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Laverty DJ, Gupta SK, Bradshaw GA, Hunter AS, Carlson BL, Calmo NM, Chen J, Tian S, Sarkaria JN, Nagel ZD. ATM inhibition exploits checkpoint defects and ATM-dependent double strand break repair in TP53-mutant glioblastoma. Nat Commun 2024; 15:5294. [PMID: 38906885 PMCID: PMC11192742 DOI: 10.1038/s41467-024-49316-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 05/28/2024] [Indexed: 06/23/2024] Open
Abstract
Determining the balance between DNA double strand break repair (DSBR) pathways is essential for understanding treatment response in cancer. We report a method for simultaneously measuring non-homologous end joining (NHEJ), homologous recombination (HR), and microhomology-mediated end joining (MMEJ). Using this method, we show that patient-derived glioblastoma (GBM) samples with acquired temozolomide (TMZ) resistance display elevated HR and MMEJ activity, suggesting that these pathways contribute to treatment resistance. We screen clinically relevant small molecules for DSBR inhibition with the aim of identifying improved GBM combination therapy regimens. We identify the ATM kinase inhibitor, AZD1390, as a potent dual HR/MMEJ inhibitor that suppresses radiation-induced phosphorylation of DSBR proteins, blocks DSB end resection, and enhances the cytotoxic effects of TMZ in treatment-naïve and treatment-resistant GBMs with TP53 mutation. We further show that a combination of G2/M checkpoint deficiency and reliance upon ATM-dependent DSBR renders TP53 mutant GBMs hypersensitive to TMZ/AZD1390 and radiation/AZD1390 combinations. This report identifies ATM-dependent HR and MMEJ as targetable resistance mechanisms in TP53-mutant GBM and establishes an approach for simultaneously measuring multiple DSBR pathways in treatment selection and oncology research.
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Affiliation(s)
- Daniel J Laverty
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | | | | | | | | | | | - Jiajia Chen
- Mayo Clinic, Rochester, MN, 55905, USA
- Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | | | | | - Zachary D Nagel
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
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2
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Vogt M, Classen S, Krause AK, Peter NJ, Petersen C, Rothkamm K, Borgmann K, Meyer F. USP7 Deregulation Impairs S Phase Specific DNA Repair after Irradiation in Breast Cancer Cells. Biomedicines 2024; 12:762. [PMID: 38672118 PMCID: PMC11047985 DOI: 10.3390/biomedicines12040762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/13/2024] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
The ubiquitin specific protease 7 (USP7) is a deubiquitinating enzyme with numerous substrates. Aberrant expression of USP7 is associated with tumor progression. This study aims to investigate how a deregulated USP7 expression affects chromosomal instability and prognosis of breast cancer patients in silico and radiosensitivity and DNA repair in breast cancer cells in vitro. The investigations in silico were performed using overall survival and USP7 mRNA expression data of breast cancer patients. The results showed that a high USP7 expression was associated with increased chromosomal instability and decreased overall survival. The in vitro experiments were performed in a luminal and a triple-negative breast cancer cell line. Proliferation, DNA repair, DNA replication stress, and survival after USP7 overexpression or inhibition and irradiation were analyzed. Both, USP7 inhibition and overexpression resulted in decreased cellular survival, distinct radiosensitization and an increased number of residual DNA double-strand breaks in the S phase following irradiation. RAD51 recruitment and base incorporation were decreased after USP7 inhibition plus irradiation and more single-stranded DNA was detected. The results show that deregulation of USP7 activity disrupts DNA repair in the S phase by increasing DNA replication stress and presents USP7 as a promising target to overcome the radioresistance of breast tumors.
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Affiliation(s)
| | | | | | | | | | | | | | - Felix Meyer
- Department of Radiotherapy & Radiation Oncology, Hubertus Wald Tumor Center—University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.V.); (S.C.); (A.K.K.); (N.-J.P.); (C.P.); (K.R.); (K.B.)
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3
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Chen J, Laverty DJ, Talele S, Bale A, Carlson BL, Porath KA, Bakken KK, Burgenske DM, Decker PA, Vaubel RA, Eckel-Passow JE, Bhargava R, Lou Z, Hamerlik P, Harley B, Elmquist WF, Nagel ZD, Gupta SK, Sarkaria JN. Aberrant ATM signaling and homology-directed DNA repair as a vulnerability of p53-mutant GBM to AZD1390-mediated radiosensitization. Sci Transl Med 2024; 16:eadj5962. [PMID: 38354228 PMCID: PMC11064970 DOI: 10.1126/scitranslmed.adj5962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 01/19/2024] [Indexed: 02/16/2024]
Abstract
ATM is a key mediator of radiation response, and pharmacological inhibition of ATM is a rational strategy to radiosensitize tumors. AZD1390 is a brain-penetrant ATM inhibitor and a potent radiosensitizer. This study evaluated the spectrum of radiosensitizing effects and the impact of TP53 mutation status in a panel of IDH1 wild-type (WT) glioblastoma (GBM) patient-derived xenografts (PDXs). AZD1390 suppressed radiation-induced ATM signaling, abrogated G0-G1 arrest, and promoted a proapoptotic response specifically in p53-mutant GBM in vitro. In a preclinical trial using 10 orthotopic GBM models, AZD1390/RT afforded benefit in a cohort of TP53-mutant tumors but not in TP53-WT PDXs. In mechanistic studies, increased endogenous DNA damage and constitutive ATM signaling were observed in TP53-mutant, but not in TP53-WT, PDXs. In plasmid-based reporter assays, GBM43 (TP53-mutant) showed elevated DNA repair capacity compared with that in GBM14 (p53-WT), whereas treatment with AZD1390 specifically suppressed homologous recombination (HR) efficiency, in part, by stalling RAD51 unloading. Furthermore, overexpression of a dominant-negative TP53 (p53DD) construct resulted in enhanced basal ATM signaling, HR activity, and AZD1390-mediated radiosensitization in GBM14. Analyzing RNA-seq data from TCGA showed up-regulation of HR pathway genes in TP53-mutant human GBM. Together, our results imply that increased basal ATM signaling and enhanced dependence on HR represent a unique susceptibility of TP53-mutant cells to ATM inhibitor-mediated radiosensitization.
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Affiliation(s)
- Jiajia Chen
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Daniel J. Laverty
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Surabhi Talele
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55905, USA
| | - Ashwin Bale
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Brett L. Carlson
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
| | - Kendra A. Porath
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
| | - Katrina K. Bakken
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Paul A. Decker
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55905, USA
| | - Rachael A. Vaubel
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Rohit Bhargava
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Zhenkun Lou
- Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Brendan Harley
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - William F. Elmquist
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55905, USA
| | - Zachary D. Nagel
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Shiv K. Gupta
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
| | - Jann N. Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
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4
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Yao W, Li S, Liu R, Jiang M, Gao L, Lu Y, Liang X, Zhang H. Long non-coding RNA PVT1: A promising chemotherapy and radiotherapy sensitizer. Front Oncol 2022; 12:959208. [PMID: 35965522 PMCID: PMC9373174 DOI: 10.3389/fonc.2022.959208] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 06/30/2022] [Indexed: 12/14/2022] Open
Abstract
The long non-coding RNA (lncRNA) PVT1 was first found to activate variant translocations in the plasmacytoma of mice. Human lncPVT1 is located on chromosome 8q24.21, at the same locus as the well-known MYC oncogene. LncPVT1 has been found to promote the progression of various malignancies. Chemoresistance and radioresistance seriously affect tumor treatment efficacy and are associated with the dysregulation of physiological processes in cancer cells, including apoptosis, autophagy, stemness (for cancer stem cells, CSC), hypoxia, epithelial–mesenchymal transition (EMT), and DNA damage repair. Previous studies have also implicated lncPVT1 in the regulation of these physiological mechanisms. In recent years, lncPVT1 was found to modulate chemoresistance and radioresistance in some cancers. In this review, we discuss the mechanisms of lncPVT1-mediated regulation of cellular chemoresistance and radioresistance. Due to its high expression in malignant tumors and sensitization effect in chemotherapy and radiotherapy, lncPVT1 is expected to become an effective antitumor target and chemotherapy and radiotherapy sensitizer, which requires further study.
