Polymorphisms in the DNA Repair Genes XPC, XPD, and XPG and Risk of Cutaneous Melanoma: a Case-Control Analysis

Anti-cancer mechanisms of natural isoflavones against melanoma

The incidence of skin-related neoplasms has generally increased in recent years. Melanoma arises from malignant mutations in melanocytes in the basal layer of the epidermis and is a fatal skin cancer that seriously threatens human health. Isoflavones are polyphenolic compounds widely present in legumes and have drawn scientists' attention, because they have good efficacy against a variety of cancers, including melanoma, without significant toxic side effects and resistance. In this review article, we summarize the research progress of isoflavones in melanoma, including anti-melanoma roles and mechanisms of isoflavones via inhibition of tyrosinase activity, melanogenesis, melanoma cell growth, invasion of melanoma cells, and induction of apoptosis in melanoma cells. This information is important for the prevention, clinical treatment, and prognosis and survival of melanoma.

The relationship between single nucleotide polymorphisms and skin cancer susceptibility: A systematic review and network meta-analysis

Background

Single nucleotide polymorphisms (SNPs) interfere with the function of certain genes and thus may influence the probability of skin cancer. The correlation between SNPs and skin cancer (SC) lacks statistical power, however. Therefore, the purpose of this study was to identify the gene polymorphisms involved in skin cancer susceptibility using network meta-analysis and to determine the relationship between SNPs and SC risk.

Methods

PubMed, Embase, and Web of Science were searched for articles including "SNP" and different types of SC as keywords between January 2005 and May 2022. The Newcastle-Ottawa Scale was used to assess bias judgments. The odds ratio (ORs) and their 95% confidence intervals (CIs) were determined to estimate heterogeneity within and between studies. Meta-analysis and network meta-analysis were carried out to identify the SNPs associated with SC. The P-score of each SNP was compared to obtain the rank of probability. Subgroup analyses were performed by cancer type.

Results

A total of 275 SNPs from 59 studies were included in the study. Two subgroup SNP networks using the allele model and dominant model were analyzed. The alternative alleles of rs2228570 (FokI) and rs13181 (ERCC2) were the first-ranking SNPs in both subgroups one and two of the allele model, respectively. The homozygous dominant genotype and heterozygous genotype of rs475007 in subgroup one and the homozygous recessive genotype of rs238406 in subgroup two were most likely to be associated with skin cancer based on the dominant model.

Conclusions

According to the allele model, SNPs FokI rs2228570 and ERCC2 rs13181 and, according to the dominant model, SNPs MMP1 rs475007 and ERCC2 rs238406 are closely linked to SC risk.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

XPG is Modulated by miR-4715-3p and rs873601 Genotypes in Lung Cancer

Objective

XPG (Xeroderma pigmentosum group G, XPG), a single strand-specific DNA endonuclease in the nucleotide excision repair pathway, has been implicated in lung cancer. Potentially functional rs873601 in XPG is consistently associated with gastrointestinal cancer, and miR-4715-3p, targeting 3UTR of XPG, also influences the process of gastrointestinal carcinogenesis, however, the relationships between XPG and miR-4715-3p and rs873601 in lung cancer have not been elucidated.

Methods

A case-control study included 264 lung cancer patients and 264 cancer-free healthy controls and was designed to determine the relationships between rs873601 and lung cancer and the effect of miR-4715-3p on XPG expression in lung cancer. Fifty matched cases and controls were randomly selected from the lung cancer and control groups to assess the relationships between the expression levels of miR-4715-3p and XPG determined by using qRT-PCR. The association of rs873601 with lung cancer was analyzed by mass spectrometry, and function prediciton of rs873601 genotypes explored by web-based bioinformatics.

Results

miR-4715-3p in the lung cancer group was significantly increased compared with that in the control group (P = 0.011), upregulation of miR-4715-3p correlated with an increase in XPG mRNA (r = 0.399, P <0.05) in the lung cancer group. The AA genotype was associated with increased risk of lung cancer compared with the AG and GG genotypes of rs873601 (AG vs AA: OR = 0.231, 95% CI: 0.155–0.345, P <0.001 GG vs AA: OR = 0.300, 95% CI: 0.131–0.719, P = 0.003). The genetic association remained significant after adjustment for age, sex, smoking, and drinking, and rs873601-AA was associated with an increase in XPG mRNA in the lung cancer group. The results of web-based bioinformatics analysis indicated rs873601 genotypes might change XPG-RNA stability and bindability between XPG and miR-4715-3p.

Conclusion

Our data characterized that miR-4715-3p and rs873601 genotypes modified XPG expression in lung cancer. These findings may help to elucidate the mechanisms governing lung cancer.

Association of DNA repair gene XPC Ala499Val (rs2228000 C>T) and Lys939Gln (rs2228001 A>C) polymorphisms with the risk of chronic myeloid leukemia: A case-control study in a South Indian population

BACKGROUND

Xeroderma pigmentosum complementation group C (XPC), a DNA repair protein, plays an important role in the maintenance of genomic integrity and is essential for the nucleotide excision repair pathway. Polymorphisms in the XPC gene may alter DNA repair leading to genetic instability and oncogenesis. The present study aimed to assess the relationship between the XPC Ala499Val (rs2228000 C>T) and Lys939Gln (rs2228001 A>C) non-synonymous polymorphisms and susceptibility to chronic myeloid leukemia (CML) pathogenesis, disease progression and the response to targeted therapeutic regimen, imatinib mesylate.

METHODS

This case-control study included 212 cases and 212 controls, and the genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism assays.

RESULTS

Our results showed significant association of variant CT (odds ratio = 1.92, 95% confidence interval = 1.21-3.06, p = 0.003) and TT (odds ratio = 2.84, 95% confidence interval = 1.22-6.71, p = 0.007) genotypes in patients with the XPC Ala499Val polymorphism and CML risk. In addition, these genotypes were associated with CML progression to advanced phases (p = 0.006), splenomegaly (p = 0.017) and abnormal lactate dehydrogenase levels (p = 0.03). XPC Lys939Gln was found to correlate with a poor response to therapy, showing borderline significant association with minor cytogenetic response (p = 0.08) and a poor molecular response (p = 0.06). Significant association of the Ala499Val and Lys939Gln polymorphisms with prognosis was observed (Hasford high risk, p = 0.031 and p = 0.019, respectively). Haplotype analysis showed a strong correlation of variant TC haplotype with poor therapy responses (minor cytogenetic response, p = 0.019; poor molecular response, p < 0.0001).

CONCLUSIONS

In conclusion, our results suggest that XPC Ala499Val is a high-penetrance CML susceptibility polymorphism. Both polymorphisms studied are considered as genetic markers with respect to assessing disease progression, therapy response and prognosis in CML patients.

