Poly (AT) deletion/insertion polymorphism of the XPC gene contributes to urinary system cancer susceptibility: a meta-analysis

Molecular Landscape for Malignant Transformation in Diffuse Astrocytoma

Background  Malignant transformation (MT) of low-grade gliomas changes dramatically the natural history to poor prognosis. Currently, factors associated with MT of gliomas have been inconclusive, in particular, diffuse astrocytoma (DA).

Objective  The present study aimed to explore the molecular abnormalities related to MT in the same patients with different MT stages.

Methods  Twelve specimens from five DA patients with MT were genotyped using next-generation sequencing (NGS) to identify somatic variants in different stages of MT. We used cross-tabulated categorical biological variables and compared the mean of continuous variables to assess for association with MT.

Results  Ten samples succussed to perform NGS from one male and four females, with ages ranging from 28 to 58 years. The extent of resection was commonly a partial resection following postoperative temozolomide with radiotherapy in 25% of cases. For molecular findings, poly-T-nucleotide insertion in isocitrate dehydrogenase 1 (IDH1) was significantly related to MT as a dose–response relationship (Mann–Whitney's U test, p  = 0.02). Also, mutations of KMT2C and GGT1 were frequently found in the present cohort, but those did not significantly differ between the two groups using Fisher's exact test.

Conclusion  In summary, we identified a novel relationship between poly-T insertion polymorphisms that established the pathogenesis of MT in DA. A further study should be performed to confirm the molecular alteration with more patients.

DNA Repair Gene Polymorphisms and Susceptibility to Urothelial Carcinoma in a Southeastern European Population

Single nucleotide polymorphisms (SNPs) in DNA repair genes may predispose to urothelial carcinoma of the bladder (UCB). This study focused on three specific SNPs in a population with high exposure to environmental carcinogens including tobacco and alcohol. A case-control study design was used to assess for presence of XPC PAT +/-, XRCC3 Thr241Met, and ERCC2 Lys751Gln DNA repair gene SNPs in peripheral blood from patients with UCB and healthy individuals. One hundred patients and equal number of healthy subjects were enrolled. The XPC PAT +/+ genotype was associated with a 2-fold increased risk of UCB (OR = 2.16; 95%CI: 1.14-4; p = 0.01). The -/+ and +/+ XPC PAT genotypes were more frequently present in patients with multiple versus single tumors (p = 0.01). No association was detected between ERCC2 Lys751Gln genotypes/alleles, and risk for developing UCB. Presence of the XRCC3 TT genotype (OR = 0.14; 95%CI:0.07-0.25; p < 0.01) and of the T allele overall (OR = 0.26; 95%CI:0.16-0.41; p < 0.01) conferred a protective effect against developing UCB. The XPC PAT -/+ and XRCC3 Thr241Met SNPs are associated with predisposition to UCB. The XPC PAT -/+ SNP is also an indicator of bladder tumor multiplicity, which might require a more individualized surveillance and treatment.

A33512C and Intronic Poly(AT) Insertion/Deletion (PAT-/+) Polymorphisms of the XPC Gene and Their Association With the Risk of Breast Cancer

BACKGROUND

Several lines of evidence suggest that A33512C and intronic poly(AT) insertion/deletion (PAT-/+) polymorphisms of the XPC gene is associated with various types of malignancy. This case-control study aimed to determine the possible association between A33512C and PAT-/+ polymorphisms of the XPC gene and breast cancer (BC).

PATIENTS AND METHODS

A total of 200 women diagnosed with BC as cases and 200 ethnically matched healthy controls were genotyped for A33512C and PAT-/+ polymorphisms of the XPC gene by PCR-restriction fragment length polymorphism and PCR methods, respectively. The possible association between XPC A33512C and PAT-/+ polymorphisms with the risk of BC were also analyzed.