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Affiliation(s)
- Weiping Yao
- Graduate Department, Bengbu Medical College, Bengbu, China
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Shuang Li
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- Graduate Department, Jinzhou Medical University, Jinzhou, China
| | - Ruiqi Liu
- Graduate Department, Bengbu Medical College, Bengbu, China
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Mingyun Jiang
- Graduate Department, Bengbu Medical College, Bengbu, China
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Liang Gao
- Cancer Center, Department of Medical Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Yanwei Lu
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Xiaodong Liang
- Graduate Department, Bengbu Medical College, Bengbu, China
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Haibo Zhang, zhbdoctor @163.com; Xiaodong Liang,
| | - Haibo Zhang
- Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Haibo Zhang, zhbdoctor @163.com; Xiaodong Liang,
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Subtil FSB, Gröbner C, Recknagel N, Parplys AC, Kohl S, Arenz A, Eberle F, Dikomey E, Engenhart-Cabillic R, Schötz U. Dual PI3K/mTOR Inhibitor NVP-BEZ235 Leads to a Synergistic Enhancement of Cisplatin and Radiation in Both HPV-Negative and -Positive HNSCC Cell Lines. Cancers (Basel) 2022; 14:cancers14133160. [PMID: 35804930 PMCID: PMC9265133 DOI: 10.3390/cancers14133160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary Head and neck cancers (HNSCCs), especially in the advanced stages, are predominantly treated by radiochemotherapy, including cisplatin. The cure rates are clearly higher for HPV-positive HNSCCs when compared to HPV-negative HNSCCs. For both entities, this treatment is accompanied by serious adverse reactions, mainly due to cisplatin administration. We reported earlier that for both HPV-positive and negative HNSCC cells, the effect of radiotherapy was strongly enhanced when pretreated using the dual PI3K/mTOR inhibitor NVP-BEZ235 (BEZ235). The current study shows that for HPV-positive cells, BEZ235 will strongly enhance the effect of cisplatin alone. More important, preincubation with BEZ235 was found to alter the purely additive effect normally seen when cisplatin is combined with radiation into a strong synergistic enhancement. This tri-modal combination might allow for the enhancement of the effect of radiochemotherapy, even with reduced cisplatin. Abstract The standard of care for advanced head and neck cancers (HNSCCs) is radiochemotherapy, including cisplatin. This treatment results in a cure rate of approximately 85% for oropharyngeal HPV-positive HNSCCs, in contrast to only 50% for HPV-negative HNSCCs, and is accompanied by severe side effects for both entities. Therefore, innovative treatment modalities are required, resulting in a better outcome for HPV-negative HNSCCs, and lowering the adverse effects for both entities. The effect of the dual PI3K/mTOR inhibitor NVP-BEZ235 on a combined treatment with cisplatin and radiation was studied in six HPV-negative and six HPV-positive HNSCC cell lines. Cisplatin alone was slightly more effective in HPV-positive cells. This could be attributed to a defect in homologous recombination, as demonstrated by depleting RAD51. Solely for HPV-positive cells, pretreatment with BEZ235 resulted in enhanced cisplatin sensitivity. For the combination of cisplatin and radiation, additive effects were observed. However, when pretreated with BEZ235, this combination changed into a synergistic interaction, with a slightly stronger enhancement for HPV-positive cells. This increase could be attributed to a diminished degree of DSB repair in G1, as visualized via the detection of γH2AX/53BP1 foci. BEZ235 can be used to enhance the effect of combined treatment with cisplatin and radiation in both HPV-negative and -positive HNSCCs.
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Affiliation(s)
- Florentine S. B. Subtil
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Carolin Gröbner
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Niklas Recknagel
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Ann Christin Parplys
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Sibylla Kohl
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Andrea Arenz
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Fabian Eberle
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Ekkehard Dikomey
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Rita Engenhart-Cabillic
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
| | - Ulrike Schötz
- Department of Radiotherapy and Radiooncology, Philipps-University, 35043 Marburg, Germany; (F.S.B.S.); (C.G.); (N.R.); (A.C.P.); (S.K.); (A.A.); (F.E.); (E.D.); (R.E.-C.)
- Correspondence: ; Tel.: +49-6421-28-21978
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6
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Köcher S, Zech HB, Krug L, Gatzemeier F, Christiansen S, Meyer F, Rietow R, Struve N, Mansour WY, Kriegs M, Petersen C, Betz C, Rothkamm K, Rieckmann T. A Lack of Effectiveness in the ATM-Orchestrated DNA Damage Response Contributes to the DNA Repair Defect of HPV-Positive Head and Neck Cancer Cells. Front Oncol 2022; 12:765968. [PMID: 35719921 PMCID: PMC9204973 DOI: 10.3389/fonc.2022.765968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Patients with human papillomavirus-positive squamous cell carcinoma of the head and neck (HPV+ HNSCC) have a favorable prognosis compared to those with HPV-negative (HPV−) ones. We have shown previously that HPV+ HNSCC cell lines are characterized by enhanced radiation sensitivity and impaired DNA double-strand break (DSB) repair. Since then, various publications have suggested a defect in homologous recombination (HR) and dysregulated expression of DSB repair proteins as underlying mechanisms, but conclusions were often based on very few cell lines. When comparing the expression levels of suggested proteins and other key repair factors in 6 HPV+ vs. 5 HPV− HNSCC strains, we could not confirm most of the published differences. Furthermore, HPV+ HNSCC strains did not demonstrate enhanced sensitivity towards PARP inhibition, questioning a general HR defect. Interestingly, our expression screen revealed minimal levels of the central DNA damage response kinase ATM in the two most radiosensitive HPV+ strains. We therefore tested whether insufficient ATM activity may contribute to the enhanced cellular radiosensitivity. Irrespective of their ATM expression level, radiosensitive HPV+ HNSCC cells displayed DSB repair kinetics similar to ATM-deficient cells. Upon ATM inhibition, HPV+ cell lines showed only a marginal increase in residual radiation-induced γH2AX foci and induction of G2 cell cycle arrest as compared to HPV− ones. In line with these observations, ATM inhibition sensitized HPV+ HNSCC strains less towards radiation than HPV− strains, resulting in similar levels of sensitivity. Unexpectedly, assessment of the phosphorylation kinetics of the ATM targets KAP-1 and Chk2 as well as ATM autophosphorylation after radiation did not indicate directly compromised ATM activity in HPV-positive cells. Furthermore, ATM inhibition delayed radiation induced DNA end resection in both HPV+ and HPV− cells to a similar extent, further suggesting comparable functionality. In conclusion, DNA repair kinetics and a reduced effectiveness of ATM inhibition clearly point to an impaired ATM-orchestrated DNA damage response in HPV+ HNSCC cells, but since ATM itself is apparently functional, the molecular mechanisms need to be further explored.