Influence of functional variants Asp312Asn and Lys751Gln of Xeroderma Pigmentosum Group D (XPD) and Glutathione S-transferase Mu 1 (GSTM1) and Theta 1 (GSTT1) genes on cutaneous melanoma susceptibility and prognosis

We aimed to evaluate whether variants in repair (XPD Asp312Asn, XPD Lys751Gln) and detoxification (GSTM1, GSTT1) genes alter risk, clinicopathological aspects and survival of cutaneous melanoma (CM). Genotyping was performed in 229 CM patients and 258 controls. Individuals with XPD 312Asp/Asn or Asn/Asn plus GSTT1 null genotype were under 2.00 (95% CI: 1.06-3.79), and XPD 312Asn/Gln haplotype was under 1.44-fold (95% CI: 0.99-2.08) increased risks to CM than others. Individuals with GSTM1 plus GSTT1 null genotype had 9.61-fold (95% CI: 2.28-40.38) increased risk of metastatic CM. At 60 months of follow-up, patients with XPD 751Gln/Gln plus GSTT1 null and GSTM1 null plus GSTT1 null genotype presented 7.36 and 3.05 more chances of evolving to death in multivariate Cox analysis, respectively. In conclusion, our data indicate, for the first time, that specific variant combinations of XPD, GSTM1 and GSTT1 may increase susceptibility to CM and influence patients' clinicopathological features and survival.

Comprehensive assessment of the association between XPC rs2228000 and cancer susceptibility based on 26835 cancer cases and 37069 controls

Objectives In the present study, we examined available articles from online databases to comprehensively investigate the effect of the XPC (xeroderma pigmentosum complementation group C) rs2228000 polymorphism on the risk of different types of clinical cancer.

Methods We conducted a group of overall and subgroup pooling analyses after retrieving the data from four databases (updated till September 2019). The P-value of association, OR (odds ratios), and 95% CI (confidence interval) were calculated.

Results We selected a total of 71 eligible studies with 26835 cancer cases and 37069 controls from the 1186 retrieved articles. There is an enhanced susceptibility for bladder cancer cases under T vs. C [P=0.004; OR (95% CI) = 1.25 (1.07, 1.45)], TT vs. CC [P=0.001; 1.68 (1.25, 2.26)], CT+TT vs. CC [P=0.016; 1.26 (1.04, 1.53)], and TT vs. CC+ CT [P=0.001; 1.49 (1.18, 1.90)] compared with negative controls. Additionally, there is an increased risk of breast cancer under T vs. C, TT vs. CC and TT vs. CC+ CT (P<0.05, OR > 1). Nevertheless, there is a decreased risk of gastric cancer cases in China under T vs. C [P=0.020; 0.92 (0.85, 0.99)], CT vs. CC [P=0.001, 0.83 (0.73, 0.93)], and CT+TT vs. CC [P=0.003, 0.84 (0.76, 0.94)].

Conclusions The TT genotype of XPC rs2228000 may be linked to an increased risk of bladder and breast cancer, whereas the CT genotype is likely to be associated with reduced susceptibility to gastric cancer in the Chinese population.

Cloning of the XPD gene and its function in malignant melanoma cells

The xeroderma pigmentosum group D (XPD) gene is a member of the transcription factor IIH complex and serves an important role in gene repair. Previous studies have suggested that genetic variants of the XPD gene may be associated with an increased risk of cutaneous melanoma. However, the exact mechanism remains unclear. In the present study, the XPD gene was cloned, and its localization and function in malignant melanoma cells were investigated. The human full length XPD gene was cloned via reverse transcription-PCR using the total RNA extracted from human cervical squamous cell carcinoma epithelial HeLa cells. Subsequently, the gene was inserted into a plasmid fused to green fluorescent protein (GFP; pEGFP-N1/XPD), and pEGFP-N1/XPD and pcDNA3.1(+)/XPD were transfected into human malignant melanoma A375 cells using Lipofectamine^® 2000. The expression levels of XPD were detected by western blotting. The Golgi marker GM130 and the endoplasmic reticulum membrane protein marker KDEL were used for immunofluorescence staining, and the subcellular localization of XPD was observed under a fluorescence microscope. Cell proliferation was measured using an MTT assay. The recombinant pEGFP-N1/XPD plasmid expressing the human wild-type XPD gene was successfully constructed by restriction enzyme digestion and assessed by gene sequencing. XPD was localized in the endoplasmic reticulum of malignant melanoma A375 cells, as confirmed by immunofluorescence staining. Furthermore, MTT assays indicated that XPD inhibited the proliferation of malignant melanoma A375 cells. The present study provides a basis for further investigation of the biological effects and functions of XPD in malignant melanoma cells.

Association of XPC Polymorphisms with Cutaneous Malignant Melanoma Risk: Evidence from a Meta-Analysis

BACKGROUND

A number of studies have reported that the xeroderma pigmentosum complementation group C (XPC) polymorphisms are associated with cutaneous malignant melanoma (CMM) susceptibility. But the results of those studies were inconsistent. Here, we performed a study to obtain a more conclusive result on the association of XPC polymorphisms with risk of CMM.

METHODS

The XPC Lys939Gln and Ala499Val polymorphisms were genotyped in 150 CMM cases and 150 controls by PCR-RFLP assay. Subsequently, all published relevant studies were identified through a comprehensive literature search in PubMed, Web of Science, and CNKI databases. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the strength of correlation.

RESULTS

There was no significant association between XPC Lys939Gln and Ala499Val polymorphisms and CMM risk in our population. A total of 15 case-control studies including ten studies with 5,990 cases and 7,697 controls on XPC Lys939Gln and five studies with 3,139 cases and 3,721 controls on XPC Ala499Val polymorphism were selected. Pooled data revealed that XPC Lys939Gln (C vs. A: OR = 1.108, 95% CI 1.008- 1.217; P = 0.033) and Ala499Val (C vs. A: OR = 0.918, 95% CI 0.850-0.992; p = 0.031; CC+CA vs. AA: OR = 0.904, 95% CI 0.819-0.997; p = 0.043) polymorphisms were significantly associated with an increased risk of CMM. Moreover, stratified analyses by ethnicity revealed that the XPC Ala499Val and Lys939Gln polymorphisms were significantly associated with risk of CMM in Caucasians and mixed populations, respectively.

CONCLUSIONS

This meta-analysis result suggested that XPC Lys939Gln and Ala499Val polymorphisms were significantly associated with risk of CMM.

Histone Modifications as Biomarkers for Immunotherapy

Recent advances in immunotherapy have revolutionized the treatment of certain cancers. Some patients show a durable response to these immunotherapies, while others show little benefit or develop resistance. Identification of biomarkers to predict responsiveness will be helpful for informing treatment strategies; and would furthermore lead to the identification of molecular pathways dysregulated in nonresponding patients that could be targeted for therapeutic development. Pathways of epigenetic modification, such as histone posttranslational modifications (PTMs), have been shown to be dysregulated in certain cancer and immune cells. Histones are abundant cellular proteins readily assayed with high-throughput technologies, making them attractive targets as biomarkers. We explore promising advancements for using histone PTMs as immunotherapy responsiveness biomarkers in both cancer and immune cells, and provide a methodological workflow for assaying histone PTMs in relevant samples.

