Gene Summary

Gene:DDB2; damage specific DNA binding protein 2
Aliases: XPE, DDBB, UV-DDB2
Summary:This gene encodes a protein that is necessary for the repair of ultraviolet light-damaged DNA. This protein is the smaller subunit of a heterodimeric protein complex that participates in nucleotide excision repair, and this complex mediates the ubiquitylation of histones H3 and H4, which facilitates the cellular response to DNA damage. This subunit appears to be required for DNA binding. Mutations in this gene cause xeroderma pigmentosum complementation group E, a recessive disease that is characterized by an increased sensitivity to UV light and a high predisposition for skin cancer development, in some cases accompanied by neurological abnormalities. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2014]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:DNA damage-binding protein 2
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (13)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • DNA
  • Risk Factors
  • Transcriptional Activation
  • Breast Cancer
  • Melanoma
  • Oligonucleotide Array Sequence Analysis
  • Chromosome 11
  • Smoking
  • Fibroblasts
  • HeLa Cells
  • Cullin Proteins
  • Lung Cancer
  • Xeroderma Pigmentosum Group D Protein
  • Melanocytes
  • Single Nucleotide Polymorphism
  • Biomarkers, Tumor
  • Messenger RNA
  • Pyrimidine Dimers
  • Stomach Cancer
  • Genotype
  • DNA-Binding Proteins
  • Molecular Sequence Data
  • Base Sequence
  • Transcription
  • Signal Transduction
  • Ultraviolet Rays
  • Gene Expression Profiling
  • Genetic Predisposition
  • CDKN1A
  • Histones
  • Cancer Gene Expression Regulation
  • Cell Proliferation
  • Sulfides
  • DNA Damage
  • Apoptosis
  • Mutation
  • Protein Binding
  • DNA Repair
  • Skin Cancer
  • Cell Cycle
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: DDB2 (cancer-related)

Borchert S, Wessolly M, Schmeller J, et al.
Gene expression profiling of homologous recombination repair pathway indicates susceptibility for olaparib treatment in malignant pleural mesothelioma in vitro.
BMC Cancer. 2019; 19(1):108 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Malignant pleural mesothelioma (MPM) is a tumour arising from pleural cavities with poor prognosis. Multimodality treatment with pemetrexed combined with cisplatin shows unsatisfying response-rates of 40%. The reasons for the rather poor efficacy of chemotherapeutic treatment are largely unknown. However, it is conceivable that DNA repair mechanisms lead to an impaired therapy response. We hypothesize a major role of homologous recombination (HR) for genome stability and survival of this tumour. Therefore, we analysed genes compiled under the term "BRCAness". An inhibition of this pathway with olaparib might abrogate this effect and induce apoptosis.
METHODS: We investigated the response of three MPM cell lines and lung fibroblasts serving as a control to treatment with pemetrexed, cisplatin and olaparib. Furthermore, we aimed to find possible correlations between response and gene expression patterns associated with BRCAness phenotype. Therefore, 91 clinical MPM samples were digitally screened for gene expression patterns of HR members.
RESULTS: A BRCAness-dependent increase of apoptosis and senescence during olaparib-based treatment of BRCA-associated-protein 1 (BAP1)-mutated cell lines was observed. The gene expression pattern identified could be found in approx. 10% of patient samples. Against this background, patients could be grouped according to their defects in the HR system. Gene expression levels of Aurora Kinase A (AURKA), RAD50 as well as DNA damage-binding protein 2 (DDB2) could be identified as prognostic markers in MPM.
CONCLUSIONS: Defects in HR compiled under the term BRCAness are a common event in MPM. The present data can lead to a better understanding of the underlaying cellular mechanisms and leave the door wide open for new therapeutic approaches for this severe disease with infaust prognosis. Response to Poly (ADP-ribose)-Polymerase (PARP)-Inhibition could be demonstrated in the BAP1-mutated NCI-H2452 cells, especially when combined with cisplatin. Thus, this combination therapy might be effective for up to 2/3 of patients, promising to enhance patients' clinical management and outcome.

Ramos J, Das J, Felty Q, et al.
NRF1 motif sequence-enriched genes involved in ER/PR -ve HER2 +ve breast cancer signaling pathways.
Breast Cancer Res Treat. 2018; 172(2):469-485 [PubMed] Related Publications
Nuclear respiratory factor 1 (NRF1) transcription factor has recently been shown to control breast cancer progression. However, mechanistic aspects by which NRF1 may contribute to susceptibility to different breast tumor subtypes are still not fully understood. Since transcriptional control of NRF1 seems to be dependent on epidermal growth factor receptor signaling, herein, we investigated the role of NRF1 in estrogen receptor/progesterone receptor negative, but human epidermal growth factor receptor 2-positive (ER/PR -ve HER2 +ve) breast cancer. We found that both mRNA and protein levels of NRF1 and its transcriptional activity were significantly higher in ER/PR -ve HER2 +ve breast cancer samples compared to normal breast tissues. This was consistent with our observation of higher NRF1 protein expression in the experimental model of HER2+ breast cancer brain metastasis. To identify network-based pathways involved in the susceptibility to the ER/PR -ve HER2 +ve breast cancer subtype, the NRF1 transcriptional regulatory genome-wide landscape was analyzed using the approach consisting of a systematic integration of ChIP DNA-seq, RNA-Microarray, NRF1 protein-DNA motif binding, signal pathway analysis, and Bayesian machine learning. Our findings show that a high percentage of known HER2+ breast cancer susceptibility genes, including EGFR, IGFR, and E2F1, are under transcriptional control of NRF1. Promoters of several genes from the KEGG HER2+ breast cancer pathway and 11 signaling pathways linked to 6 hallmarks of cancer contain the NRF1 motif. By pathway analysis, key breast cancer hallmark genes of epithelial-mesenchymal transition, stemness, cell apoptosis, cell cycle regulation, chromosomal integrity, and DNA damage/repair were highly enriched with NRF1 motifs. In addition, we found using Bayesian network-based machine learning that 30 NRF1 motif-enriched genes including growth factor receptors-FGFR1, IGF1R; E2Fs transcription factor family-E2F1, E2F3; MAPK pathway-SHC2, GRB2, MAPK1; PI3K-AKT-mTOR signaling pathway-PIK3CD, PIK3R1, PIK3R3, RPS6KB2; WNT signaling pathway-WNT7B, DLV1, DLV2, GSK3B, NRF1, and DDB2, known for its role in DNA repair and involvement in early events associated with metastatic progression of breast cancer cells, were associated with HER2-amplified breast cancer. Machine learning search further revealed that the likelihood of HER2-positive breast cancer is almost 100% in a patient with the high NRF1 expression combined with expression patterns of high E2F3, GSK3B, and MAPK1, low or no change in E2F1 and FGFR1, and high or no change in PIK3R3. In summary, our findings suggest novel roles of NRF1 and its regulatory networks in susceptibility to the ER/PR -ve HER2 +ve aggressive breast cancer subtype. Clinical confirmation of our machine learned Bayesian networks will have significant impact on our understanding of the role of NRF1 as a valuable biomarker for breast cancer diagnosis and prognosis as well as provide strong rationale for future studies to develop NRF1 signaling-based therapeutics to target HER2+ breast cancer.

