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Kuang Y, Kang J, Li H, Liu B, Zhao X, Li L, Jin X, Li Q. Multiple functions of p21 in cancer radiotherapy. J Cancer Res Clin Oncol 2021; 147:987-1006. [PMID: 33547489 DOI: 10.1007/s00432-021-03529-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/10/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Greater than half of cancer patients experience radiation therapy, for both radical and palliative objectives. It is well known that researches on radiation response mechanisms are conducive to improve the efficacy of cancer radiotherapy. p21 was initially identified as a widespread inhibitor of cyclin-dependent kinases, transcriptionally modulated by p53 and a marker of cellular senescence. It was once considered that p21 acts as a tumour suppressor mainly to restrain cell cycle progression, thereby resulting in growth suppression. With the deepening researches on p21, p21 has been found to regulate radiation responses via participating in multiple cellular processes, including cell cycle arrest, apoptosis, DNA repair, senescence and autophagy. Hence, a comprehensive summary of the p21's functions in radiation response will provide a new perspective for radiotherapy against cancer. METHODS We summarize the recent pertinent literature from various electronic databases, including PubMed and analyzed several datasets from Gene Expression Omnibus database. This review discusses how p21 influences the effect of cancer radiotherapy via involving in multiple signaling pathways and expounds the feasibility, barrier and risks of using p21 as a biomarker as well as a therapeutic target of radiotherapy. CONCLUSION p21's complicated and important functions in cancer radiotherapy make it a promising therapeutic target. Besides, more thorough insights of p21 are needed to make it a safe therapeutic target.
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Affiliation(s)
- Yanbei Kuang
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou, 730000, Gansu, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou, 730000, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Lanzhou, 730000, Gansu, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian Kang
- College of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Hongbin Li
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, 730050, China
| | - Bingtao Liu
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou, 730000, Gansu, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou, 730000, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Lanzhou, 730000, Gansu, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xueshan Zhao
- The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Linying Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou, 730000, Gansu, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou, 730000, China
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Lanzhou, 730000, Gansu, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaodong Jin
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou, 730000, Gansu, China.
- Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou, 730000, China.
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Lanzhou, 730000, Gansu, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou, 730000, Gansu, China.
- Key Laboratory of Heavy Ion Radiation Biology and Medicine, Chinese Academy of Sciences, Lanzhou, 730000, China.
- Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Lanzhou, 730000, Gansu, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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Down-Regulation of miR-23a-3p Mediates Irradiation-Induced Neuronal Apoptosis. Int J Mol Sci 2020; 21:ijms21103695. [PMID: 32456284 PMCID: PMC7279507 DOI: 10.3390/ijms21103695] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/19/2020] [Accepted: 05/21/2020] [Indexed: 12/13/2022] Open
Abstract
Radiation-induced central nervous system toxicity is a significant risk factor for patients receiving cancer radiotherapy. Surprisingly, the mechanisms responsible for the DNA damage-triggered neuronal cell death following irradiation have yet to be deciphered. Using primary cortical neuronal cultures in vitro, we demonstrated that X-ray exposure induces the mitochondrial pathway of intrinsic apoptosis and that miR-23a-3p plays a significant role in the regulation of this process. Primary cortical neurons exposed to irradiation show the activation of DNA-damage response pathways, including the sequential phosphorylation of ATM kinase, histone H2AX, and p53. This is followed by the p53-dependent up-regulation of the pro-apoptotic Bcl2 family molecules, including the BH3-only molecules PUMA, Noxa, and Bim, leading to mitochondrial outer membrane permeabilization (MOMP) and the release of cytochrome c, which activates caspase-dependent apoptosis. miR-23a-3p, a negative regulator of specific pro-apoptotic Bcl-2 family molecules, is rapidly decreased after neuronal irradiation. By increasing the degradation of PUMA and Noxa mRNAs in the RNA-induced silencing complex (RISC), the administration of the miR-23a-3p mimic inhibits the irradiation-induced up-regulation of Noxa and Puma. These changes result in an attenuation of apoptotic processes such as MOMP, the release of cytochrome c and caspases activation, and a reduction in neuronal cell death. The neuroprotective effects of miR-23a-3p administration may not only involve the direct inhibition of pro-apoptotic Bcl-2 molecules downstream of p53 but also include the attenuation of secondary DNA damage upstream of p53. Importantly, we demonstrated that brain irradiation in vivo results in the down-regulation of miR-23a-3p and the elevation of pro-apoptotic Bcl2-family molecules PUMA, Noxa, and Bax, not only broadly in the cortex and hippocampus, except for Bax, which was up-regulated only in the hippocampus but also selectively in isolated neuronal populations from the irradiated brain. Overall, our data suggest that miR-23a-3p down-regulation contributes to irradiation-induced intrinsic pathways of neuronal apoptosis. These regulated pathways of neurodegeneration may be the target of effective neuroprotective strategies using miR-23a-3p mimics to block their development and increase neuronal survival after irradiation.