Current state of melanoma diagnosis and treatment

Melanoma is the deadliest form of skin cancer. In the early stages, melanoma can be treated successfully with surgery alone and survival rates are high, but after metastasis survival rates drop significantly. Therefore, early and correct diagnosis is key for ensuring patients have the best possible prognosis. Melanoma misdiagnosis accounts for more pathology and dermatology malpractice claims than any cancer other than breast cancer, as an early misdiagnosis can significantly reduce a patient's chances of survival. As far as treatment for metastatic melanoma goes, there have been several new drugs developed over the last 10 years that have greatly improved the prognosis of patients with metastatic melanoma, however, a majority of patients do not show a lasting response to these treatments. Thus, new biomarkers and drug targets are needed to improve the accuracy of melanoma diagnosis and treatment. This article will discuss the major advancements of melanoma diagnosis and treatment from antiquity to the present day.

cAMP-mediated regulation of melanocyte genomic instability: A melanoma-preventive strategy

Malignant melanoma of the skin is the leading cause of death from skin cancer and ranks fifth in cancer incidence among all cancers in the United States. While melanoma mortality has remained steady for the past several decades, melanoma incidence has been increasing, particularly among fair-skinned individuals. According to the American Cancer Society, nearly 10,000 people in the United States will die from melanoma this year. Individuals with dark skin complexion are protected damage generated by UV-light due to the high content of UV-blocking melanin pigment in their epidermis as well as better capacity for melanocytes to cope with UV damage. There is now ample evidence that suggests that the melanocortin 1 receptor (MC1R) is a major melanoma risk factor. Inherited loss-of-function mutations in MC1R are common in melanoma-prone persons, correlating with a less melanized skin complexion and poorer recovery from mutagenic photodamage. We and others are interested in the MC1R signaling pathway in melanocytes, its mechanisms of enhancing genomic stability and pharmacologic opportunities to reduce melanoma risk based on those insights. In this chapter, we review melanoma risk factors, the MC1R signaling pathway, and the relationship between MC1R signaling and DNA repair.

XPG rs17655 G>C polymorphism associated with cancer risk: evidence from 60 studies

Xeroderma pigmentosum group G (XPG), a key component in nucleotide excision repair pathway, functions to cut DNA lesions during DNA repair. Genetic variations that alter DNA repair gene expression or function may decrease DNA repair ability and impair genome integrity, thereby predisposing to cancer. The association between XPG rs17655 G>C polymorphism and cancer risk has been investigated extensively, but the results remain contradictory. To get a more accurate conclusion, we performed a comprehensive meta-analysis of 60 case-control studies, involving 27,098 cancer cases and 30,535 healthy controls. Crude odds ratios (ORs) and 95% confidence interval (CIs) were calculated to determine the association of interest. Pooled analysis indicated that the XPG rs17655 G>C polymorphism increased the risk of overall cancer (CC vs. GG: OR=1.10, 95% CI=1.00-1.20; CG vs. GG: OR=1.06, 95% CI=1.02-1.11; CG+CC vs. GG: OR=1.07, 95% CI=1.02-1.12; C vs. G: OR=1.05, 95% CI=1.01-1.09). Stratification analysis by cancer type further showed that this polymorphism was associated with increased risk of gastric cancer and colorectal cancer. This meta-analysis indicated that the XPG gene rs17655 G>C polymorphism was associated with increased overall cancer risk, especially the risk of gastric cancer and colorectal cancer. Further validation experiments are needed to strength our conclusion.

Predictive value of excision repair cross-complementing group 2 gene Lys751Gln and Asp312Asn polymorphisms in melanoma risk

Epidemiological studies have assessed the association between excision repair cross-complementing group 2 (ERCC2) Lys751Gln and Asp312Asn polymorphisms and melanoma risk with conflicting results. Relevant articles were searched from PubMed, Embase, and Web of Science with a time limit of 3 September 2016. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of the association. We performed this meta-analysis with 12 studies including 6157 cases and 8873 controls for Lys751Gln and nine studies including 5037 cases and 7542 controls for Asp312Asn polymorphism. Overall, no significant associations were found under all the models for Lys751Gln polymorphism, and significant associations were found for Asp312Asn polymorphism for AA versus GG (OR=1.12, 95% CI=1.00-1.26) and for the recessive model (OR=1.11, 95% CI=1.00-1.24). In the stratification analyses by source of control: for Lys751Gln polymorphism, significant associations were found for CC versus AA (OR=1.19, 95% CI=1.04-1.36) and the recessive model (OR=1.15, 95% CI=1.02-1.30); for Asp312Asn polymorphism, significant associations were found for AA versus GG (OR=1.31, 95% CI=1.11-1.53) and the recessive model (OR=1.29, 95% CI=1.11-1.50). This meta-analysis suggested that both the Lys751Gln and Asp312Asn polymorphisms were risk factors for melanoma risk in population-based subgroup.

Association between the ERCC2 Asp312Asn polymorphism and risk of cancer

Cancer is the leading cause of death in economically developed countries and the second leading cause of death in developing countries. The relationship between genetic polymorphisms and the risk of cancers has been widely researched. Excision repair cross-complementing group 2 (ERCC2) gene plays important roles in the nucleotide excision repair pathway. There is contrasting evidence on the association between the ERCC2 Asp312Asn polymorphism and the risk of cancer. We conducted a comprehensive meta-analysis in order to assess the correlation between these factors. We searched the PubMed, EMBASE, Science Direct, Web of Science, and CNKI databases for studies published from January 1, 2005 to January 1, 2016. Finally, 86 articles with 38,848 cases and 48,928 controls were included in the analysis. The overall analysis suggested a significant association between the ERCC2 Asp312Asn polymorphism and cancer risk. Furthermore, control source, ethnicity, genotyping method, and cancer type were used for subgroup analysis. The result of a trial sequential analysis indicated that the cumulative evidence is adequate; hence, further trials were unnecessary in the overall analysis for homozygote comparison. In summary, our results suggested that ERCC2 Asp312Asn polymorphism is associated with increased cancer risk. A significantly increased cancer risk was observed in Asian populations, but not in Caucasian populations. Furthermore, the ERCC2 Asp312Asn polymorphism is associated with bladder, esophageal, and gastric cancers, but not with breast, head and neck, lung, prostate, and skin cancers, and non-Hodgkin lymphoma. Further multi-center, well-designed studies are required to validate our results.

Autophagic UVRAG Promotes UV-Induced Photolesion Repair by Activation of the CRL4(DDB2) E3 Ligase

UV-induced DNA damage, a major risk factor for skin cancers, is primarily repaired by nucleotide excision repair (NER). UV radiation resistance-associated gene (UVRAG) is a tumor suppressor involved in autophagy. It was initially isolated as a cDNA partially complementing UV sensitivity in xeroderma pigmentosum (XP), but this was not explored further. Here we show that UVRAG plays an integral role in UV-induced DNA damage repair. It localizes to photolesions and associates with DDB1 to promote the assembly and activity of the DDB2-DDB1-Cul4A-Roc1 (CRL4(DDB2)) ubiquitin ligase complex, leading to efficient XPC recruitment and global genomic NER. UVRAG depletion decreased substrate handover to XPC and conferred UV-damage hypersensitivity. We confirmed the importance of UVRAG for UV-damage tolerance using a Drosophila model. Furthermore, increased UV-signature mutations in melanoma correlate with reduced expression of UVRAG. Our results identify UVRAG as a regulator of CRL4(DDB2)-mediated NER and suggest that its expression levels may influence melanoma predisposition.

A meta-analysis of XPC Lys939Gln polymorphism and melanoma susceptibility

BACKGROUND

It has been reported that polymorphisms of XPC Lys939Gln may affect the risk of melanom. However, the results have been inconsistent.We performed a comprehensive meta-analysis to determine the association between XPC Lys939Gln polymorphism and melanoma susceptibility.

METHODS

Based on comprehensive searches of the MEDLINE, EMBASE and ISI Web of knowledge, China National Knowledge Infrastructure (CNKI) and Wanfang Database, we identified eligible studies about the association between XPC Lys939Gln polymorphism and melanoma risk.