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Affiliation(s)
- Sabrina Köcher
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Henrike Barbara Zech
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Mildred-Scheel Cancer Career Center HaTriCS, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Leonie Krug
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fruzsina Gatzemeier
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sabrina Christiansen
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Felix Meyer
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ruth Rietow
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Research Department, Cell and Gene Therapy, Department of Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nina Struve
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Mildred-Scheel Cancer Career Center HaTriCS, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wael Yassin Mansour
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Mildred-Scheel Cancer Career Center HaTriCS, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Malte Kriegs
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Cordula Petersen
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Betz
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kai Rothkamm
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Rieckmann
- Department of Otorhinolaryngology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- *Correspondence: Thorsten Rieckmann,
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7
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SFN Enhanced the Radiosensitivity of Cervical Cancer Cells via Activating LATS2 and Blocking Rad51/MDC1 Recruitment to DNA Damage Site. Cancers (Basel) 2022; 14:cancers14081872. [PMID: 35454780 PMCID: PMC9026704 DOI: 10.3390/cancers14081872] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/05/2022] [Accepted: 03/30/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Radiotherapy is the main treatment for cervical cancer patients in advanced stages. However a considerable number of patients are not sensitive to radiotherapy. Dysregulation of DNA double-strand break (DSB) repair is characteristic of cancer cells in a radiotherapy-resistance state. The aim of this study is to explore Sulforaphane (SFN) downstream target and the radiotherapy sensitization mechanism in cervical cancer. We identified SFN as cervical cancer cells radiotherapy sensitizer and LATS2 served as a downstream target of SFN treatment. SFN treatment resulted in the inhibition of the homologous recombination (HR) pathway, and LATS2 has an indispensable contribution to this SFN-facilitated radiotherapy sensitization. Abstract Background: Sulforaphane (SFN) is one kind of phytochemical anticancer drug. It inhibits cancer cell proliferation and promotes cell apoptosis while the mechanism behind is still uncertain. We aimed to explore its downstream target and the radiotherapy sensitization mechanism in cervical cancer. Methods: We treated established cervical cancer cells line (SiHa, HeLa, C33A) with SFN followed by irradiation, and explored its survival, apoptosis, and DNA damage repair in vitro and validated the radiosensitivity of SFN treatment in vivo. We conducted mRNA sequencing to identify differentially expressed mRNAs after SFN treatment. We further investigated SFN downstream target and its involvement in DNA damage repair under irradiation. Results: We found that SFN inhibited the survival of cervical cancer cells under radiotherapy treatment in vitro and prolonged the survival period after radiotherapy in the mouse tumorigenic model. SFN increased the protein expression of LATS2 and promoted apoptosis of cervical cancer cells. Overexpressed LATS2 decreased the cellular survival rate of cervical cancer cells. Additionally, SFN treatment and LATS2 overexpression prevented MDC1 and Rad51 from accumulating in the nucleus in cervical cancer cells after being exposed to ionized radiation. LATS2 loss intervened with SFN-alleviated RAD51 and MDC1 nucleus accumulation and resumed the repairment of DNA damage. Conclusion: We identified SFN as cervical cancer cells radiotherapy sensitizer and LATS2 served as a downstream target of SFN treatment. SFN treatment resulted in the inhibition of the homologous recombination (HR) pathway, and LATS2 has an indispensable contribution to this SFN-facilitated radiotherapy sensitization.
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8
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Köcher S, Volquardsen J, Perugachi Heinsohn A, Petersen C, Roggenbuck D, Rothkamm K, Mansour WY. Fully automated counting of DNA damage foci in tumor cell culture: A matter of cell separation. DNA Repair (Amst) 2021; 102:103100. [PMID: 33812230 DOI: 10.1016/j.dnarep.2021.103100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/18/2021] [Accepted: 03/14/2021] [Indexed: 11/17/2022]
Abstract
Analysis and quantification of residual, unrepaired DNA double-strand breaks by detecting damage-associated γH2AX or 53BP1 foci is a promising approach to evaluate radiosensitivity or radiosensitization in tumor cells. Manual foci quantification by eye is well-established but unsatisfactory due to inconsistent foci numbers between different observers, lack of information about foci size and intensity and the time-consuming scoring process. Therefore, automated foci counting is an important goal. Several software solutions for automated foci counting in separately acquired fluorescence microscopy images have been established. The AKLIDES NUK technology by Medipan combines automated microscopy and image processing/ counting, enabling affordable high throughput foci analysis as a routine application. Using this machine, automated foci counting is well established for lymphocytes but has not yet been reported for adherent tumor cells with their irregularly shaped nuclei and heterogeneous foci textures. Here we aimed to use the AKLIDES NUK system for adherent tumor cells growing in clusters. We identified cell separation as a critical step to ensure fast and reliable automated nuclei detection. We validated our protocol for the fully automated quantification of (i) the IR-dose dependent increase and (ii) the ATM as well as PARP inhibitor-induced radiosensitization. Collectively, with this protocol the AKLIDES NUK system facilitates cost effective, fast and high throughput quantitative fluorescence microscopic analysis of DNA damage induced foci such as γH2AX and 53BP1 in adherent tumor cells.
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Affiliation(s)
- S Köcher
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - J Volquardsen
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - A Perugachi Heinsohn
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Petersen
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - D Roggenbuck
- Institute of Biotechnology, Faculty Environment and Natural Sciences, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany; Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, Senftenberg, Germany
| | - K Rothkamm
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - W Y Mansour
- Department of Radiotherapy and Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Tumor Biology Department, National Cancer Institute, Cairo University, Cairo, Egypt; Mildred-Scheel Cancer Career Center HATRICs4, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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9
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Dual PI3K/mTOR Inhibitor NVP-BEZ235 Enhances Radiosensitivity of Head and Neck Squamous Cell Carcinoma (HNSCC) Cell Lines Due to Suppressed Double-Strand Break (DSB) Repair by Non-Homologous End Joining. Cancers (Basel) 2020; 12:cancers12020467. [PMID: 32085396 PMCID: PMC7072694 DOI: 10.3390/cancers12020467] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/27/2020] [Accepted: 02/07/2020] [Indexed: 12/24/2022] Open
Abstract
The PI3K/Akt/mTOR pathway is frequently altered in human papillomavirus (HPV)-positive and negative squamous cell carcinoma of the head and neck (HNSCC) and overstimulation is associated with poor prognosis. PI3K drives Akt activation and constitutive signaling acts pro-proliferative, supports cell survival, DNA repair, and contributes to radioresistance. Since the small molecule NVP-BEZ235 (BEZ235) is a potent dual inhibitor of this pathway, we were interested whether BEZ235 could be an efficient radiosensitizer. The 50 nM BEZ235 was found to abrogate endogenous and irradiation-induced phosphorylation of Akt (Ser473). The anti-proliferative capacity of the drug resulted in an increase in G1-phase cells. Repair of radiation-induced DNA double-strand breaks (DSBs) was strongly suppressed. Reduction in DSB repair was only apparent in G1- but not in G2-phase cells, suggesting that BEZ235 primarily affects non-homologous end joining. This finding was confirmed using a DSB repair reporter gene assay and could be attributed to an impaired phosphorylation of DNA-PKcs (S2056). Cellular radiosensitivity increased strongly after BEZ235 addition in all HNSCC cell lines used, especially when irradiated in the G0 or G1 phase. Our data indicate that targeting the PI3K/Akt/mTOR pathway by BEZ235 with concurrent radiotherapy may be considered an effective strategy for the treatment of HNSCC, regardless of the HPV and Akt status.
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10
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Mathematical Model of ATM Activation and Chromatin Relaxation by Ionizing Radiation. Int J Mol Sci 2020; 21:ijms21041214. [PMID: 32059363 PMCID: PMC7072770 DOI: 10.3390/ijms21041214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/29/2020] [Accepted: 02/09/2020] [Indexed: 12/24/2022] Open
Abstract
We propose a comprehensive mathematical model to study the dynamics of ionizing radiation induced Ataxia-telangiectasia mutated (ATM) activation that consists of ATM activation through dual mechanisms: the initiative activation pathway triggered by the DNA damage-induced local chromatin relaxation and the primary activation pathway consisting of a self-activation loop by interplay with chromatin relaxation. The model is expressed as a series of biochemical reactions, governed by a system of differential equations and analyzed by dynamical systems techniques. Radiation induced double strand breaks (DSBs) cause rapid local chromatin relaxation, which is independent of ATM but initiates ATM activation at damage sites. Key to the model description is how chromatin relaxation follows when active ATM phosphorylates KAP-1, which subsequently spreads throughout the chromatin and induces global chromatin relaxation. Additionally, the model describes how oxidative stress activation of ATM triggers a self-activation loop in which PP2A and ATF2 are released so that ATM can undergo autophosphorylation and acetylation for full activation in relaxed chromatin. In contrast, oxidative stress alone can partially activate ATM because phosphorylated ATM remains as a dimer. The model leads to predictions on ATM mediated responses to DSBs, oxidative stress, or both that can be tested by experiments.