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Russo LC, Farias JO, Forti FL. DUSP3 maintains genomic stability and cell proliferation by modulating NER pathway and cell cycle regulatory proteins. Cell Cycle 2020; 19:1545-1561. [PMID: 32380926 DOI: 10.1080/15384101.2020.1762043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The DUSP3 phosphatase regulates cell cycle, proliferation, apoptosis and senescence of different cell types, lately shown as a mediator of DNA repair processes. This work evaluated the impact of DUSP3 loss of function (lof) on DNA repair-proficient fibroblasts (MRC-5), NER-deficient cell lines (XPA and XPC) and translesion DNA synthesis (TLS)-deficient cells (XPV), after UV-radiation stress. The levels of DNA strand breaks, CPDs and 6-4-PPs have accumulated over time in all cells under DUSP3 lof, with a significant increase in NER-deficient lines. The inefficient repair of these lesions increased sub-G1 population of XPA and XPC cells 24 hours after UV treatment, notably marked by DUSP3 lof, which is associated with a reduced cell population in G1, S and G2/M phases. It was also detected an increase in S and G2/M populations of XPV and MRC-5 cells after UV-radiation exposure, which was slightly attenuated by DUSP3 lof due to a discrete increase in sub-G1 cells. The cell cycle progression was accompanied by changes in the levels of the main Cyclins (A1, B1, D1 or E1), CDKs (1, 2, 4 or 6), and the p21 Cip1 inhibitor, in a DUSP3-dependent manner. DUSP3 lof affected the proliferation of MRC-5 and XPA cells, with marked worsening of the XP phenotype after UV radiation. This work highlights the roles of DUSP3 in DNA repair fitness and in the fine control of regulatory proteins of cell cycle, essential mechanisms to maintenance of genomic stability.
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Affiliation(s)
- Lilian Cristina Russo
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
| | - Jessica Oliveira Farias
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
| | - Fabio Luis Forti
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
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Molecular signaling cascades involved in nonmelanoma skin carcinogenesis. Biochem J 2017; 473:2973-94. [PMID: 27679857 DOI: 10.1042/bcj20160471] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/10/2016] [Indexed: 12/17/2022]
Abstract
Nonmelanoma skin cancer (NMSC) is the most common cancer worldwide and the incidence continues to rise, in part due to increasing numbers in high-risk groups such as organ transplant recipients and those taking photosensitizing medications. The most significant risk factor for NMSC is ultraviolet radiation (UVR) from sunlight, specifically UVB, which is the leading cause of DNA damage, photoaging, and malignant transformation in the skin. Activation of apoptosis following UVR exposure allows the elimination of irreversibly damaged cells that may harbor oncogenic mutations. However, UVR also activates signaling cascades that promote the survival of these potentially cancerous cells, resulting in tumor initiation. Thus, the UVR-induced stress response in the skin is multifaceted and requires coordinated activation of numerous pathways controlling DNA damage repair, inflammation, and kinase-mediated signal transduction that lead to either cell survival or cell death. This review focuses on the central signaling mechanisms that respond to UVR and the subsequent cellular changes. Given the prevalence of NMSC and the resulting health care burden, many of these pathways provide promising targets for continued study aimed at both chemoprevention and chemotherapy.
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Mirzayans R, Andrais B, Kumar P, Murray D. The Growing Complexity of Cancer Cell Response to DNA-Damaging Agents: Caspase 3 Mediates Cell Death or Survival? Int J Mol Sci 2016; 17:ijms17050708. [PMID: 27187358 PMCID: PMC4881530 DOI: 10.3390/ijms17050708] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 04/25/2016] [Accepted: 05/03/2016] [Indexed: 02/07/2023] Open
Abstract
It is widely stated that wild-type p53 either mediates the activation of cell cycle checkpoints to facilitate DNA repair and promote cell survival, or orchestrates apoptotic cell death following exposure to cancer therapeutic agents. This reigning paradigm has been challenged by numerous discoveries with different human cell types, including solid tumor-derived cell lines. Thus, activation of the p53 signaling pathway by ionizing radiation and other DNA-damaging agents hinders apoptosis and triggers growth arrest (e.g., through premature senescence) in some genetic backgrounds; such growth arrested cells remain viable, secrete growth-promoting factors, and give rise to progeny with stem cell-like properties. In addition, caspase 3, which is best known for its role in the execution phase of apoptosis, has been recently reported to facilitate (rather than suppress) DNA damage-induced genomic instability and carcinogenesis. This observation is consistent with an earlier report demonstrating that caspase 3 mediates secretion of the pro-survival factor prostaglandin E2, which in turn promotes enrichment of tumor repopulating cells. In this article, we review these and related discoveries and point out novel cancer therapeutic strategies. One of our objectives is to demonstrate the growing complexity of the DNA damage response beyond the conventional “repair and survive, or die” hypothesis.