RESULTS

A total of 4631 cases and 5111 controls in studies were included in this meta-analysis. All studies were conducted in Caucasian populations. Allele model (Gln vs. Lys: P = 0.22; OR = 1.07, 95% CI = 0.96-1.18), and homozygous model (Gln/Gln vs. Lys/Lys: P = 0.66; OR = 1.03, 95% CI = 0.91-1.17) did not show increased risk of developing melanoma. Similarly, dominant model Gln/Gln and Gln/Lys vs. Lys/Lys: P = 0.07; OR = 1.17, 95% CI = 0.99-1.40) and recessive model (Gln/Gln vs. Gln/Lys and Lys/Lys: P = 0.67; OR = 1.03, 95% CI = 0.90-1.19) failed to show increased risk of developing melanoma.

CONCLUSION

Our pooled data suggest that there was no evidence for a major role of XPC Lys939Gln polymorphism in the pathogenesis of melanoma.

Current evidences on the XPG Asp1104His polymorphism and melanoma susceptibility: a meta-analysis based on case-control studies

Previous studies evaluating the association between the XPG Asp1104His polymorphism and melanoma susceptibility remained controversial. To draw a more precise estimation of the relationship, a total of eight published case-control studies containing 5,212 cases and 7,045 controls were included for meta-analysis. Overall, a significant association was found between the XPG Asp1104His polymorphism and melanoma susceptibility for the dominant model (OR = 2.42, 95 % CI = 2.26-2.60). In subgroup analysis by source of control, there was an obvious association was found among Population-based subgroup for the dominant model CC+GC vs GG (OR 2.51, 95 % CI 2.28-2.77), among the Hospital-based subgroup, an obvious association was also found for the dominant model CC+GC vs GG (OR 2.34, 95 % CI 2.12-2.58). This meta-analysis suggested that the XPG Asp1104His polymorphism was a risk factor for melanoma susceptibility.

Association between the XPG Asp1104His and XPF Arg415Gln polymorphisms and risk of cancer: a meta-analysis

BACKGROUND

The XPG (xeroderma pigmentosum type G) Asp1104His and XPF (xeroderma pigmentosum type F) Arg415Gln polymorphisms had been implicated in cancer susceptibility. The previous published data on the association between XPG Asp1104His and XPF Arg415Gln polymorphisms and cancer risk remained controversial.

METHODOLOGY/PRINCIPAL FINDINGS

To derive a more precise estimation of the association between the XPG Asp1104His and XPF Arg415Gln polymorphisms and overall cancer risk, we performed a meta-analysis to investigate the association between cancer susceptibility and XPG Asp1104His (32,162 cases and 39,858 controls from 66 studies) and XPF Arg415Gln polymorphisms (17,864 cases and 20,578 controls from 32 studies) in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly elevated cancer risk was found when all studies were pooled into the meta-analysis of XPG Asp1104His (dominant model: OR = 1.05, 95% CI = 1.00-1.10; Asp/His vs. Asp/Asp: OR = 1.06, 95% CI = 1.01-1.11). In the further stratified and sensitivity analyses, significantly decreased lung cancer risk was found for XPF Arg415Gln (dominant model: OR = 0.82, 95% CI = 0.71-0.96; Arg/Gln versus Arg/Arg: OR = 0.83, 95% CI = 0.71-0.97; additive model: OR = 0.83, 95% CI = 0.72-0.95) and significantly increased other cancer risk was found among hospital-based studies for XPG Asp1104His (dominant model: OR = 1.23, 95% CI = 1.02-1.49).

CONCLUSIONS/SIGNIFICANCE

In summary, this meta-analysis suggests that XPF Arg415Gln polymorphism may be associated with decreased lung cancer risk and XPG Asp1104His may be a low-penetrant risk factor in some cancers development. And larger scale primary studies are required to further evaluate the interaction of XPG Asp1104His and XPF Arg415Gln polymorphisms and cancer risk in specific populations.

Dupuytren's disease and the risk of malignant neoplasms

The object of this study was the investigation of the risk of occurrence of malignant neoplasms in 508 patients with Dupuytren's disease (DD) and in 2157 of their 1st degree relatives. In the first stage of the study, we evaluated the tumour spectrum as well as the age of the patient at diagnosis of cancers in DD families along with the observed and expected frequencies of malignancies. In the second stage of the study, we examined the distribution of 20 common mutations/polymorphisms in 12 known cancer susceptibility genes among DD patients and 508 matched healthy controls. No such study has been published to date. Results. No significant differences were noted between malignancies diagnosed among members of DD families and the general population. Molecular examination of 20 mutations/polymorphisms in 12 cancer susceptibility genes in Dupuytren's patients and controls showed a statistically significant association of one mutation with Dupuytren disease: D312M in XPD (OR = 1.75, p = 0.004). We observed a tendency toward changed frequencies of occurrence of central nervous system tumors, laryngeal cancer and non-melanoma skin cancers in DD families. The results of our study indicate a lack of a strong association between Dupuytren disease and familial cancer risk.

Quantitative assessment of the association between XPC Lys939Gln polymorphism and cutaneous melanoma risk

Previous studies evaluating the association between XPC Lys939Gln polymorphism and cutaneous melanoma risk reported conflicting findings. We searched PubMed and Embase databases up to May 16, 2013 to identify eligible studies on the association between XPC Lys939Gln polymorphism and cutaneous melanoma risk. Finally, a total of seven case-control studies including 3,971 cases of cutaneous melanoma and 5,873 controls were included in the meta-analysis. Statistical analysis was performed with STATA version 11.0. Odds ratios (ORs) with 95 % confidence intervals (95 % CIs) were used to assess the strength of the association. Overall, there was no association between XPC Lys939Gln polymorphism and cutaneous melanoma risk under all five genetic models (Gln vs. Lys: OR = 1.11, 95 % CI = 0.98-1.26, P = 0.10; GlnGln vs. LysLys: OR = 1.26, 95 % CI = 0.98-1.61, P = 0.07; LysGln vs. LysLys: OR = 1.04, 95 % CI = 0.88-1.22, P = 0.64; GlnGln/LysGln vs. LysLys: OR = 1.10, 95 % CI = 0.92-1.31, P = 0.29; GlnGln vs. LysLys/LysGln: OR = 1.19, 95 % CI = 0.99-1.43, P = 0.06). Subgroup analysis in Caucasians showed that there was an obvious association between XPC Lys939Gln polymorphism and cutaneous melanoma risk in Caucasians (GlnGln vs. LysLys/LysGln: OR = 1.12, 95 % CI = 1.00-1.25, P = 0.05). Sensitivity analysis by omitting one study in turns showed that the significance of the pooled ORs was not stable. In addition, there was some evidence of publication bias in the meta-analysis, and meta-analyses of the studies with large sample size did not find the obvious association between XPC Lys939Gln polymorphism and cutaneous melanoma risk in Caucasians. Therefore, there is little evidence for the association between XPC Lys939Gln polymorphism and cutaneous melanoma risk.

