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DNA repair gene polymorphisms and risk of head and neck cancer in the Tunisian population.

Altered activity of DNA repair enzymes may be involved in modulating cancer susceptibility and pathogenesis of head and neck cancer (HNC). We conducted a case-control study to test the association between three common single-nucleotide polymorphisms of XRCC1, ERCC2, and ERCC3 genes with HNC risk in Tunisian patients. To the best of our knowle dge, this is the first report on polymorphisms in XRCC1, ERCC2, and ERCC3 and susceptibility to HNC in our population. The genotype analyses of XRCC1 Arg399Gln, ERCC2 Lys751Gln, and ERCC3 7122 A>G polymorphisms for 169 HNC patients, and 261 controls were

XPA-mediated regulation of global nucleotide excision repair by ATR Is p53-dependent and occurs primarily in S-phase.

Cell cycle checkpoints play an important role in regulation of DNA repair pathways. However, how the regulation occurs throughout the cell cycle remains largely unknown. Here we demonstrate that nucleotide excision repair (NER) is regulated by the ATR/p53 checkpoint via modulation of XPA nuclear import and that this regulation occurs in a cell cycle-dependent manner. We show that depletion of p53 abrogated the UV-induced nuclear translocation of XPA, while silencing of Chk1 or MAPKAP Kinase-2 (MK2) had no effect. Inhibition of p53 transcriptional activities and silencing of p53-Ser15 phosphory

Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin.

BACKGROUND: One of the most commonly used classes of anti-cancer drugs presently in clinical practice is the platinum-based drugs, including cisplatin. The efficacy of cisplatin therapy is often limited by the emergence of resistant tumours following treatment. Cisplatin resistance is multi-factorial but can be associated with increased DNA repair capacity, mutations in p53 or loss of DNA mismatch repair capacity. METHODS: RNA interference (RNAi) was used to reduce the transcription-coupled nucleotide excision repair (TC-NER) capacity of several prostate and colorectal carcinoma cell lines wi

Comprehensive analysis of DNA repair gene polymorphisms and survival in patients with early stage non-small-cell lung cancer.

This study was conducted to analyze a comprehensive panel of single nucleotide polymorphisms (SNP) in DNA repair genes to determine the relationship between polymorphisms and the survival outcome of patients with early stage non-small-cell lung cancer (NSCLC). Three hundred and ten consecutive patients with surgically resected NSCLC were enrolled. Forty-eight SNP in 27 DNA repair genes were genotyped and their associations with overall survival (OS) and disease-free survival (DFS) were analyzed. Individually, six SNP exhibited significant associations with survival outcome. When the six SNP we

Recruitment of fanconi anemia and breast cancer proteins to DNA damage sites is differentially governed by replication.

Fanconi anemia (FA) is characterized by cellular hypersensitivity to DNA crosslinking agents, but how the Fanconi pathway protects cells from DNA crosslinks and whether FA proteins act directly on crosslinks remain unclear. We developed a chromatin-IP-based strategy termed eChIP and detected association of multiple FA proteins with DNA crosslinks in vivo. Interdependence analyses revealed that crosslink-specific enrichment of various FA proteins is controlled by distinct mechanisms. BRCA-related FA proteins (BRCA2, FANCJ/BACH1, and FANCN/PALB2), but not FA core and I/D2 complexes, require repl

Reduced expression of human DNA repair genes in esophageal squamous-cell carcinoma in china.

Epidemiological studies indicated that the incidence of esophageal squamous-cell carcinoma (ESCC) is associated with exposure to a variety of environmental factors. To determine whether the baseline expression of genes involved in DNA damage and repair induced by these carcinogens is associated with higher risk for ESCC, a case-control study was undertaken and the relative expression levels of six DNA repair genes (MGMT, hOGG1, XRCC1, XPD, hMLH1, and hMSH2) were determined in peripheral blood mononuclear cells (PBMC). One hundred patients with newly diagnosed, untreated ESCC and 117 healthy co

Characterization of a clonal isolate of an oxaliplatin resistant ovarian carcinoma cell line A2780/C10.

A single cell clonal sub-line A2780/C10B that is 18-fold resistant to oxaliplatin and approximately threefold cross-resistant to cisplatin and exhibiting a metastasis associated cellular phenotype was characterized for mechanisms of resistance. The cell line exhibited a 50% reduction in the accumulation of both oxaliplatin and cisplatin relative to the parent line, while extensive decline in Pt-DNA adduct levels occurred only following oxaliplatin treatment. The basal GSH levels were fivefold higher in A2780/C10B compared to A2780 and had a fivefold elevation in gamma-GT suggesting this may be

Arabidopsis UVH6, a homolog of human XPD and yeast RAD3 DNA repair genes, functions in DNA repair and is essential for plant growth.