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Affiliation(s)
- Razmik Mirzayans
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada.
| | - Bonnie Andrais
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada.
| | - Piyush Kumar
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada.
| | - David Murray
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada.
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Andrade-Lima LC, Andrade LN, Menck CFM. ATR suppresses apoptosis after UVB irradiation by controlling both translesion synthesis and alternative tolerance pathways. J Cell Sci 2014; 128:150-9. [PMID: 25380827 DOI: 10.1242/jcs.161596] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ultraviolet (UV) light can stall replication forks owing to the formation of bulky lesions in the DNA. Replication across these blocking lesions occurs through translesion DNA synthesis, and cells activate the ATR damage responses to UV. However, it remains unclear whether lesion bypass requires the replication checkpoint because ATR is not necessary for PCNA ubiquitylation. We observed that ATR knockdown by siRNA increased replication stress and promoted early induction of apoptosis following UVB irradiation in SV40-immortalized human cells, including cells from XP-V and XP-C patients. XP-V cells were further sensitized by the silencing, indicating that DNA polymerase η (Pol η) remains active despite ATR control. However, following UVB irradiation, ATR-depleted cells were unable to achieve mitosis, as would be expected after the loss of a DNA checkpoint control. Thus, ATR also regulates replication arrest recovery following UVB-induced damage, independently of Pol η, in SV40-immortalized cell lines. The ATR-mediated DNA damage response regulates replication and different tolerance pathways, and in these cells, ATR depletion induces replication catastrophe, which contributes to explain the potential of ATR inhibition to protect against UVB-induced carcinogenesis.
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Affiliation(s)
- Leonardo C Andrade-Lima
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Luciana N Andrade
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
| | - Carlos F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil
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Mirzayans R, Andrais B, Scott A, Wang YW, Murray D. Ionizing radiation-induced responses in human cells with differing TP53 status. Int J Mol Sci 2013; 14:22409-35. [PMID: 24232458 PMCID: PMC3856071 DOI: 10.3390/ijms141122409] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/29/2013] [Accepted: 11/04/2013] [Indexed: 12/20/2022] Open
Abstract
Ionizing radiation triggers diverse responses in human cells encompassing apoptosis, necrosis, stress-induced premature senescence (SIPS), autophagy, and endopolyploidy (e.g., multinucleation). Most of these responses result in loss of colony-forming ability in the clonogenic survival assay. However, not all modes of so-called clonogenic cell "death" are necessarily advantageous for therapeutic outcome in cancer radiotherapy. For example, the crosstalk between SIPS and autophagy is considered to influence the capacity of the tumor cells to maintain a prolonged state of growth inhibition that unfortunately can be succeeded by tumor regrowth and disease recurrence. Likewise, endopolyploid giant cells are able to segregate into near diploid descendants that continue mitotic activities. Herein we review the current knowledge on the roles that the p53 and p21(WAF1) tumor suppressors play in determining the fate of human fibroblasts (normal and Li-Fraumeni syndrome) and solid tumor-derived cells after exposure to ionizing radiation. In addition, we discuss the important role of WIP1, a p53-regulated oncogene, in the temporal regulation of the DNA damage response and its contribution to p53 dynamics post-irradiation. This article highlights the complexity of the DNA damage response and provides an impetus for rethinking the nature of cancer cell resistance to therapeutic agents.
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Affiliation(s)
- Razmik Mirzayans
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada; E-Mails: (B.A.); (A.S.); (Y.W.W.); (D.M.)
| | - Bonnie Andrais
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada; E-Mails: (B.A.); (A.S.); (Y.W.W.); (D.M.)
| | - April Scott
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada; E-Mails: (B.A.); (A.S.); (Y.W.W.); (D.M.)
| | - Ying W. Wang
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada; E-Mails: (B.A.); (A.S.); (Y.W.W.); (D.M.)
| | - David Murray
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada; E-Mails: (B.A.); (A.S.); (Y.W.W.); (D.M.)