A majority of human melanoma cell lines exhibits an S phase-specific defect in excision of UV-induced DNA photoproducts

It is well established that efficient removal of highly-promutagenic UV-induced dipyrimidine photoproducts via nucleotide excision repair (NER) is required for protection against sunlight-associated malignant melanoma. Nonetheless, the extent to which reduced NER capacity might contribute to individual melanoma susceptibility in the general population remains unclear. Here we show that among a panel of 14 human melanoma strains, 11 exhibit significant inhibition of DNA photoproduct removal during S phase relative to G0/G1 or G2/M. Evidence is presented that this cell cycle-specific NER defect correlates with enhanced apoptosis and reduced clonogenic survival following UV irradiation. In addition, melanoma strains deficient in S phase-specific DNA photoproduct removal manifest significantly lower levels of phosphorylated histone H2AX at 1 h post-UV, suggesting diminished activation of ataxia telangiectasia and Rad 3-related (ATR) kinase, i.e., a primary orchestrator of the cellular response to UV-induced DNA replication stress. Consistently, in the case of DNA photoproduct excision-proficient melanoma cells, siRNA-mediated depletion of ATR (but not of its immediate downstream effector kinase Chk1) engenders deficient NER specifically during S. On the other hand simultaneous siRNA-mediated depletion of ataxia telangiectasia mutated kinase (ATM) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) exerts no significant effect on either phosphorylation of H2AX at 1 h post-UV or the efficiency of DNA photoproduct removal. Our data suggest that defective NER exclusively during S phase, possibly associated with decreased ATR signaling, may constitute an heretofore unrecognized determinant in melanoma pathogenesis.

Associations of Lys939Gln and Ala499Val polymorphisms of the XPC gene with cancer susceptibility: a meta-analysis

XPC polymorphisms may alter DNA repair capacity, thus leading to genetic instability and carcinogenesis. Numerous studies have investigated the associations of XPC Lys939Gln (rs2228001) and Ala499Val (rs2228000) polymorphisms with cancer susceptibility; however, the findings are inconclusive. We searched literature from MEDLINE and EMBASE for eligible publications that assessed the associations between these two polymorphisms and cancer risk. We also assessed genotype-mRNA expression correlation data from HapMap for rs2228001 and rs2228000 in normal cell lines derived from 270 subjects with different ethnicities. The final analysis included 62 published studies of 25,708 cases and 30,432 controls for the Lys939Gln and 34 studies with 14,877 cases and 17,888 controls for the Ala499Val. Overall, Lys939Gln was significantly associated with an increased overall cancer risk (Gln/Gln vs. Lys/Lys: OR = 1.16, 95% CI = 1.07 - 1.25, p < 0.001; recessive model: OR = 1.14, 95% CI = 1.06 - 1.22, p < 0.001; dominant model: OR = 1.06, 95% CI = 1.01 - 1.11, p = 0.015 and Gln vs. Lys: OR = 1.07, 95% CI = 1.03 - 1.10, p < 0.001) and further stratifications showed an increased risk for bladder, lung and colorectal cancer, Asian populations and population-based studies. Likewise, Ala499Val was also significantly associated with an increased overall cancer risk (Val/Val vs. Ala/Ala: OR = 1.21, 95% CI = 1.07 - 1.36, p = 0.003 and recessive model: OR = 1.20, 95% CI = 1.08 - 1.34, p = 0.001) and further stratification showed an increased risk for breast and bladder cancer, particularly in Asian populations. Interestingly, significantly correlation between XPC genotypes and mRNA expression was found only for Asian populations as well. Despite some limitations, this meta-analysis established some solid statistical evidence for an association between XPC polymorphisms and cancer risk, which warrants further validation in single large studies.

Do not underestimate nucleotide excision repair: it predicts not only melanoma risk but also survival outcome

Nucleotide excision repair (NER) removes UV-induced DNA damage and other bulky DNA lesions thereby maintaining genomic integrity. Dr. Qingyi Wei’s group demonstrated over the last decade that NER fidelity and single nucleotide polymorphisms (SNPs) in NER genes constitute melanoma risk biomarkers. In this issue (Li et al.) they provide evidence that SNPs in NER genes may also predict melanoma survival.

DNA repair and cell cycle checkpoint defects as drivers and therapeutic targets in melanoma

The ultraviolet radiation (UVR) component of sunlight is the major environmental risk factor for melanoma, producing DNA lesions that can be mutagenic if not repaired. The high level of mutations in melanomas that have the signature of UVR-induced damage indicates that the normal mechanisms that detect and repair this damage must be defective in this system. With the exception of melanoma-prone heritable syndromes which have mutations of repair genes, there is little evidence for somatic mutation of known repair genes. Cell cycle checkpoint controls are tightly associated with repair mechanisms, arresting cells to allow for repair before continuing through the cell cycle. Checkpoint signaling components also regulate the repair mechanisms. Defects in checkpoint mechanisms have been identified in melanomas and are likely to be responsible for increased mutation load in melanoma. Loss of the checkpoint responses may also provide an opportunity to target melanomas using a synthetic lethal approach to identify and inhibit mechanisms that compensate for the defective checkpoints.

Xeroderma pigmentosum genes and melanoma risk

Xeroderma pigmentosum is a rare autosomal recessive disease that is associated with a severe deficiency in nucleotide excision repair. The presence of a distinct the nucleotide excision repair (NER) mutation signature in melanoma suggests that perturbations in this critical repair process are likely to be involved with disease risk. We hypothesized that persons with polymorphic NER gene(s) are likely to have reduced NER activity and are consequently at an increased risk of melanoma development. We assessed the association between 94 SNPs within seven XP genes (XPA-XPG) and the melanoma risk in the Polish population. We genotyped 714 unselected melanoma patients and 1,841 healthy adults to determine if there were any polymorphisms differentially represented in the disease group. We found that a significantly decreased risk of melanoma was associated with the Xeroderma pigmentosum complementation (XPC) rs2228000_CT genotype (odds ratio [OR] = 0.15; p < 0.001) and the rs2228000_TT genotype (OR = 0.11; p < 0.001) compared to the reference genotype. Haplotype analysis within XPC revealed the rs2228001_A + G1475A_G + G2061A_A + rs2228000_T + rs3731062_C haplotype (OR = 0.26; p < 0.05) was associated with a significantly decreased disease risk. The haplotype analysis within the Xeroderma pigmentosum group D (XPD) showed a modest association between two haplotypes and a decrease in melanoma risk. There were no major differences between the prevalence of the XP polymorphisms among young or older patients with melanoma. Linkage disequilibrium of XPC: rs2228001, G1475A, G2061A, rs2228000 and rs3731062 was found. The data from our study support the notion that only XPC and XPD genes are associated with melanoma susceptibility.