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11
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Köcher S, Beyer B, Lange T, Nordquist L, Volquardsen J, Burdak‐Rothkamm S, Schlomm T, Petersen C, Rothkamm K, Mansour WY. A functional
ex vivo
assay to detect PARP1‐EJ repair and radiosensitization by PARP‐inhibitor in prostate cancer. Int J Cancer 2019; 144:1685-1696. [DOI: 10.1002/ijc.32018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/13/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Sabrina Köcher
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Burkhard Beyer
- Martini‐Klinik, Prostate Cancer CenterUniversity Medical Hamburg Eppendorf Hamburg Germany
| | - Tobias Lange
- Institute of AnatomyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Lena Nordquist
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Jennifer Volquardsen
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Susanne Burdak‐Rothkamm
- Department of Radiotherapy and RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Thorsten Schlomm
- Martini‐Klinik, Prostate Cancer CenterUniversity Medical Hamburg Eppendorf Hamburg Germany
| | - Cordula Petersen
- Department of Radiotherapy and RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Kai Rothkamm
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Wael Yassin Mansour
- Laboratory of Radiobiology and Experimental RadiooncologyUniversity Medical Center Hamburg‐Eppendorf Hamburg Germany
- Department of Tumor BiologyNational Cancer Institute, Cairo University Cairo Egypt
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12
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Liu H, Wang X, Huang A, Gao H, Sun Y, Jiang T, Shi L, Wu X, Dong Q, Sun X. Silencing Artemis Enhances Colorectal Cancer Cell Sensitivity to DNA-Damaging Agents. Oncol Res 2018; 27:29-38. [PMID: 29426373 PMCID: PMC7848410 DOI: 10.3727/096504018x15179694020751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Artemis is a key protein of NHEJ (nonhomologous end joining), which is the major pathway for the repair of IR-induced DSBs in mammalian cells. However, the expression of Artemis in tumors and the influence of silencing Artemis on tumor sensitivity to radiation have not been investigated fully. In this study, we investigated how the expression levels of Artemis may affect the treatment outcome of radiotherapy and chemotherapy in colorectal cancer cells. First, we found that the expression of Artemis is strong in some human rectal cancer samples, being higher than in adjacent normal tissues using immunohistochemical staining. We then knocked down Artemis gene in a human colorectal cancer cell line (RKO) using lentivirus-mediated siRNAs. Compared to the control RKO cells, the Artemis knockdown cells showed significantly increased sensitivity to bleomycin, etoposide, camptothecin, and IR. Induced by DNA-damaging agents, delayed DNA repair kinetics was found by the γ-H2AX foci assay, and a significantly increased cell apoptosis occurred in the Artemis knockdown RKO cells through apoptosis detection methods and Western blot. We also found that the p53/p21 signaling pathway may be involved in the apoptosis process. Taken together, our study indicates that manipulating Artemis can enhance colorectal cancer cell sensitivity to DNA-damaging agents. Therefore, Artemis can serve as a therapeutic target in rectal cancer therapy.
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Affiliation(s)
- Hai Liu
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, P.R. China
| | - Xuanxuan Wang
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, P.R. China
| | - Aihua Huang
- Department of Pathology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, P.R. China
| | - Huaping Gao
- Department of Pharmacy, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, P.R. China
| | - Yikan Sun
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Tingting Jiang
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, P.R. China
| | - Liming Shi
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, P.R. China
| | - Xianjie Wu
- Department of Dermatology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P.R. China
| | - Qinghua Dong
- Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, P.R. China
| | - Xiaonan Sun
- Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, P.R. China
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13
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Chalasani SL, Kawale AS, Akopiants K, Yu Y, Fanta M, Weinfeld M, Povirk LF. Persistent 3'-phosphate termini and increased cytotoxicity of radiomimetic DNA double-strand breaks in cells lacking polynucleotide kinase/phosphatase despite presence of an alternative 3'-phosphatase. DNA Repair (Amst) 2018; 68:12-24. [PMID: 29807321 DOI: 10.1016/j.dnarep.2018.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/07/2018] [Indexed: 02/08/2023]
Abstract
Polynucleotide kinase/phosphatase (PNKP) has been implicated in non-homologous end joining (NHEJ) of DNA double-strand breaks (DSBs). To assess the consequences of PNKP deficiency for NHEJ of 3'-phosphate-ended DSBs, PNKP-deficient derivatives of HCT116 and of HeLa cells were generated using CRISPR/CAS9. For both cell lines, PNKP deficiency conferred sensitivity to ionizing radiation as well as to neocarzinostatin (NCS), which specifically induces DSBs bearing protruding 3'-phosphate termini. Moreover, NCS-induced DSBs, detected as 53BP1 foci, were more persistent in PNKP -/- HCT116 cells compared to their wild-type (WT) counterparts. Surprisingly, PNKP-deficient whole-cell and nuclear extracts were biochemically competent in removing both protruding and recessed 3'-phosphates from synthetic DSB substrates, albeit much less efficiently than WT extracts, suggesting an alternative 3'-phosphatase. Measurements by ligation-mediated PCR showed that PNKP-deficient HeLa cells contained significantly more 3'-phosphate-terminated and fewer 3'-hydroxyl-terminated DSBs than parental cells 5-15 min after NCS treatment, but this difference disappeared by 1 h. These results suggest that, despite presence of an alternative 3'-phosphatase, loss of PNKP significantly sensitizes cells to 3'-phosphate-terminated DSBs, due to a 3'-dephosphorylation defect.
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Affiliation(s)
- Sri Lakshmi Chalasani
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Ajinkya S Kawale
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Konstantin Akopiants
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Yaping Yu
- Centre for Genome Engineering, University of Calgary, Calgary, AB, Canada
| | - Mesfin Fanta
- Department of Oncology, Cross Cancer Institute and University of Alberta, Edmonton, AB, Canada
| | - Michael Weinfeld
- Department of Oncology, Cross Cancer Institute and University of Alberta, Edmonton, AB, Canada
| | - Lawrence F Povirk
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
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14
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He Y, Jing Y, Wei F, Tang Y, Yang L, Luo J, Yang P, Ni Q, Pang J, Liao Q, Xiong F, Guo C, Xiang B, Li X, Zhou M, Li Y, Xiong W, Zeng Z, Li G. Long non-coding RNA PVT1 predicts poor prognosis and induces radioresistance by regulating DNA repair and cell apoptosis in nasopharyngeal carcinoma. Cell Death Dis 2018; 9:235. [PMID: 29445147 PMCID: PMC5833381 DOI: 10.1038/s41419-018-0265-y] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 12/09/2017] [Accepted: 12/12/2017] [Indexed: 12/14/2022]
Abstract
The long non-coding RNA, plasmacytoma variant translocation 1 (PVT1), is highly expressed in a variety of tumors, and is believed to be a potential oncogene. However, the role and mechanism of action of PVT1 in the carcinogenesis and progression of nasopharyngeal carcinomas (NPCs) remains unclear. In this study, for the first time, we have discovered that PVT1 shows higher expression in NPCs than in normal nasopharyngeal epithelial tissue, and patients with NPCs who show higher expression of PVT1 have worse progression-free and overall survivals. Additionally, we observed that the proliferation of NPC cells decreased, and their rate of apoptosis increased; these results indicated that the knockdown of PVT1 expression in the NPC cells induced radiosensitivity. Further, we have shown that the knockdown of PVT1 expression can induce apoptosis in the NPC cells by influencing the DNA damage repair pathway after radiotherapy. In general, our study shows that PVT1 may be a novel biomarker for prognosis and a new target for the treatment of NPCs. Additionally, targeting PVT1 may be a potential strategy for the clinical management of NPC and for the improvement of the curative effect of radiation in NPCs.
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MESH Headings
- Apoptosis/genetics
- Carcinoma, Squamous Cell/diagnosis
- Carcinoma, Squamous Cell/genetics
- Carcinoma, Squamous Cell/mortality
- Carcinoma, Squamous Cell/therapy
- Caspases/genetics
- Caspases/metabolism
- Cell Line, Tumor
- Cell Proliferation
- DNA Repair
- DNA, Neoplasm/genetics
- DNA, Neoplasm/metabolism
- Databases, Genetic
- Follow-Up Studies
- Gamma Rays/therapeutic use
- Gene Expression Regulation, Neoplastic
- Humans
- Nasopharyngeal Carcinoma/diagnosis
- Nasopharyngeal Carcinoma/genetics
- Nasopharyngeal Carcinoma/mortality
- Nasopharyngeal Carcinoma/therapy
- Poly(ADP-ribose) Polymerases/genetics
- Poly(ADP-ribose) Polymerases/metabolism
- Prognosis
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Long Noncoding/antagonists & inhibitors
- RNA, Long Noncoding/genetics
- RNA, Long Noncoding/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Radiation Tolerance/genetics
- Signal Transduction
- Survival Analysis
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Affiliation(s)
- Yi He
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yizhou Jing
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Fang Wei
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yanyan Tang
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Liting Yang
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Jia Luo
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Pei Yang
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Qianxi Ni
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Jinmeng Pang
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Qianjin Liao
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Fang Xiong
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Can Guo
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Bo Xiang
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Xiaoling Li
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Ming Zhou
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yong Li
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Wei Xiong
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhaoyang Zeng
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China.
