DNA repair genes XPC, XPD, XRCC1, and XRCC3 are associated with risk and survival of squamous cell carcinoma of the head and neck

Association of ERCC2/XPD polymorphisms and the risk of head and neck carcinoma: a systematic review, meta-analysis, trial sequential analysis, network analysis, and functional effects

OBJECTIVES AND AIMS

The combination of genetic and environmental factors may contribute to the carcinogenesis of HNC. Despite the reported associations between xeroderma pigmentosum group D (XPD) polymorphisms and HNC, the results have been inconsistent, with different studies reporting varying results. Therefore, our aim is to assess the association of three XPD polymorphisms (rs13181, rs1799793, and rs238406) in a comprehensive meta-analysis.

MATERIALS AND METHODS

An exhaustive literature review was performed across several databases, including PubMed, Web of Science, Scopus, and Cochrane Library, up to November 18, 2023, without any restrictions. The effect sizes were presented as the odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

Thirty-nine articles including 56 studies were entered into the meta-analysis. Evaluating rs13181, rs1799793, and rs238406 polymorphisms in five genetic models, just significant associations were found for rs1799793 polymorphism in heterozygous and dominant models. The findings reported that the ethnicity and the cancer subtype for rs13181, the ethnicity, the sample size, and the control source for rs1799793, and the ethnicity and the control source for rs238406 polymorphisms were effective factors in the pooled results. Trial sequential analysis suggested that the studies included an insufficient number of individuals. Sensitivity analysis reported stability of pooled results. The XPD protein variants were predicted to be benign.

CONCLUSIONS

The study reveals a significant association between the rs1799793 polymorphism and HNC, but not rs13181 and rs238406 polymorphisms. Future studies should also aim to minimize the impact of confounding factors and heterogeneity to ensure more accurate results.

Genetic Mutations Associated with Inflammatory Response Caused by HPV Integration in Oropharyngeal Squamous Cell Carcinoma

(1) Background: Head and neck cancer (HNC) ranks as the sixth most prevalent cancer in the world. In addition to the traditional risk factors such as alcohol and tobacco consumption, the implication of the human papillomavirus (HPV) is becoming increasingly significant, particularly in oropharyngeal cancer (OPC). (2) Methods: This study is based on a review analysis of different articles and repositories investigating the mutation profile of HPV-related OPC and its impact on patient outcomes. (3) Results: By compiling data from 38 datasets involving 8311 patients from 12 countries, we identified 330 genes that were further analyzed. These genes were enriched for regulation of the inflammatory response (RB1, JAK2, FANCA, CYLD, SYK, ABCC1, SYK, BCL6, CEBPA, SRC, BAP1, FOXP1, FGR, BCR, LRRK2, RICTOR, IGF1, and ATM), among other biological processes. Hierarchical cluster analysis showed the most relevant biological processes were linked with the regulation of mast cell cytokine production, neutrophil activation and degranulation, and leukocyte activation (FDR < 0.001; p-value < 0.05), suggesting that neutrophils may be involved in the development and progression of HPV-related OPC. (4) Conclusions: The neutrophil infiltration and HPV status emerge as a potential prognostic factor for OPC. HPV-infected HNC cells could potentially lead to a decrease in neutrophil infiltration. By gaining a better molecular understanding of HPV-mediated neutrophil immunosuppression activity, it is possible to identify a meaningful target to boost antitumor immune response in HNC and hence to improve the survival of patients with HNC.

New insights into redox-related risk factors and therapeutic targets in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common cancer in the oral cavity accounting for 90 % of oral cancer with a global incidence of 350.000 new cases per year. Curative resection along with adjuvant radiation therapy or a combination of radiotherapy with chemotherapy remain as gold standard in treating OSCC. Still, local recurrence, lymph nodal recurrence, and complications of radiation remain the main cause of tumor-related mortality. Reactive oxygen species are not only correlated to the etiology of OSCC due to oxidative DNA damage, lipid peroxidation or effecting signal transduction cascades that effect cell proliferation and tumorigenesis, but are also of great interest in the therapy of OSCC patients. As induced oxidative stress can be used therapeutically for the induction of tumor cell death, redox targets might be a therapeutic addition to the conventional treatment options. In this review, we discuss markers of impaired redox homeostasis as well as potential redox-related treatment targets in OSCC.