Variants in nucleotide excision repair core genes and susceptibility to recurrence of squamous cell carcinoma of the oropharynx

Genetically determined capacity for NER may modulate both cancer risk and prognosis. Thus, we evaluated associations of seven selected variants in the NER core genes with recurrence risk in 658 squamous cell carcinoma of the oropharynx (SCCOP) patients treated principally by radiation. The seven polymorphisms in the core NER genes (XPC-rs2228000, XPC-rs2228001, XPD-rs1799793, XPD-rs13181, XPG-rs17655, ERCC1-rs3212986 and XPA-rs1800975) were genotyped using PCR-RFLP method and log-rank test and multivariable Cox models were used to evaluate the associations in both dominant and recessive genetic models. In a dominant model, we found that polymorphisms of XPC-rs2228000, XPD-rs1799793 and XPG-rs17655 were significantly associated with disease-free survival (log-rank, p = 0.014; p = 0.00008; p = 0.0007, respectively), and these polymorphisms were significantly associated with recurrence risk of SCCOP (hazard ratio (HR) = 1.6, 95% confidence interval (CI) 1.1-2.3 for XPC-rs2228000; HR = 0.4, 95% 0.3-0.6 for XPD-rs1799793 and HR = 0.5, 95% CI 0.4-0.8 for XPG-rs17655) after multivariable adjustment. Moreover, the borderline significant or significant associations were also found for these three polymorphisms in HPV16/18-positive SCCOP patients (HR = 1.6, 95% CI 1.0-4.1 for XPC-rs2228000; HR = 0.2, 95% CI 0.1-0.5 for XPD-rs1799793 and HR = 0.1, 95% CI 0.0-0.9 for XPG-rs17655). However, similarly significant associations were not found for these polymorphisms in a recessive model. These findings suggest that polymorphisms of XPC-rs2228000, XPD-rs1799793 and XPG-rs17655 in the NER core genes may contribute to recurrence risk of SCCOP, particularly HPV-positive SCCOP, in a dominant but not in a recessive model. However, validation of these results is warranted.

Polymorphisms of nucleotide excision repair genes predict melanoma survival

Melanoma is the most highly malignant skin cancer, and nucleotide excision repair (NER) is involved in melanoma susceptibility. In this analysis of 1,042 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 two in XPA, 14 in XPC, three in XPE, four in ERCC1, 10 in ERCC2, eight 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 the 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 markedly 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.

Comprehensive assessment of the association of ERCC2 Lys751Gln polymorphism with susceptibility to cutaneous melanoma

Previous studies evaluating the association between excision repair cross-complimentary group 2 (ERCC2) Lys751Gln polymorphism and susceptibility to cutaneous melanoma reported conflicting findings. We searched PubMed and Wangfang Medical databases up to October 16, 2012 to identify eligible studies. A total of 8 case-control studies including 3,492 cases and 5,381 controls were included in the meta-analysis. Statistical analysis was performed with Review Manage version 5.1. Odds ratios (ORs) with 95 % confidence intervals (95 %CIs) were used to assess the strength of the association. There was no obvious between-study heterogeneity among those eight studies under all four comparison models. Overall, there was a significant association between ERCC2 Lys751Gln polymorphism and susceptibility to cutaneous melanoma under three genetic models (for Gln versus Lys: OR = 1.08, 95 % CI = 1.01-1.15, P = 0.02; for GlnGln versus LysLys: OR = 1.16, 95 % CI = 1.01-1.33, P = 0.03; for GlnGln/LysGln versus LysLys: OR = 1.10, 95 % CI = 1.01-1.21, P = 0.04). Sensitivity analysis by omitting one study a time showed the significance of the pooled ORs was stable under all those three genetic models above. Therefore, the meta-analysis suggests that there is a significant association between ERCC2 Lys751Gln polymorphism and susceptibility to cutaneous melanoma.

Association between the ERCC5 Asp1104His polymorphism and cancer risk: a meta-analysis

BACKGROUND

Excision repair cross complementing group 5 (ERCC5 or XPG) plays an important role in regulating DNA excision repair, removal of bulky lesions caused by environmental chemicals or UV light. Mutations in this gene cause a rare autosomal recessive syndrome, and its functional single nucleotide polymorphisms (SNPs) may alter DNA repair capacity phenotype and cancer risk. However, a series of epidemiological studies on the association between the ERCC5 Asp1104His polymorphism (rs17655, G>C) and cancer susceptibility generated conflicting results.

METHODOLOGY/PRINCIPAL FINDINGS

To derive a more precise estimation of the association between the ERCC5 Asp1104His polymorphism and overall cancer risk, we performed a meta-analysis of 44 published case-control studies, in which a total of 23,490 cases and 27,168 controls were included. To provide additional biological plausibility, we also assessed the genotype-gene expression correlation from the HapMap phase II release 23 data with 270 individuals from 4 ethnic populations. When all studies were pooled, we found no statistical evidence for a significantly increased cancer risk in the recessive genetic models (His/His vs. Asp/Asp: OR = 0.99, 95% CI: 0.92-1.06, P = 0.242 for heterogeneity or His/His vs. Asp/His + Asp/Asp: OR = 0.98, 95% CI: 0.93-1.03, P = 0.260 for heterogeneity), nor in further stratified analyses by cancer type, ethnicity, source of controls and sample size. In the genotype-phenotype correlation analysis from 270 individuals, we consistently found no significant correlation of the Asp1104His polymorphism with ERCC5 mRNA expression.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis suggests that it is unlikely that the ERCC5 Asp1104His polymorphism may contribute to individual susceptibility to cancer risk.

Ethnicity and cutaneous melanoma in the city of Sao Paulo, Brazil: a case-control study

BACKGROUND

Over the last century the incidence of cutaneous melanoma has increased worldwide, a trend that has also been observed in Brazil. The identified risk factors for melanoma include the pattern of sun exposure, family history, and certain phenotypic features. In addition, the incidence of melanoma might be influenced by ethnicity. Like many countries, Brazil has high immigration rates and consequently a heterogeneous population. However, Brazil is unique among such countries in that the ethnic heterogeneity of its population is primarily attributable to admixture. This study aimed to evaluate the contribution of European ethnicity to the risk of cutaneous melanoma in Brazil.

METHODOLOGY/PRINCIPAL FINDINGS

We carried out a hospital-based case-control study in the metropolitan area of Sao Paulo, Brazil. We evaluated 424 hospitalized patients (202 melanoma patients and 222 control patients) regarding phenotypic features, sun exposure, and number of grandparents born in Europe. Through multivariate logistic regression analysis, we found the following variables to be independently associated with melanoma: grandparents born in Europe-Spain (OR = 3.01, 95% CI: 1.03-8.77), Italy (OR = 3.47, 95% CI: 1.41-8.57), a Germanic/Slavic country (OR = 3.06, 95% CI: 1.05-8.93), or ≥ 2 European countries (OR = 2.82, 95% CI: 1.06-7.47); eye color-light brown (OR = 1.99, 95% CI: 1.14-3.84) and green/blue (OR = 4.62; 95% CI 2.22-9.58); pigmented lesion removal (OR = 3.78; 95% CI: 2.21-6.49); no lifetime sunscreen use (OR = 3.08; 95% CI: 1.03-9.22); and lifetime severe sunburn (OR = 1.81; 95% CI: 1.03-3.19).

CONCLUSIONS

Our results indicate that European ancestry is a risk factor for cutaneous melanoma. Such risk appears to be related not only to skin type, eye color, and tanning capacity but also to others specific characteristics of European populations introduced in the New World by European immigrants.

Polymorphisms in the ERCC5 gene and risk of esophageal squamous cell carcinoma (ESCC) in Eastern Chinese populations

BACKGROUND

Excision repair cross complementing group 5 (ERCC5 or XPG) plays an important role in regulating DNA excision repair; its functional single nucleotide polymorphisms (SNPs) may alter DNA repair capacity and thus contribute to cancer risk.