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8
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Al-Khalaf HH, Aboussekhra A. ATR controls the UV-related upregulation of the CDKN1A mRNA in a Cdk1/HuR-dependent manner. Mol Carcinog 2013; 53:979-87. [PMID: 23813879 DOI: 10.1002/mc.22066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 05/13/2013] [Accepted: 05/31/2013] [Indexed: 11/10/2022]
Abstract
Ultraviolet (UV) light is a carcinogenic agent that upregulates the expression of several genes involved in various cellular processes, including cell cycle checkpoints and apoptosis. The universal cyclin-dependent kinase inhibitor p21(WAF1/Cip1) plays major roles in these processes, and the level of its corresponding message increases several times in response to UV-induced DNA damage. This upregulation is mainly posttranscriptional owing to HuR-dependent mRNA stabilization. Since the protein kinase Atr plays major roles during the cellular response to UV damage, we sought to investigate its possible implication in the stabilization of the p21(WAF1/Cip1) coding mRNA. We have shown that the UV-dependent accumulation of the CDKN1A mRNA is indeed under the control of the Atr protein kinase. Upon UV damage, Atr allows nuclear-cytoplasmic shuttling of the HuR protein, which binds the CDKN1A mRNA and reduces its turnover. This ATR-dependent effect is mediated through UV-related phosphorylation/inactivation of the Cdk1 protein kinase by Atr, which leads to the dissociation of HuR from Cdk1. Indeed, inhibition or shRNA specific knockdown of CDK1 in ATR-deficient cells enhanced the cytoplasmic level of HuR and restored the CDKN1A mRNA upregulation in response to UV damage. These results show that ATR stabilizes the CDKN1A message in response to UV damage through Cdk1-related cytoplasmic accumulation of HuR.
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Affiliation(s)
- Huda H Al-Khalaf
- Department of Molecular Oncology, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia; The Joint Center for Genomics Research, King Abdulaziz City for Science and Technology, Riyadh, Kingdom of Saudi Arabia
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Bernal-Lopez MR, Garrido-Sanchez L, Gomez-Carrillo V, Gallego-Perales JL, Llorente-Cortes V, Calleja F, Gomez-Huelgas R, Badimon L, Tinahones FJ. Antioxidized LDL antibodies are associated with different metabolic pathways in patients with atherosclerotic plaque and type 2 diabetes. Diabetes Care 2013; 36. [PMID: 23193212 PMCID: PMC3609493 DOI: 10.2337/dc12-1030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Oxidized lipoproteins and antioxidized LDL antibodies (antioxLDL abs) have been detected in human plasma and atherosclerotic lesions. The principle aim of this study was to analyze the possible relationship between IgG and IgM antioxLDL abs and factors involved in different metabolic pathways (inflammation, lipid metabolism, apoptosis, and cell cycle arrest profile) in the occluded popliteal artery (OPA) compared with the femoral vein (FV). RESEARCH DESIGN AND METHODS Fifteen patients with advanced atherosclerosis and type 2 diabetes undergoing lower limb amputation participated in this study. Each patient had OPA and FV biopsy specimens and peripheral arterial occlusive disease. By real-time PCR, gene expression was analyzed from the OPA and FV specimens, and antioxLDL ab levels were measured by specific enzyme-linked immunosorbent assay. RESULTS The OPA and FV showed a positive correlation between only IgM antioxLDL ab levels and the expression of genes involved in different metabolic pathways, including inflammation (TFPI), apoptosis (BAX, caspase 3, AKT1), plaque disruption (MMP2 and MMP10), lipid metabolism (SCARB1, PPARg), and cell turnover (CDKN1A), and genes for transcription and growth factors (NFkB and VEGFA, respectively). CONCLUSIONS The results show that gene expression in the metabolic pathways (apoptosis, lipid metabolism, and inflammation) in the OPA and FV are directly related to the levels of IgM antioxLDL abs.
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Affiliation(s)
- M Rosa Bernal-Lopez
- Biomedical Research Laboratory, Endocrinology and Nutrition Department, Hospital Clinico Virgen de la Victoria, Málaga, Spain.
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Falcone G, Mazzola A, Michelini F, Bossi G, Censi F, Biferi MG, Minghetti L, Floridia G, Federico M, Musio A, Crescenzi M. Cytogenetic analysis of human cells reveals specific patterns of DNA damage in replicative and oncogene-induced senescence. Aging Cell 2013; 12:312-5. [PMID: 23167636 DOI: 10.1111/acel.12034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2012] [Indexed: 11/29/2022] Open
Abstract
Senescence is thought to be triggered by DNA damage, usually indirectly assessed as activation of the DNA damage response (DDR), but direct surveys of genetic damage are lacking. Here, we mitotically reactivate senescent human fibroblasts to evaluate their cytogenetic damage. We show that replicative senescence is generally characterized by telomeric fusions. However, both telomeric and extratelomeric aberrations are prevented by hTERT, indicating that even non-telomeric damage descends from the lack of telomerase. Compared with replicative senescent cells, oncogene-induced senescent fibroblasts display significantly higher levels of DNA damage, depicting how oncogene activation can catalyze the generation of further, potentially tumorigenic, genetic damage.