RESULTS

PAT-/+ polymorphism of the XPC gene was significantly associated with increased risk of BC (P < .05), whereas there was no association between XPC A33512C polymorphism and BC (P > .05). The frequency of the XPC PAT+ allele in BC patients was significantly higher than those in healthy controls (odds ratio, 0.561; 95% confidence interval, 0.403-0.779; P < .05). The combined genotypes AC/PAT+/+ and CC/PAT+/+ were significantly associated with increased risk of BC.

CONCLUSION

The prevalence of XPC PAT+ allele was significantly higher in patients with high-tumor-stage disease compared to healthy controls. Overall, the significantly higher frequency of the PAT+ allele in the BC group compared to the control group may suggest an etiologic link between the presence of the PAT+ allele and the risk of BC.

Genetic diversity and functional effect of common polymorphisms in genes involved in the first heterodimeric complex of the Nucleotide Excision Repair pathway

Nucleotide excision repair is a multistep process that recognizes and eliminates a spectrum of DNA damages. Five proteins, namely XPC, RAD23, Centrin 2, DDB1 and DDB2 act as a heterodimeric complex at the early steps of the NER pathway and play a crucial role in the removal of DNA lesions. Several exonic mutations on genes coding for these proteins have been identified as associated with Xeroderma-pigmentosum (XP), a rare monogenic disorder. However, the role of regulatory polymorphisms in disease development and inter-ethnic diversity is still not well documented. Due to the high incidence rate of XP in Tunisia, we performed a genotyping analysis of 140 SNPs found on these 5 genes in a set of 135-subjects representing the general Tunisian-population. An inter-ethnic comparison based on the genotype frequency of these SNPs have been also conducted. For the most relevant variants, we performed a comprehensive assessment of their functional effects. Linkage disequilibrium and principal component analysis showed that the Tunisian-population is an admixed and intermediate population between Sub-Saharan Africans and Europeans. Using variable factor maps, we identified a list of 20 polymorphisms that contribute considerably to the inter-ethnic diversity of the NER complex. In-silico functional analysis showed that SNPs on XPC, DDB1 and DDB2 are associated with eQTLs mainly DDB2-rs10838681 that seems to decrease significantly the expression level of ACP2 (p = 6.1 × 10^-26). Statistical analysis showed that the allelic frequency of DDB2-rs10838681 in Tunisia is significantly different from all other populations. Using rVarBase, we identified 5 variants on XPC, DDB1 and DDB2 that seem to alter the binding sites of several transcription factors considered as key players in DNA-repair pathways. Results presented in this study provide the first report on regulatory polymorphisms of the NER-complex genes in Tunisia. These results may also help to establish a baseline database for future association and functional studies.

Genetic variants of nucleotide excision repair pathway and outcomes of induction therapy in acute myeloid leukemia

Aim: Acute myeloid leukemia (AML) is a heterogeneous disease in pathogenesis and response to therapy. Nucleotide excision repair (NER) pathway has a major role in the elimination of genotoxic effects of chemotherapeutic agents. We aimed to clarify the effects of selected variants of XPD, XPC, ERCC5 and ERCC1 genes on the outcomes of induction therapy. Materials & methods: The prevalence of NER genetic variants was evaluated in 67 subjects with AML and their effects on clinical outcomes were analyzed by χ² test. Results: The XPD 751 Lys variant was associated with improved response to chemotherapy compared with XPD 751 Gln and Lys/Gln variants (p = 0.023; odds ratio: 4.5; 95% CI: 1.14-17.73). There were no associations between other genotypes and any outcomes. Conclusion: Current findings suggest that XPD Lys751Gln variant could be considered as a prognostic factor in AML.

