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Barbara Pascucci, Alessandra Fragale, Veronica Marabitti, Giuseppe Leuzzi, Angelo Salvatore Calcagnile, Eleonora Parlanti, Annapaola Franchitto, Eugenia Dogliotti, Mariarosaria D'Errico
CS proteins have been involved in the repair of a wide variety of DNA lesions. Here, we analyse the role of CS proteins in DNA break repair by studying histone H2AX phosphorylation in different cell cycle phases and DNA break repair by comet assay in CS-A and CS-B primary and transformed cells. Following methyl methane sulphate treatment a significant accumulation of unrepaired single strand breaks was detected in CS cells as compared to normal cells, leading to accumulation of double strand breaks in S and G2 phases...
February 20, 2018: Oncotarget
S Wang, Z Zou, X Luo, Y Mi, H Chang, D Xing
Liver receptor homolog-1 (LRH1) has been shown to promote tumor proliferation and development. However, the functions of LRH1 in mediating cancer cells chemoresistance are still not clear. Here, we found LRH1 levels were significantly elevated in primary breast cancer tissues in patients who developed early recurrence. Similarly, adriamycin (ADR)-resistant breast cancer cell lines also exerted high LRH1 expression. Indeed, overexpression of LRH1 attenuated cytotoxicity of chemotherapeutic drugs ADR and cisplatin (DDP) in breast cancer cells in vitro and in nude mice tumor model...
March 16, 2018: Oncogene
Peter V Deraska, Colin O'Leary, Hunter D Reavis, Shelby Labe, Tru-Khang Dinh, Jean-Bernard Lazaro, Christopher Sweeney, Alan D D'Andrea, David Kozono
Despite optimal chemotherapy, radiotherapy (RT), and/or surgery, non-small-cell lung carcinoma (NSCLC) remains the leading cause of cancer-related death in the US and worldwide. Thoracic RT, a mainstay in the treatment of locally advanced NSCLC, is often restricted in efficacy by a therapeutic index limited by sensitivity of tissues surrounding the malignancy. Therefore, radiosensitizers that can improve the therapeutic index are a vital unmet need. Inhibition of the NF-κB pathway is a proposed mechanism of radiosensitization...
December 2018: Cell Death Discovery
Xuanxuan Wang, Hai Liu, Liming Shi, Xiaoli Yu, Yanjun Gu, Xiaonan Sun
LncRNA in non-homologous end joining (NHEJ) pathway 1 (LINP1) is an lncRNA which promotes therapeutic resistance in triple-negative breast cancer (TNBC). However, the expression and function of LINP1 in cervical cancer is not yet well-understood. In this study, we evaluated the expression levels of LINP1 in tumor tissues and cell lines of cervical cancer. We found that LINP1 associates with NHEJ proteins (Ku80 and DNA-PKcs). LINP1 translocates from cytosol to nucleus in response to irradiation. In addition, LINP1 knockdown significantly increases the levels of cleaved caspase3 and PARP, leading to enhanced cell apoptosis after ionizing radiation (IR)...
March 12, 2018: Cell Cycle
Christoph Oing, Pierre Tennstedt, Ronald Simon, Jennifer Volquardsen, Kerstin Borgmann, Carsten Bokemeyer, Cordula Petersen, Ekkehard Dikomey, Kai Rothkamm, Wael Y Mansour
Here we report that BCL2 blocks DNA double strand break (DSB) repair via nonhomologous end-joining (NHEJ), through sequestration of KU80 protein outside the nucleus. We find that this effect is associated with a repair switch to the error-prone PARP1-dependent end-joining (PARP1-EJ). We present in-vitro proof-of-concept for therapeutic targeting of this switch using PARP inhibitor to specifically enhance the radiosensitivity of BCL2-overexpressing cells. Given its erroneous behavior, PARP1-EJ might allow for the accumulation of genetic alterations and tumor progression...