METHODOLOGY/PRINCIPAL FINDINGS

In a hospital-based case-control study of 1115 esophageal squamous cell carcinoma (ESCC) cases and 1117 cancer-free controls, we genotyped three potentially functional SNPs of ERCC5 (SNPs, rs2296147T>C, rs2094258C>T and rs873601G>A) and estimated crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for their associations with risk of ESCC using unconditional logistic regression models. We also calculated false-positive report probabilities (FPRPs) for significant findings. We found that compared with the TT genotype, ERCC5 rs2296147 C variant genotypes were associated with a significantly lower ESCC risk (CT: adjusted OR = 0.76, 95% CI = 0.63-0.93, CT/CC: adjusted OR = 0.80, 95% CI = 0.67-0.96); however, this risk was not observed for the other two SNPs (rs2094258C>T and rs873601 G>A), nor in further stratification and haplotype analysis.

CONCLUSIONS/SIGNIFICANCES

These findings suggested that ERCC5 polymorphisms may contribute to risk of ESCC in Eastern Chinese populations, but the effect was weak and needs further validation by larger population-based case-control studies.

Common polymorphisms in CYP1A1, GSTM1, GSTT1, GSTP1 and XPD genes and endogenous DNA damage

Endogenous DNA damage levels were analyzed in relation to polymorphisms in genes encoding phase I detoxifying enzyme-CYP1A1, phase II detoxifying enzymes-GSTM1, GSTT1, GSTP1 and enzyme involved in nucleotide excision repair-XPD. The study group consisted of 220 healthy non-smoking volunteers; 90 men and 130 woman, 25-60 years old (44 ± 10 years). The level of DNA damage (% DNA in tail) was evaluated by alkaline comet assay. The genetic variants were determined by restriction fragment length polymorphism PCR. The highest level of DNA damage (6.7%) was found in carriers of both: AA variant of XPD gene and M1 null variant of GSTM1 gene. The lowest level of DNA breaks (3.7%) was associated with the genotype GSTP1-AA/GSTM1 (+).

Prognostic parameters for the primary care of melanoma patients: what is really risky in melanoma?

Due to intensified research in recent years, the understanding of the molecular mechanisms involved in the development of melanoma has dramatically improved. The discovery of specific, causal mutations such as BRAF or KIT oncogenes not only renders a targeted and thus more effective therapeutic approach possible, but also gives rise to a new genetic-based classification. Targeting just a few out of several potential mutations, BRAF-Inhibitors such as PLX 4032 achieved already tremendous results in the therapy of metastatic melanoma. Up to now, the correlation of clinical, histomorphologic, and genetic features is, however, not understood. Even more, is it not well known precisely what kind of molecular changes predispose the primary melanoma for metastasis. The identification of morphological surrogates and prognostic parameters in tumors with such genetic alteration seems therefore crucial when differentiating and classifying this heterogeneous tumor entity in more detail and thus facilitates the stratification of prognosis as well as therapy. This review summarizes the current understanding of carcinogenesis and gives a detailed overview of known morphologic and potentially future genetic prognostic parameters in malignant melanoma.

Susceptibility of XPD and RAD51 genetic variants to carcinoma of urinary bladder in North Indian population

For the present study, two polymorphisms, xeroderma pigmentosum, complementation group D (XPD) Lys751Gln and RAD51 135G/C were studied with regard to bladder cancer. For XPD Lys751Gln polymorphism, an increased risk of bladder cancer was found to be associated with the Gln variant allele (odds ratio [OR]=1.86, 95% confidence interval [CI]=1.27-2.73), on taking AA (Lys/Lys) as the referent genotype. In males, the XPD 751C (Gln) allele was found to be associated with a significantly increased risk (OR=2.33, 95% CI=1.52-3.56). The inhabitants of rural areas showed a significantly increased risk with the XPD Gln allele (OR=2.59, 95% CI=1.46-4.62) when compared with those of urban areas. In smokers (OR=5.30, 95% CI=2.42-11.68), alcohol drinkers (OR=4.33, 95% CI=2.17-8.70), and nonvegetarians (OR=2.21, 95% CI=1.26-3.87), the XPD Gln allele showed a significantly increased risk toward bladder cancer. For RAD51 135G/C polymorphism, no significant difference was observed in the allelic and genotypic frequencies. Even after stratification, no significant association could be seen. After stratifying histopathologically, the RAD51 CC genotype was associted with decreased risk in subjects having superficial stage (OR=0.51, 95% CI=0.27-0.99) and with those having G2 grade (OR=0.24, 95% CI=0.09-0.62) of bladder cancer. XPD polymorphism may be a predisposing factor, but the same cannot be said for RAD51 gene polymorphism.

DNA repair genes polymorphism (XPG and XRCC1) and association of prostate cancer in a north Indian population

Prostate cancer is the most commonly diagnosed cancer in men worldwide and is the second leading cause of cancer related mortality. Genetic background may account for the difference in susceptibility of individuals to different diseases and the relationship between genetic polymorphism and some diseases has been extensively studied. There are several common polymorphisms in genes encoding DNA repair enzymes, some of these polymorphisms are reported to result in subtle structural alterations of the repair enzyme and modulation of the repair capacity. The aim of the present study was to analyze the effect of XPG Asp 1104His and XRCC1 Arg309Gln polymorphisms on risk of prostate cancer in north Indian population. Statistically significant increased risk of prostate cancer was observed on individuals that posses His/His genotype of XPG (OR 2.53, 95% CI 0.99-6.56, P = 0.031). In this study 150 prostate cancer diagnosed patients, 150 healthy controls and 150 BPH (benign prostate hyper plasia) were recruited from north Indian population. Moreover, individuals that carried the Gln/Gln genotype of XRCC1 also showed statistically increased risk of prostate cancer (OR 2.06, 95% CI 1.07-4.00, P = 0.033). The Asp/Asp of XPG and Gln/Gln of XRCC1 in combination showed statistically increased risk of prostate cancer in cases (OR 3.29, 95% CI 1.09-10.16, P = 0.032).

XPD Lys751Gln polymorphism and esophageal cancer risk: A meta-analysis involving 2288 cases and 4096 controls

AIM: To evaluate the association between xeroderma pigmentosum group D (XPD), genetic polymorphism Lys751Gln and esophageal cancer risk.

METHODS: We searched PubMed up to September 1, 2010 to identify eligible studies. A total of 10 case-control studies including 2288 cases and 4096 controls were included in the meta-analysis. Statistical analysis was performed with Review Manage version 4.2. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association.

RESULTS: The results suggested that there is no significant association between XPD Lys751Gln polymorphism and esophageal cancer susceptibility in the overall population. However, in subgroup analysis by histology type, a significant association was found between XPD Lys751Gln polymorphism and esophageal adenocarcinoma (for CC vs AA: OR = 1.25, 95% CI = 1.01-1.55, P = 0.05 for heterogeneity).

CONCLUSION: Our meta-analysis suggested that XPD Lys751Gln polymorphism may be associated with increased risk of esophageal adenocarcinoma.