Recent Advances in Nasopharyngeal Cancer Management: From Diagnosis to Theranostics

Abstract:

Nasopharyngeal cancer (NPC) is one of the most common head and neck cancers. NPC differs significantly from other cancers in its etiology, epidemiology, clinical behavior, and treatment. Being highly radiosensitive, the standard treatment for NPC is radiotherapy. However, radioresistance hampers the success of treatment and may cause local recurrence and distant metastases in NPC patients. In this review, we discuss the updated protocols for NPC diagnosis and treatment based on recent literature with an emphasis on the mechanisms of radioresistance at the molecular level with a special focus on genetic and epigenetic events, affecting genes involved in xenobiotic detoxification and DNA repair. We also highlight the importance of some cellular and Epstein Barr viral miRNAs targeting specific DNA repair factors and consequently promoting NPC radioresistance. These molecular markers may serve as promising tools for diagnosis, prognosis, and radioresistance prediction to guide theranostics of patients with NPC in the future.

Gene polymorphisms and prognosis of head and neck squamous cell carcinoma: a systematic review

Background

Head and neck squamous cell carcinomas (HNSCCs) are associated with variable prognosis even with similar clinical characteristics and treatments. Gene polymorphisms have been suggested as prognostic factors for HNSCC which can justified this variable prognosis. So, the aim was to review literatures on gene polymorphisms and prognosis of HNSCCs.

Materials and methods

A systematic search was conducted using PubMed, Web of science, SCOPUS, Google Scholar and Cochrane library databases to find all related articles published up to December 2021 in the field of gene polymorphisms and HNSCC prognosis.

Results

Of 1029 initial searched articles, 71 articles were selected for inclusion in this systematic review. About 93 genes and 204 polymorphisms have been discussed in these articles. Among the most studied polymorphisms, the XRCC1 Arg399Gln and Arg194Trp polymorphisms were not associated with survival in most studies; the ERCC1 C19007T polymorphism had no significant association in any of the studies. Different gene polymorphisms of glutathione s-transferase family, including GSTM1 deletion, GSTT1 deletion and GSTP1 A313G, were not associated with survival in included studies. There are conflicting results regarding the association between polymorphisms such as ERCC2 A35931C, Asp312Asn, ERCC5 rs1047768 and rs17655 with HNSCC prognosis. Less studied polymorphisms, such as hOGG1 rs1052133 or the VEGF rs699947, were generally not associated with HNSCC prognosis.

Conclusion

Reviewed articles reported varied and contradictory results regarding the association of gene polymorphisms and HNSCC prognosis, which necessitates further studies along with meta-analysis on the results of such studies.

MLH1, MSH2, MRE11, and XRCC1 in Oral Leukoplakia and Oral Squamous Cell Carcinoma

BACKGROUND

DNA damage is accumulated in the cells over time as the result of both exogenous and endogenous factors. The objective of this study was to analyze the immunohistochemical expression of the repair proteins in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Paraffin blocks were selected from the archives of the Laboratory of Hospital Clinico Universitario de Santiago de Compostela, Spain. The sample was composed of 16 cases of OL without dysplasia, 14 cases of OL with dysplasia, and 15 cases of OSCC. The patients' clinical data were collected and immunohistochemical analysis was performed for MLH1, MSH2, MRE11, and XRCC1. The data were submitted to the χ2 and the Kruskal-Wallis (P≤0.05) tests.

RESULTS

MSH2 was overexpressed in OSCC (P=0.020) and was positive in 100% of patients with OL with dysplasia or OSCC (P=0.019). Positivity for MLH1 was significantly associated with comorbidity (P=0.040), especially in patients who presented with 2 or more pathologies (P=0.028). XRCC1 positivity was also associated with comorbidity (P=0.039). No significant associations were found for the MRE11A expression. Although the simultaneous positivity for the 4 markers was observed in presence of comorbidities (P=0.006).

