X-ray Repair Cross-complementing Research Articles

XRCC1 is linked to poor prognosis in adenocarcinoma of the esophagogastric junction after radiotherapy: transcriptome and alternative splicing events analysis.

This study aimed to (i) investigate the relationship between X-ray repair cross-complementing protein 1 gene (XRCC1) and prognosis in patients with adenocarcinoma of the esophagogastric junction (AEG), and (ii) analyze the roles of XRCC1 in human gastric adenocarcinoma (AGS) cells following X-ray radiation. A total of 46 AEG patients were enrolled and examined for XRCC1 protein by immunohistochemistry. XRCC1 was knocked down in AGS cells by transfection, and AGS cells were subsequently exposed to 6Gy of X-ray radiation. XRCC1 mRNA and protein expression was examined via quantitative real-time PCR (qRT-PCR) and Western blot analysis. The apoptosis of AGS cells was examined by flow cytometer. RNA-sequencing technology was used to identified differentially expressed genes and alternative splicing events following XRCC1 knockdown and radiation exposure. XRCC1 positivity was strongly associated with distant metastasis, pathological tumor-node-metastasis (pTNM) classification, and radiotherapy resistance in AEG patients. A significant difference in progression-free survival was observed between AEG patients with low and high XRCC1 protein expression. The knockdown of XRCC1 notably exacerbated the effects of X-ray radiation on apoptosis in AGS cells. Additionally, X-ray radiation modified the expression of genes related to apoptosis and immune response in XRCC1-knockdown AGS cells. Furthermore, the generation of splice variants was influenced by XRCC1 knockdown in AGS cells. XRCC1 may serve as a key oncogene that elucidates the role of alternative splicing events in the progression of AEG following X-ray treatment.

C-Myc-XRCC2-FOS axis promotes the proliferation and the resistance to Doxorubicin of NSCLC

Lung cancer represents one of the most prevalent malignant neoplasms, commanding an alarming incidence and mortality rate globally. Non-small cell lung cancer (NSCLC), constituting approximately 80 %-90 % of all lung cancer cases, is the predominant pathological manifestation of this disease, with a disconcerting 5-year survival rate scarcely reaching 10 %. Extensive prior investigations have elucidated that the aberrant expression of X-ray repair cross-complementing gene 2 (XRCC2), a critical meiotic gene intricately involved in the DNA damage repair process, is intimately associated with tumorigenesis. Nevertheless, the precise roles and underlying mechanistic pathways of XRCC2 in NSCLC remain largely elusive. In the present study, we discerned an overexpression of XRCC2 within NSCLC patient tissues, particularly in high-grade samples, when juxtaposed with normal tissues. Targeted knockdown of XRCC2 notably impeded the proliferation of NSCLC both in vitro and in vivo. Comprehensive RNA sequencing and flow rescue assays unveiled that XRCC2 augments the proliferation of NSCLC cells through the down-regulation of FOS expression. Moreover, the c-Myc gene was definitively identified as an XRCC2 transcriptional factor by means of chromatin immunoprecipitation (ChIP) and luciferase reporter assays, whereby pharmacological attenuation of c-Myc expression, in conjunction with Doxorubicin, synergistically curtailed NSCLC cell growth both in vitro and in vivo. Collectively, our findings proffer critical insights into the novel c-Myc-XRCC2-FOS axis in promoting both proliferation and resistance to Doxorubicin in NSCLC cells, thereby extending a promising avenue for potential new diagnostic strategies and therapeutic interventions in NSCLC.