To evaluate the genetic control of stress responses in Arabidopsis, we have analyzed a mutant (uvh6-1) that exhibits increased sensitivity to UV light, a yellow-green leaf coloration, and mild growth defects. We have mapped the uvh6-1 locus to chromosome I and have identified a candidate gene, AtXPD, within the corresponding region. This gene shows sequence similarity to the human (Homo sapiens) XPD and yeast (Saccharomyces cerevisiae) RAD3 genes required for nucleotide excision repair. We propose that UVH6 is equivalent to AtXPD because uvh6-1 mutants carry a mutation in a conserved residue o

Hepatitis B virus X protein inhibits nucleotide excision repair.

Human hepatitis B virus (HBV) is a major risk factor of human hepatocellular carcinoma. Both in vivo and in vitro studies have shown that HBV X protein (HBx) can bind to the p53 tumor-suppressor protein and interfere with the role that p53 plays in the cellular response to DNA damage. Our previous work has shown that HBx protein inhibits p53 sequence-specific transcriptional activation, p53-mediated apoptosis and p53 binding to the TFIIH transcription-nucleotide excision repair (NER) factors, including XPB and XPD. To investigate whether HBx interferes with the NER pathway, we utilized cell-pr

Association between Molecular Genetic Markers of DNA Repair and Cell Cycle Control Genes and Response to Platinum-Based Chemotherapy in Ovarian Cancer Patients.

We analyzed associations of polymorphic markers of DNA repair genes (XRCC1, ERCC2), cell cycle control genes (TP53, MDM2, and CDKN1A), methylation of promoter region, and mutation 5382insC of BRCA1 gene in ovarian cancer with effectiveness of platinumbased chemotherapy assessed by the median of progression-free survival time for markers of DNA repair genes and by relapse risk for all studied markers. An increase in the median of progression-free survival time for carriers of the Gln allele (р=0.025) and Gln/Gln genotype (р=0.022) of the Gln399Arg XRCC1 was observed during the 19-months period

Unexpected cancer-predisposition gene variants in Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome patients without underlying germline PTEN mutations.

Patients with heritable cancer syndromes characterized by germline PTEN mutations (termed PTEN hamartoma tumor syndrome, PHTS) benefit from PTEN-enabled cancer risk assessment and clinical management. PTEN-wildtype patients (~50%) remain at increased risk of developing certain cancers. Existence of germline mutations in other known cancer susceptibility genes has not been explored in these patients, with implications for different medical management. We conducted a 4-year multicenter prospective study of incident patients with features of Cowden/Cowden-like (CS/CS-like) and Bannayan-Riley-Ruva

Influence of XPC, XPD, XPF, and XPG gene polymorphisms on the risk and the outcome of acute myeloid leukemia in a Romanian population.

XPC, XPD, XPF, and XPG genes are implicated in the nucleotide excision repair (NER) system. Gene polymorphisms in NER repair system may influence the individual's capacity to recognize and repair DNA lesions, thus increasing the cancer risk. We hypothesized that these gene polymorphisms might influence the probability of developing acute myeloid leukemia (AML). We investigated the XPC, XPD, XPF, and XPG gene polymorphisms in 108 AML cases and 163 healthy controls. Also cytogenetic analyses besides FLT3 and DNMT3A mutations status were investigated. We found that variant genotypes (heterozygous

Associations of DNA-repair gene polymorphisms with a genetic susceptibility to ionizing radiation in residents of areas with high radon (222Rn) concentration.

PURPOSE: To investigate the individual radiosensitivity of the human genome in long-term residents of areas with high radon concentration. MATERIALS AND METHODS: The materials used for this investigation were venous blood samples extracted from children living in the boarding school of Tashtagol (Kemerovo Region, Russia). Cytogenetic damage assessment was performed using the cytokinesis-block micronucleus assay (CBMN) on peripheral blood lymphocytes. PCR, gel electrophoresis and product detection using a transilluminator were used to determine polymorphisms in the genes ADPRT (rs 1136410), hO

AGXT and ERCC2 polymorphisms are associated with clinical outcome in metastatic colorectal cancer patients treated with 5-FU/oxaliplatin.