CONCLUSIONS

This study supports the effect of the overexpression of MSH2 protein in samples of OL with dysplasia and OSCC, most notably in patients who present with comorbidities and negativity for OL without dysplasia.

PARP inhibitors in head and neck cancer: Molecular mechanisms, preclinical and clinical data

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have revolutionized the treatment landscape in several cancers. PARPi increase DNA damage particularly in tumors with underlying defects in DNA repair. In addition to PARPi-induced DNA damage, PARPi enhance immune priming and induce adaptive upregulation of programmed death ligand 1 (PD-L1) expression. Patients with head and neck squamous cell carcinoma (HNSCC) are characterized by aberrant DNA repair pathways, including nucleotide excision repair (NER), base excision repair (BER) and DNA double-strand breaks (DSBs) repair and these deregulated repair mechanisms are implicated in both the pathogenesis of the disease and the outcome of therapy. Cisplatin represents the cornerstone of treatment of HNSCC and cisplatin resistance impedes successful treatment outcomes. To this end, research strategies that are testing modulation of cisplatin sensitivity by PARPi are of particular interest. Moreover, given the immune modulating effects of PARPi and the recent approval of Programmed Cell Death- 1 (PD-1) checkpoint inhibitors in HNSCC, the design of trials combining PARPi and PD-1 checkpoint inhibitors represent a rational research strategy. In this review, we summarize data supporting the integration of PARP inhibitors into HNSCC therapeutic strategy.

A short review on DNA damage and repair effects in lip cancer

Increasing trend in oral cancer (0.6% per year) and its related mortality has been reported worldwide since 2010. The United States alone reports an increase of 57% within the past 10 years. This emphasizes the need not only for designing strategies of prevention and planning but also for an effective treatment regime for the various oral cancers. Cancers of the lips, tongue, cheeks, floor of the mouth, and hard palate have been primarily classified under the category of oral cancers. If left undiagnosed, these cancers can be life threatening. Amongst these, the most undesignated and understudied cancer type is the lip carcinoma, which is either categorized under oral cancer or/as well as skin cancer or head and neck cancer. However, lip cancer corresponds to 25-30% of all diagnosed oral cancers. Though the etiology of lip cancer is not yet fully understood, numerous risk factors involved in its development are now being studied. The cells in the lip region are continuously exposed to various DNA damaging agents from endogenous as well as exogenous sources. Flaws in DNA repair mechanisms involved in eliminating these damages may be linked to the origin of carcinogenesis. Accumulation of DNA damage and defect in repair mechanisms may play a role in lip carcinogenesis and progression. This literature review is an exhaustive compilation of the research work performed on the role of DNA damage and repair responses in lip carcinoma which will pave a path for researchers to identify predictive DNA repair biomarker/s for lip cancer, and its diagnosis, prevention, and treatment.

DNA repair, NFKβ, and TP53 polymorphisms associated with potentially malignant disorders and oral squamous cell carcinoma in Argentine patients

OBJECTIVE

An important strategy in cancer prevention is to identify individual susceptibilities for cancer development through the genomic profile. Developing countries such as Argentina have no data on genetic composition. The aim of this study was to evaluate the single nucleotide polymorphisms of genes related to DNA repair (XCCR3, XPD), cell cycle arrest/apoptosis (TP53), and inflammation (NFKβ) of patients with precancer and oral cancer and to contribute to recognizing potential risk of developing these pathologies, and incorporate the risk patients into a clinical follow-up program in Córdoba, Argentina.

STUDY DESIGN

A cross-sectional study was performed on 140 patients with oral squamous cell carcinoma (OSCC), oral potentially malignant disorders (OPMDs), and controls. Genotyping of single nucleotide polymorphisms was performed using allele-specific polymerase chain reaction or restriction fragment length polymorphism techniques. The variables were evaluated by bivariate and multivariate statistical methods, with P < .05 statistically significant.

RESULTS

The multiple correspondence analyses showed that patients with OSCC are clustered with the T allele of XRCC3 T241 M and the C allele of TP53 R72 P, and patients with OPMDs are clustered with the T allele of NFKβ-519.