March 8, 2018: Cancer Letters
Vivek Tripathi, Himanshi Agarwal, Swati Priya, Harish Batra, Priyanka Modi, Monica Pandey, Dhurjhoti Saha, Sathees C Raghavan, Sagar Sengupta
Mutations in BLM in Bloom Syndrome patients predispose them to multiple types of cancers. Here we report that BLM is recruited in a biphasic manner to annotated DSBs. BLM recruitment is dependent on the presence of NBS1, MRE11 and ATM. While ATM activity is essential for BLM recruitment in early phase, it is dispensable in late phase when MRE11 exonuclease activity and RNF8-mediated ubiquitylation of BLM are the key determinants. Interaction between polyubiquitylated BLM and NBS1 is essential for the helicase to be retained at the DSBs...
March 9, 2018: Nature Communications
Tian Zhang, Xiaojie Liu, Xiuli Chen, Jing Wang, Yuwen Wang, Dong Qian, Qingsong Pang, Ping Wang
Positive cofactor 4 (PC4) participates in DNA damage repair and involved in nonhomologous end joining (NHEJ). Our previous results demonstrated that knockdown of PC4 downregulated the expression of XRCC4-like factor (XLF) in esophageal squamous cell carcinoma. However, the mechanism how PC4 regulates the expression of XLF remains unclear. Here, we found that knockdown of PC4 increased radiosensitivity of non-small cell lung cancer (NSCLC) both in vivo and in vitro. Furthermore, we found that PC4 knockdown downregulated the expression of XLF, whereas recovering XLF expression restored radioresistance in the PC4-knockdown NSCLC cells...
March 9, 2018: Cancer Medicine
Conglei Li, Thergiory Irrazabal, Clare C So, Maribel Berru, Likun Du, Evelyn Lam, Alexanda K Ling, Jennifer L Gommerman, Qiang Pan-Hammarström, Alberto Martin
Class switch recombination (CSR) has a fundamental function during humoral immune response and involves the induction and subsequent repair of DNA breaks in the immunoglobulin (Ig) switch regions. Here we show the role of Usp22, the SAGA complex deubiquitinase that removes ubiquitin from H2B-K120, in the repair of programmed DNA breaks in vivo. Ablation of Usp22 in primary B cells results in defects in γH2AX and impairs the classical non-homologous end joining (c-NHEJ), affecting both V(D)J recombination and CSR...
March 8, 2018: Nature Communications
Mengyu Shen, Huidong Zhang, Wei Shen, Zhenyu Zou, Shuguang Lu, Gang Li, Xuesong He, Melissa Agnello, Wenyuan Shi, Fuquan Hu, Shuai Le
Pseudomonas aeruginosa is an opportunistic pathogen with a relatively large genome, and has been shown to routinely lose genomic fragments during environmental selection. However, the underlying molecular mechanisms that promote chromosomal deletion are still poorly understood. In a recent study, we showed that by deleting a large chromosomal fragment containing two closely situated genes, hmgA and galU, P. aeruginosa was able to form 'brown mutants', bacteriophage (phage) resistant mutants with a brown color phenotype...
March 5, 2018: Nucleic Acids Research
Alisa Dewan, Mengtan Xing, Marie Benner Lundbæk, Raquel Gago-Fuentes, Carole Beck, Per Arne Aas, Nina-Beate Liabakk, Siri Sæterstad, Khac Thanh Phong Chau, Bodil Merete Kavli, Valentyn Oksenych
To ensure genome stability, mammalian cells employ several DNA repair pathways. Nonhomologous DNA end joining (NHEJ) is the DNA repair process that fixes double-strand breaks throughout the cell cycle. NHEJ is involved in the development of B and T lymphocytes through its function in V(D)J recombination and class switch recombination (CSR). NHEJ consists of several core and accessory factors, including Ku70, Ku80, XRCC4, DNA ligase 4, DNA-PKcs, Artemis, and XLF. Paralog of XRCC4 and XLF (PAXX) is the recently described accessory NHEJ factor that structurally resembles XRCC4 and XLF and interacts with Ku70/Ku80...
