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Steffens Reinhardt L, Groen K, Newton C, Avery-Kiejda KA. The role of truncated p53 isoforms in the DNA damage response. Biochim Biophys Acta Rev Cancer 2023; 1878:188882. [PMID: 36977456 DOI: 10.1016/j.bbcan.2023.188882] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/23/2023] [Accepted: 02/25/2023] [Indexed: 03/28/2023]
Abstract
The tumour suppressor p53 is activated following genotoxic stress and regulates the expression of target genes involved in the DNA damage response (DDR). The discovery that p53 isoforms alter the transcription of p53 target genes or p53 protein interactions unveiled an alternative DDR. This review will focus on the role p53 isoforms play in response to DNA damage. The expression of the C-terminally truncated p53 isoforms may be modulated via DNA damage-induced alternative splicing, whereas alternative translation plays an important role in modulating the expression of N-terminally truncated isoforms. The DDR induced by p53 isoforms may enhance the canonical p53 DDR or block cell death mechanisms in a DNA damage- and cell-specific manner, which could contribute to chemoresistance in a cancer context. Thus, a better understanding of the involvement of p53 isoforms in the cell fate decisions could uncover potential therapeutic targets in cancer and other diseases.
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Affiliation(s)
- Luiza Steffens Reinhardt
- School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Newcastle, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Kira Groen
- School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Newcastle, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Cheryl Newton
- School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Newcastle, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Kelly A Avery-Kiejda
- School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Newcastle, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia.
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2
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Osterburg C, Dötsch V. Structural diversity of p63 and p73 isoforms. Cell Death Differ 2022; 29:921-937. [PMID: 35314772 PMCID: PMC9091270 DOI: 10.1038/s41418-022-00975-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 01/25/2023] Open
Abstract
Abstract
The p53 protein family is the most studied protein family of all. Sequence analysis and structure determination have revealed a high similarity of crucial domains between p53, p63 and p73. Functional studies, however, have shown a wide variety of different tasks in tumor suppression, quality control and development. Here we review the structure and organization of the individual domains of p63 and p73, the interaction of these domains in the context of full-length proteins and discuss the evolutionary origin of this protein family.
Facts
Distinct physiological roles/functions are performed by specific isoforms.
The non-divided transactivation domain of p63 has a constitutively high activity while the transactivation domains of p53/p73 are divided into two subdomains that are regulated by phosphorylation.
Mdm2 binds to all three family members but ubiquitinates only p53.
TAp63α forms an autoinhibited dimeric state while all other vertebrate p53 family isoforms are constitutively tetrameric.
The oligomerization domain of p63 and p73 contain an additional helix that is necessary for stabilizing the tetrameric states. During evolution this helix got lost independently in different phylogenetic branches, while the DNA binding domain became destabilized and the transactivation domain split into two subdomains.
Open questions
Is the autoinhibitory mechanism of mammalian TAp63α conserved in p53 proteins of invertebrates that have the same function of genomic quality control in germ cells?
What is the physiological function of the p63/p73 SAM domains?
Do the short isoforms of p63 and p73 have physiological functions?
What are the roles of the N-terminal elongated TAp63 isoforms, TA* and GTA?
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Alternative Splicing in Cancer and Immune Cells. Cancers (Basel) 2022; 14:cancers14071726. [PMID: 35406498 PMCID: PMC8996879 DOI: 10.3390/cancers14071726] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 12/31/2022] Open
Abstract
Splicing is a phenomenon enabling the excision of introns from pre-mRNA to give rise to mature mRNA. All the 20,000 genes of the human genome are concerned by this mechanism. Nevertheless, it is estimated that the proteome is composed of more than 100,000 proteins. How to go from 20,000 genes to more than 100,000 proteins? Alternative splicing (AS) is in charge of this diversity of proteins. AS which is found in most of the cells of an organism, participates in normal cells and in particular in immune cells, in the regulation of cellular behavior. In cancer, AS is highly dysregulated and involved in almost all of the hallmarks that characterize tumor cells. In view of the close link that exists between tumors and the immune system, we present in this review the literature relating to alternative splicing and immunotherapy. We also provide a global but not exhaustive view of AS in the immune system and tumor cells linked to the events that can lead to AS dysregulation in tumors.
