Association of XRCC1 p. Arg194Trp gene polymorphism with the risk of hepatocellular carcinoma in HCV Egyptian population: A pilot case-control study.

Background: Hepatocellular carcinoma (HCC) is the most common and fatal primary liver cancer. Genetic variants of DNA repair systems can reduce DNA repair capability and increase HCC risk. Objectives: This study aimed to examine, in Egyptian hepatitis C virus (HCV) patients, the relationship between the X-ray repair cross-complementing group 1 (XRCC1) rs1799782 single nucleotide polymorphism (SNP) and HCC susceptibility. Methods: We included 100 adult HCV-positive patients with HCC and 100 adult HCV-positive patients with liver cirrhosis as pathological controls. XRCC1 rs1799782 SNP genotyping was done in both groups using quantitative real-time PCR (qPCR). The distribution of genotypes in patients and controls was compared using several inheritance models. Results: We found that the CT genotype, when analyzed under both the co-dominant (OR (95 % CI): 2.147 (1.184-3.893), p = .012) and the over-dominant (OR (95 % CI): 2.055 (1.153-3.660), p = .015) models, as well as the combined CT and TT genotypes under the dominant model (OR (95 % CI) of 1.991 (1.133-3.497), p = .017), were associated with increased susceptibility to HCC. The frequency of the T allele was higher among HCC participants (32%) compared to those with cirrhosis (23.5%) and carrying the T allele increased the risk of HCC by 1.532 times, however, these associations did not reach statistical significance (p-values >0.05). Moreover, the variant T allele was associated with worse clinical manifestations and laboratory results among the HCC group, but AFP levels were not affected significantly. Conclusions: Egyptians with XRCC1 rs1799782 SNP may have a higher risk of HCV-related HCC. More extensive multi-center prospective investigations must confirm this association.

Frequency of pharmacogenomic variants affecting efficacy and safety of anti-cancer drugs in a south Asian population from Sri Lanka.

BACKGROUND: Therapy with anti-cancer drugs remain the cornerstone of treating cancer. The effectiveness and safety of anti-cancer drugs vary significantly among individuals due to genetic factors influencing the drug response and metabolism. Data on the pharmacogenomic variations in Sri Lankans related to anti-cancer therapy is sparse. As current treatment guidelines in Sri Lanka often do not consider local pharmacogenomic variants, this study aimed to explore the diversity of pharmacogenomic variants in the Sri Lankan population to pave the way for personalized treatment approaches and improve patient outcomes. METHODS: Pharmacogenomic data regarding variant-drug pairs of genes CYP2D6, DPYD, NUDT15, EPAS1, and XRCC1 with clinical annotations labelled as evidence levels 1A-2B were obtained from the Pharmacogenomics Knowledgebase database. Their frequencies in Sri Lankans were obtained from an anonymized database that was derived from 541 Sri Lankans who underwent exome sequencing at the Human Genetics Unit, Faculty of Medicine, University of Colombo. Variations in DPYD, NUDT15, and EPAS1 genes are related to increased toxicity to fluoropyrimidines, mercaptopurines, and sorafenib respectively. Variations in CYP2D6 and XRCC1 genes are related to changes in efficacy of tamoxifen and platinum compounds, respectively. Minor allele frequencies of these variants were calculated and compared with other populations. RESULTS: MAFs of rs1065852 c.100 C > T (CYP2D6), rs3918290 c.1905 + 1G > A (DPYD), rs56038477 c.1236G > A (DPYD), rs7557402 c.1035-7 C > G (EPAS1), rs116855232 c.415 C > T (NUDT15*3), and rs25487 c.1196 A > G (XRCC1) were: 12.9% [95%CI:10.9-14.9], 1.5% [95%CI:0.8-2.2], 1.2% [95%CI:0.5-1.8], 37.7% [95%CI:34.8-40.6], 8.3% [95%CI:6.7-10.0], and 64.0% [95%CI:61.1-66.8], respectively. Frequencies of rs1065852 c.100 C > T (CYP2D6), rs7557402 c.1035-7 C > G (EPAS1), and rs25487 (XRCC1) were significantly lower in Sri Lankans, while frequencies of rs116855232 c.415 C > T (NUDT15*3) and rs56038477 c.1236G > A (DPYD) were significantly higher in Sri Lankans when compared to some Western and Asian populations. CONCLUSION: Sri Lankans are likely to show lower toxicity risk with sorafenib (rs7557402 c.84,131 C > G) and, higher toxicity risk with fluoropyrimidines (rs56038477 c.1236G > A) and mercaptopurine (rs116855232 c.415 C > T), and reduced effectiveness with tamoxifen (rs1065852 c.100 C > T) and platinum compounds (rs25487). These findings highlight the potential contribution of these genetic variations to the individual variability in anti-cancer dosage requirements among Sri Lankans.