CONCLUSION

Our preliminary results showed that the C allele of the Pro72 variant of TP53 was related to OSSC and OPMD, and the T allele of NFKβ-519 is related to OPMDs in Argentine patients.

Evidence for different molecular parameters in head and neck squamous cell carcinoma of nonsmokers and nondrinkers: Systematic review and meta-analysis on HPV, p16, and TP53

BACKGROUND

The goal of this review was to present an overview of the currently identified molecular parameters in head and neck squamous cell carcinoma (HNSCC) of nonsmokers and nondrinkers (NSND).

METHODS

Following the PRISMA guidelines, a systematic search was performed using the electronic databases PubMed, Embase, and Google Scholar.

RESULTS

Of the 902 analyzed unique studies, 74 were included in a quantitative synthesis and 24 in a meta-analysis. Human papillomavirus (HPV) was reported as a molecular parameter in 38 studies, followed by p16 and TP53 (23 and 14 studies, respectively). The variety of other molecular parameters concerned sporadic findings in small numbers of NSND.

CONCLUSIONS

HNSCC in NSND is more often related to HPV and p16 overexpression compared to tumors of smokers-drinkers. In a third of virus-negative tumors, TP53 mutations were detected with a mutational profile associated with aging and ultraviolet light exposure rather than to tobacco consumption.

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.

Expression profile of DNA repair proteins and histone H3 lys-9 acetylation in cutaneous and oral lichen planus

OBJECTIVES

To analyze the expression profile of DNA repair proteins (XRCC1 and APE1) and histone acetylation (H3K9) in oral and cutaneous lichen planus, in order to investigate potential biological markers that can clarify pathogenesis of these lesions.

DESIGN AND RESULTS

The total sample consisted of 89 lichen planus cases (66 oral and 23 cutaneous). Analysis of APE1 and XRCC1 expression was performed by immunohistochemistry in 44 oral and 20 cutaneous lichen planus, whereas the analysis of H3K9 acetylation was performed by immunofluorescence in 42 oral and 11 cutaneous lichen planus.

RESULTS

Immunoreactivity for APE1 and XRCC1 was significantly higher in cutaneous lichen planus than in oral lichen planus (P = 0.003 and P = 0.034, respectively). There was a significant and moderate positive correlation between APE1 and XRCC1 in the oral group (Rho = 0.544; P < 0.0001). In oral cases, there were no statistically significant results comparing APE1 and XRCC1 expression between reticular and erosive cases (P > 0.05). Evaluation of H9K3 histone acetylation levels did not reveal significant results comparing oral to cutaneous lichen planus, neither comparing erosive to reticular (P > 0.05).

CONCLUSIONS

Changes in the expression profile of the DNA repair proteins exerted greater influence in pathogenesis of cutaneous lichen planus than oral lichen planus, in addition, H3K9 histone acetylation is an epigenetic event found in both lesions.

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.

ERCC2 gene single-nucleotide polymorphism as a prognostic factor for locally advanced head and neck carcinomas after definitive cisplatin-based radiochemotherapy

Identifying patients with locally advanced head and neck carcinoma on high risk of recurrence after definitive concurrent radiochemotherapy is of key importance for the selection for consolidation therapy and for individualized treatment intensification. In this multicenter study we analyzed recurrence-associated single-nucleotide polymorphisms (SNPs) in DNA repair genes in tumor DNA from 132 patients with locally advanced head and neck carcinoma (LadHnSCC). Patients were treated with definitive radiotherapy and simultaneous cisplatin-based chemotherapy at six partner sites of the German Cancer Consortium (DKTK) Radiation Oncology Group from 2005 to 2011. For validation, a group of 20 patients was available. Score selection method using proportional hazard analysis and leave-one-out cross-validation were performed to identify markers associated with outcome. The SNPs rs1799793 and rs13181 were associated with survival and the same SNPs and in addition rs17655 with freedom from loco-regional relapse (ffLRR) in the trainings datasets from all patients. The homozygote major rs1799793 genotype at the ERCC2 gene was associated with better (Hazard ratio (HR): 0.418 (0.234-0.744), p = 0.003) and the homozygote minor rs13181 genotype at ERCC2 with worse survival (HR: 2.074, 95% CI (1.177-3.658), p = 0.017) in comparison to the other genotypes. At the ffLRR endpoint, rs1799793 and rs13181 had comparable prognostic value. The rs1799793 and rs13181 genotypes passed the leave-one-out cross-validation procedure and associated with survival and ffLRR in patients with LadHnSCC treated with definitive radiochemotherapy. While findings were confirmed in a small validation dataset, further validation is underway within a prospective biomarker study of the DKTK.