Keam SP, Gulati T, Gamell C, et al.
Biodosimetric transcriptional and proteomic changes are conserved in irradiated human tissue.
Radiat Environ Biophys. 2018; 57(3):241-249 [PubMed] Related Publications
Transcriptional dosimetry is an emergent field of radiobiology aimed at developing robust methods for detecting and quantifying absorbed doses using radiation-induced fluctuations in gene expression. A combination of RNA sequencing, array-based and quantitative PCR transcriptomics in cellular, murine and various ex vivo human models has led to a comprehensive description of a fundamental set of genes with demonstrable dosimetric qualities. However, these are yet to be validated in human tissue due to the scarcity of in situ-irradiated source material. This represents a major hurdle to the continued development of transcriptional dosimetry. In this study, we present a novel evaluation of a previously reported set of dosimetric genes in human tissue exposed to a large therapeutic dose of radiation. To do this, we evaluated the quantitative changes of a set of dosimetric transcripts consisting of FDXR, BAX, BCL2, CDKN1A, DDB2, BBC3, GADD45A, GDF15, MDM2, SERPINE1, TNFRSF10B, PLK3, SESN2 and VWCE in guided pre- and post-radiation (2 weeks) prostate cancer biopsies from seven patients. We confirmed the prolonged dose-responsivity of most of these transcripts in in situ-irradiated tissue. BCL2, GDF15, and to some extent TNFRSF10B, were markedly unreliable single markers of radiation exposure. Nevertheless, as a full set, these genes reliably segregated non-irradiated and irradiated tissues and predicted radiation absorption on a patient-specific basis. We also confirmed changes in the translated protein product for a small subset of these dosimeters. This study provides the first confirmatory evidence of an existing dosimetric gene set in less-accessible tissues-ensuring peripheral responses reflect tissue-specific effects. Further work will be required to determine if these changes are conserved in different tissue types, post-radiation times and doses.

Liu J, Li H, Sun L, et al.
The Differential Expression of Core Genes in Nucleotide Excision Repair Pathway Indicates Colorectal Carcinogenesis and Prognosis.
Biomed Res Int. 2018; 2018:9651320 [PubMed] Free Access to Full Article Related Publications
Background: Nucleotide excision repair (NER) plays a critical role in maintaining genome integrity. This study aimed to investigate the expression of NER genes and their associations with colorectal cancer (CRC) development.
Method: Expressions of NER genes in CRC and normal tissues were analysed by ONCOMINE. The Cancer Genome Atlas (TCGA) data were downloaded to explore relationship of NER expression with clinicopathological parameters and survival of CRC.
Results: ERCC1, ERCC2, ERCC5, and DDB2 were upregulated while ERCC4 was downregulated in CRC. For colon cancer, high ERCC3 expression was related to better T stage; ERCC5 expression indicated deeper T stage and distant metastasis; DDB2 expression suggested earlier TNM stage. For rectal cancer, ERCC2 expression correlated with favourable T stage; XPA expression predicted worse TNM stage. ERCC2 expression was associated with worse overall survival (OS) in colon cancer (HR = 1.53,
Conclusion: ERCC1, ERCC2, ERCC4, ERCC5, and DDB2 were differently expressed in CRC and normal tissues; ERCC2, ERCC3, ERCC5, XPA, and DDB2 correlated with clinicopathological parameters of CRC, while ERCC2, ERCC4, and XPC might predict CRC prognosis.

Huang S, Fantini D, Merrill BJ, et al.
DDB2 Is a Novel Regulator of Wnt Signaling in Colon Cancer.
Cancer Res. 2017; 77(23):6562-6575 [PubMed] Free Access to Full Article Related Publications
Deregulation of the Wnt/β-catenin signaling pathway drives the development of colorectal cancer, but understanding of this pathway remains incomplete. Here, we report that the damage-specific DNA-binding protein DDB2 is critical for β-catenin-mediated activation of RNF43, which restricts Wnt signaling by removing Wnt receptors from the cell surface. Reduced expression of DDB2 and RNF43 was observed in human hyperplastic colonic foci. DDB2 recruited EZH2 and β-catenin at an upstream site in the

Lacombe J, Brooks C, Hu C, et al.
Analysis of Saliva Gene Expression during Head and Neck Cancer Radiotherapy: A Pilot Study.
Radiat Res. 2017; 188(1):75-81 [PubMed] Free Access to Full Article Related Publications
Saliva, a biological fluid, is a promising candidate for novel approaches to prognosis, clinical diagnosis, monitoring and management of patients with both oral and systemic diseases. However, to date, saliva has not been widely investigated as a biomarker for radiation exposure. Since white blood cells are also present in saliva, it should theoretically be possible to investigate the transcriptional biomarkers of radiation exposure classically studied in whole blood. Therefore, we collected whole blood and saliva samples from eight head and neck cancer patients before the start of radiation treatment, at mid-treatment and after treatment. We then used a panel of five genes: BAX, BBC3, CDKN1A, DDB2 and MDM2, designated for assessing radiation dose in whole blood to evaluate gene expression changes that can occur during radiotherapy. The results revealed that the expression of the five genes did not change in whole blood. However, in saliva, CDKN1A and DDB2 were significantly overexpressed at the end, compared to the start, of radiotherapy, and MDM2 was significantly underexpressed between mid-treatment and at the end of treatment. Interestingly, CDKN1A and DDB2 expressions also showed an increasing monotonic relationship with total radiation dose received during radiotherapy. To our knowledge, these results show for the first time the ability to detect gene expression changes in saliva after head and neck cancer radiotherapy, and pave the way for further promising studies validating saliva as a minimally invasive means of biofluid collection to directly measure radiation dose escalation during treatment.