March 2018: FEBS Open Bio
Raquel Gago-Fuentes, Mengtan Xing, Siri Sæterstad, Antonio Sarno, Alisa Dewan, Carole Beck, Stefano Bradamante, Magnar Bjørås, Valentyn Oksenych
DNA repair consists of several cellular pathways which recognize and repair damaged DNA. The classical nonhomologous DNA end-joining (NHEJ) pathway repairs double-strand breaks in DNA. It is required for maturation of both B and T lymphocytes by supporting V(D)J recombination as well as B-cell differentiation during class switch recombination (CSR). Inactivation of NHEJ factors Ku70, Ku80, XRCC4, DNA ligase 4, DNA-PKcs, and Artemis impairs V(D)J recombination and blocks lymphocyte development. Paralogue of XRCC4 and XLF (PAXX) is an accessory NHEJ factor that has a significant impact on the repair of DNA lesions induced by ionizing radiation in human, murine, and chicken cells...
March 2018: FEBS Open Bio
Hongjian Gong, Yuxi Zhang, Kunpeng Jiang, Shengfan Ye, Shuming Chen, Qinghe Zhang, Jinrong Peng, Jun Chen
Tumour repressor p53 isoform Δ133p53 is a target gene of p53 and an antagonist of p53-mediated apoptotic activity. We recently demonstrated that Δ133p53 promotes DNA double-strand break (DSB) repair by upregulating transcription of the repair genes RAD51, LIG4 and RAD52 in a p53-independent manner. However, Δ133p53 lacks the transactivation domain of full-length p53, and the mechanism by which it exerts transcriptional activity independently of full-length p53 remains unclear. In this report, we describe the accumulation of high levels of both Δ133p53 and p73 (a p53 family member) at 24 h post γ-irradiation (hpi)...
March 6, 2018: Cell Death and Differentiation
Yibo Zhang, Zhiwei Zhang, Wei Ge
Homology-directed recombination (HDR)-mediated genome editing is a powerful approach for both basic functional study and disease modeling. Although some studies have reported HDR-mediated precise editing in non-rodent models, the efficiency of establishing pure mutant animal lines that carry specific amino acid substitutions remains low. Furthermore, because the efficiency of nonhomologous end joining (NHEJ)-induced insertion and deletion (indel) mutations is normally much higher than that of HDR-induced point mutations, it is often difficult to identify the latter in the background of indel mutations...
March 2, 2018: Journal of Biological Chemistry
Charlene H Emerson, Christopher R Lopez, Albert Ribes-Zamora, Erica J Polleys, Christopher L Williams, Lythou Yeo, Jacques E Zaneveld, Rui Chen, Alison A Bertuch
The Ku heterodimer acts centrally in non-homologous end-joining (NHEJ) of DNA double strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null ( yku 70Δ or yku80Δ ) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ...
March 2, 2018: Genetics
Barbara Bukowska, Boleslaw T Karwowski
The clustered DNA lesions are a characteristic feature of ionizing radiation and are defined as two or more damage sites formed within 20 bps after the passage of a single radiation track. The clustered DNA lesions are divided into two major groups: double-stranded breaks (DSBs) and non-DSB clusters also known as Oxidatively-induced Clustered DNA Lesions (OCDLs), which could involve either two opposing strands or the same strand. As irradiation is gaining greater interest in cancer treatment as well as in imaging techniques, the detailed knowledge of its genotoxicity and the mechanisms of repair of radiation-induced DNA damage remain issues to explore...