X-ray Repair Cross Complementing 1 (XRCC1) Gene Polymorphism in Hepatocellular Carcinoma (HCC)

Abstract Background Several risk factors for hepatocellular carcinoma (HCC) have been identified, including chronic infection of hepatitis B virus (HBV) and hepatitis C virus (HCV). Nevertheless, only a fraction of infected patients develops HCC during their lifetime suggesting that genetic factors might modulate HCC development. The human X-ray repair cross- complementing protein 1 (XRCC1) gene encodes for one of the major repair factors involved in base excision repair (BER), which is reported to be associated with the risk of several cancers. A few studies have explored the association between risk of hepatocellular carcinoma (HCC) and single-nucleotide polymorphisms (SNPs) in different DNA repair genes. Aim of the Work to investigate the possible association between XRCC1-G28152A (rs25487) single nucleotide polymorphism (SNP) and hepatocellular carcinoma (HCC) in chronic hepatitis C patients. Patients and Methods The study included 35 patients who had HCC and 15 patients who had liver cirrhosis. XRCC1 gene polymorphism was done to all participants by RT-PCR After collection of relevant clinical data and basic laboratory tests. Results A statistically higher frequency of XRCC1 (GG, GA) genotypes and increased (G) allele frequency in patients with HCC was found in comparison to cirrhotic HCV patients as well as control group but Our results revealed that the genotypic and allelic frequencies of XRCC1 gene polymorphism rs25487 didn’t show statistically significant difference between HCC patients group and liver cirrhosis control group. Conclusion The present study had demonstrated that there was no significant association between XRCC1 gene polymorphism (rs25487) and HCC in the sample of Egyptian population included in our study. Also, non-significant differences among the XRCC1 genotypes and alleles were found regarding age, sex, BMI and laboratory data including CBC, AFP, coagulation profile (PT, INR), liver function test ( total protein, albumin, AST, total bilirubin and direct bilirubin), BCLC and Milan criteria. While a statistically significant difference was observed as regards PTT and ALT between genotypes.

Ganoderic acid A suppresses autophagy by regulating the circFLNA/miR-486-3p/CYP1A1/XRCC1 axis to strengthen the sensitivity of lung cancer cells to cisplatin.

Reportedly, ganoderic acid A (GA-A) increases the sensitivity of hepatocellular carcinoma cells to cisplatin (DDP) chemotherapy. Therefore, this study aims to fathom the influence of GA-A on lung cancer cells. After the construction of A549/DDP cells through exposure to DDP, the effects of GA-A on A549 and A549/DDP cells were revealed by cellular functional assays, western blot and quantitative reverse transcription PCR (qRT-PCR). The DDP-resistant lung cancer tumor was established in vivo, followed by further validation of the mechanism of GA-A. GA-A suppressed the viability, migration, and invasion while downregulating Beclin and autophagy marker LC3II/LC3I levels and upregulating P62 levels in A549 and A549/DDP cells. These effects were reversed by circFLNA overexpression. Also, GA-A reinforced the sensitivity of A549/DDP cells to DDP, elevated the apoptosis and regulated the circFLNA/miR-486-3p/cytochrome P450 family 1 subfamily A member 1 (CYP1A1)/X-ray repair cross-complementing 1 (XRCC1) axis. The reversal effects of circFLNA overexpression on GA-A-induced viability and apoptosis of A549/DDP cells could all be counteracted in the presence of 3MA. GA-A inhibited lung cancer tumor growth and blocked autophagy. GA-A suppresses autophagy by regulating the circFLNA/miR-486-3p/CYP1A1/XRCC1 axis to strengthen the sensitivity of lung cancer cells to DDP.

Abstract 6103: The association of genetic polymorphisms in DNA repair genes XRCC1 and 3 with cervical cancer risk among Bangladeshi females