de Sousa JF, Torrieri R, Serafim RB, et al.
Expression signatures of DNA repair genes correlate with survival prognosis of astrocytoma patients.
Tumour Biol. 2017; 39(4):1010428317694552 [PubMed] Related Publications
Astrocytomas are the most common primary brain tumors. They are very resistant to therapies and usually progress rapidly to high-grade lesions. Here, we investigated the potential role of DNA repair genes in astrocytoma progression and resistance. To this aim, we performed a polymerase chain reaction array-based analysis focused on DNA repair genes and searched for correlations between expression patters and survival prognoses. We found 19 genes significantly altered. Combining these genes in all possible arrangements, we found 421 expression signatures strongly associated with poor survival. Importantly, five genes (DDB2, EXO1, NEIL3, BRCA2, and BRIP1) were independently correlated with worse prognoses, revealing single-gene signatures. Moreover, silencing of EXO1, which is remarkably overexpressed, promoted faster restoration of double-strand breaks, while NEIL3 knockdown, also highly overexpressed, caused an increment in DNA damage and cell death after irradiation of glioblastoma cells. These results disclose the importance of DNA repair pathways for the maintenance of genomic stability of high-grade astrocytomas and suggest that EXO1 and NEIL3 overexpression confers more efficiency for double-strand break repair and resistance to reactive oxygen species, respectively. Thereby, we highlight these two genes as potentially related with tumor aggressiveness and promising candidates as novel therapeutic targets.

Blasiak J
DNA-Damaging Anticancer Drugs - A Perspective for DNA Repair- Oriented Therapy.
Curr Med Chem. 2017; 24(15):1488-1503 [PubMed] Related Publications
DNA-damaging drugs in cancer present two main problems: therapeutic resistance and side effects and both can associate with DNA repair, which can be targeted in cancer therapy. Bleomycin (BLM) induces complex DNA damages, including strand breaks, base loss and 3'-phosphoglycolate (3'PG) residues repaired by several pathways, but 3'PGs must be processed to the 3'-OH ends, usually by tyrosyl-DNA phosphodiesterase 1 (Tdp1). Therefore, targeting Tdp1 can improve anticancer therapy with BLM. Mitomycin C (MMC) produces a variety of adducts with DNA, including inter-strand cross-links (ICLs) and Xeroderma pigmentosum (XP) proteins, including XPG, XPE and XPF can be crucial for the initial stage of ICL repair, so they can be targeted by inhibitors to increase toxicity of MMC in cancer cells. Although these proteins are essential for nucleotide excision repair (NER), their decreased activity may not be fatal in normal cells as almost all NER substrates can be repaired by other pathways. Four-stranded DNA, resulted mainly from guanine quadruplexes (G-4s), are highly overexpressed at the end of telomeres, where they can inhibit telomerase, hence stabilization G-4s at the telomeres ends can hamper proliferation of cancer cells. Quadruplexes are also found in the promoters of genes important for cancer and are resolved by DNA helicases, which can be targeted in cancer along with stabilization of quadruplexes. As cancer cells often have defects in DNA repair pathway(s), they can be subjected by synthetic lethality, with the most promising results with poly(ADP-ribose) polymerase 1 (PARP-1) and DNA-dependent protein kinase, catalytic subunit (DNA-PKCS).

Yeomans A, Lemm E, Wilmore S, et al.
PEITC-mediated inhibition of mRNA translation is associated with both inhibition of mTORC1 and increased eIF2α phosphorylation in established cell lines and primary human leukemia cells.
Oncotarget. 2016; 7(46):74807-74819 [PubMed] Free Access to Full Article Related Publications
Increased mRNA translation drives carcinogenesis and is an attractive target for the development of new anti-cancer drugs. In this work, we investigated effects of phenethylisothiocyanate (PEITC), a phytochemical with chemopreventive and anti-cancer activity, on mRNA translation. PEITC rapidly inhibited global mRNA translation in human breast cancer-derived MCF7 cells and mouse embryonic fibroblasts (MEFs). In addition to the known inhibitory effects of PEITC on mTORC1 activity, we demonstrate that PEITC increased eIF2α phosphorylation. PEITC also increased formation of stress granules which are typically associated with eIF2α phosphorylation and accumulation of translationally stalled mRNAs. Analysis of genetically modified MEFs demonstrated that optimal inhibition of global mRNA translation by PEITC was dependent on eIF2α phosphorylation, but not mTORC1 inhibition. We extended this study into primary leukemic B cells derived from patients with chronic lymphocytic leukaemia (CLL). CLL cells were stimulated in vitro with anti-IgM to mimic binding of antigen, a major driver of this leukemia. In CLL cells, PEITC increased eIF2α phosphorylation, inhibited anti-IgM-induced mTORC1 activation and decreased both basal and anti-IgM-induced global mRNA translation. PEITC also inhibited transcription and translation of MYC mRNA and accumulation of the MYC oncoprotein, in anti-IgM-stimulated cells. Moreover, treatment of CLL cells with PEITC and the BTK kinase inhibitor ibrutinib decreased anti-IgM-induced translation and induced cell death to a greater extent than either agent alone. Therefore, PEITC can inhibit both global and mRNA specific translation (including MYC) via effects on multiple regulatory pathways. Inhibition of mRNA translation may contribute to the chemopreventive and anti-cancer effects of PEITC.

Edmondson DA, Karski EE, Kohlgruber A, et al.
Transcript Analysis for Internal Biodosimetry Using Peripheral Blood from Neuroblastoma Patients Treated with (131)I-mIBG, a Targeted Radionuclide.
Radiat Res. 2016; 186(3):235-44 [PubMed] Free Access to Full Article Related Publications
Calculating internal dose from therapeutic radionuclides currently relies on estimates made from multiple radiation exposure measurements, converted to absorbed dose in specific organs using the Medical Internal Radiation Dose (MIRD) schema. As an alternative biodosimetric approach, we utilized gene expression analysis of whole blood from patients receiving targeted radiotherapy. Collected blood from patients with relapsed or refractory neuroblastoma who received (131)I-labeled metaiodobenzylguanidine ((131)I-mIBG) at the University of California San Francisco (UCSF) was used to compare calculated internal dose with the modulation of chosen gene expression. A total of 40 patients, median age 9 years, had blood drawn at baseline, 72 and 96 h after (131)I-mIBG infusion. Whole-body absorbed dose was calculated for each patient based on the cumulated activity determined from injected mIBG activity and patient-specific time-activity curves combined with (131)I whole-body S factors. We then assessed transcripts that were the most significant for describing the mixed therapeutic treatments over time using real-time polymerase chain reaction (RT-PCR). Modulation was evaluated statistically using multiple regression analysis for data at 0, 72 and 96 h. A total of 10 genes were analyzed across 40 patients: CDKN1A; FDXR; GADD45A; BCLXL; STAT5B; BAX; BCL2; DDB2; XPC; and MDM2. Six genes were significantly modulated upon exposure to (131)I-mIBG at 72 h, as well as at 96 h. Four genes varied significantly with absorbed dose when controlling for time. A gene expression biodosimetry model was developed to predict absorbed dose based on modulation of gene transcripts within whole blood. Three transcripts explained over 98% of the variance in the modulation of gene expression over the 96 h (CDKN1A, BAX and DDB2). To our knowledge, this is a novel study, which uses whole blood collected from patients treated with a radiopharmaceutical, to characterize biomarkers that may be useful for biodosimetry. Our data indicate that transcripts, which have been previously identified as biomarkers of external exposures in ex vivo whole blood and in vivo radiotherapy patients, are also good early indicators of internal exposure. However, for internal sources of radiation, the biokinetics and physical decay of the radionuclide strongly influence the gene expression.