The TIMELESS and PARP1 interaction suppresses replication-associated DNA gap accumulation.

TIMELESS (TIM) in the fork protection complex acts as a scaffold of the replisome to prevent its uncoupling and ensure efficient DNA replication fork progression. Nevertheless, its underlying basis for coordinating leading and lagging strand synthesis to limit single-stranded DNA (ssDNA) exposure remains elusive. Here, we demonstrate that acute degradation of TIM at ongoing DNA replication forks induces the accumulation of ssDNA gaps stemming from defective Okazaki fragment (OF) processing. Cells devoid of TIM fail to support the poly(ADP-ribosyl)ation necessary for backing up the canonical OF processing mechanism mediated by LIG1 and FEN1. Consequently, recruitment of XRCC1, a known effector of PARP1-dependent single-strand break repair, to post-replicative ssDNA gaps behind replication forks is impaired. Physical disruption of the TIM-PARP1 complex phenocopies the rapid loss of TIM, indicating that the TIM-PARP1 interaction is critical for the activation of this compensatory pathway. Accordingly, combined deficiency of FEN1 and the TIM-PARP1 interaction leads to synergistic DNA damage and cytotoxicity. We propose that TIM is essential for the engagement of PARP1 to the replisome to coordinate lagging strand synthesis with replication fork progression. Our study identifies TIM as a synthetic lethal target of OF processing enzymes that can be exploited for cancer therapy.

Chromosomal Damage, Chromosome Instability, and Polymorphisms in GSTP1 and XRCC1 as Biomarkers of Effect and Susceptibility in Farmers Exposed to Pesticides.

In the department of Boyacá, Colombia, agriculture stands as one of the primary economic activities. However, the escalating utilization of pesticides within this sector has sparked concern regarding its potential correlation with elevated risks of genotoxicity, chromosomal alterations, and carcinogenesis. Furthermore, pesticides have been associated with a broad spectrum of genetic polymorphisms that impact pivotal genes involved in pesticide metabolism and DNA repair, among other processes. Nonetheless, our understanding of the genotoxic effects of pesticides on the chromosomes (as biomarkers of effect) in exposed farmers and the impact of genetic polymorphisms (as susceptibility biomarkers) on the increased risk of chromosomal damage is still limited. The aim of our study was to evaluate chromosomal alterations, chromosomal instability, and clonal heterogeneity, as well as the presence of polymorphic variants in the GSTP1 and XRCC1 genes, in peripheral blood samples of farmers occupationally exposed to pesticides in Aquitania, Colombia, and in an unexposed control group. Our results showed statistically significant differences in the frequency of numerical chromosomal alterations, chromosomal instability, and clonal heterogeneity levels between the exposed and unexposed groups. In addition, we also found a higher frequency of chromosomal instability and clonal heterogeneity in exposed individuals carrying the heterozygous GSTP1 AG and XRCC1 (exon 10) GA genotypes. The evaluation of chromosomal alterations and chromosomal instability resulting from pesticide exposure, combined with the identification of polymorphic variants in the GSTP1 and XRCC1 genes, and further research involving a larger group of individuals exposed to pesticides could enable the identification of effect and susceptibility biomarkers. Such markers could prove valuable for monitoring individuals occupationally exposed to pesticides.

Correlations of SDF-1ɑ and XRCC1 gene polymorphisms with the risk of renal cancer development and bioinformatics studies of SDF-1α and XRCC1 and the prognosis of renal cancer.

To study the relationships between stromal cell-derived factor-1 (SDF-1ɑ) and renal cell carcinoma (RCC) susceptibility and the presence of single nucleotide polymorphisms in the human X-ray cross-complementary repair gene (XRCC1). Compare SDF-1 based on RCC related data in the TCGA database α, The expression difference of XRCC1 between RCC tissue and normal tissue; Collect 166 newly diagnosed RCC cases and 166 healthy individuals who underwent physical examinations during the same period, and detect genotype using iMLDR method. The results The rs1801157 locus (C:T) of the SDF-1α gene was not significantly associated with the pathohistological type, the rs1799782 locus (G:A) of the XRCC1 gene was associated with the pathohistological type of RCC, and there were interactions between rs1799782 and smoking, alcohol consumption, pesticide exposure, hair dye, and urine holding. The rs1799782 locus of the XRCC1 gene may be a key factor in the pathogenesis and pathological development of RCC. High SDF-1ɑ expression is a protective factor for the overall survival of patients with RCC, and SDF-1ɑ and XRCC1 may be important for the treatment of RCC.