Expression of DNA repair genes in oral squamous cell carcinoma using reverse transcription-quantitative polymerase chain reaction

OBJECTIVE

The aim of this study was to evaluate the expression of DNA repair genes in cases of oral squamous cell carcinoma (OSCC).

STUDY DESIGN

Expression of the MLH1, MSH2, MLH3, ATM, MRE11A, XRCC1, and PMS2 genes was evaluated by reverse transcription-quantitative polymerase chain reaction in the OSCC group (32 patients) and the control group (15 patients). The groups were compared by using the Mann-Whitney test, with Bonferroni correction. Associations between gene expression levels and clinical data were explored by using Pearson's and Spearman's correlation coefficients, with P value less than .05 indicating a significant difference.

RESULTS

The MLH1, MSH2, MLH3, ATM, MRE11A, XRCC1, and PMS2 genes were downregulated in the OSCC group compared with the control group, with significant values for MLH1 (P < .0001); MSH2 (P = .038); MLH3 (P < .0001); ATM (P < .0001); MRE11A (P < .0001); XRCC1 (P = .0004); and PMS2 (P = .008). Analysis of the correlation between gene expression and clinical data only revealed a significant negative correlation between age and expression of the PMS2 gene.

CONCLUSIONS

Expression of the DNA repair genes MLH1, MSH2, MLH3, ATM, MRE11 AMRE11A, XRCC1, and PMS2 was reduced in OSCC.

Immunohistochemical expression of TFIIH and XPF in oral tongue squamous cell carcinoma

PURPOSE

The query for biomarkers that indicate tumor aggressiveness and the host's response to treatment is still one of the leading aims of cancer research. To investigate a possible role for DNA nucleotide repair proteins in oral cancer behavior, this study evaluated the immunoexpression of the proteins TFIIH and XPF and its association with clinical, histological, and survival parameters in oral tongue squamous-cell carcinoma (OTSCC).

METHODS

TFIIH and XPF immunoexpressions were evaluated in 82 cases of oral tongue squamous-cell carcinoma. Tumor budding and depth of invasion were assessed for histopathological grading (BD model).

RESULTS

Tumor cells exhibited high expression of TFIIH and XPF, which was associated to nodal status; both proteins were not associated with other clinical parameters, histopathological grading or survival. Tumor size, nodal status, tumor staging, and depth of invasion > 4 mm were significantly associated to disease-specific survival.

CONCLUSIONS

We have demonstrated that the overexpression of TFIIH correlates positively with node metastasis, while XPF correlates negatively with node metastasis; therefore, the expression of XPF and TFIIH had a potential value for predicting the progression of OTSCC patients.

Association of hOGG1 Ser326Cys, ITGA2 C807T, TNF-A -308G>A and XPD Lys751Gln polymorphisms with the survival of Malaysian NPC patients

Background

Nasopharyngeal carcinoma is a rare form of cancer across the world except in certain areas such as Southern China, Hong Kong and Malaysia. NPC is considered a relatively radiosensitive tumor and patients diagnosed at early stages tend to survive longer compared to those with advanced disease. Given that early symptoms of NPC are non-specific and that the nasopharynx is relatively inaccessible, less invasive screening methods such as biomarker screening might be the key to improve NPC survival and management. A number of genes with their respective polymorphisms have been shown in past studies to be associated with survival of various cancers. hOGG1 and XPD genes encode for a DNA glycosylase and a DNA helicase respectively; both are proteins that are involved in DNA repair. ITGA2 is the alpha subunit of the transmembrane receptor integrin and is mainly responsible for cell-cell and cell-extracellular matrix interaction. TNF-α is a cytokine that is released by immune cells during inflammation.