Dong TK, Ona K, Scandurra AE, et al.
Deficient Nucleotide Excision Repair in Squamous Cell Carcinoma Cells.
Photochem Photobiol. 2016; 92(5):760-6 [PubMed] Related Publications
Squamous cell carcinomas (SCCs) are associated with ultraviolet radiation and multiple genetic changes, but the mechanisms leading to genetic instability are unclear. SCC cell lines were compared to normal keratinocytes for sensitivity to ultraviolet radiation, DNA repair kinetics and DNA repair protein expression. Relative to normal keratinocytes, four SCC cell lines were all variably sensitive to ultraviolet radiation and, except for the SCC25 cell line, were deficient in global repair of cyclobutane pyrimidine dimers, although not 6-4 photoproducts. Impaired DNA repair of cyclobutane pyrimidine dimers was associated with reduced mRNA expression from XPC but not DDB2 genes which each encode key DNA damage recognition proteins. However, levels of XPC or DDB2 proteins or both were variably reduced in repair-deficient SCC cell lines. p53 levels did not correlate with DNA repair activity or with XPC and DDB2 levels, but p63 levels were deficient in cell lines with reduced global repair. Repair-proficient SCC25 cells depleted of p63 lost XPC expression, early global DNA repair activity and UV resistance. These results demonstrate that some SCC cell lines are deficient in global nucleotide excision repair and support a role for p63 as a regulator of nucleotide excision repair in SCCs.

Budden T, Davey RJ, Vilain RE, et al.
Repair of UVB-induced DNA damage is reduced in melanoma due to low XPC and global genome repair.
Oncotarget. 2016; 7(38):60940-60953 [PubMed] Free Access to Full Article Related Publications
UVB exposure leads to DNA damage, which when unrepaired induces C>T transitions. These mutations are found throughout the melanoma genome, particularly in non-transcribed regions. The global genome repair (GGR) branch of nucleotide excision repair (NER) is responsible for repairing UV-induced DNA damage across non-transcribed and silent regions of the genome. This study aimed to examine the relationship between UVB and GGR in melanoma. DNA repair capacity and relative expression of NER in melanocytes and melanoma cell lines before and after treatment with UVB was quantified. Transcript expression from 196 melanomas was compared to clinical parameters including solar elastosis and whole transcriptome data collected. Melanoma cell lines showed significantly reduced DNA repair when compared to melanocytes, most significantly in the S phase of the cell cycle. Expression of GGR components XPC, DDB1 and DDB2 was significantly lower in melanoma after UVB. In the melanoma tumours, XPC expression correlated with age of diagnosis and low XPC conferred significantly poorer survival. The same trend was seen in the TCGA melanoma dataset. Reduced GGR in melanoma may contribute to the UV mutation spectrum of the melanoma genome and adds further to the growing evidence of the link between UV, NER and melanoma.

Liu J, Deng N, Xu Q, et al.
Polymorphisms of multiple genes involved in NER pathway predict prognosis of gastric cancer.
Oncotarget. 2016; 7(30):48130-48142 [PubMed] Free Access to Full Article Related Publications
Nucleotide excision repair (NER) is a versatile system that repairs various DNA damage. Polymorphisms of core NER genes could change NER ability and affect gastric cancer (GC) prognosis. We systematically analyzed the association between 43 SNPs of ten key NER pathway genes (ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, ERCC6, ERCC8, XPA, XPC, and DDB2) and overall survival (OS) of 373 GC patients in Chinese. Genotyping was performed by Sequenom MassARRAY platform. We found for the first time that carriers of ERCC2 rs50871 GG genotype demonstrated significantly increased hazards of death than GT/TT individuals (HR=2.55, P=0.002); ERCC6 rs1917799 heterozygote GT were associated with significantly shorter OS than wild-type TT (adjusted HR=1.68, P=0.048); patients with DDB2 rs3781619 GG genotype suffered higher hazards of death compared with AG/AA carriers (adjusted HR=2.30, P=0.003). Patients with ERCC1 rs3212961 AA/AC genotype exhibited longer OS than CC genotype (adjusted HR=0.63, P=0.028); ERCC5 rs2094258 AA/AG genotype revealed significantly favorable OS compared with GG genotype (adjusted HR=0.65, P=0.033); DDB2 rs830083 CG genotype could increase OS compared with GG genotype (adjusted HR=0.61, P=0.042). Furthermore, patients simultaneously carrying two "hazard" genotypes exhibited even significantly worse survival with HR of 3.75, 3.76 and 6.30, respectively. Similarly, combination of "favorable" genotypes predicted better prognosis with HR of 0.56, 0.49 and 0.33, respectively. In conclusion, ERCC2 rs50871 G/T, ERCC6 rs1917799 G/T, DDB2 rs3781619 A/G polymorphisms could predict shorter OS while ERCC1 rs3212961 A/C, ERCC5 rs2094258 A/G, DDB2 rs830083 C/G polymorphisms could predict longer OS of GC, which might serve as promising biomarkers for GC prognosis.

Yang Y, He S, Wang Q, et al.
Autophagic UVRAG Promotes UV-Induced Photolesion Repair by Activation of the CRL4(DDB2) E3 Ligase.
Mol Cell. 2016; 62(4):507-19 [PubMed] Free Access to Full Article Related Publications
UV-induced DNA damage, a major risk factor for skin cancers, is primarily repaired by nucleotide excision repair (NER). UV radiation resistance-associated gene (UVRAG) is a tumor suppressor involved in autophagy. It was initially isolated as a cDNA partially complementing UV sensitivity in xeroderma pigmentosum (XP), but this was not explored further. Here we show that UVRAG plays an integral role in UV-induced DNA damage repair. It localizes to photolesions and associates with DDB1 to promote the assembly and activity of the DDB2-DDB1-Cul4A-Roc1 (CRL4(DDB2)) ubiquitin ligase complex, leading to efficient XPC recruitment and global genomic NER. UVRAG depletion decreased substrate handover to XPC and conferred UV-damage hypersensitivity. We confirmed the importance of UVRAG for UV-damage tolerance using a Drosophila model. Furthermore, increased UV-signature mutations in melanoma correlate with reduced expression of UVRAG. Our results identify UVRAG as a regulator of CRL4(DDB2)-mediated NER and suggest that its expression levels may influence melanoma predisposition.