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Affiliation(s)
| | - Alessia Mazzola
- Department of Cell Biology and Neurosciences; National Institute of Health; Rome; Italy
| | - Flavia Michelini
- Department of Cell Biology and Neurosciences; National Institute of Health; Rome; Italy
| | - Gianluca Bossi
- Department of Molecular Oncology; Regina Elena Cancer Institute; Rome; Italy
| | - Federica Censi
- National Centre for Rare Diseases; National Institute of Health; Rome; Italy
| | - Maria G. Biferi
- Department of Cell Biology and Neurosciences; National Institute of Health; Rome; Italy
| | - Luisa Minghetti
- Department of Cell Biology and Neurosciences; National Institute of Health; Rome; Italy
| | - Giovanna Floridia
- National Centre for Rare Diseases; National Institute of Health; Rome; Italy
| | | | | | - Marco Crescenzi
- Department of Cell Biology and Neurosciences; National Institute of Health; Rome; Italy
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Ray A, Milum K, Battu A, Wani G, Wani AA. NER initiation factors, DDB2 and XPC, regulate UV radiation response by recruiting ATR and ATM kinases to DNA damage sites. DNA Repair (Amst) 2013; 12:273-83. [PMID: 23422745 DOI: 10.1016/j.dnarep.2013.01.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 01/07/2013] [Accepted: 01/16/2013] [Indexed: 12/27/2022]
Abstract
ATR and ATM kinases are central to the checkpoint activation in response to DNA damage and replication stress. However, the nature of the signal, which initially activates these kinases in response to UV damage, is unclear. Here, we have shown that DDB2 and XPC, two early UV damage recognition factors, are required for the damage-specific ATR and ATM recruitment and phosphorylation. ATR and ATM physically interacted with XPC and promptly localized to the UV damage sites. ATR and ATM recruitment and their phosphorylation were negatively affected in cells defective in DDB2 or XPC functions. Consequently, the phosphorylation of ATR and ATM substrates, Chk1, Chk2, H2AX, and BRCA1 was significantly reduced or abrogated in mutant cells. Furthermore, UV exposure of cells defective in DDB2 or XPC resulted in a marked decrease in BRCA1 and Rad51 recruitment to the damage site. Conversely, ATR- and ATM-deficiency failed to affect the recruitment of DDB2 and XPC to the damage site, and therefore did not influence the NER efficiency. These findings demonstrate a novel function of DDB2 and XPC in maintaining a vital cross-talk with checkpoint proteins, and thereby coordinating subsequent repair and checkpoint activation.
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Affiliation(s)
- Alo Ray
- Department of Radiology, The Ohio State University, Columbus, OH 43210, United States.
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Targeting protective autophagy exacerbates UV-triggered apoptotic cell death. Int J Mol Sci 2012; 13:1209-1224. [PMID: 22312313 PMCID: PMC3269747 DOI: 10.3390/ijms13011209] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 01/30/2023] Open
Abstract
Autophagy is activated by various stresses, including DNA damage, and previous studies of DNA damage-induced autophagy have focused on the response to chemotherapeutic drugs, ionizing radiation, and reactive oxygen species. In this study, we investigated the biological significance of autophagic response to ultraviolet (UV) irradiation in A549 and H1299 cells. Our results indicated that UV induces on-rate autophagic flux in these cells. Autophagy inhibition resulting from the knockdown of beclin-1 and Atg5 reduced cell viability and enhanced apoptosis. Moreover, we found that ATR phosphorylation was accompanied by microtubule-associated protein 1 light chain 3B II (LC3B-II) expression during the early phases following UV irradiation, which is a well-established inducer of ATR. Knocking down ATR further attenuated the reduction in LC3B-II at early stages in response to UV treatment. Despite the potential role of ATR in autophagic response, reduced ATR expression does not affect autophagy induction during late phases (24 and 48 h after UV treatment). The result is consistent with the reduced ATR phosphorylation at the same time points and suggests that autophagic response at this stage is activated via a distinct pathway. In conclusion, this study demonstrated that autophagy acts as a cytoprotective mechanism against UV-induced apoptosis and that autophagy induction accompanied with apoptosis at late stages is independent of ATR activation.
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