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.

XRCC1 rs1799782 Promotes DNA Damage Repair in Lung Cancer Cells by Enhancing Its Binding to FOXA1 to Facilitate FOXA1-Mediated Transcription of XRCC1.

BACKGROUND: X-ray repair cross complementing 1 (XRCC1) rs1799782 polymorphism is associated with an increased risk of lung cancer (LC). The aim of this study is to analyze the underlying biological mechanisms. METHODS: Dual luciferase reporter assay was utilized to verify the impact of XRCC1 polymorphism upon promoter activity of XRCC1. Cell counting kit-8 (CCK-8) assay, colony formation assay, senescence-associated beta-galactosidase (SA-ß-gal) staining, and immunofluorescent staining were used to assess the viability, proliferation, senescence, and DNA damage of LC cells. Senescence-related proteins (cyclin dependent kinase inhibitor 1A (P21) and eukaryotic translation elongation factor 1-alpha (EF1A)) were quantified by Western blot. Chromatin immunoprecipitation was applied to validate the binding affinity of forkhead box A1 (FOXA1) and XRCC1. FOXA1-specific short hairpin RNA (shFOXA1) was used to perform the rescue assay. RESULTS: In LC cells, XRCC1 rs1799782 promoted viability and proliferation, inhibited senescence, and resulted in upregulation of EF1A as well as downregulation of P21 and phosphorylated H2A.X variant histone (γH2AX). XRCC1 rs1799782 promoted FOXA1-mediated transcription of XRCC1 through enhancing its binding to FOXA1. shFOXA1 counteracted the effects of XRCC1 rs1799782 upon the viability, proliferation, and senescence of LC cells. CONCLUSIONS: XRCC1 rs1799782 promotes DNA damage repair in LC cells through enhancing its binding to FOXA1, which facilitates FOXA1-mediated transcription of XRCC1.

Mammalian DNA ligases; roles in maintaining genome integrity.

The joining of breaks in the DNA phosphodiester backbone is essential for genome integrity. Breaks are generated during normal processes such as DNA replication, cytosine demethylation during differentiation, gene rearrangement in the immune system and germ cell development. In addition, they are generated either directly by a DNA damaging agent or indirectly due to damage excision during repair. Breaks are joined by a DNA ligase that catalyzes phosphodiester bond formation at DNA nicks with 3' hydroxyl and 5' phosphate termini. Three human genes encode ATP-dependent DNA ligases. These enzymes have a conserved catalytic core consisting of three subdomains that encircle nicked duplex DNA during ligation. The DNA ligases are targeted to different nuclear DNA transactions by specific protein-protein interactions. Both DNA ligase IIIα and DNA ligase IV form stable complexes with DNA repair proteins, XRCC1 and XRCC4, respectively. There is functional redundancy between DNA ligase I and DNA ligase IIIα in DNA replication, excision repair and single-strand break repair. Although DNA ligase IV is a core component of the major double-strand break repair pathway, non-homologous end joining, the other enzymes participate in minor, alternative double-strand break repair pathways. In contrast to the nucleus, only DNA ligase IIIα is present in mitochondria and is essential for maintaining the mitochondrial genome. Human immunodeficiency syndromes caused by mutations in either LIG1 or LIG4 have been described. Preclinical studies with DNA ligase inhibitors have identified potentially targetable abnormalities in cancer cells and evidence that DNA ligases are potential targets for cancer therapy.

Modulation of gene expression and influence of gene polymorphisms related to genotoxicity and redox status on occupational exposure to inhaled anesthetics.