Yamashita T, Okura M, Ishii-Osai Y, Hida T
Diagnosis of eight groups of xeroderma pigmentosum by genetic complementation using recombinant adenovirus vectors.
J Dermatol. 2016; 43(10):1167-1173 [PubMed] Related Publications
Because patients with xeroderma pigmentosum (XP) must avoid ultraviolet (UV) light from an early age, an early diagnosis of this disorder is essential. XP is composed of seven genetic complementation groups, XP-A to -G, and a variant type (XP-V). To establish an easy and accurate diagnosis of the eight disease groups, we constructed recombinant adenoviruses that expressed one of the XP cDNA. When fibroblasts derived from patients with XP-A, -B, -C, -D, -F or -G were infected with the adenovirus expressing XPA, XPB, XPC, XPD, XPF or XPG, respectively, and UV-C at 5-20 J/m

Wang B, Xu Q, Yang HW, et al.
The association of six polymorphisms of five genes involved in three steps of nucleotide excision repair pathways with hepatocellular cancer risk.
Oncotarget. 2016; 7(15):20357-67 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Hundreds of single nucleotide polymorphisms (SNPs) of the genes encoding nucleotide excision repair (NER) proteins are involved in every step of the DNA recognition-unwinding-incision process, which may affect cancer risk. However, only a limited number of studies have examined the association of NER SNPs with hepatocellular cancer (HCC) risk.
RESULTS: In screening stage, single-locus analysis showed that six SNPs in five genes were associated with HCC risk, including three risk SNPs (XPA rs10817938, XPC rs1870134 and ERCC2 rs238417) and three protective SNPs (ERCC1 rs2298881 and rs3212961, and ERCC5 rs873601). In verification stage, only XPC rs1870134 was verified to be associated with HCC risk (P = 4.7 × 10-4). Furthermore, multivariate logistic regression and MDR analysis consistently revealed a gene-gene interaction among ERCC1 rs2298881 and XPC rs1870134 SNPs associated with HCC risk (Pinteraction = 0.023). When analyzing the effect of the positive SNP on the mRNA expression, we found XPC rs1870134 GG genotype which was associated with an increased HCC risk showed lower XPC mRNA expression.
METHODS: This study designed as "screening-verification" experiments and included a total of 1472 participants (570 HCC patients vs. 902 controls). We explored 39 SNPs in eight genes involved in NER Pathways, including XPA, XPC, DDB2, ERCC3, ERCC2, ERCC1, ERCC4 and ERCC5, using Sequenom MassARRAY and KASPar platform. Eighty-six cases of HCC and the neighboring noncancerous tissues were subjected to the measurement of mRNA expression level of the promising gene.
CONCLUSIONS: XPC promoter rs1870134 SNP and SNP-SNP interaction were associated with HCC risk.

Barbieux C, Bacharouche J, Soussen C, et al.
DDB2 (damaged-DNA binding 2) protein: a new modulator of nanomechanical properties and cell adhesion of breast cancer cells.
Nanoscale. 2016; 8(9):5268-79 [PubMed] Related Publications
DDB2, known for its role in DNA repair, was recently shown to reduce mammary tumor invasiveness by inducing the transcription of IκBα, an inhibitor of NF-κB activity. Since cellular adhesion is a key event during the epithelial to mesenchymal transition (EMT) leading to the invasive capacities of breast tumor cells, the aim of this study was to investigate the role of DDB2 in this process. Thus, using low and high DDB2-expressing MDA-MB231 and MCF7 cells, respectively, in which DDB2 expression was modulated experimentally, we showed that DDB2 overexpression was associated with a decrease of adhesion abilities on glass and plastic areas of breast cancer cells. Then, we investigated cell nanomechanical properties by atomic force microscopy (AFM). Our results revealed significant changes in the Young's Modulus value and the adhesion force in MDA-MB231 and MCF7 cells, whether DDB2 was expressed or not. The cell stiffness decrease observed in MDA-MB231 and MCF7 expressing DDB2 was correlated with a loss of the cortical actin-cytoskeleton staining. To understand how DDB2 regulates these processes, an adhesion-related gene PCR-Array was performed. Several adhesion-related genes were differentially expressed according to DDB2 expression, indicating that important changes are occurring at the molecular level. Thus, this work demonstrates that AFM technology is an important tool to follow cellular changes during tumorigenesis. Moreover, our data revealed that DDB2 is involved in early events occurring during metastatic progression of breast cancer cells and will contribute to define this protein as a new marker of metastatic progression in this type of cancer.

Liu J, Sun L, Xu Q, et al.
Association of nucleotide excision repair pathway gene polymorphisms with gastric cancer and atrophic gastritis risks.
Oncotarget. 2016; 7(6):6972-83 [PubMed] Free Access to Full Article Related Publications
Polymorphisms of NER genes could change NER ability, thereby altering individual susceptibility to GC. We systematically analyzed 39 SNPs of 8 key genes of NER pathway in 2686 subjects including 898 gastric cancer (GC), 851 atrophic gastritis (AG) and 937 controls (CON) in northern Chinese. SNP genotyping were performed using Sequenom MassARRAY platform. The results demonstrated that DDB2 rs830083 GG genotype was significantly associated with increased GC risk compared with wild-type CC (OR=2.32, P= 6.62 × 10-9); XPC rs2607775 CG genotype conferred a 1.73 increased odds of GC risk than non-cancer subjects compared with wild-type CC (OR=1.73, P= 3.04 × 10-4). The combined detection of these two polymorphisms demonstrated even higher GC risk (OR=3.05). Haplotype analysis suggested that DDB2 rs2029298-rs326222-rs3781619-rs830083 GTAG haplotype was significantly associated with disease risk in each step of CON→AG→GC development (AG vs. CON: OR=2.88, P= 7.51 × 10-7; GC vs. AG: OR=2.90, P=5.68 × 10-15; GC vs. CON: OR=8.42, P=2.22 × 10-15); DDB2 GTAC haplotype was associated with reduced risk of GC compared with CON (OR=0.63, P= 8.31 × 10-12). XPC rs1870134-rs2228000-rs2228001-rs2470352-rs2607775 GCAAG haplotype conferred increased risk of GC compared with AG (OR=1.88, P= 6.98 × 10-4). XPA rs2808668 and drinking, DDB2 rs326222, rs3781619, rs830083 and smoking demonstrated significant interactions in AG; XPC rs2607775 had significant interaction with smoking in GC. In conclusion, NER pathway polymorphisms especially in "damage incision" step were significantly associated with GC risk and had interactions with environment factors. The detection of NER pathway polymorphisms such as DDB2 and XPC might be applied in the prediction of GC risk and personalized prevention in the future. NER pathway polymorphisms especially in "damage incision" step were significantly associated with GC risk and had interactions with environment factors, which might be applied in the prediction of GC risk and personalized prevention in the future.