Abstract Introduction and Objective: Worldwide, cervical cancer ranks the second most common cancer in women. Sequence variations in DNA repair genes X-ray repair cross complementing (XRCC) 1 and 3 genes can lead to can result cellular function aberration leading to cancers. Single nucleotide polymorphisms (SNPs) in XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) genes have been shown to cause individual variation in their DNA repair capacity. The aim of this study was to investigate the association of XRCC1 Arg399Gln and XRCC3 Thr241Met SNPs with susceptibility to cervical cancer among Bangladeshi populations. Methods: In the current case-control study 124 cervical cancer patients and 148 age matched healthy controls were recruited. Genomic DNAs were isolated from peripheral blood collected from the participants and genotyped for candidate SNPs using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results: For XRCC1, heterozygous Arg/Gln and combined heterozygous plus variant homozygous Gln/Gln genotypes showed 1.78-fold (95% CI 1.0037 to 2.8771, p=0.0484) and 1.8627-fold (95% CI 1.1470 to 3.0250, p = 0.0119) increased risk of cervical cancer, respectively, when compared with normal homozygous Arg/Arg genotype. The variant Gln allele was positively associated with cervical cancer by 1.68-fold increase (95% CI 1.1732 to 2.3980, p = 0.0046). Similarly, for XRCC3, Thr/Met heterozygous and combined Thr/Met + Met/Met genotypes were found to be associated with 1.6993-fold (95% CI 1.0398 to 3.0166, p=0.0354) and 1.8312-fold (95% CI 1.0890 to 3.0791, p = 0.0225) higher risk, respectively, when compared with normal homozygous Thr/Thr genotypes. The variant Met allele showed significant association with 1.71-fold increased risk. Conclusion: XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) SNPs may be positively associated with increased cervical cancer risk in Bangladeshi females. Citation Format: Md Mustafizur Rahman, Laboni Das, Sadia Rahman, Amir Hossain, Razia Sultana. The association of genetic polymorphisms in DNA repair genes XRCC1 and 3 with cervical cancer risk among Bangladeshi females [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6103.

XRCC1: a potential prognostic and immunological biomarker in LGG based on systematic pan-cancer analysis.

X-ray repair cross-complementation group 1 (XRCC1) is a pivotal contributor to base excision repair, and its dysregulation has been implicated in the oncogenicity of various human malignancies. However, a comprehensive pan-cancer analysis investigating the prognostic value, immunological functions, and epigenetic associations of XRCC1 remains lacking. To address this knowledge gap, we conducted a systematic investigation employing bioinformatics techniques across 33 cancer types. Our analysis encompassed XRCC1 expression levels, prognostic and diagnostic implications, epigenetic profiles, immune and molecular subtypes, Tumor Mutation Burden (TMB), Microsatellite Instability (MSI), immune checkpoints, and immune infiltration, leveraging data from TCGA, GTEx, CELL, Human Protein Atlas, Ualcan, and cBioPortal databases. Notably, XRCC1 displayed both positive and negative correlations with prognosis across different tumors. Epigenetic analysis revealed associations between XRCC1 expression and DNA methylation patterns in 10 cancer types, as well as enhanced phosphorylation. Furthermore, XRCC1 expression demonstrated associations with TMB and MSI in the majority of tumors. Interestingly, XRCC1 gene expression exhibited a negative correlation with immune cell infiltration levels, except for a positive correlation with M1 and M2 macrophages and monocytes in most cancers. Additionally, we observed significant correlations between XRCC1 and immune checkpoint gene expression levels. Lastly, our findings implicated XRCC1 in DNA replication and repair processes, shedding light on the precise mechanisms underlying its oncogenic effects. Overall, our study highlights the potential of XRCC1 as a prognostic and immunological pan-cancer biomarker, thereby offering a novel target for tumor immunotherapy.

Association between XRCC2 Arg188His Polymorphism and Breast Cancer Susceptibility: A Systematic Review and Meta-Analysis.

Breast cancer is one of the most common cancers in the world and leading cause of cancer-related death among women. Several studies indicated that Arg188His (rs3218536) polymorphism of X-ray repair cross-complementing 2 (XRCC2) may be associated with breast cancer risk. However, this association remains ambiguous. Thus, we performed a meta-analysis to provide more precise conclusion on this issue. A comprehensive search in PubMed, Google Scholar and ISI Web of Science was performed to select all relevant studies. Odds ratios (OR) with corresponding 95% confidence intervals (CI) were applied to assess the strength of the relationships. A total of 17 studies with 5694 breast cancer cases and 6450 healthy subjects were identified. The pooled data revealed that XRCC2 Arg188His polymorphism was marginally with susceptibility to breast cancer globally under the heterozygote contrast (OR = 0.929, 95% CI = 0.873-0.987, p=0.018). Moreover, subgroup analysis by ethnicity revealed that this polymorphism was associated with breast cancer risk among Caucasians. On the whole, the present study demonstrates that the XRCC2 Arg188His polymorphism may contribute to an increased risk of breast cancer.