The extensive use of inhalational anesthetics contributes to both indoor and outdoor (environmental) pollution. The influence of genetic susceptibility on DNA damage and oxidative stress and the possible modulation of gene expression have not yet been investigated upon occupational exposure to waste anesthetic gases (WAGs). This study assessed 8-oxoguanine DNA glycosylase 1 (OGG1) and superoxide dismutase 2 (SOD2) gene expression, which are related to oxidized DNA repair and antioxidant capacity, respectively, and the influence of their polymorphisms (OGG1 rs1052133 and SOD2 rs4880) in 100 professionals highly exposed to WAGs and 93 unexposed volunteers (control group). Additionally, X-ray repair cross complementing 1 (XRCC1 rs25487 and rs1799782) and ataxia telangiectasia mutated (ATM rs600931) gene polymorphisms as well as genetic instability (micronucleus-MN and nuclear bud-NBUD) and oxidative stress (malondialdehyde-MDA and ferric reducing antioxidant power-FRAP) biomarkers were assessed in the groups (control and exposed) and in the subgroups of the exposed group according to job occupation (anesthesiologists versus surgeons/technicians). Except for the ATM TT controls (associated with increased FRAP), there were no influences of OGG1, XRCC1, ATM, and SOD2 polymorphisms on MN, NBUD, MDA, and FRAP values in exposed or control subjects. No significant difference in the expression of either gene evaluated (OGG1 and SOD2) was found between the exposed and control groups. Increased OGG1 expression was observed among OGG1 -/Cys individuals only in the control group. Among the exposed group, anesthesiologists had a greater duration of WAG exposure (both h/week and years) than surgeons/technicians, which was associated with increased MDA and decreased antioxidant capacity (FRAP) and SOD2 expression (redox status). Higher expression of OGG1 was found in -/Cys surgeons/technicians than in anesthesiologists with the same genotype. Increased antioxidant capacity was noted in the surgeons/technicians carrying the ATM T allele and in those carrying XRCC1 -/Gln. Increased MN was influenced by OGG1 -/Cys in surgeons/technicians. Anesthesiologists with ATM CC exhibited increased MN, and those carrying the C allele (CC/CT genotype) exhibited increased NBUD. SOD2 polymorphism did not seem to be relevant for WAG exposure. These findings contribute to advancing the knowledge on genetic susceptibility/gene expression/genetic instability/oxidative stress, including differences in job occupation considering the workload, in response to occupational exposure to WAGs.

Extreme acute radiation-induced toxicity in a patient with polymorphous low-grade adenocarcinoma of the nasopharynx and rare variants in DNA repair genes.

BACKGROUND: Polymorphous low-grade adenocarcinoma (PLGA) is an extremely rare finding in the nasopharynx. There are no guidelines for the treatment of PLGA in this localization. Radiotherapy may be administered to treat this malignancy; however, in radiosensitive individuals, it is associated with a risk of severe radiotherapy-induced toxicity. METHODS: We present a case of a 73-year-old woman with locally advanced polymorphous low-grade adenocarcinoma of the nasopharynx who developed a severe adverse acute reaction to radiotherapy leading to treatment discontinuation. Despite intensive treatment, the patient died 40 days after RT initiation. Whole genome sequencing was performed using DNA from peripheral blood mononuclear cells in the search for variants that could explain such extreme toxicity. RESULTS: We identified a combination of pathogenic variants that may have contributed to the patient's reaction to radiation therapy, including predisposing variants in XRCC1, XRCC3, and LIG4. We also identified candidate variants, not previously described in this context, which could be associated with radiation toxicity based on plausible mechanisms. We discuss previous reports of this rare tumor from the literature and known contributors to radiation-induced toxicity. CONCLUSIONS: Genetic causes should be considered in cases of extreme radiosensitivity, especially when is not explained by clinical factors.

Impact of polß/XRCC1 Interaction Variants on the Efficiency of Nick Sealing by DNA Ligase IIIα in the Base Excision Repair Pathway.

Base excision repair (BER) requires a coordination from gap filling by DNA polymerase (pol) ß to subsequent nick sealing by DNA ligase (LIG) IIIα at downstream steps of the repair pathway. X-ray cross-complementing protein 1 (XRCC1), a non-enzymatic scaffolding protein, forms repair complexes with polß and LIGIIIα. Yet, the impact of the polß mutations that affect XRCC1 interaction and protein stability on the repair pathway coordination during nick sealing by LIGIIIα remains unknown. Our results show that the polß colon cancer-associated variant T304 exhibits a reduced interaction with XRCC1 and the mutations in the interaction interface of V303 loop (L301R/V303R/V306R) and at the lysine residues (K206A/K244A) that prevent ubiquitin-mediated degradation of the protein exhibit a diminished repair protein complex formation with XRCC1. Furthermore, we demonstrate no significant effect on gap and nick DNA binding affinity of wild-type polß by these mutations. Finally, our results reveal that XRCC1 leads to an efficient channeling of nick repair products after nucleotide incorporation by polß variants to LIGIIIα, which is compromised by the L301R/V303R/V306R and K206A/K244A mutations. Overall, our findings provide insight into how the mutations in the polß/XRCC1 interface and the regions affecting protein stability could dictate accurate BER pathway coordination at the downstream steps involving nick sealing by LIGIIIα.