Yao S, Haddad SA, Hu Q, et al.
Genetic variations in vitamin D-related pathways and breast cancer risk in African American women in the AMBER consortium.
Int J Cancer. 2016; 138(9):2118-26 [PubMed] Free Access to Full Article Related Publications
Studies of genetic variations in vitamin D-related pathways and breast cancer risk have been conducted mostly in populations of European ancestry, and only sparsely in African Americans (AA), who are known for a high prevalence of vitamin D deficiency. We analyzed 24,445 germline variants in 63 genes from vitamin D-related pathways in the African American Breast Cancer Epidemiology and Risk (AMBER) consortium, including 3,663 breast cancer cases and 4,687 controls. Odds ratios (OR) were derived from logistic regression models for overall breast cancer, by estrogen receptor (ER) status (1,983 ER positive and 1,098 ER negative), and for case-only analyses of ER status. None of the three vitamin D-related pathways were associated with breast cancer risk overall or by ER status. Gene-level analyses identified associations with risk for several genes at a nominal p ≤ 0.05, particularly for ER- breast cancer, including rs4647707 in DDB2. In case-only analyses, vitamin D metabolism and signaling pathways were associated with ER- cancer (pathway-level p = 0.02), driven by a single gene CASR (gene-level p = 0.001). The top SNP in CASR was rs112594756 (p = 7 × 10(-5), gene-wide corrected p = 0.01), followed by a second signal from a nearby SNP rs6799828 (p = 1 × 10(-4), corrected p = 0.03). In summary, several variants in vitamin D pathways were associated with breast cancer risk in AA women. In addition, CASR may be related to tumor ER status, supporting a role of vitamin D or calcium in modifying breast cancer phenotypes.

Zhao F, Shang Y, Zeng C, et al.
Association of single nucleotide polymorphisms of DNA repair genes in NER pathway and susceptibility to pancreatic cancer.
Int J Clin Exp Pathol. 2015; 8(9):11579-86 [PubMed] Free Access to Full Article Related Publications
In our study, we conducted a case-control study to investigate the association of ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, XPA, XPC and DDB2 gene polymorphisms in the risk of pancreatic cancer. Between May 2012 and May 2014, a total of 246 patients with who were newly diagnosed with histopathologically confirmed primary pancreatic cancer and 246 controls were selected into our study. Genotyping of ERCC1 rs3212986 and rs11615, ERCC2 rs13181, ERCC3 rs4150441, ERCC4 rs6498486, ERCC5 rs873601, XPA rs2808668, XPC rs2228000, XPC rs2228001 and DDB2 rs2029298 were analyzed using polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). By conditional logistic regression analysis, individuals carrying with TT genotype of ERCC1 rs3212986 and GG genotype of ERCC2 rs13181 were associated with increased risk of pancreatic cancer when compared with wide-type genotype, and the adjusted ORs (95% CI) were 2.40 (1.29-4.52) and 2.27 (1.26-4.15), respectively. We found that individuals carrying with GT+TT genotype of ERCC1 rs3212986 and TG+GG genotype of ERCC2 rs1318 gene polymorphisms were correlated with higher risk of pancreatic cancer in smokers when compared with non-smokers, and the adjusted ORs (95% CI) were 1.89 (1.05-3.40) and 1.88 (1.06-3.34), respectively. In conclusion, our study suggests that ERCC1 rs3212986 and ERCC2 rs1318 gene polymorphisms contribute to the development of pancreatic cancer, especially in smokers.

Xie X, Wang M, Mei J, et al.
Pyruvate kinase M2 interacts with DNA damage-binding protein 2 and reduces cell survival upon UV irradiation.
Biochem Biophys Res Commun. 2015; 467(2):427-33 [PubMed] Related Publications
Pyruvate Kinase M2 (PKM2) is highly expressed in many solid tumors and associated with metabolism reprogramming and proliferation of tumors. Here, we report that PKM2 can bind to DNA Damage-Binding Protein 2 (DDB2), which is necessary for global nucleotide excision repair of UV induced DNA damage. The binding is promoted by UV irradiation and K433 acetylation of PKM2. Over expression of PKM2 facilitates phosphorylation of DDB2 and impairs DDB2-DDB1 binding. Furthermore, knocking down of PKM2 increases cell survival upon UV irradiation, while over expression of PKM2 reduces cell survival and over expression of DDB2-DDB1 reverts this effect. These results reveal a previously unknown regulation of PKM2 on DDB2 and provide a possible mechanism for UV induced tumorigenesis.

Qiao S, Guo W, Liao L, et al.
DDB2 is involved in ubiquitination and degradation of PAQR3 and regulates tumorigenesis of gastric cancer cells.
Biochem J. 2015; 469(3):469-80 [PubMed] Related Publications
DDB2 (damage-specific DNA-binding protein 2) is the product of the xeroderma pigmentosum group E gene which is involved in the initiation of nucleotide excision repair via an ubiquitin ligase complex together with DDB1 and CUL4A (cullin 4A). PAQR3 (progestin and adipoQ receptor family member III) is a newly discovered tumour suppressor that is implicated in the development of many types of human cancers. In the present paper, we report that DDB2 is involved in ubiquitination and degradation of PAQR3. DDB2 is able to interact with PAQR3 in vivo and in vitro. Both overexpression and knockdown experiments reveal that the protein expression level, protein stability and polyubiquitination of PAQR3 are changed by DDB2. Negative regulation of EGF (epidermal growth factor)- and insulin-induced signalling by PAQR3 is also altered by DDB2. At the molecular level, Lys(61) of PAQR3 is targeted by DDB2 for ubiquitination. The cell proliferation rate and migration of gastric cancer cells are inhibited by DDB2 knockdown and such effects are abrogated by PAQR3 knockdown, indicating that the effect of DDB2 on the cancer cells is mediated by PAQR3. Collectively, our studies not only pinpoint that DDB2 is a post-translational regulator of PAQR3, but also indicate that DDB2 may play an active role in tumorigenesis via regulating PAQR3.