Role of rs873601 Polymorphisms in Prognosis of Lung Cancer Patients Treated with Platinum-Based Chemotherapy.

Lung cancer is still the most lethal malignancy in the world, according to the report of Cancer Statistics in 2021. Platinum-based chemotherapy combined with immunotherapy is the first-line treatment in lung cancer patients. However, the 5-year survival rate is always affected by the adverse reactions and drug resistance caused by platinum-based chemotherapy. DNA damage and repair system is one of the important mechanisms that can affect the response to chemotherapy and clinical outcomes in lung cancer patients. The objective of this study is to find the relationship between the polymorphisms of DNA repair genes with the prognosis of platinum-based chemotherapy in lung cancer patients. We performed genotyping in 17 single nucleotide polymorphisms (SNPs) of Excision Repair Cross-Complementation group (ERCC) genes and X-ray Repair Cross-Complementing (XRCC) genes of 345 lung cancer patients via Sequenom MassARRAY. We used Cox proportional hazard models, state, and plink to analyze the associations between SNPs and the prognosis of lung cancer patients. We found that the ERCC5 rs873601 was associated with the overall survival time in lung cancer patients treated with platinum-based chemotherapy (p = 0.031). There were some polymorphisms that were related to the prognosis in specific subgroups of lung cancer. Rs873601 showed a great influence on the prognosis of patients more than 55 years, Small Cell Lung Cancer (SCLC), and smoking patients. Rs2444933 was associated with prognosis in age less than 55 years, SCLC, metastasis, and stage III/IV/ED patients. Rs3740051 played an important role in the prognosis of SCLC and metastasis patients. Rs1869641 was involved in the prognosis of SCLC patients. Rs1051685 was related to the prognosis in non-metastasis patients. The ERCC5 rs873601 (G>A) was a valuable biomarker for predicting the prognosis in lung cancer patients treated with platinum-based chemotherapy.

Single nucleotide polymorphisms rs148582811 regulates its host gene ARVCF expression to affect nicotine-associated hippocampus-dependent memory

Although numerous susceptibility loci are nominated for nicotine dependence (ND), no report showed any association of ARVCF with ND. Through genome-wide sequencing analysis, we first identified genetic variants associated nominally with ND and then replicated them in an independent sample. Of the six replicated variants, rs148582811 in ARVCF located in the enhancer-associated marker peak is attractive. The effective-median-based Mendelian randomization analysis indicated that ARVCF is a causal gene for ND. RNA-seq analysis detected decreased ARVCF expression in smokers compared to nonsmokers. Luciferase reporter assays indicated that rs148582811 and its located DNA fragment allele-specifically regulated ARVCF expression. Immunoprecipitation analysis revealed that transcription factor X-ray repair cross-complementing protein 5 (XRCC5) bound to the DNA fragment containing rs148582811 and allele-specifically regulated ARVCF expression at the mRNA and protein levels. With the Arvcf knockout mouse model, we showed that Arvcf deletion not only impairs hippocampus-dependent learning and memory, but also alleviated nicotine-induced memory deficits.

BRCA1 expression and its combined low expression with PARP1 and ERCC1 predict chemotherapeutic response in ovarian cancer