Upregulation of XRCC1 DNA Repair Gene, Interleukin-8, and Bcl-2 Antiapoptotic Gene Levels in Kurdish Patients with Gastric Adenocarcinoma.

Gastric cancer (GC) is one of the deadliest tumors due to its competence to invade and metastasize. The DNA repair gene (XRCC1), interleukin-8 (IL-8) gene, and B-cell lymphoma 2 (Bcl-2) gene play a crucial role in the development and progression of GC. This study aimed to evaluate the expression of these target genes in GC patients in the Kurdistan region of Iraq. Gastric cancer tissues were collected from 29 patients diagnosed with gastric adenocarcinoma that underwent gastric resection, and 21 tissue samples were obtained from healthy patients that underwent gastroscopy. The gastric tissues were collected in different hospitals in Erbil and Sulaymaniyah cities in the Kurdistan region of Iraq. Moreover, the data regarding Helicobacter pylori, age, gender, and stage of the disease were recorded and analyzed using GraphPad Prism. The gene expression levels of XRCC1, IL-8, and Bcl-2 from gastric tissue were studied by real-time quantitative polymerase chain reaction. The results showed that H. pylori infection was equally distributed among males and females in the tissues of gastric patients, while most of the H. pylori-negative patients were females. It is also found that gastric patients aged 30-60 years old are more commonly tested for the H. pylori test. Accordingly, in this study, patients diagnosed with gastric inflammation more often tested positive for H. pylori, while patients diagnosed with gastric cancer tested negative for this infection. Additionally, it was found that the target genes (XRCC1, IL-8, and Bcl-2) were significantly upregulated in GC patients, compared to the healthy group. Finally, the result revealed that XRCC1, IL-8, and Bcl-2 were upregulated in the Kurdish patients with GC, compared to the healthy control group. Targeting XRCC1, IL-8, and Bcl-2 genes can be an interesting field and promising strategy for cancer treatment.

Overexpression of XRCC1 is Associated with Poor Survival in Patients with Head and Neck Squamous Carcinoma and Has Potential to Be Used as Targeted Therapy by Synthetic Lethality.

Background: Head neck squamous cell carcinoma (HNSC) is globally prevalent cancer attributed to tobacco habit. Despite the significant advances in early diagnosis and treatment of HNSC chemo-radio resistance are routinely observed in patients. Aberrant DNA repair mechanisms mainly microhomology mediated DNA end joining (MMEJ) pathway causing deleterious mutations and is implicated in treatment resistance. X-ray cross complimenting group 1 (XRCC1) has recently been shown to play an essential role in MMEJ making XRCC1 a potential therapeutic target to render tumors chemo-radiosensitive. This study analyzes the correlation between the expression level of XRCC1 gene with survival, regulation by miRNA and synthetic lethality partners in HNSCC. Materials and Methods: XRCC1 gene expression was evaluated in 520 HNSC patients and 44 of normal tissues using the UALCAN (TCGA) database and its correlation with survival outcome of HNSC patients was analyzed by Kaplan-Meier plot. Infiltration of immune cells in tumors was analyzed by "Tumor-Infiltrating Immune Estimation Resource (TIMER) and promoter methylation status of XRCC1 in samples was analysed by UALCAN. STRING was used to find gene interacting partners of XRCC1.  Results: XRCC1 was significantly overexpressed in primary tumor of HNSCC and significantly increased with tumor stages and grade and associated with poor survival rate. High XRCC1 expression in HNSC was positively correlated with infiltration level of B cells naïsve, CD4+ and macrophages. Conclusion: These results indicate that XRCC1 is a prognostic marker for predicting survival in HNSC patients. Understanding how XRCC1 leads to treatment resistance and modulate immune response can lead to development of targeted therapy.

Exploring homologous recombination repair and base excision repair pathway genes for possible diagnostic markers in hematologic malignancies.