Polymorphisms in XPC gene and risk for prostate cancer

Single nucleotide polymorphisms (SNP) in repair gene DNA such as XPC gene can reduce the DNA repair capacity (DRC). Reduced DRC induce genetic instability and may increase the susceptibility to prostate cancer (PC). We conducted a case-controls study to examine the relationship between XPC Lys939Gln and XPC-PAT polymorphisms and the risk for prostate cancer in Tunisian population. We have also correlated molecular results with clinical parameters (Gleason score and TNM status) and lifestyle factors (tobacco status, alcohol consumption, and exposition to professional risk factors) of prostate cancer patients. We have found that the XPC Lys939Gln polymorphism was not associated with a risk of prostate cancer. However the XPC PAT I/I genotype was found to be associated with 3.83-fold increased risk of prostate cancer compared to controls (p = 0.00006; OR 3.83; 95% CI (1.83-8.05)). The test of linkage disequilibrium showed that XPC-PAT polymorphism is in linkage disequilibrium with XPC Lys939Gln variants. The combined analysis of XPC Lys939Gln and XPC-PAT variants showed that patients who inherited (Lys/Gln + PAT D/D) genotypes were protected against prostate cancer development compared to controls. In the other hand, no significant association has been found between XPC polymorphisms and clinical parameters or between XPC polymorphisms and lifestyle factors.

Association of XPC Gene Polymorphisms with Colorectal Cancer Risk in a Southern Chinese Population: A Case-Control Study and Meta-Analysis

Xeroderma pigmentosum group C (XPC) is a key component of the nucleotide excision repair (NER) pathway. Dysfunctional XPC protein may impair NER-mediated DNA repair capacity and further lead to genomic instability and carcinogenesis. Two common nonsynonymous polymorphisms in the XPC gene, Lys939Gln (rs2228001 A > C) and Ala499Val (rs2228000 C > T), have been investigated in various types of cancer. We genotyped these two polymorphisms in 1141 cases with histologically confirmed colorectal cancer (CRC) and 1173 healthy controls to explore their causative association with CRC susceptibility. Overall, no association was observed between these two variants and the risk of CRC. Our meta-analysis also confirmed a lack of overall association. Stratified analyses were performed by age, gender, smoking status, pack-year, drinking status, tumor sites, and Duke's stages. We found that XPC Lys939Gln polymorphism was significantly associated with an increased CRC risk in subjects at 57 years of age or younger (adjusted odds ratio (OR) = 1.37, 95% confidence interval (CI) = 1.004-1.86, p = 0.047) and non-drinkers (adjusted OR = 1.53, 95% CI = 1.10-2.12, p = 0.011). Our results indicated that XPC Lys939Gln may be a low-penetrance CRC susceptibility polymorphism. Our findings warrant further validation.

Polymorphisms in the XPC gene and gastric cancer susceptibility in a Southern Chinese population

Previous studies have reported that XPC gene polymorphisms may modify the individual susceptibility to gastric cancer. In this case-control study with a total of 1,142 cases and 1,173 controls, four potentially functional polymorphisms were genotyped in the XPC gene (rs2228001 A>C, rs2228000 C>T, rs2607775 C>G, and rs1870134 G>C) by Taqman assays and their associations were analyzed with the risk of gastric cancer in a Southern Chinese population. No significant association between any of XPC polymorphisms and gastric cancer risk was detected except for a borderline association with the rs2228000 CT/TT genotype (crude odds ratio =0.86, 95% confidence interval =0.73-1.02, P=0.088) when compared to the rs2228000 CC genotype. Further stratified analysis revealed that the protective effect of rs2228000 CT/TT on the risk of gastric cancer was only significant among subjects older than 58 years. In summary, results indicated that genetic variations in XPC gene may play a weak effect on gastric cancer susceptibility in Southern Chinese population, which warrants further confirmation in larger prospective studies with different ethnic populations.

