoker subgroup. A 12.47-fold increased risk was observed for the carriers of GPX1 TT, SOD2 CT and XPD CC genotypes for HNSCC. This is the first study presenting the potential roles of SOD2, GPX1 and XPD polymorphisms in interaction and under three genetic models in the development of HNSCC. The results suggest that these polymorphisms slightly modify the risk in HNSCC development individually but are significantly higher when they functioned and were evaluated together.

Genetic Polymorphisms Along with Dietary and Environmental Factors Enhance the Susceptibility to Nasopharyngeal Carcinoma in Nagaland of Northeast India

This study investigated the association of seven widely known DNA repair gene polymorphisms (hOGG1 Ser326Cys, XRCC1 Arg194Trp, XRCC1 Arg280His, XRCC1 Arg399Gln, XPC Val499Ala, XPD Lys751Gln and ERCC1 Cys8092Ala) with dietary and environmental factors for Nasopharyngeal Carcinoma (NPC) susceptibility in Nagaland of Northeast India. The genotypes were determined in 128 NPC patients and 180 healthy controls by PCR-RFLP. XRCC1 Arg280His, XPC Val499Ala and ERCC1 Cys8092Ala were found to be associated with NPC risk. Tobacco smoking and burning of firewood for cooking were also found to be a risk factor for NPC. The haplotype analysis of five single-nucleotide polymorphisms (SNPs) XRCC1 Arg194Trp, XRCC1 Arg280His, XRCC1 Arg399Gln, XPD Lys751Gln and ERCC1 Cys8092Ala identified haplotype TGAAC to be significantly associated with NPC. Multifactor dimensionality reduction (MDR) analysis suggested ERCC1 Cys8092Ala to be the best one-factor model that could predict NPC risk. From this study, we conclude that examining the synergistic interactions of various gene-environmental factors together is a better approach to understand NPC susceptibility, instead of their individual effects.

Association between XRCC1 single-nucleotide polymorphisms and susceptibility to nasopharyngeal carcinoma: An update meta-analysis

BACKGROUND

Many studies have investigated polymorphisms of X-ray repair cross-complementing protein 1 (XRCC1) and risk of nasopharyngeal carcinoma (NPC), but the results are somewhat contradictory in different studies. There is an urgent need to keep in step with the relevant observational studies to more comprehend the effects of XRCC1 variants on the NPC risk.

METHODS

A systematic literature search accompanied with meta-analysis was carried out to obtain a detailed evaluation on the association between XRCC1 polymorphisms and NPC risk.

RESULTS

Meta-analyses showed that there was no statistically significant association observed between Arg194Trp/Arg280His variants in the XRCC1 gene and NPC risk with all genetic models, when relatively larger samples were pooled into the update meta-analysis. The reassessment suggested NPC risk was significantly increased with Arg399Gln polymorphism. The significant association was identified in homozygous, recessive, and allelic models, more than previously reported.

CONCLUSION

We confirmed that Arg399Gln polymorphism of XRCC1 gene is a potential predictor for susceptibility to NPC, especially for Asians. More studies are required to evaluate the association in different populations.

Increased expression of ERCC2 gene in head and neck cancer is associated with aggressive tumors: a systematic review and case-control study

INTRODUCTION

The excision repair cross-complementation group 2 (ERCC2) ATP-dependent helicase is an essential member of the DNA repair pathway. It has been observed to be differentially expressed in different cancers, which shows its involvement in carcinogenesis.

AIM

In the present study we have tried to determine the association of expression patterns of this gene with head and neck carcinogenesis.

METHOD

We first carried out a systematic review of the available studies on the role of ERCC2 in head and neck cancer (HNC). In order to test the hypothesis that the expression patterns of XPD/ERCC2 play a critical role in HNC pathogenesis, we then conducted a population based case-control study on 81 head and neck tumor samples and adjacent normal-tissue control samples. Reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative polymerase chain reaction (qPCR) were used to assess ERCC2 deregulation at the mRNA level.

RESULT

Expression analysis showed that the ERCC2 expression level was significantly upregulated (p<0.05) in HNC tissues compared with adjacent normal tissues. Furthermore, the expression pattern of ERCC2 was correlated with the expression pattern of Ki-67 and a significant correlation (r = 0.230, p<0.03) was observed between ERCC2 and Ki-67. Spearman's correlation also showed a significant correlation between ERCC2 expression and tumor stage (r = 0.271, p<0.02) and grade (r = 0.228, p<0.02) of HNC.

CONCLUSIONS

Our data suggest that deregulation of ERCC2 in HNC has the potential to predict a more aggressive cancer phenotype and may be considered a possible biomarker for improved diagnosis and prognosis of HNC.