Hematologic malignancies (HMs) are a collection of malignant transformations, originating from the cells in the bone marrow and lymphoid organs. HMs comprise three main types; leukemia, lymphoma, and multiple myeloma. Globally, HMS accounts for approximately 10% of newly diagnosed cancer. DNA repair pathways defend the cells from recurrent DNA damage. Defective DNA repair mechanisms such as homologous recombination repair (HRR), nucleotide excision repair (NER), and base excision repair (BER) pathways may lead to genomic instability, which initiates HM progression and carcinogenesis. Expression deregulation of HRR, NER, and BER has been investigated in various malignancies. However, no studies have been reported to assess the differential expression of selected DNA repair genes combinedly in HMs. The present study was designed to assess the differential expression of HRR and BER pathway genes including RAD51, XRCC2, XRCC3, APEX1, FEN1, PARP1, and XRCC1 in blood cancer patients to highlight their significance as diagnostic/ prognostic marker in hematological malignancies. The study cohort comprised of 210 blood cancer patients along with an equal number of controls. For expression analysis, q-RT PCR was performed. DNA damage was measured in blood cancer patients and controls using the comet assay and LORD Q-assay. Data analysis showed significant downregulation of selected genes in blood cancer patients compared to healthy controls. To check the diagnostic value of selected genes, the Area under curve (AUC) was calculated and 0.879 AUC was observed for RAD51 (p < 0.0001) and 0.830 (p < 0.0001) for APEX1. Kaplan-Meier analysis showed that downregulation of RAD51 (p < 0.0001), XRCC3 (p < 0.02), and APEX1 (p < 0.0001) was found to be associated with a significant decrease in survival of blood cancer patients. Cox regression analysis showed that deregulation of RAD51 (p < 0.0001), XRCC2 (p < 0.02), XRCC3 (p < 0.003), and APEX1 (p < 0.00001) was found to be associated with the poor prognosis of blood cancer patients. Comet assay showed an increased number of comets in blood cancer patients compared to controls. These results are confirmed by performing the LORD q-assay and an increased frequency of lesions/Kb was observed in selected genes in cancer patients compared to controls. Our results showed significant downregulation of RAD51, XRCC2, XRCC3, APEX1, FEN1, PARP1, and XRCC1 genes with increased DNA damage in blood cancer patients. The findings of the current research suggested that deregulated expression of HRR and BER pathway genes can act as a diagnostic/prognostic marker in hematologic malignancies.

XRCC1 R194W and R399Q Polymorphisms and Colorectal Cancer Risk in a Northeastern Mexican Population.

Colorectal cancer (CRC) is one of the most common cancers worldwide. Its etiopathogenesis is complex, mainly influenced by genetic instability caused by the accumulation of mutations. The XRCC1 gene, which is involved in DNA repair, has been associated with CRC through the R194W (C194T) and R399Q (G399A) polymorphisms, but the results are inconsistent. Here, we analyzed the association of these polymorphisms with sporadic CRC in a northeastern Mexican population, including 155 male CRC patients and 155 male controls. Genotyping was performed using the RFLP method. An association with CRC was found for the 399A allele (G vs A; OR = 1.48 (1.03-2.13), P=0.034) and for the 399AA genotype in a codominant model (AA vs GG; OR = 3.11 (1.06-9.10), P=0.031). In contrast, there were no significant differences between CRC patients and controls for the C194T polymorphism (C vs T; OR = 0.82 (0.52-1.31), P=0.41). These results are consistent with many similar studies, but further research is needed to verify whether the XRCC1 R194W and R399Q polymorphisms play a role in CRC etiology. The functional significance of these polymorphisms is unclear, but some studies suggest that they influence DNA repair capacity and, thus, cancer risk.

The XRCC1 and TP53 gene polymorphisms are associated with advanced-stage disease and early distant metastasis at diagnosis in non-small cell lung cancer.

Background: Studies on single nucleotide polymorphisms (SNPs) in non-small cell lung cancer (NSCLC) suggest that DNA repair capacity may have prognostic implications for disease recurrence and survival. However, there is no study investigating the relationship between SNPs and the risk of metastasis at the time of initial diagnosis in patients with NSCLC. Objective: This study aimed to investigate the potential predictive value of SNPs in detecting the risk of metastasis at the time of initial diagnosis and poor prognosis in patients with NSCLC. Material and Methods: In this prospective cohort study, we evaluated 275 patients with NSCLC. Analysis of SNPs from peripheral blood cells was performed by a polymerase chain reaction. Excision repair cross-complementing group 1 (ERCC1)- Asn118Asn, excision repair cross-complementing group 2 (ERCC2)-Lys751Gln, X-ray repair cross-complementing group 1 (XRCC1)-Arg399Gln, and tumor protein 53 (TP53)-Arg72Pro polymorphisms were evaluated in conjunction with the development of metastasis. Results: The ERCC1 normal genotype, ERCC2 heterozygote genotype, XRCC1 normal genotype, and TP53 normal genotype were associated with a higher stage and more advanced-stage disease at the time of initial diagnosis (P = 0.027, 0.005, <0.001, and 0.006, respectively). Also, XRCC1 normal genotype and TP53 normal genotype were associated with the risk of metastasis at the time of initial diagnosis (P = <0.001 and 0.002, respectively). Moreover, the XRCC1 normal genotype was associated with the risk of brain metastasis at the time of initial diagnosis (P = 0.031). Conclusions: We showed that SNPs are related to a higher stage and more advanced-stage disease at the time of initial diagnosis in patients with NSCLC, and XRCC1 and TP53 gene polymorphisms are associated with the risk of metastasis. These results may contribute to the identification of high-risk groups and may help to earlier diagnosis and treatment in patients with NSCLC.