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China.
| | - Guiyuan Li
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China.
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China.
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15
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Sun C, Han C, Jiang Y, Han N, Zhang M, Li G, Qiao Q. Inhibition of GRP78 abrogates radioresistance in oropharyngeal carcinoma cells after EGFR inhibition by cetuximab. PLoS One 2017; 12:e0188932. [PMID: 29232380 PMCID: PMC5726659 DOI: 10.1371/journal.pone.0188932] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/15/2017] [Indexed: 01/24/2023] Open
Abstract
The EGFR-specific mAb cetuximab is one of the most effective treatments for oropharyngeal carcinoma, while patient responses to EGFR inhibitors given alone are modest. Combination treatment with radiation can improve the efficacy of treatment through increasing radiosensitivity, while resistance to radiation after administration of cetuximab limits its efficiency. Radiation and drugs can damage the endoplasmic reticulum (ER) homeostatic state and result in ER stress (ERS), subsequently causing resistance to radiation and drugs. Whether the ERS pathway is involved in radioresistance after administration of cetuximab has not been reported. Herein, we show that cetuximab could increase the radiosensitivity of FaDu cells but not Detroit562 cells. In addition, cetuximab inhibited the radiation-induced activation of the ERS signalling pathway IRE1α/ATF6-GRP78 in FaDu cells, while this effect was absent in Detroit562 cells. Silencing GRP78 increased the radiosensitivity of oropharyngeal carcinoma cells and inhibited radiation-induced DNA double-strand-break (DSB) repair and autophagy. More interestingly, silencing GRP78 abrogated resistance to cetuximab and radiation in Detroit562 cells and had a synergistic effect with cetuximab in increasing the radiosensitivity of FaDu cells. Immunohistochemistry showed that overexpression of both GRP78 and EGFR was associated with a poor prognosis in oropharyngeal carcinoma patients (P<0.05). Overall, the results of this study show that radioresistance after EGFR inhibition by cetuximab is mediated by the ERS signalling pathway IRE1α/ATF6-GRP78. This suppression was consequently unable to inhibit radiation-induced DSB repair and autophagy in oropharyngeal carcinoma cells, which conferred resistance to radiotherapy and cetuximab. These results suggest that the cooperative effects of radiotherapy and cetuximab could be further improved by inhibiting GRP78 in non-responsive oropharyngeal carcinoma patients.
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Affiliation(s)
- Chaonan Sun
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Chuyang Han
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Yuanjun Jiang
- Department of Urology, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Ning Han
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Miao Zhang
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Guang Li
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Qiao Qiao
- Department of Radiotherapy, the First Hospital of China Medical University, Shenyang, Liaoning, China
- * E-mail:
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16
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Xu D, Du Q, Han C, Wang Z, Zhang X, Wang T, Zhao X, Huang Y, Tong D. p53 signaling modulation of cell cycle arrest and viral replication in porcine circovirus type 2 infection cells. Vet Res 2016; 47:120. [PMID: 27899159 PMCID: PMC5129207 DOI: 10.1186/s13567-016-0403-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/20/2016] [Indexed: 11/10/2022] Open
Abstract
Porcine circovirus type 2 (PCV2) is a ubiquitous pathogen in the swine industry worldwide. Previous studies have shown that PCV2 infection induces host cell apoptosis through up-regulation of p53. To further identify the regulatory roles of p53 signaling in the process of PCV2 infection, we established p53 gene knockout PK15 cell lines using the genomic editor tool CRISPR/Cas9, and further investigated the roles of p53 in modulating the cell cycle and viral replication in this study. The results show that PCV2 infection induced obvious S phase accumulation in wild-type PK15 cells and a compromised S phase accumulation in the p53 gene mutation cells (813PK15p53m/m), but did not induce obvious S phase accumulation in the p53 gene knockout cells (148PK15p53−/−) compared with the respective mock infection. PCV2 infection activated p53 signaling, up-regulated the expression of p21, Cyclin E, and down-regulated Cyclin A, CDK2. In p53 deficient cells, however, PCV2-induced changes in Cyclin A, CDK2, and Cyclin E were efficiently reversed to the basal levels. Detection of PCV2 replication showed decreased viral ORF1 genomic DNA in p53 deficient cells (148PK15p533−/−) and p53 mutated cells (813PK15p53m/m) compared with p53 wild-type cells after different synchronization treatment. Furthermore, PCV2 viral genomic DNA and Cap protein levels were higher in the cells released from S phase synchronized cells than in the cells released from the G0/G1 phase or G2/M phase-synchronized, or asynchronous cells after 18 h post-infection. Taken together, this study demonstrates that PCV2 infection induces S phase accumulation to favor viral replication in host cells through activation of the p53 pathway.
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Affiliation(s)
- Dan Xu
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Qian Du
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Cong Han
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Zengguo Wang
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xiujuan Zhang
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Tongtong Wang
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xiaomin Zhao
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China
| | - Yong Huang
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China.
| | - Dewen Tong
- College of Veterinary Medicine, Northwest A&F University, 22 Xinong Rd, Yangling, Shaanxi, 712100, People's Republic of China.
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17
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Kari V, Mansour WY, Raul SK, Baumgart SJ, Mund A, Grade M, Sirma H, Simon R, Will H, Dobbelstein M, Dikomey E, Johnsen SA. Loss of CHD1 causes DNA repair defects and enhances prostate cancer therapeutic responsiveness. EMBO Rep 2016; 17:1609-1623. [PMID: 27596623 DOI: 10.15252/embr.201642352] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/11/2016] [Indexed: 01/08/2023] Open
Abstract
The CHD1 gene, encoding the chromo-domain helicase DNA-binding protein-1, is one of the most frequently deleted genes in prostate cancer. Here, we examined the role of CHD1 in DNA double-strand break (DSB) repair in prostate cancer cells. We show that CHD1 is required for the recruitment of CtIP to chromatin and subsequent end resection during DNA DSB repair. Our data support a role for CHD1 in opening the chromatin around the DSB to facilitate the recruitment of homologous recombination (HR) proteins. Consequently, depletion of CHD1 specifically affects HR-mediated DNA repair but not non-homologous end joining. Together, we provide evidence for a previously unknown role of CHD1 in DNA DSB repair via HR and show that CHD1 depletion sensitizes cells to PARP inhibitors, which has potential therapeutic relevance. Our findings suggest that CHD1 deletion, like BRCA1/2 mutation in ovarian cancer, may serve as a marker for prostate cancer patient stratification and the utilization of targeted therapies such as PARP inhibitors, which specifically target tumors with HR defects.
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Affiliation(s)
- Vijayalakshmi Kari
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Wael Yassin Mansour
- Department of Tumor Biology, National Cancer Institute, Cairo University, Cairo, Egypt.,Laboratory of Radiobiology and Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sanjay Kumar Raul
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Simon J Baumgart
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Andreas Mund
- Chromatin Structure and Function Group, Protein Signaling Program, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marian Grade
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Hüseyin Sirma
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ronald Simon
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hans Will
- Institute for Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Matthias Dobbelstein
- Institute of Molecular Oncology, University Medical Center Göttingen, Göttingen, Germany
| | - Ekkehard Dikomey
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Steven A Johnsen
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
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Dale Rein I, Solberg Landsverk K, Micci F, Patzke S, Stokke T. Replication-induced DNA damage after PARP inhibition causes G2 delay, and cell line-dependent apoptosis, necrosis and multinucleation. Cell Cycle 2016; 14:3248-60. [PMID: 26312527 PMCID: PMC4825575 DOI: 10.1080/15384101.2015.1085137] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
PARP inhibitors have been approved for treatment of tumors with mutations in or loss of BRCA1/2. The molecular mechanisms and particularly the cellular phenotypes resulting in synthetic lethality are not well understood and varying clinical responses have been observed. We have investigated the dose- and time-dependency of cell growth, cell death and cell cycle traverse of 4 malignant lymphocyte cell lines treated with the PARP inhibitor Olaparib. PARP inhibition induced a severe growth inhibition in this cell line panel and increased the levels of phosphorylated H2AX-associated DNA damage in S phase. Repair of the remaining replication related damage caused a G2 phase delay before entry into mitosis. The G2 delay, and the growth inhibition, was more pronounced in the absence of functional ATM. Further, Olaparib treated Reh and Granta-519 cells died by apoptosis, while U698 and JVM-2 cells proceeded through mitosis with aberrant chromosomes, skipped cytokinesis, and eventually died by necrosis. The TP53-deficient U698 cells went through several rounds of DNA replication and mitosis without cytokinesis, ending up as multinucleated cells with DNA contents of up to 16c before dying. In summary, we report here for the first time cell cycle-resolved DNA damage induction, and cell line-dependent differences in the mode of cell death caused by PARP inhibition.