Zhao R, Cui T, Han C, et al.
DDB2 modulates TGF-β signal transduction in human ovarian cancer cells by downregulating NEDD4L.
Nucleic Acids Res. 2015; 43(16):7838-49 [PubMed] Free Access to Full Article Related Publications
The expression of DNA damage-binding protein 2 (DDB2) has been linked to the prognosis of ovarian cancer and its underlying transcription regulatory function was proposed to contribute to the favorable treatment outcome. By applying gene microarray analysis, we discovered neural precursor cell expressed, developmentally downregulated 4-Like (NEDD4L) as a previously unidentified downstream gene regulated by DDB2. Mechanistic investigation demonstrated that DDB2 can bind to the promoter region of NEDD4L and recruit enhancer of zeste homolog 2 histone methyltransferase to repress NEDD4L transcription by enhancing histone H3 lysine 27 trimethylation (H3K27me3) at the NEDD4L promoter. Given that NEDD4L plays an important role in constraining transforming growth factor β signaling by targeting activated Smad2/Smad3 for degradation, we investigated the role of DDB2 in the regulation of TGF-β signaling in ovarian cancer cells. Our data indicate that DDB2 enhances TGF-β signal transduction and increases the responsiveness of ovarian cancer cells to TGF-β-induced growth inhibition. The study has uncovered an unappreciated regulatory mode that hinges on the interaction between DDB2 and NEDD4L in human ovarian cancer cells. The novel mechanism proposes the DDB2-mediated fine-tuning of TGF-β signaling and its downstream effects that impinge upon tumor growth in ovarian cancers.

Phelps D, Bondra K, Seum S, et al.
Inhibition of MDM2 by RG7388 confers hypersensitivity to X-radiation in xenograft models of childhood sarcoma.
Pediatr Blood Cancer. 2015; 62(8):1345-52 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Curative therapy for childhood sarcoma presents challenges when complete resection is not possible. Ionizing radiation (XRT) is used as a standard modality at diagnosis or recurrence for childhood sarcoma; however, local recurrence is still problematic. Most childhood sarcomas are TP53 wild type at diagnosis, although approximately 5-10% have MDM2 amplification or overexpression.
PROCEDURES: The MDM2 inhibitor, RG7388, was examined alone or in combination with XRT (20Gy given in 2 Gy daily fractions) to immune-deficient mice bearing Rh18 (embryonal) or a total of 30 Gy in 2 Gy fractions to mice bearing Rh30 (alveolar) rhabdomyosarcoma xenografts. RG7388 was administered by oral gavage using two schedules (daily ×5; schedule 1 or once weekly; schedule 2). TP53-responsive gene products (p21, PUMA, DDB2, and MIC1) as well as markers of apoptosis were analyzed.
RESULTS: RG7388 showed no significant single agent antitumor activity. Twenty Grays XRT induced complete regressions (CR) of Rh18 with 100 percent tumor regrowth by week 7, but no tumor regrowth at 20 weeks when combined with RG7388. RG7388 enhanced time to recurrence combined with XRT in Rh30 xenografts compared to 30 Gy XRT alone. RG7388 did not enhance XRT-induced local skin toxicity. Combination treatments induced TP53 responsive genes more rapidly and to a greater magnitude than single agent treatments.
CONCLUSIONS: RG7388 enhanced the activity of XRT in both rhabdomyosarcoma models without increasing local XRT-induced skin toxicity. Changes in TP53-responsive genes were consistent with the synergistic activity of RG7388 and XRT in the Rh18 model.

Kabátková M, Zapletal O, Tylichová Z, et al.
Inhibition of β-catenin signalling promotes DNA damage elicited by benzo[a]pyrene in a model of human colon cancer cells via CYP1 deregulation.
Mutagenesis. 2015; 30(4):565-76 [PubMed] Related Publications
Deregulation of Wnt/β-catenin signalling plays an important role in the pathogenesis of colorectal cancer. Interestingly, this pathway has been recently implicated in transcriptional control of cytochrome P450 (CYP) family 1 enzymes, which are responsible for bioactivation of a number of dietary carcinogens. In the present study, we investigated the impact of inhibition of Wnt/β-catenin pathway on metabolism and genotoxicity of benzo[a]pyrene (BaP), a highly mutagenic polycyclic aromatic hydrocarbon and an efficient ligand of the aryl hydrocarbon receptor, which is known as a primary regulator of CYP1 expression, in cellular models derived from colorectal tumours. We observed that a synthetic inhibitor of β-catenin, JW74, significantly increased formation of BaP-induced DNA adducts in both colorectal adenoma and carcinoma-derived cell lines. Using the short interfering RNA (siRNA) targeting β-catenin, we then found that β-catenin knockdown in HCT116 colon carcinoma cells significantly enhanced formation of covalent DNA adducts by BaP and histone H2AX phosphorylation, as detected by (32)P-postlabelling technique and immunocytochemistry, respectively, and it also induced expression of DNA damage response genes, such as CDKN1A or DDB2. The increased formation of DNA adducts formed by BaP upon β-catenin knockdown corresponded with enhanced production of major BaP metabolites, as well as with an increased expression/activity of CYP1 enzymes. Finally, using siRNA-mediated knockdown of CYP1A1, we confirmed that this enzyme plays a major role in formation of BaP-induced DNA adducts in HCT116 cells. Taken together, the present results indicated that the siRNA-mediated inhibition of β-catenin signalling, which is aberrantly activated in a majority of colorectal cancers, modulated genotoxicity of dietary carcinogen BaP in colon cell model in vitro, via a mechanism involving up-regulation of CYP1 expression and activity.

Sokolenko AP, Preobrazhenskaya EV, Aleksakhina SN, et al.
Candidate gene analysis of BRCA1/2 mutation-negative high-risk Russian breast cancer patients.
Cancer Lett. 2015; 359(2):259-61 [PubMed] Related Publications
Twenty one DNA repair genes were analyzed in a group of 95 BC patients, who displayed clinical features of hereditary disease predisposition but turned out to be negative for mutations in BRCA1 and BRCA2 entire coding region as well as for founder disease-predisposing alleles in CHEK2, NBN/NBS1 and ATM genes. Full-length sequencing of CHEK2 and NBN/NBS1 failed to identify non-founder mutations. The analysis of TP53 revealed a woman carrying the R282W allele; further testing of additional 108 BC patients characterized by a very young age at onset (35 years or earlier) detected one more carrier of the TP53 germ-line defect. In addition, this study confirmed non-random occurrence of PALB2 truncating mutations in Russian hereditary BC patients. None of the studied cases carried germ-line defects in recently discovered hereditary BC genes, BRIP1, FANCC, MRE11A and RAD51C. The analysis of genes with yet unproven BC-predisposing significance (BARD1, BRD7, CHEK1, DDB2, ERCC1, EXO1, FANCG, PARP1, PARP2, RAD51, RNF8, WRN) identified single women carrying a protein-truncating allele, WRN R1406X. DNA sequencing of another set of 95 hereditary BC cases failed to reveal additional WRN heterozygous genotypes. Since WRN is functionally similar to the known BC-predisposing gene, BLM, it deserves to be analyzed in future hereditary BC studies. Furthermore, this investigation revealed a number of rare missense germ-line variants, which are classified as probably protein-damaging by online in silico tools and therefore may require further consideration.