ERCC5 p.Asp1104His and ERCC2 p.Lys751Gln polymorphisms are independent prognostic factors for the clinical course of melanoma

Genetic variants in DNA repair enzymes contribute to the susceptibility to cutaneous melanoma; consequently, we analyzed whether common nonsynonymous single-nucleotide polymorphisms in DNA repair enzyme genes might also influence the course of disease. To this end, we determined eight polymorphisms of seven different DNA repair enzymes in 742 patients with cutaneous melanoma, and correlated these with overall survival. Univariate Cox proportional hazards model analyses revealed that ERCC5 (XPG) 1104 His/His was significantly associated with impaired survival. Indeed, the univariate hazard ratio (HR) was 2.8 times higher for patients with ERCC5 1104 His/His (P<0.001) compared with ERCC5 1104 Asp/Asp. Accordingly, the 5-year survival rate was 55% (95% confidence interval 43-71) for patients with ERCC5 1104 His/His, whereas 82% (95% confidence interval 78-86) of patients with ERCC5 1104 Asp/Asp were still alive at this time. Importantly, adjusted Cox regression analysis not only confirmed ERCC5 1104 His/His as an independent prognostic factor (multivariate HR=4.5; P<0.001), but also revealed the significant impact of ERCC2 (XPD) 751 Gln/Gln on prognosis, with a 2.2-fold increased HR compared with ERCC2 751 Lys/Lys (P=0.009). Thus, ERCC5 codon 1104 and ERCC2 codon 751 polymorphisms are independent prognostic factors in patients with cutaneous melanoma.

Nucleotide excision repair gene expression after Cisplatin treatment in melanoma

Two of the hallmark features of melanoma are its development as a result of chronic UV radiation exposure and the limited efficacy of cisplatin in the disease treatment. Both of these DNA-damaging agents result in large helix-distorting DNA damage that is recognized and repaired by nucleotide excision repair (NER). The aim of this study was to examine the expression of NER gene transcripts, p53, and p21 in melanoma cell lines treated with cisplatin compared with melanocytes. Basal expression of all genes was greater in the melanoma cell lines compared with melanocytes. Global genome repair (GGR) transcripts showed significantly decreased relative expression (RE) in melanoma cell lines 24 hours after cisplatin treatment. The basal RE of p53 was significantly higher in the melanoma cell lines compared with the melanocytes. However, induction of p53 was only significant in the melanocytes at 6 and 24 hours after cisplatin treatment. Inhibition of p53 expression significantly decreased the expression of all the GGR transcripts in melanocytes at 6 and 24 hours after cisplatin treatment. Although the RE levels were lower with p53 inhibition, the induction of the GGR genes was very similar to that in the control melanocytes and increased significantly across the time points. The findings from this study revealed reduced GGR transcript levels in melanoma cells 24 hours after cisplatin treatment. Our findings suggest a possible mechanistic explanation for the limited efficacy of cisplatin treatment and the possible role of UV light in melanoma.

Polymorphisms in ERCC2, MSH2, and OGG1 DNA repair genes and gallbladder cancer risk in a population of Northern India

BACKGROUND

Genetic variants of DNA repair enzymes may lead to genetic instability and contribute to gallbladder (GB) carcinogenesis.

METHODS

A case-control study (230 GB carcinogenesis patients and 230 controls) was undertaken to evaluate whether genetic variations in 3 DNA repair genes ERCC2 (Asp312Asn [rs1799793] and Lys751Gln [rs13181]), MSH2 (-118T > C [rs2303425] and IVS1 + 9G>C [rs2303426]), and OGG1 (Ser326Cys [rs1052133] and 748-15C > G [rs2072668]) are associated with GB carcinogenesis risk in a North Indian population.

RESULTS

The authors found that the ERCC2 Asp312Asn AA, MSH2 IVS1 + 9G > C CC, OGG1 Ser326Cys GG and CG + GG, and OGG1 748-15C > G GG and CG + GG genotypes were significantly associated with an increased risk of GB carcinogenesis (odds ratio [OR], 2.1, 1.8, 2.5, 1.8, 2.0, and 1.6, respectively). In contrast, ERCC2 Lys751Gln, and MSH2 -118T > C markers showed no significant associations with GB carcinogenesis risk, although because of the small sample size their effects cannot be ruled out. Female GB carcinogenesis patients with the OGG1 748-15C > G GG, OGG1 Ser326Cys GG, and ERCC2 Asp312Asn genotypes had a greater risk for developing the disease (OR, 3.6, 7.7, and 2.7, respectively). There was a significant interaction between MSH2 IVS1 + 9G > C and OGG1 748-15C > G polymorphisms (P = .001). Furthermore, individuals with > 6 variant alleles of the studied polymorphisms were at 4-fold increased risk for developing GB carcinogenesis. Classification and Regression Tree analysis revealed potential higher-order gene-gene interactions and categorized a few higher-risk subgroups for GB carcinogenesis.

CONCLUSIONS

These results suggest that genetic variants in the DNA repair pathways may be involved in GB carcinogenesis etiology.

MUTYH Tyr165Cys, OGG1 Ser326Cys and XPD Lys751Gln polymorphisms and head neck cancer susceptibility: a case control study

In the present study we investigated the association between three polymorphisms of the MUTYH (Tyr165Cys, rs34612342), the OGG1 (Ser326Cys, rs1052133) and the XPD (Lys751Gln, rs13181) genes with head and neck cancer risk. Genotypes were determined in DNA from peripheral blood lymphocytes of 265 patients with head and neck squamous cell carcinoma (HNSCC) as well as 280 cancer-free controls by PCR-restriction fragment length polymorphisms. We found an association between HNSCC and the Ser326Cys (OR 1.69; 95% CI 1.19-2.45) as well as Cys326Cys (OR 4.56; 95% CI 2.07-10.05) variants of the OGG1 gene. The gene-gene interaction between MUTYH and OGG1 as well as OGG1 and XPD polymorphic variants may contribute to higher prevalence of HNSCC. We also found an association between Ser326Cys and Cys326Cys variants of OGG1 gene and smoking status in HNSCC patients (OR 1.97; 95% CI 1.25-3.11), (OR 3.54; 95% CI 1.39-9.04), respectively. Moreover, we also observed a protective association between Tyr165Cys variant of the MUTYH gene and non-smoking status in HNSCC (OR 0.34; 95% CI 0.17-0.66). We also found a link between gene-gene interaction (MUTYH and OGG1 or OGG1 and XPD) and smoking (ORs 2.17-4.20 and 2.18-5.23) or non-smoking status (ORs 0.11 and 7.61) in HNSCC patients, respectively. In conclusion our data showed that the Ser326Cys polymorphism of the OGG1 gene may modify the risk of HNSCC associated with smoking. Finally we suggested that this polymorphism might be used as predictive factor for head and neck cancer in Polish population.

Similar nucleotide excision repair capacity in melanocytes and melanoma cells

Sunlight UV exposure produces DNA photoproducts in skin that are repaired solely by nucleotide excision repair in humans. A significant fraction of melanomas are thought to result from UV-induced DNA damage that escapes repair; however, little evidence is available about the functional capacity of normal human melanocytes, malignant melanoma cells, and metastatic melanoma cells to repair UV-induced photoproducts in DNA. In this study, we measured nucleotide excision repair in both normal melanocytes and a panel of melanoma cell lines. Our results show that in 11 of 12 melanoma cell lines tested, UV photoproduct repair occurred as efficiently as in primary melanocytes. Importantly, repair capacity was not affected by mutation in the N-RAS or B-RAF oncogenes, nor was a difference observed between a highly metastatic melanoma cell line (A375SM) or its parental line (A375P). Lastly, we found that although p53 status contributed to photoproduct removal efficiency, its role did not seem to be mediated by enhanced expression or activity of DNA binding protein DDB2. We concluded that melanoma cells retain capacity for nucleotide excision repair, the loss of which probably does not commonly contribute to melanoma progression.