Objective: This study aimed to evaluate the associations of immunohistochemical expressions of various deoxyribonucleic acid repair proteins, either individually or combined, with the response to platinum-based chemotherapy and overall survival in epithelial ovarian cancer.Material and Methods: This retrospective cohort study included patients with epithelial ovarian cancer who were treated by primary cytoreductive surgery with adjuvant platinum-based chemotherapy at Songklanagarind Hospital between January 2008 and December 2019. Immunohistochemistry analysis of breast cancer type 1 (BRCA1), poly (ADP-ribose) polymerase 1 (PARP1), X-ray repair cross-complementing 1 (XRCC1), and excision repair cross-complementation group 1 (ERCC1) expression was performed. Logistic regression was used to evaluate factors associated with chemotherapeutic response and Cox regression was applied for survival analysis.Results: Chemotherapeutic response was achieved in 205 of 249 patients (82.3%). Low BRCA1 expression was associated with good response (odds ratio [OR] 5.01, 95% confidence interval [CI] 1.78–14.1) and favorable overall survival (hazard ratio 0.61, 95% CI 0.38–0.98). PARP1, XRCC1, and ERCC1 showed no significant predictive or prognostic roles; however, combined low expression of PARP1/BRCA1 (OR 7.62, 95% CI 1.69–34.31) and ERCC1/BRCA1 (OR 6.98, 95% CI 1.5–32.52) additively enhanced response compared to high/high expressions.Conclusion: This study provides evidence that epithelial ovarian cancer (EOC) with low BRCA1 expression is more likely to be responsive to platinum-based therapy and is associated with favorable overall survival compared to tumors with high BRCA1 expression. The study supports a potential therapeutic strategy involving co-depletion of PARP1/BRCA and ERCC1/BRCA1 expression, although additional studies are needed.

Cytosine–phosphate–guanine oligodeoxynucleotides alleviate radiation-induced kidney injury in cervical cancer by inhibiting DNA damage and oxidative stress through blockade of PARP1/XRCC1 axis

BackgroundRadiotherapy can cause kidney injury in patients with cervical cancer. This study aims to investigate the possible molecular mechanisms by which CpG-ODNs (Cytosine phosphate guanine-oligodeoxynucleotides) regulate the PARP1 (poly (ADP-ribose) polymerase 1)/XRCC1 (X-ray repair cross-complementing 1) signaling axis and its impact on radiation kidney injury (RKI) in cervical cancer radiotherapy.MethodsThe GSE90627 dataset related to cervical cancer RKI was obtained from the Gene Expression Omnibus (GEO) database. Bioinformatics databases and R software packages were used to analyze the target genes regulated by CpG-ODNs. A mouse model of RKI was established by subjecting C57BL/6JNifdc mice to X-ray irradiation. Serum blood urea nitrogen (BUN) and creatinine levels were measured using an automated biochemical analyzer. Renal tissue morphology was observed through HE staining, while TUNEL staining was performed to detect apoptosis in renal tubular cells. ELISA was conducted to measure levels of oxidative stress-related factors in mouse serum and cell supernatant. An in vitro cell model of RKI was established using X-ray irradiation on HK-2 cells for mechanism validation. RT-qPCR was performed to determine the relative expression of PARP1 mRNA. Cell proliferation activity was assessed using the CCK-8 assay, and Caspase 3 activity was measured in HK-2 cells. Immunofluorescence was used to determine γH2AX expression.ResultsBioinformatics analysis revealed that the downstream targets regulated by CpG-ODNs in cervical cancer RKI were primarily PARP1 and XRCC1. CpG-ODNs may alleviate RKI by inhibiting DNA damage and oxidative stress levels. This resulted in significantly decreased levels of BUN and creatinine in RKI mice, as well as reduced renal tubular and glomerular damage, lower apoptosis rate, decreased DNA damage index (8-OHdG), and increased levels of antioxidant factors associated with oxidative stress (SOD, CAT, GSH, GPx). Among the CpG-ODNs, CpG-ODN2006 had a more pronounced effect. CpG-ODNs mediated the inhibition of PARP1, thereby suppressing DNA damage and oxidative stress response in vitro in HK-2 cells. Additionally, PARP1 promoted the formation of the PARP1 and XRCC1 complex by recruiting XRCC1, which in turn facilitated DNA damage and oxidative stress response in renal tubular cells. Overexpression of either PARP1 or XRCC1 reversed the inhibitory effects of CpG-ODN2006 on DNA damage and oxidative stress in the HK-2 cell model and RKI mouse model.ConclusionCpG-ODNs may mitigate cervical cancer RKI by blocking the activation of the PARP1/XRCC1 signaling axis, inhibiting DNA damage and oxidative stress response in renal tubule epithelial cells.