Association Between the XRCC1, GSTM1, and GSTT1 Polymorphisms in Model of Thyroid Cancer: A Meta-Analysis.

Thyroid cancer is the most common malignant tumor of the endocrine system, and its incidence is increasing worldwide each year. This study aimed to explore the association between XRCC1, GSTM1, and GSTT1 polymorphisms in the model of thyroid cancer. The experiment was conducted by searching PubMed, Embase, and Web of Science, with the last search performed in March 2022. A total of 12 studies were included in this meta-analysis, with sample sizes ranging from 211 to 1124. The proportion of XRCC1 polymorphisms (rs25489, GG) in thyroid cancer was slightly lower than that of the normal control group, but the difference was not statistically significant (Mean difference=1.13, 95% CI: 0.99-1.28, p=0.08). The proportion of XRCC1 polymorphisms (rs25489, GA) in thyroid cancer was significantly lower than that of the normal control group (Mean difference=1.32, 95% CI: 1.16-1.52, p<0.00001). The proportion of XRCC1 polymorphisms (rs25489, AA) in thyroid cancer was slightly lower than that of the normal control group, but again, the difference was not statistically significant (Mean difference=0.78, 95% CI: 0.61-1.01, p=0.06). Similarly, the proportion of XRCC1 polymorphisms (rs25487, GG) and (rs25487, GA) in thyroid cancer was lower than that of the normal control group, but the differences were not statistically significant (p=0.22 and p=0.49, respectively). In conclusion, this study found that the proportion of XRCC1 polymorphisms (rs25489, AA) in thyroid cancer was lower than that of the normal control group.

Single Nucleotide Polymorphisms in DNA Repair Genes (XRCC1, XRCC2, XRCC3) and Their Association with Radiotherapy Toxicity among Head and Neck Cancer Patients:A Study from South-Western Maharashtra.

BACKGROUND: The genetic polymorphisms in DNA repair genes and their correlation with normal tissue toxicity in response to radiation therapy has not been consistently proven in many of the studies done in head and neck cancers (HNC). This study was intended to investigate the association of most common single nucleotide polymorphisms of DNA repair genes with acute radiation induced toxicities such as skin reactions and oral mucositis in normal tissue from HNC patients receiving radiotherapy from South-Western Maharashtra. METHODS: Two hundred HNC patients receiving radiotherapy were enrolled in this study and the radiation injuries in the form of skin reactions and oral mucositis were recorded. Three single nucleotide polymorphisms (SNPs) rs1799782, rs25489) rs25487 of XRCC1 gene, rs3218536in XRCC2 gene and rs861539 SNP of XRCC3 gene were studied by PCR-RFLP and direct DNA sequencing.  Results: The univariate analysis of SNPs of XRCC1, XRCC2 and XRCC3, the obtained results verified that XRCC1 polymorphism at 194Trp of exon 6 (OR=0.69, 95% CI: 0.28-1.71; p=0.433), codon 280 at exon 9 ((OR=1.05, 95% CI: 0.42-2.63; p=0.911) and codon 399 of at exon 10(OR=1.06, 95% CI: 0.52-2.15; p=0.867) and XRCC2 polymorphism at codon 188 at exon 3 (OR=1.07, 95% CI: 0.46-2.47; p=0.866) and 241Met variant genotype of XRCC3 (OR=2.63 95% CI: 0.42-16.30; p=0.298) showed no association with degree of radiotherapy associated dermatitis or mucositis in HNC patients. CONCLUSION: The findings from this study postulated that none of rs1799782, rs25489, rs25487 SNPs of XRCC1, rs3218536 SNP of XRCC2 nor rs861539 SNP of XRCC3 were associated with increased toxicity of radiotherapy in HNC patients of south-western Maharashtra. 
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Impact of Interaction between Single Nucleotide Polymorphism of XRCC1, XRCC2, XRCC3 with Tumor Suppressor Tp53 Gene Increases Risk of Breast Cancer: A Hospital Based Case-Control Study.