Methods

Restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was used to genotype all the aforementioned gene polymorphisms. Kaplan-Meier survival function, log-rank test and Cox regression were used to investigate the effect of gene polymorphisms on the all-cause survival of NPC.

Results

NPC cases carrying T/T genotype of ITGA2 C807T have poorer all-cause survival compared to those with C/C genotypes, with an adjusted HR of 2.06 (95% CI = 1.14–3.72) in individual model. The 5-year survival rate of C/C carriers was 55% compared to those with C/T and T/T where the survival rates were 50% and 43%, respectively.

Conclusion

The finding from the present study showed that ITGA2 C807T polymorphism could be potentially useful as a prognostic biomarker for NPC. However, the prognostic value of ITGA2 C807T polymorphism has to be validated by well-designed further studies with larger patient numbers.

Role of Xeroderma Pigmentosum Group D in Cell Cycle and Apoptosis in Cutaneous Squamous Cell Carcinoma A431 Cells

BACKGROUND Cutaneous squamous cell carcinoma (cSCC) is the second most widespread cancer in humans and its incidence is rising. Novel therapy with better efficacy is needed for clinical treatment of cSCC. Many studies have shown the importance of DNA repair pathways during the development of cancer. A key nucleotide excision repair (NER) protein, xeroderma pigmentosum group D (XPD), is responsible for the excision of a large variety of bulky DNA lesions. MATERIAL AND METHODS To explore the role of XPD in A431 cells, we overexpressed XPD in A431 cells and performed MTT assay, flow cytometry, and Western blot analysis to examine cell proliferation, cell apoptosis, and genes expression. RESULTS We found that the overexpression of XPD suppressed cell viability, induced cell cycle arrest at G1 phase, and promoted cell apoptosis. Additionally, XPD blocked the expression of c-myc, cdc25A, and cdk2, and improved the levels of HIPK2 and p53. CONCLUSIONS These results provide new evidence to reveal the role of XPD in cSCC A431 cells and suggest that XPD may serve as an anti-oncogene during cSCC development.

Association of DNA repair genes polymorphisms and mutations with increased risk of head and neck cancer: a review

DNA repair mechanisms allow maintain genomic stability and proper functioning within the cells. Any aberrations may cause an increased risk of many diseases such as cancer. The most crucial risk factors for head and neck squamous cell carcinoma are behavioral factors, predominantly chronic exposure to tobacco, alcohol addiction, and infection with human papillomavirus or Epstein–Barr virus. These agents can induce DNA damage; therefore, cells must activate appropriate mechanisms in order to function correctly. Cancer cells are marked with genomic instability, which is associated with a greater tendency for the accumulation of a DNA damage and increased chemo- and radioresistance. Multiple studies have assessed the correlation of increased head and neck cancer (HNC) risk with polymorphism in the DNA repair genes. However, they suggest that interaction of DNA repair genes mutations with susceptibility to HNC depends on a patient’s race and risk factors, especially tobacco smoking. Further identification of these sequence variations must be performed. In this review, we discuss the current knowledge about the DNA repair genes mutations and polymorphisms associated with the high risk of head and neck treatment.

A Polymorphism Located Near PMAIP1/Noxa Gene Influences Susceptibility to Hodgkin Lymphoma Development in South India

Background:

Single nucleotide polymorphisms (SNPs) in DNA repair and Toll-like receptor (TLR) genes have been reported to be associated with Hodgkin Lymphoma (HL) risk. Since such associations may be ethnicity dependent, polymorphisms in TLR4 rs1554973, Xeroderma pigmentosum C (XPC) rs2228000, rs2228001 and a variant near PMAIP1/Noxa gene rs8093763 were here investigated with regard to HL susceptibility in a south Indian population. Normative frequencies of SNPs were established and compared with data for 1000 genome populations.