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Affiliation(s)
- Idun Dale Rein
- a Group for Molecular Radiation Biology ; Department of Radiation Biology ; The Norwegian Radium Hospital ; Oslo , Norway
| | - Kirsti Solberg Landsverk
- a Group for Molecular Radiation Biology ; Department of Radiation Biology ; The Norwegian Radium Hospital ; Oslo , Norway
| | - Francesca Micci
- b Section of Cancer Cytogenetics, Institute for Medical Informatics, The Norwegian Radium Hospital ; Oslo , Norway.,c Centre for Cancer Biomedicine, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital ; Oslo , Norway
| | - Sebastian Patzke
- a Group for Molecular Radiation Biology ; Department of Radiation Biology ; The Norwegian Radium Hospital ; Oslo , Norway
| | - Trond Stokke
- a Group for Molecular Radiation Biology ; Department of Radiation Biology ; The Norwegian Radium Hospital ; Oslo , Norway
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19
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Torres-Huerta AL, Martínez-Miguel RM, Bazán-Tejeda ML, Bermúdez-Cruz RM. Characterization of recombinase DMC1B and its functional role as Rad51 in DNA damage repair in Giardia duodenalis trophozoites. Biochimie 2016; 127:173-86. [DOI: 10.1016/j.biochi.2016.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 05/22/2016] [Indexed: 01/08/2023]
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20
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Bakr A, Köcher S, Volquardsen J, Reimer R, Borgmann K, Dikomey E, Rothkamm K, Mansour WY. Functional crosstalk between DNA damage response proteins 53BP1 and BRCA1 regulates double strand break repair choice. Radiother Oncol 2015; 119:276-81. [PMID: 26615718 DOI: 10.1016/j.radonc.2015.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/28/2015] [Accepted: 11/01/2015] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to elucidate the impact of DNA damage response (DDR) proteins 53BP1 and BRCA1 on the double-strand break (DSB)-repair choice. This is important not only in order to understand the underlying mechanisms of DSB-repair pathway regulation but also to determine the therapeutic implications for BRCA1-associated tumors. MATERIALS AND METHODS Human tumor cell lines A549 and HeLa were used. Non-homologous end-joining (NHEJ) and homologous recombination (HR) were assessed using NHEJ and HR reporter constructs. Colocalization of HR-proteins RPA and RAD51 with 53BP1 was evaluated by confocal microscopy and 3D-analysis. RESULTS We demonstrate a specific crosstalk between 53BP1 and BRCA1. While 53BP1 does not colocalize with RPA or RAD51 and prohibits the recruitment of BRCA1 to DSBs to stimulate NHEJ, BRCA1 promotes the 53BP1 displacement specifically in S/G2-phase to allow end-resection, initiating HR. HR-efficiency was restored in BRCA1-depleted cells upon additional 53BP1-knockdown. Further, we found that 53BP1-mediated end protection precedes BRCA1-dependent end-resection. CONCLUSION These results demonstrate that the interplay between 53BP1/NHEJ and BRCA1/HR is of great relevance for tumor treatment, as the 53BP1 status would be highly important for the treatment response of BRCA1-associated tumors.
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Affiliation(s)
- Ali Bakr
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Sabrina Köcher
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Jennifer Volquardsen
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Rudolph Reimer
- Heinrich-Pette-Institute Leibniz-Institute for Experimental Virology, Hamburg, Germany
| | - Kerstin Borgmann
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Ekkehard Dikomey
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Kai Rothkamm
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany
| | - Wael Y Mansour
- Laboratory of Radiobiology and Experimental Radio-oncology, University Medical Center Hamburg Eppendorf, Germany; Tumor Biology Department, National Cancer Institute, Cairo University, Egypt.
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21
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Solovjeva L, Firsanov D, Vasilishina A, Chagin V, Pleskach N, Kropotov A, Svetlova M. DNA double-strand break repair is impaired in presenescent Syrian hamster fibroblasts. BMC Mol Biol 2015; 16:18. [PMID: 26458748 PMCID: PMC4601148 DOI: 10.1186/s12867-015-0046-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 09/28/2015] [Indexed: 12/21/2022] Open
Abstract
Background Studies of DNA damage response are critical for the comprehensive understanding of age-related changes in cells, tissues and organisms. Syrian hamster cells halt proliferation and become presenescent after several passages in standard conditions of cultivation due to what is known as «culture stress». Using proliferating young and non-dividing presenescent cells in primary cultures of Syrian hamster fibroblasts, we defined their response to the action of radiomimetic drug bleomycin (BL) that induces DNA double-strand breaks (DSBs). Results The effect of the drug was estimated by immunoblotting and immunofluorescence microscopy using the antibody to phosphorylated histone H2AX (gH2AX), which is generally accepted as a DSB marker. At all stages of the cell cycle, both presenescent and young cells demonstrated variability of the number of gH2AX foci per nucleus. gH2AX focus induction was found to be independent from BL-hydrolase expression. Some differences in DSB repair process between BL-treated young and presenescent Syrian hamster cells were observed: (1) the kinetics of gH2AX focus loss in G0 fibroblasts of young culture was faster than in cells that prematurely stopped dividing; (2) presenescent cells were characterized by a slower recruitment of DSB repair proteins 53BP1, phospho-DNA-PK and phospho-ATM to gH2AX focal sites, while the rate of phosphorylated ATM/ATR substrate accumulation was the same as that in young cells. Conclusions Our results demonstrate an impairment of DSB repair in prematurely aged Syrian hamster fibroblasts in comparison with young fibroblasts, suggesting age-related differences in response to BL therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12867-015-0046-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ljudmila Solovjeva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
| | - Denis Firsanov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia. .,Saint-Petersburg's State Pediatric Medical University, Ministry of Health of Russian Federation, 2 Litovskaya st., Saint Petersburg, 194100, Russia.
| | - Anastasia Vasilishina
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
| | - Vadim Chagin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
| | - Nadezhda Pleskach
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
| | - Andrey Kropotov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
| | - Maria Svetlova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretski ave., Saint Petersburg, 194064, Russia.
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22
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Rodemann HP, Bodis S. Cutting-edge research in basic and translational radiation biology/oncology reflections from the 14th International Wolfsberg Meeting on Molecular Radiation Biology/Oncology 2015. Radiother Oncol 2015; 116:335-41. [DOI: 10.1016/j.radonc.2015.09.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 09/04/2015] [Accepted: 09/05/2015] [Indexed: 01/11/2023]
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23
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Role for Artemis nuclease in the repair of radiation-induced DNA double strand breaks by alternative end joining. DNA Repair (Amst) 2015; 31:29-40. [DOI: 10.1016/j.dnarep.2015.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 04/14/2015] [Accepted: 04/15/2015] [Indexed: 11/24/2022]
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24
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Krajewska M, Fehrmann RSN, de Vries EGE, van Vugt MATM. Regulators of homologous recombination repair as novel targets for cancer treatment. Front Genet 2015; 6:96. [PMID: 25852742 PMCID: PMC4367534 DOI: 10.3389/fgene.2015.00096] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 02/23/2015] [Indexed: 12/20/2022] Open
Abstract
To cope with DNA damage, cells possess a complex signaling network called the ‘DNA damage response’, which coordinates cell cycle control with DNA repair. The importance of this network is underscored by the cancer predisposition that frequently goes along with hereditary mutations in DNA repair genes. One especially important DNA repair pathway in this respect is homologous recombination (HR) repair. Defects in HR repair are observed in various cancers, including hereditary breast, and ovarian cancer. Intriguingly, tumor cells with defective HR repair show increased sensitivity to chemotherapeutic reagents, including platinum-containing agents. These observations suggest that HR-proficient tumor cells might be sensitized to chemotherapeutics if HR repair could be therapeutically inactivated. HR repair is an extensively regulated process, which depends strongly on the activity of various other pathways, including cell cycle pathways, protein-control pathways, and growth factor-activated receptor signaling pathways. In this review, we discuss how the mechanistic wiring of HR is controlled by cell-intrinsic or extracellular pathways. Furthermore, we have performed a meta-analysis on available genome-wide RNA interference studies to identify additional pathways that control HR repair. Finally, we discuss how these HR-regulatory pathways may provide therapeutic targets in the context of radio/chemosensitization.