The objective of the study was to investigate whether specific single nucleotide polymorphisms (SNPs) with influence on drug transport, biotransformation and repair mechanisms are associated with treatment outcome and toxicity in metastatic colorectal cancer (mCRC). We genotyped blood samples from 519 mCRC patients treated with first-line 5-fluorouracil and oxaliplatin +/- cetuximab for 17 SNPs in 10 genes involved in membrane transport (ABCC1 and ABCC2), drug biotransformation (GSTP1 and AGXT) and DNA repair (ERCC1, ERCC2, XRCC1, XRCC3, XPG and MSH6). The AGXT-rs34116584 and the ERCC2-rs23840

DNA repair gene polymorphisms predict favorable clinical outcome in advanced non-small-cell lung cancer.

BACKGROUND: Genetic polymorphisms of genes involved in DNA repair and glutathione metabolic pathways may affect patients' response to platinum-based chemotherapy. We retrospectively assessed whether single nucleotide polymorphisms (SNP) of DNA-repair genes ERCC1, XPD, XRCC1 and glutathione S-transferase genes GSTP1, GSTT1 and GSTM1 predict overall survival (OS), response and toxicity in 119 non-small-cell lung cancer (NSCLC) patients treated with platinum-based regimens as first- or second-line chemotherapy. PATIENTS AND METHODS: Patients' genotypes were determined by PCR-RFLP and sequencing

Bladder cancer and polymorphisms of DNA repair genes (XRCC1, XRCC3, XPD, XPG, APE1, hOGG1).

Carcinogenic molecules from cigarettes are known to cause DNA damage to bladder epithelial cells, but such damage can be corrected by some DNA repair mechanisms such as base and nucleotide excision repair, double-strand repair and mismatch repair. Various gene products play a role in these DNA repair systems. The aim of this study was to investigate six of these genes (XRCC1, XRCC3, XPD, XPG, APE1, hOGG1) each of which has a separate role in these repair mechanisms. The study was performed on 83 bladder cancer patients and 45 healthy controls. The genes were amplified by polymerase chain react

UV-Induced stabilization of c-fos and other short-lived mRNAs.

Irradiation of cells with short-wavelength ultraviolet light (UVC) changes the program of gene expression, in part within less than 15 min. As one of the immediate-early genes in response to UV, expression of the oncogene c-fos is upregulated. This immediate induction is regulated at the transcriptional level and is transient in character, due to the autocatalyzed shutoff of transcription and the rapid turnover of c-fos mRNA. In an experiment analyzing the kinetics of c-fos mRNA expression in murine fibroblasts irradiated with UVC, we found that, in addition to the initial transient induction,

Ku70/Ku80 protein complex inhibits the binding of nucleotide excision repair proteins on linear DNA in vitro.

We have previously reported that the incision efficiency of the nucleotide excision repair (NER) reaction measured in vitro with cell-free human protein extracts was reduced by up to 80% on a linearized damaged plasmid DNA substrate when compared to supercoiled damaged DNA. The inhibition stemed from the presence of the DNA-end binding Ku70/Ku80 heterodimer which is the regulatory subunit of the DNA-dependent protein kinase (DNA-PK). Here, the origin of the repair inhibition was assessed by a new in vitro assay in which circular or linear plasmid DNA, damaged or undamaged, was quantitatively a

Targeted therapy for advanced Basal-cell carcinoma: vismodegib and beyond.

Basal-cell carcinoma is a commonly occurring skin malignancy that has the potential to progress into locally invasive or resistant disease, as well as spread distantly. Due to advances in the molecular understanding of the disease over the last two decades, it has been discovered that the Hedgehog pathway plays an important role in the pathogenesis of this disease and can be exploited as a treatment target. Several agents that inhibit the Hedgehog pathway have reached clinical studies and one drug, vismodegib, has recently been US Food and Drug Administration (FDA) approved based on clinical a

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… However, a variety of hereditary syndromes can result in an increased risk of developing BCC tumors, including nevoid BCC syndrome, Bazex–Dupré–Christol syndrome, Rombo syndrome, Oley syndrome, and xeroderma pigmentosum [ 8 ]. …

Loci associated with genomic damage levels in chronic kidney disease patients and controls.

Chronic kidney disease (CKD) is a multifactorial disorder with an important genetic component, and several studies have demonstrated potential associations with allelic variants. In addition, CKD patients are also characterized by high levels of genomic damage. Nevertheless, no studies have established relationships between DNA damage, or genomic instability present in CKD patients, and gene polymorphisms. To fill in this gap, the potential role of polymorphisms in genes involved in base excision repair (OGG1, rs1052133; MUTYH, rs3219489; XRCC1, rs25487), nucleotide excision repair (ERCC2/XPD,