Methods:

We conducted a case control study consisting of 200 healthy volunteers and 101 cases with HL. DNA samples were genotyped using real-time PCR. Linkage disequilibrium (LD) analysis between rs2228000 and rs2228001 was performed using HaploView (version 4.2).

Results:

Among the studied variants, we observed that a variant rs8093763 located near PMAIP1/Noxa gene was associated with HL risk (OR=1.72 and 95% CI=1.004-2.93). The major allele frequencies of XPC (rs2228000 and rs2228001), TLR4 (rs1554973) and PMAIP1/NOXA (rs8093763) variants were 79%, 66%, 67% and 59% respectively. The studied frequencies were significantly different from 1000 genome populations.

Conclusion:

The results suggest that a variant rs8093763 located near the PMAIP1/Noxa gene may modify risk of HL. We found variation in distribution of polymorphic frequencies between the study population and 1000 genome populations. The results may help identify individual risk of development of HL in our south Indian population.

Genetic variants in ERCC1 and XPC predict survival outcome of non-small cell lung cancer patients treated with platinum-based therapy

Nucleotide excision repair (NER) plays a vital role in platinum-induced DNA damage during chemotherapy. We hypothesize that regulatory single nucleotide polymorphisms (rSNPs) of the core NER genes modulate clinical outcome of patients with advanced non-small cell lung cancer (NSCLC) treated with platinum-based chemotherapy (PBS). We investigated associations of 25 rSNPs in eight NER genes with progression free survival (PFS) and overall survival (OS) in 710 NSCLC patients. We found that ERCC1 rs3212924 AG/GG and XPC rs2229090 GC/CC genotypes were associated with patients’ PFS (HR_adj = 1.21, 95% CI = 1.03–1.43, P_adj = 0.021 for ERCC1 and HR_adj = 0.80, 95% CI = 0.68–0.94, P_adj = 0.007 for XPC), compared with the AA and GG genotypes, respectively. The association of XPC rs2229090 was more apparent in adenocarcinoma than in squamous cell carcinoma patients. Additionally, ERCC4 rs1799798 GA/AA genotypes were associated with poorer OS (HR_adj = 1.32, 95% CI = 1.04–1.69, P_adj = 0.026), compared with the GG genotype. The expression quantitative trait loci analysis revealed that ERCC1 rs3212924 and XPC rs2229090 might regulate transcription of their genes, which is consistent with their associations with survival. Larger studies are needed to validate our findings with further functional studies to elucidate the mechanisms underlying these observed associations.

DNA base excision repair proteins APE-1 and XRCC-1 are overexpressed in oral tongue squamous cell carcinoma

BACKGROUND

DNA repair systems play a critical role in protecting the human genome from damage caused by carcinogens. Modifications in DNA repair genes may be responsible for tumor development and resistance of malignant cells to chemotherapeutic agents. The major pathway for oxidative DNA damage repair is the base excision repair pathway. This study aimed to assess the immunoexpression of DNA repair proteins APE-1 and XRCC-1 and its association with clinical, histologic, and survival parameters in oral tongue squamous cell carcinoma, to investigate a possible role for those proteins in tumor behavior.

METHODS

The expression of APE-1 and XRCC-1 was evaluated by immunohistochemistry in 82 cases of oral tongue squamous cell carcinoma. Histopathological grading was performed for each case. Pearson's chi-square and Fisher's exact tests were used to determine the association between protein expressions and clinicopathological features of tumors, whereas Kaplan-Meier curves and Cox regression were used to analyze disease-specific and disease-free survival. Statistical significance was set at P ≤ 0.05.

RESULTS

APE-1 was highly expressed in the nucleus and cytoplasm in 64.6% of cases, and XRCC-1 showed overexpression only in the nucleus in 61% of cases. High expression of XRCC-1 was significantly associated with tumors at early clinical stages (I and II, P < 0.01) and nodal status (P = 0.03). Both proteins were not associated with other clinical parameters, histopathological grading, or survival.

CONCLUSIONS

DNA base excision repair proteins APE-1 and XRCC-1 are upregulated in oral tongue squamous cell carcinoma, and XRCC-1 expression is associated with better clinical staging and nodal status.