BACKGROUND: At present very little information is available on combined effects of DNA repair genes with tumor suppressor gene polymorphisms and their association with cancer susceptibility. No such association studies have been carried out with breast cancer or any other cancer from India. Present study was conducted to study the combined effects of SNPs of XRCC1, XRCC2, XRCC3 with Arg72Pro and Arg249Ser SNPs of TP53 gene in risk of BC in rural parts of India. METHODS: The polymorphisms of Arg194Trp, Arg280His, Arg399Gln of XRCC1, Arg188His of XRCC2 and Thr241Met of  XRCC3 with Arg72Pro and Arg249Ser of TP53 gene polymorphisms was studied by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method. The association among the polymorphisms with breast cancer risk was studied by Odds ratio within 95% confidence interval and SNP-SNP interaction were confirmed by logistic regression analysis. RESULTS: The results of genotype frequency distribution of XRCC1, XRCC2, XRCC3 genotypes showed positive association between XRCC1 Arg280His polymorphism and BC risk (OR=4.54; 95% CI: 3.36- 6.15; p<0.0001).  Also the heterozygous genotypes Arg188His of XRCC2 (OR=1.58; 95% CI: 1.13- 2.21; p=0.007) and Thr241Met genotype of XRCC3 (OR=2.13; 95% CI: 1.44- 3.13; p=0.0001) were associated with BC risk. The combination of heterozygous Arg280His genotype of XRCC1 along with Arg72Pro genotype of TP53 increased the risk of BC (OR=4.53; 95% CI: 2.85-7.20); p<0.0001). Similarly,  the combined effect of heterozygous Arg/His genotype of XRCC1 with heterozygous Arg/Ser genotype of TP53 at codon 249 showed significant association with increased BC risk (OR=5.08; 95% CI: 2.86-9.04); p<0.0001). CONCLUSION: The findings derived from our study concluded that the heterozygous variant Arg280His genotype of XRCC1 and Thr241Met polymorphism of XRCC3 in combination with heterozygous arginine72proline genotype and heterozygous Arg249Ser polymorphism of TP53 showed significant association with breast cancer risk in Maharashtrian women.

Genetic variants of antioxidant and xenobiotic metabolizing enzymes and their association with prostate cancer: A meta-analysis and functional in silico analysis.

The development and progression of prostate cancer (PCa) depends on complex interactions between genetic, environmental and dietary factors that modulate the carcinogenesis process. Interactions between chemical exposures and genetic polymorphisms in genes encoding xenobiotic metabolizing enzymes (XME), antioxidant enzymes and DNA repair enzymes have been reported as the main drivers of cancer. Thus, a better understanding of the causal risk factors for PCa will provide avenues to identify men at increased risk and will contribute to develop effective detection and prevention methods. We performed a meta-analysis on 17,518 cases and 42,507 controls obtained from 42 studies to determine whether seven SNPs and one CNV pertaining to oxidative stress, xenobiotic detoxification and DNA repair enzymes are associated with the risk of PCa (GPX1 (rs1050450), XRCC1 (rs25487), PON1 (rs662), SOD2 (rs4880), CAT (rs1001179), GSTP1 (rs1695) and CNV GSTM1). A significant increased risk of PCa was found for SOD2 (rs4880) ORGG+GA vs. AA 1.08; 95%CI 1.01-1.15, CAT (rs1001179) ORTT vs. TC+CC 1.39; 95%CI 1.17-1.66, PON1 (rs662) ORCT vs. CC+TT 1.17; 95%CI 1.01-1.35, GSTP1 (rs1695) ORGG vs. GA+AA 1.20; 95%CI 1.05-1.38 and GSTM1 (dual null vs. functional genotype) ORN vs. NN1+NN2 1.34; 95%CI 1.10-1.64. The meta-analysis showed that the CNV GSTM1, and the SNPs GSTP1 (rs1695) and CAT (rs1001179) are strongly associated with a greater risk of PCa and, to a lesser extent, the genetic variants SOD2 (rs4880) and PON1 (rs662). Although several antioxidant enzymes and XME play an important role in the PCa development, other risk factors such as chemical exposures should also be considered to gain insight on PCa risk. The functional in silico analysis showed that the genetic variants studied had no clinical implication regarding malignancy, except for GPX1 (rs1050450) SNP.