Asnaghi L, Alkatan H, Mahale A, et al.
Identification of multiple DNA copy number alterations including frequent 8p11.22 amplification in conjunctival squamous cell carcinoma.
Invest Ophthalmol Vis Sci. 2014; 55(12):8604-13 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Little is known about the molecular alterations that drive formation and growth of conjunctival squamous cell carcinoma (cSCC). We therefore sought to identify genetic changes that could be used as diagnostic markers or therapeutic targets.
METHODS: The DNA extracted from 10 snap-frozen cSCC tumor specimens and 2 in situ carcinomas was analyzed using array-based comparative genomic hybridization (aCGH), and further examined with NanoString and quantitative PCR.
RESULTS: The number of regions of DNA loss ranged from 1 to 23 per tumor, whereas gains and amplifications ranged from 1 to 15 per tumor. Most large regions of chromosomal gain and loss were confirmed by NanoString karyotype analysis. The commonest alteration was amplification of 8p11.22 in 9 tumors (75%), and quantitative PCR analysis revealed 100-fold or greater overexpression of ADAM3A mRNA from 8p11.22 locus. In addition, recurring losses were observed at 14q13.2 and 22q11.23, both lost in 5 (42%) of the 12 tumors, and at 12p13.31, lost in 4 (33%) of the 12 samples. Of the eight loci associated with the DNA damage repair syndrome xeroderma pigmentosum, three showed loss of at least one allele in our aCGH analysis, including XPA (9q22.33, one tumor), XPE/DDB2 (11p11.2, one tumor) and XPG/ERCC5 (13q33.1, three tumors).
CONCLUSIONS: Conjunctival SCC contains a range of chromosomal alterations potentially important in tumor formation and growth. Amplification of 8p11.22 and overexpression of ADAM3A suggests a potential role for this protease. Our findings also suggest that defects in DNA repair loci are important in sporadic cSCC.

Ben Rekaya M, Laroussi N, Messaoud O, et al.
A founder large deletion mutation in Xeroderma pigmentosum-Variant form in Tunisia: implication for molecular diagnosis and therapy.
Biomed Res Int. 2014; 2014:256245 [PubMed] Free Access to Full Article Related Publications
Xeroderma pigmentosum Variant (XP-V) form is characterized by a late onset of skin symptoms. Our aim is the clinical and genetic investigations of XP-V Tunisian patients in order to develop a simple tool for early diagnosis. We investigated 16 suspected XP patients belonging to ten consanguineous families. Analysis of the POLH gene was performed by linkage analysis, long range PCR, and sequencing. Genetic analysis showed linkage to the POLH gene with a founder haplotype in all affected patients. Long range PCR of exon 9 to exon 11 showed a 3926 bp deletion compared to control individuals. Sequence analysis demonstrates that this deletion has occurred between two Alu-Sq2 repetitive sequences in the same orientation, respectively, in introns 9 and 10. We suggest that this mutation POLH NG_009252.1: g.36847_40771del3925 is caused by an equal crossover event that occurred between two homologous chromosomes at meiosis. These results allowed us to develop a simple test based on a simple PCR in order to screen suspected XP-V patients. In Tunisia, the prevalence of XP-V group seems to be underestimated and clinical diagnosis is usually later. Cascade screening of this founder mutation by PCR in regions with high frequency of XP provides a rapid and cost-effective tool for early diagnosis of XP-V in Tunisia and North Africa.

Sehgal M, Singh TR
Systems biology approach for mutational and site-specific structural investigation of DNA repair genes for xeroderma pigmentosum.
Gene. 2014; 543(1):108-17 [PubMed] Related Publications
Xeroderma pigmentosum (XP) is a rare genetic skin disorder caused due to the extreme sensitivity for ultraviolet (UV) radiations. On its exposure, DNA acquires damages leading to skin and often neurological abnormalities. The DNA repair implicated in fixing UV-induced damages is NER and mutations in genes involved in NER and TLS form the basis of XP. The analyses of such mutations are vital for understanding XP and involved cancer genetics to facilitate the identification of crucial biomarkers and anticancer therapeutics. We detected the deleterious nsSNPs and examined them at structure-level by altering the structure, estimating secondary structure, solvent accessibility and performing site specific analysis. Crucial phosphorylation sites were also identified for their role in the disorder. These mutational and structural analyses offer valuable insight to the fundamental association of genetic mutations with phenotypic variations in XP and will assist experimental biologists to evaluate the mutations and their impact on genome.

Han C, Zhao R, Liu X, et al.
DDB2 suppresses tumorigenicity by limiting the cancer stem cell population in ovarian cancer.
Mol Cancer Res. 2014; 12(5):784-94 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Ovarian cancer is an extremely aggressive disease associated with a high percentage of tumor recurrence and chemotherapy resistance. Understanding the underlying mechanism of tumor relapse is crucial for effective therapy of ovarian cancer. DNA damage-binding protein 2 (DDB2) is a DNA repair factor mainly involved in nucleotide excision repair. Here, a novel role was identified for DDB2 in the tumorigenesis of ovarian cancer cells and the prognosis of patients with ovarian cancer. Overexpressing DDB2 in human ovarian cancer cells suppressed its capability to recapitulate tumors in athymic nude mice. Mechanistic investigation demonstrated that DDB2 is able to reduce the cancer stem cell (CSC) population characterized with high aldehyde dehydrogenase activity in ovarian cancer cells, probably through disrupting the self-renewal capacity of CSCs. Low DDB2 expression correlates with poor outcomes among patients with ovarian cancer, as revealed from the analysis of publicly available gene expression array datasets. Given the finding that DDB2 protein expression is low in ovarian tumor cells, enhancement of DDB2 expression is a promising strategy to eradicate CSCs and would help to halt ovarian cancer relapse.
IMPLICATIONS: DDB2 status has prognostic potential, and elevating its expression eradicates CSCs and could reduce ovarian cancer relapse.

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