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Affiliation(s)
- Małgorzata Krajewska
- Department of Medical Oncology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Rudolf S N Fehrmann
- Department of Medical Oncology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Elisabeth G E de Vries
- Department of Medical Oncology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Marcel A T M van Vugt
- Department of Medical Oncology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen Groningen, Netherlands
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Kobayashi J, Saito Y, Okui M, Miwa N, Komatsu K. Increased oxidative stress in AOA3 cells disturbs ATM-dependent DNA damage responses. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 782:42-50. [PMID: 25868131 DOI: 10.1016/j.mrgentox.2015.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 03/15/2015] [Accepted: 03/17/2015] [Indexed: 12/29/2022]
Abstract
Ataxia telangiectasia (AT) is caused by a mutation in the ataxia-telangiectasia-mutated (ATM) gene; the condition is associated with hyper-radiosensitivity, abnormal cell-cycle checkpoints, and genomic instability. AT patients also show cerebellar ataxia, possibly due to reactive oxygen species (ROS) sensitivity in neural cells. The ATM protein is a key regulator of the DNA damage response. Recently, several AT-like disorders have been reported. The genes responsible for them are predicted to encode proteins that interact with ATM in the DNA-damage response. Ataxia with oculomotor apraxia types 1-3 (AOA1, 2, and 3) result in a neurodegenerative and cellular phenotype similar to AT; however, the basis of this phenotypic similarity is unclear. Here, we show that the cells of AOA3 patients display aberrant ATM-dependent phosphorylation and apoptosis following γ-irradiation. The ATM-dependent response to H2O2 treatment was abrogated in AOA3 cells. Furthermore, AOA3 cells had reduced ATM activity. Our results suggest that the attenuated ATM-related response is caused by an increase in endogenous ROS in AOA3 cells. Pretreatment of cells with pyocyanin, which induces endogenous ROS production, abolished the ATM-dependent response. Moreover, AOA3 cells had decreased homologous recombination (HR) activity, and pyocyanin pretreatment reduced HR activity in HeLa cells. These results indicate that excess endogenous ROS represses the ATM-dependent cellular response and HR repair in AOA3 cells. Since the ATM-dependent cell-cycle checkpoint is an important block to carcinogenesis, such inactivation of ATM may lead to tumorigenesis as well as neurodegeneration.
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Affiliation(s)
- Junya Kobayashi
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan.
| | - Yuichiro Saito
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan
| | - Michiyo Okui
- Biomedical Engineering Center, Toin University of Yokohama, Yokohama 225-8503, Japan
| | - Noriko Miwa
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan
| | - Kenshi Komatsu
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan
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26
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Bakr A, Oing C, Köcher S, Borgmann K, Dornreiter I, Petersen C, Dikomey E, Mansour WY. Involvement of ATM in homologous recombination after end resection and RAD51 nucleofilament formation. Nucleic Acids Res 2015; 43:3154-66. [PMID: 25753674 PMCID: PMC4381069 DOI: 10.1093/nar/gkv160] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 02/18/2015] [Indexed: 12/03/2022] Open
Abstract
Ataxia-telangiectasia mutated (ATM) is needed for the initiation of the double-strand break (DSB) repair by homologous recombination (HR). ATM triggers DSB end resection by stimulating the nucleolytic activity of CtIP and MRE11 to generate 3′-ssDNA overhangs, followed by RPA loading and RAD51 nucleofilament formation. Here we show for the first time that ATM is also needed for later steps in HR after RAD51 nucleofilament formation. Inhibition of ATM after completion of end resection did not affect RAD51 nucleofilament formation, but resulted in HR deficiency as evidenced by (i) an increase in the number of residual RAD51/γH2AX foci in both S and G2 cells, (ii) the decrease in HR efficiency as detected by HR repair substrate (pGC), (iii) a reduced SCE rate and (iv) the radiosensitization of cells by PARP inhibition. This newly described role for ATM was found to be dispensable in heterochromatin-associated DSB repair, as KAP1-depletion did not alleviate the HR-deficiency when ATM was inhibited after end resection. Moreover, we demonstrated that ATR can partly compensate for the deficiency in early, but not in later, steps of HR upon ATM inhibition. Taken together, we describe here for the first time that ATM is needed not only for the initiation but also for the completion of HR.
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Affiliation(s)
- A Bakr
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - C Oing
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany Department of Oncology, Hematology and Bone Marrow Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - S Köcher
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - K Borgmann
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - I Dornreiter
- Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Hamburg 20251, Germany
| | - C Petersen
- Department of Radiotherapy & Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - E Dikomey
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - W Y Mansour
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany Tumor Biology Department, National Cancer Institute, Cairo University, Cairo 11796, Egypt
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Abstract
Infiltrating ductal adenocarcinoma of the pancreas is a real enigma. On one hand, it is one of the most deadly of all of the solid malignancies. On the other hand, the neoplastic glands can be remarkably well-differentiated, and it can be difficult to distinguish between a reactive non-neoplastic gland and a gland of invasive adenocarcinoma. In this review, we will present diagnostic criteria that one can "hang your hat on" when establishing the diagnosis of infiltrating ductal adenocarcinoma of the pancreas. We will also review clinically important features of the disease, and, with the impending incorporation of molecular genetics into everyday practice, we will emphasize clinical applications of cancer genetics.
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Affiliation(s)
- Ralph H Hruban
- Department of Pathology, the Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins University School of Medicine, Weinberg 2242, 401 N Broadway, Baltimore, Maryland 21231; Department of Oncology, the Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
| | - David S Klimstra
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York
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28
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Dutta B, Ren Y, Hao P, Sim KH, Cheow E, Adav S, Tam JP, Sze SK. Profiling of the Chromatin-associated Proteome Identifies HP1BP3 as a Novel Regulator of Cell Cycle Progression. Mol Cell Proteomics 2014; 13:2183-97. [PMID: 24830416 DOI: 10.1074/mcp.m113.034975] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Indexed: 12/31/2022] Open
Abstract
The chromatin-associated proteome (chromatome) regulates cellular gene expression by restricting access of transcriptional machinery to template DNA, and dynamic re-modeling of chromatin structure is required to regulate critical cell functions including growth and replication, DNA repair and recombination, and oncogenic transformation in progression to cancer. Central to the control of these processes is efficient regulation of the host cell cycle, which is maintained by rapid changes in chromatin conformation during normal cycle progression. A global overview of chromatin protein organization is therefore essential to fully understand cell cycle regulation, but the influence of the chromatome and chromatin binding topology on host cell cycle progression remains poorly defined. Here we used partial MNase digestion together with iTRAQ-based high-throughput quantitative proteomics to quantify chromatin-associated proteins during interphase progression. We identified a total of 481 proteins with high confidence that were involved in chromatin-dependent events including transcriptional regulation, chromatin re-organization, and DNA replication and repair, whereas the quantitative data revealed the temporal interactions of these proteins with chromatin during interphase progression. When combined with biochemical and functional assays, these data revealed a strikingly dynamic association of protein HP1BP3 with the chromatin complex during different stages of interphase, and uncovered a novel regulatory role for this molecule in transcriptional regulation. We report that HP1BP3 protein maintains heterochromatin integrity during G1-S progression and regulates the duration of G1 phase to critically influence cell proliferative capacity.