February 25, 2018: Current Medicinal Chemistry
Cristina Maranto, Vindhya Udhane, David T Hoang, Lei Gu, Vitali Alexeev, Kareem M Malas, Karmel Cardenas, Jonathan R Brody, Ulrich Rodeck, Carmen Bergom, Kenneth A Iczkowski, Kenneth Jacobsohn, William A See, Sara M Schmitt, Marja T Nevalainen
PURPOSE: The standard treatment for organ-confined prostate cancer (PC) is surgery or radiation, and locally advanced PC is typically treated with radiotherapy alone or in combination with androgen deprivation therapy. Here, we investigated whether Stat5a/b participates in regulation of double strand DNA break repair in PC, and whether Stat5 inhibition may provide a novel strategy to sensitize PC to radiation therapy. EXPERIMENTAL DESIGN: Stat5a/b regulation of DNA repair in PC was evaluated by comet and clonogenic survival assays, followed by assays specific to Homologous Recombination (HR) DNA repair and Non-Homologous End-Joining (NHEJ) DNA repair...
February 26, 2018: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
Marek Adamowicz, Fabrizio d'Adda di Fagagna, Jelena Vermezovic
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) controls one of the most frequently used DNA repair pathways in a cell, the non-homologous end joining (NHEJ) pathway. However, the exact role of DNA-PKcs in NHEJ remains poorly defined. Here we show that NOTCH1 attenuates DNA-PKcs-mediated autophosphorylation, as well as the phosphorylation of its specific substrate XRCC4. Surprisingly, NOTCH1-expressing cells do not display any significant impairment in the DNA damage repair, nor cellular survival, and remain sensitive to small molecule DNA-PKcs inhibitor...
February 1, 2018: Mutation Research
Amy Ferreccio, Julie Mathieu, Damien Detraux, Somasundaram Logeshwaran, Christopher Cavanaugh, Bryce Sopher, Karin Fischer, Thomas Bello, Assis M Hussein, Shiri Levy, Savannah Cook, Sonia B Sidhu, Filippo Artoni, Nathan J Palpant, Hans Reinecke, Yuliang Wang, Patrick Paddison, Charles Murry, Suman Jayadev, Carol Ware, Hannele Ruohola-Baker
To easily edit the genome of naïve human embryonic stem cells (hESC), we introduced a dual cassette encoding an inducible Cas9 into the AAVS1 site of naïve hESC (iCas9). The iCas9 line retained karyotypic stability, expression of pluripotency markers, differentiation potential, and stability in 5iLA and EPS pluripotency conditions. The iCas9 line induced efficient homology-directed repair (HDR) and non-homologous end joining (NHEJ) based mutations through CRISPR-Cas9 system. We utilized the iCas9 line to study the epigenetic regulator, PRC2 in early human pluripotency...
February 22, 2018: Cell Cycle
Laura J Eccles, Andrew C Bell, Simon N Powell
When Fanconi Anemia (FA) proteins were depleted in human U2OS cells with integrated DNA repair reporters, we observed decreases in homologous recombination (HR), decreases in mutagenic non-homologous end joining (m-NHEJ) and increases in canonical NHEJ, which was independently confirmed by measuring V(D)J recombination. Furthermore, depletion of FA proteins resulted in reduced HR protein foci and increased NHEJ protein recruitment to replication-associated DSBs, consistent with our observation that the use of canonical NHEJ increases after depletion of FA proteins in cycling cells...
February 10, 2018: DNA Repair
Jay H Chung
DNA-dependent protein kinase (DNA-PK) is a very large holoenzyme comprised of the p470 kDa DNA-PK catalytic subunit (DNA-PKcs ) and the Ku heterodimer consisting of the p86 (Ku 80) and p70 (Ku 70) subunits. It is best known for its non-homologous end joining (NHEJ) activity, which repairs double-strand DNA (dsDNA) breaks (DSBs). As expected, the absence of DNA-PK activity results in sensitivity to ionizing radiation, which generates DSBs and defect in lymphocyte development, which requires NHEJ of the V(D)J region in the immunoglobulin and T cell receptor loci...
February 17, 2018: FEBS Journal
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