Regulation of base excision repair during adipogenesis and osteogenesis of bone marrow-derived mesenchymal stem cells

Bone marrow-derived human mesenchymal stem cells (hMSCs) can differentiate into various lineages, such as chondrocytes, adipocytes, osteoblasts, and neuronal lineages. It has been shown that the high-efficiency DNA-repair capacity of hMSCs is decreased during their differentiation. However, the underlying its mechanism during adipogenesis and osteogenesis is unknown. Herein, we investigated how alkyl-damage repair is modulated during adipogenic and osteogenic differentiation, especially focusing on the base excision repair (BER) pathway. Response to an alkylation agent was assessed via quantification of the double-strand break (DSB) foci and activities of BER-related enzymes during differentiation in hMSCs. Adipocytes showed high resistance against methyl methanesulfonate (MMS)-induced alkyl damage, whereas osteoblasts were more sensitive than hMSCs. During the differentiation, activities, and protein levels of uracil-DNA glycosylase were found to be regulated. In addition, ligation-related proteins, such as X-ray repair cross-complementing protein 1 (XRCC1) and DNA polymerase β, were upregulated in adipocytes, whereas their levels and recruitment declined during osteogenesis. These modulations of BER enzyme activity during differentiation influenced DNA repair efficiency and the accumulation of DSBs as repair intermediates in the nucleus. Taken together, we suggest that BER enzymatic activity is regulated in adipogenic and osteogenic differentiation and these alterations in the BER pathway led to different responses to alkyl damage from those in hMSCs.

Association between XRCC-1 Arg194Trp polymorphism with lung cancer in Iraqi patients

Abstract Background: Preface, DNA repair is the most efficient protective approach against DNA damage. Because the integrity of the genome is vital and crucial, the process of repairing DNA induced by carcinogens is critical. The ability to repair DNA damage may be impacted by specific genetic variants in DNA-repair genes, which may also be a risk factor for the development of cancer. The X-ray repair cross complementing-1 (XRCC-1) gene product has been linked to base-excision and single-strand repair mechanisms. Objective: The goal of this study was to examine the relation of the XRCC-1 gene with lung cancer patients. Materials and Methods: polymarease chain reaction- restriction fragment length polymorphism (PCR-RFLP) analysis was used to compare 40 lung cancer patients along with 40 sample controls. Samples were collected at Al-Amal National Hospital for cancer management, ages ranging from 40 to 70 years. Statistics were carried out by using the SPSS Software program Version 20.0. Results: The results show that the XRCC-1 (Arg194Trp) gene carried seven exons, which were shown to have different frequencies in patients and controls based on three genotypes (Arg/Trp, Arg/Arg, and Trp/Trp). Hardy–Weinberg equilibrium with chi-square for the patient (7.949) and control group (8.236). Also, the Arg/Trp genotype was present at a significantly high frequency in patients (77.5%), and the odds ratio was (14.94, confidence interval [CI] = 4.99–44.76 to CI = 0.642), whereas the Trp/Trp genotype frequency increased in the control group (72.5%). And the odds ratio for this relationship was (0.3, P = 0.001, and CI = 0.01–0.11). Conclusion: This study’s findings also suggest that the Arg/Trp genotype may be linked to lung cancer in this particular group.

PAXX binding to the NHEJ machinery explains functional redundancy with XLF.

Nonhomologous end joining is a critical mechanism that repairs DNA double-strand breaks in human cells. In this work, we address the structural and functional role of the accessory protein PAXX [paralog of x-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor (XLF)] in this mechanism. Here, we report high-resolution cryo-electron microscopy (cryo-EM) and x-ray crystallography structures of the PAXX C-terminal Ku-binding motif bound to Ku70/80 and cryo-EM structures of PAXX bound to two alternate DNA-dependent protein kinase (DNA-PK) end-bridging dimers, mediated by either Ku80 or XLF. We identify residues critical for the Ku70/PAXX interaction in vitro and in cells. We demonstrate that PAXX and XLF can bind simultaneously to the Ku heterodimer and act as structural bridges in alternate forms of DNA-PK dimers. Last, we show that engagement of both proteins provides a complementary advantage for DNA end synapsis and end joining in cells.