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Affiliation(s)
- Bamaprasad Dutta
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Yan Ren
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Piliang Hao
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Kae Hwan Sim
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Esther Cheow
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Sunil Adav
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - James P Tam
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Siu Kwan Sze
- From the ‡School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
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Sasaki MS, Tachibana A, Takeda S. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors. JOURNAL OF RADIATION RESEARCH 2014; 55:391-406. [PMID: 24366315 PMCID: PMC4014156 DOI: 10.1093/jrr/rrt133] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 10/20/2013] [Accepted: 10/22/2013] [Indexed: 06/03/2023]
Abstract
Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking.
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Affiliation(s)
- Masao S. Sasaki
- Kyoto University, 17-12 Shironosato, Nagaokakyo-shi, Kyoto 617-0835, Japan
| | - Akira Tachibana
- Department of Biology, Faculty of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto 606-8501, Japan
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30
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Sun H, Wang Y, Wang Z, Meng J, Qi Z, Yang G. Aurora-A controls cancer cell radio- and chemoresistance via ATM/Chk2-mediated DNA repair networks. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:934-44. [DOI: 10.1016/j.bbamcr.2014.01.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/17/2014] [Accepted: 01/21/2014] [Indexed: 12/18/2022]
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TACC3 deregulates the DNA damage response and confers sensitivity to radiation and PARP inhibition. Oncogene 2014; 34:1667-78. [PMID: 24769898 DOI: 10.1038/onc.2014.105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 02/28/2014] [Accepted: 03/12/2014] [Indexed: 12/21/2022]
Abstract
Deregulation of the transforming acidic coiled-coil protein 3 (TACC3), an important factor in the centrosome-microtubule system, has been linked to a variety of human cancer types. We have recently reported on the oncogenic potential of TACC3; however, the molecular mechanisms by which TACC3 mediates oncogenic function remain to be elucidated. In this study, we show that high levels of TACC3 lead to the accumulation of DNA double-strand breaks (DSBs) and disrupt the normal cellular response to DNA damage, at least in part, by negatively regulating the expression of ataxia telangiectasia mutated (ATM) and the subsequent DNA damage response (DDR) signaling cascade. Cells expressing high levels of TACC3 display defective checkpoints and DSB-mediated homologous recombination (HR) and non-homologous end joining (NHEJ) repair systems, leading to genomic instability. Importantly, high levels of TACC3 confer cellular sensitization to radiation and poly(ADP-ribose) polymerase (PARP) inhibition. Overall, our findings provide critical information regarding the mechanisms by which TACC3 contributes to genomic instability, potentially leading to cancer development, and suggest a novel prognostic, diagnostic and therapeutic strategy for the treatment of cancer types expressing high levels of TACC3.
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Köcher S, Spies-Naumann A, Kriegs M, Dahm-Daphi J, Dornreiter I. ATM is required for the repair of Topotecan-induced replication-associated double-strand breaks. Radiother Oncol 2013; 108:409-14. [PMID: 23928469 DOI: 10.1016/j.radonc.2013.06.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/21/2013] [Accepted: 06/22/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE DNA replication is a promising target for anti-cancer therapies. Therefore, the understanding of replication-associated DNA repair mechanisms is of great interest. One key factor of DNA double-strand break (DSB) repair is the PIK kinase Ataxia-Telangiectasia Mutated (ATM) but it is still unclear whether ATM is involved in the repair of replication-associated DSBs. Here, we focused on the involvement of ATM in homology-directed repair (HDR) of indirect DSBs associated with replication. MATERIAL AND METHODS Experiments were performed using ATM-deficient and -proficient human cells. Replication-associated DSBs were induced with Topotecan (TPT) and compared with γ-irradiation (IR). Cell survival was measured by clonogenic assay. Overall DSB repair and HDR were evaluated by detecting residual γH2AX/53BP1 and Rad51 foci, respectively. Cell cycle distribution was analysed by flow cytometry and protein expression by Western blot. RESULTS ATM-deficiency leads to enhanced numbers of residual DSBs, resulting in a pronounced S/G2-block and decreased survival upon TPT-treatment. In common with IR, persisting Rad51 foci were detected following TPT-treatment. CONCLUSIONS These results demonstrate that ATM is essentially required for the completion of HR-mediated repair of TPT-induced DSBs formed indirectly at replication forks.
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Affiliation(s)
- Sabrina Köcher
- Heinrich-Pette-Institute Leibniz-Institute for Experimental Virology, Hamburg, Germany; Institute of Radiobiology and Molecular Radiation Oncology, Philipps-University of Marburg, Germany.
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Rass E, Chandramouly G, Zha S, Alt FW, Xie A. Ataxia telangiectasia mutated (ATM) is dispensable for endonuclease I-SceI-induced homologous recombination in mouse embryonic stem cells. J Biol Chem 2013; 288:7086-95. [PMID: 23355489 DOI: 10.1074/jbc.m112.445825] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ataxia telangiectasia mutated (ATM) is activated upon DNA double strand breaks (DSBs) and phosphorylates numerous DSB response proteins, including histone H2AX on serine 139 (Ser-139) to form γ-H2AX. Through interaction with MDC1, γ-H2AX promotes DSB repair by homologous recombination (HR). H2AX Ser-139 can also be phosphorylated by DNA-dependent protein kinase catalytic subunit and ataxia telangiectasia- and Rad3-related kinase. Thus, we tested whether ATM functions in HR, particularly that controlled by γ-H2AX, by comparing HR occurring at the euchromatic ROSA26 locus between mouse embryonic stem cells lacking either ATM, H2AX, or both. We show here that loss of ATM does not impair HR, including H2AX-dependent HR, but confers sensitivity to inhibition of poly(ADP-ribose) polymerases. Loss of ATM or H2AX has independent contributions to cellular sensitivity to ionizing radiation. The ATM-independent HR function of H2AX requires both Ser-139 phosphorylation and γ-H2AX/MDC1 interaction. Our data suggest that ATM is dispensable for HR, including that controlled by H2AX, in the context of euchromatin, excluding the implication of such an HR function in genomic instability, hypersensitivity to DNA damage, and poly(ADP-ribose) polymerase inhibition associated with ATM deficiency.
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Affiliation(s)
- Emilie Rass
- Department of Medicine, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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Mansour WY, Bogdanova NV, Kasten-Pisula U, Rieckmann T, Köcher S, Borgmann K, Baumann M, Krause M, Petersen C, Hu H, Gatti RA, Dikomey E, Dörk T, Dahm-Daphi J. Aberrant overexpression of miR-421 downregulates ATM and leads to a pronounced DSB repair defect and clinical hypersensitivity in SKX squamous cell carcinoma. Radiother Oncol 2012. [PMID: 23199656 DOI: 10.1016/j.radonc.2012.10.020] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Cellular and clinical sensitivity to ionizing radiation (IR) is determined by DNA double-strand breaks (DSB) repair. Here, we investigate the molecular mechanism underlying the extreme response of a head and neck tumor case (SKX) to standard radiotherapy. METHODS Immunofluorescence (IF) was used for the assessment of DSB repair, Western blot and real-time PCR for protein and mRNA expression, respectively. RESULTS SKX cells exhibited a pronounced radiosensitivity associated with numerous residual γ-H2AX foci after IR. This was not associated with lacking canonical repair proteins. SKX cells did not express any ATM protein. Accordingly, immunoblotting revealed no ATM kinase activity toward substrates such as p-SMC1, p-CHK2 and p-KAP1. Sequencing of all 66 exons of ATM showed no mutation. ATM mRNA level was moderately reduced, which could be reverted by 5'-Aza-C treatment but without restoring protein levels. Importantly, we demonstrated a post-transcriptional regulation in SKX cells via 6-fold enhanced levels of miR-421, which targets the 3'-UTR of ATM mRNA. Transfection of SKX cells with either anti-miR-421 inhibitor or a microRNA-insensitive ATM vector recovered ATM expression and abrogated the hyper-radiosensitivity. CONCLUSION This is the first report describing microRNA-mediated down-regulation of ATM leading to clinically manifest tumor radiosensitivity.
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Affiliation(s)
- Wael Y Mansour
- Institute of Radiobiology and Molecular Radiation Oncology, Philipps-University, Marburg, Germany.
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