XPC: Going where no DNA damage sensor has gone before

XPC has long been considered instrumental in DNA damage recognition during global genome nucleotide excision repair (GG-NER). While this recognition is crucial for organismal health and survival, as XPC's recognition of lesions stimulates global genomic repair, more recent lines of research have uncovered many new non-canonical pathways in which XPC plays a role, such as base excision repair (BER), chromatin remodeling, cell signaling, proteolytic degradation, and cellular viability. Since the first discovery of its yeast homolog, Rad4, the involvement of XPC in cellular regulation has expanded considerably. Indeed, our understanding appears to barely scratch the surface of the incredible potential influence of XPC on maintaining proper cellular function. Here, we first review the canonical role of XPC in lesion recognition and then explore the new world of XPC function.

Attenuated XPC expression is not associated with impaired DNA repair in bladder cancer

Bladder cancer has a high incidence with significant morbidity and mortality. Attenuated expression of the DNA damage response protein Xeroderma Pigmentosum complementation group C (XPC) has been described in bladder cancer. XPC plays an essential role as the main initiator and damage-detector in global genome nucleotide excision repair (NER) of UV-induced lesions, bulky DNA adducts and intrastrand crosslinks, such as those made by the chemotherapeutic agent Cisplatin. Hence, XPC protein might be an informative biomarker to guide personalized therapy strategies in a subset of bladder cancer cases. Therefore, we measured the XPC protein expression level and functional NER activity of 36 bladder tumors in a standardized manner. We optimized conditions for dissociation and in vitro culture of primary bladder cancer cells and confirmed attenuated XPC expression in approximately 40% of the tumors. However, NER activity was similar to co-cultured wild type cells in all but one of 36 bladder tumors. We conclude, that (i) functional NER deficiency is a relatively rare phenomenon in bladder cancer and (ii) XPC protein levels are not useful as biomarker for NER activity in these tumors.

Common variants of xeroderma pigmentosum genes and prostate cancer risk

The genetic basis of prostate cancer (PC) is complex and appears to involve multiple susceptibility genes. A number of studies have evaluated a possible correlation between several NER gene polymorphisms and PC risk, but most of them evaluated only single SNPs among XP genes and the results remain inconsistent. Out of 94 SNPs located in seven XP genes (XPA-XPG) a total of 15 SNPs were assayed in 720 unselected patients with PC and compared to 1121 healthy adults. An increased risk of disease was associated with the XPD SNP, rs1799793 (Asp312Asn) AG genotype (OR=2.60; p<0.001) and with the AA genotype (OR=531; p<0.0001) compared to the control population. Haplotype analysis of XPD revealed one protective haplotype and four associated with an increased disease risk, which showed that the A allele (XPD rs1799793) appeared to drive the main effect on promoting prostate cancer risk. Polymorphism in XPD gene appears to be associated with the risk of prostate cancer.

The association between RAD23B Ala249Val polymorphism and cancer susceptibility: evidence from a meta-analysis

Background

A number of studies have investigated associations of genetic variation in RAD23B Ala249Val (rs1805329 C>T) with cancer susceptibility; however, the findings are inconsistent. We performed a meta-analysis to acquire a more precise estimation of the relationship.

Method

We searched literatures from PubMed, Embase and Web of Science. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the association between Ala249Val polymorphism and cancer risk.

Results

A total of 23 studies consisting of 10837 cases and 13971 controls were included in this meta-analysis. Overall, no significant associations were found between RAD23B Ala249Val polymorphism and cancer risk (Val/Val vs. Ala/Ala: OR = 0.97, 95% CI = 0.75–1.25; Ala/Val vs. Ala/Ala: OR = 1.08, 95% CI = 0.96–1.22; recessive model: OR = 0.93, 95% CI = 0.76–1.14 and dominant model: OR = 1.07, 95% CI = 0.94–1.20). We did not find any significant associations in the further stratification analyses by cancer type, ethnicity and source of control.

Conclusions

Despite some limitations, this meta-analysis indicates that it is unlikely that the RAD23B 249Val/Val polymorphism may contribute to the individual susceptibility to cancer risk. However, further advanced designed studies with larger sample size and different ethnicities should be conducted to confirm our results.