Gene-occupation interactions: a review of the literature on bladder and prostate cancer

Bladder cancer (BCa) and prostate cancer (PCa) are genitourinary cancers which constitute significant health problems in men and in which environmental factors play an important role. Understanding the genetic susceptibility to BCa or PCa and occupational exposure is paramount to improving cancer prevention and early detection. The aim of this review article was to address the scientific evidence on the genetic risk factors and occupational exposure associated with the occurrence of BCa and PCa. The authors identified relevant original articles that have been published between 1994 and 2023. Variations of the following search terms: "gene" and "occupational" combined with one of the following terms: "bladder cancer" or "prostate cancer" were applied for the search purpose. The authors found 342 publications of which 50 population studies met their requirements for gene-occupation interactions. In total, 34 full-text manuscripts were about BCa and 16 about PCa. These research examines the genes involved in detoxification processes of xenobiotics (glutathione S-transferase, N-acetyltransferase, cytochrome P450, UDP-glucuronosyltransferase), oxidative stress (glutathione peroxidase 1, manganese superoxide dismutase, catalase), altering DNA repair capacity (X-ray repair cross-complementing 1, base excision repair, nucleotide excision repair), tumour suppression (TP53 gene), and vitamin D pathway (vitamin D receptor gene). The role of genetic factors in the occupational exposure has not been conclusively established, but it appears the possibility of genetic involvement. Determination of environmentally responsive genes provides important mechanistic implications for the etiology of occupational cancers, and valuable input in occupational exposure limits set by taking genetic susceptibility into account. More genetic research is needed to corroborate these findings and assess their significance in the workplace. Med Pr. 2023;74(2):127-44.

CXCL12/CXCR4 Gene Polymorphism as a Putative Prognostic Factor for Metastasizing Breast Cancer Under Chemotherapy

Association between Polymorphisms of X-ray Repair Cross Complementing 5 and 6 Promoter Genes and the Risk of Metastatic Breast Cancer

The Incidence of the XRCC1 rs25487 and PON1 rs662 Polymorphisms in a Population from Central Brazil: Patterns in an Area with a High Level of Agricultural Activity.

In Brazil, high levels of agricultural activity are reflected in the consumption of enormous amounts of pesticides. The production of grain in Brazil has been estimated at 289.8 million tons in the 2022 harvest, an expansion of 14.7% compared with 2021. These advances are likely associated with a progressive increase in the occupational exposure of a population to pesticides. The Paraoxonase 1 gene (PON1) is involved in liver detoxification; the rs662 variant of this gene modifies the activity of the enzyme. The repair of pesticide-induced genetic damage depends on the protein produced by the X-Ray Repair Cross-Complementing Group 1 gene (XRCC). Its function is impaired due to an rs25487 variant. The present study describes the frequencies of the rs662 and rs25487 and their haplotypes in a sample population from Goiás, Brazil. It compares the frequencies with other populations worldwide to verify the variation in the distribution of these SNPs, with 494 unrelated individuals in the state of Goiás. The A allele of the rs25487 variant had a frequency of 26% in the Goiás population, and the modified rs662 G allele had a frequency of 42.8%. Four haplotypes were recorded for the rs25487 (G > A) and rs662 (A > G) markers, with a frequency of 11.9% being recorded for the A-G haplotype (both modified alleles), 30.8% for the G-G haplotype, 14.3% for the A-A haplotype, and 42.8% for the G-A haplotype (both wild-type alleles). We demonstrated the distribution of important SNPs associated with pesticide exposure in an area with a high agricultural activity level, Central Brazil.

Polβ/XRCC1 heterodimerization dictates DNA damage recognition and basal Polβ protein levels without interfering with mouse viability or fertility

DNA Polymerase β (Polβ) performs two critical enzymatic steps during base excision repair (BER) - gap filling (nucleotidyl transferase activity) and gap tailoring (dRP lyase activity). X-ray repair cross complementing 1 (XRCC1) facilitates the recruitment of Polβ to sites of DNA damage through an evolutionarily conserved Polβ/XRCC1 interaction interface, the V303 loop. While previous work describes the importance of the Polβ/XRCC1 interaction for human Polβ protein stability and recruitment to sites of DNA damage, the impact of disrupting the Polβ/XRCC1 interface on animal viability, physiology, and fertility is unknown. Here, we characterized the effect of disrupting Polβ/XRCC1 heterodimerization in mice and mouse cells by complimentary approaches. First, we demonstrate, via laser micro-irradiation, that mouse Polβ amino acid residues L301 and V303 are critical to facilitating Polβ recruitment to sites of DNA damage. Next, we solved the crystal structures of mouse wild type Polβ and a mutant protein harboring alterations in residues L301 and V303 (L301R/V303R). Our structural analyses suggest that Polβ amino acid residue V303 plays a role in maintaining an interaction with the oxidized form of XRCC1. Finally, we created CRISPR/Cas9-modified Polb mice with homozygous L301R/V303R mutations (PolbL301R-V303R/L301R-V303R) that are fertile yet exhibit 15% reduced body weight at 17 weeks of age, as compared to heterozygous mice. Fibroblasts derived from PolbL301R-V303R/L301R-V303R mice demonstrate that mutation of mouse Polβ’s XRCC1 interaction domain leads to an ∼85% decrease in Polβ protein levels. In all, these studies are consistent with a role for the oxidized form of XRCC1 in providing stability to the Polβ protein through Polβ/XRCC1 heterodimer formation.

TEAD Proteins Associate With DNA Repair Proteins to Facilitate Cellular Recovery From DNA Damage

Transcriptional enhanced associate domain family members 1 to 4 (TEADs) are a family of four transcription factors and the major transcriptional effectors of the Hippo pathway. In order to activate transcription, TEADs rely on interactions with other proteins, such as the transcriptional effectors Yes-associated protein and transcriptional co-activator with PDZ-binding motif. Nuclear protein interactions involving TEADs influence the transcriptional regulation of genes involved in cell growth, tissue homeostasis, and tumorigenesis. Clearly, protein interactions for TEADs are functionally important, but the full repertoire of TEAD interaction partners remains unknown. Here, we employed an affinity purification mass spectrometry approach to identify nuclear interacting partners of TEADs. We performed affinity purification mass spectrometry experiment in parallel in two different cell types and compared a wildtype TEAD bait protein to a nuclear localization sequence mutant that does not localize to the nucleus. We quantified the results using SAINT analysis and found a significant enrichment of proteins linked to DNA damage including X-ray repair cross-complementing protein 5 (XRCC5), X-ray repair cross-complementing protein 6 (XRCC6), poly(ADP-ribose) polymerase 1 (PARP1), and Rap1-interacting factor 1 (RIF1). In cellular assays, we found that TEADs co-localize with DNA damage–induced nuclear foci marked by histone H2AX phosphorylated on S139 (γH2AX) and Rap1-interacting factor 1. We also found that depletion of TEAD proteins makes cells more susceptible to DNA damage by various agents and that depletion of TEADs promotes genomic instability. Additionally, depleting TEADs dampens the efficiency of DNA double-stranded break repair in reporter assays. Our results connect TEADs to DNA damage response processes, positioning DNA damage as an important avenue for further research of TEAD proteins.

The X­Ray Repair Cross Complementing 1(XRCC1) Rs25487 Variation and Susceptibility to Cirrhosis in Patients with Chronic Hepatitis C Virus

The X­Ray Repair Cross Complementing 1(XRCC1) Rs25487 Variation and Susceptibility to Cirrhosis in Patients with Chronic Hepatitis C Virus