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4
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DEAD-Box RNA Helicases in Cell Cycle Control and Clinical Therapy. Cells 2021; 10:cells10061540. [PMID: 34207140 PMCID: PMC8234093 DOI: 10.3390/cells10061540] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 12/11/2022] Open
Abstract
Cell cycle is regulated through numerous signaling pathways that determine whether cells will proliferate, remain quiescent, arrest, or undergo apoptosis. Abnormal cell cycle regulation has been linked to many diseases. Thus, there is an urgent need to understand the diverse molecular mechanisms of how the cell cycle is controlled. RNA helicases constitute a large family of proteins with functions in all aspects of RNA metabolism, including unwinding or annealing of RNA molecules to regulate pre-mRNA, rRNA and miRNA processing, clamping protein complexes on RNA, or remodeling ribonucleoprotein complexes, to regulate gene expression. RNA helicases also regulate the activity of specific proteins through direct interaction. Abnormal expression of RNA helicases has been associated with different diseases, including cancer, neurological disorders, aging, and autosomal dominant polycystic kidney disease (ADPKD) via regulation of a diverse range of cellular processes such as cell proliferation, cell cycle arrest, and apoptosis. Recent studies showed that RNA helicases participate in the regulation of the cell cycle progression at each cell cycle phase, including G1-S transition, S phase, G2-M transition, mitosis, and cytokinesis. In this review, we discuss the essential roles and mechanisms of RNA helicases in the regulation of the cell cycle at different phases. For that, RNA helicases provide a rich source of targets for the development of therapeutic or prophylactic drugs. We also discuss the different targeting strategies against RNA helicases, the different types of compounds explored, the proposed inhibitory mechanisms of the compounds on specific RNA helicases, and the therapeutic potential of these compounds in the treatment of various disorders.
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5
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Diakite B, Kassogue Y, Dolo G, Wang J, Neuschler E, Kassogue O, Keita ML, Traore CB, Kamate B, Dembele E, Nadifi S, Murphy RL, Doumbia S, Hou L, Maiga M. p.Arg72Pro polymorphism of P53 and breast cancer risk: a meta-analysis of case-control studies. BMC MEDICAL GENETICS 2020; 21:206. [PMID: 33076844 PMCID: PMC7574232 DOI: 10.1186/s12881-020-01133-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 09/24/2020] [Indexed: 12/21/2022]
Abstract
Background The effect of the p.Arg72Pro variant of the P53 gene on the risk of development ofbreast cancer remains variable in populations. However, the use ofstrategies such aspoolingage-matched controls with disease may provide a consistent meta-analysis. Our goal was to perform a meta-analysis in order to assess the association of p.Arg72Pro variant of P53 gene with the risk of breast cancer. Methods Databases such as PubMed, Genetics Medical Literature, Harvard University Library, Web of Science and Genesis Library were used to search articles. Case-control studies with age-matched on breast cancer havingevaluated the genotype frequencies of the TP53 p.Arg72Pro polymorphism were selected. The fixed and random effects (Mantel-Haenszel) were calculated using pooled odds ratio of 95% CI to determine the risk of disease. Inconsistency was calculated to determine heterogeneity among the studies. The publication bias was estimated using the funnel plot. Results Twenty-one publications with 7841 cases and 8876 controls were evaluated in this meta-analysis. Overall, our results suggested that TP53 p.Arg72Pro was associated with the risk of breast cancer for the dominant model (OR = 1.09, 95% CI = 1.02–1.16, P = 0.01) and the additive model (OR = 1.09, 95% CI = 1.01–1.17, P = 0.03), but not for the recessive model (OR = 1.07, 95% CI = 0.97–1.18, P = 0.19). According to the ethnic group analysis, Pro allele was associated with the risk of breast cancer in Caucasians for the dominant model and additive model (P = 0.02), and Africans for the recessive model and additive model (P = 0.03). Conclusions This meta-analysis found a significant association between TP53 p.Arg72Pro polymorphism and the risk of breast cancer. Individuals carrying at least one Pro allele were more likely to have breast cancer than individuals harboring the Arg allele.
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Affiliation(s)
- Brehima Diakite
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali. .,Teaching Hospital Center of Point G, 333, Bamako, Mali. .,Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.
| | - Yaya Kassogue
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali.,Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA
| | - Guimogo Dolo
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali
| | - Jun Wang
- Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.,Institute for Global Health, Northwestern University, IL60611, Chicago, USA
| | - Erin Neuschler
- Department of Radiology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Oumar Kassogue
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali
| | | | - Cheick B Traore
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali
| | - Bakarou Kamate
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali
| | - Etienne Dembele
- Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.,Institute for Global Health, Northwestern University, IL60611, Chicago, USA
| | - Sellama Nadifi
- Hassan II University Aïn chock, 20000, Casablanca,19, Rue Tarik Ibnou Ziad,, Morocco
| | - Robert L Murphy
- Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.,Institute for Global Health, Northwestern University, IL60611, Chicago, USA
| | - Seydou Doumbia
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Teaching Hospital Center of Point G, 333, Bamako, Mali
| | - Lifang Hou
- Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.,Institute for Global Health, Northwestern University, IL60611, Chicago, USA
| | - Mamoudou Maiga
- Faculty of Medicine and Odontostomatology, 1805, Université des Sciences, des Techniques et des Technologies Sciences de Bamako (USTTB), Hamdallaye ACI, 2000, Bamako, Mali.,Preventive Medicine Department, Cancer Epidemiology and Prevention, Northwestern University, Chicago, IL, 60611, USA.,Institute for Global Health, Northwestern University, IL60611, Chicago, USA
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6
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Functional interplay between p53 and Δ133p53 in adaptive stress response. Cell Death Differ 2019; 27:1618-1632. [PMID: 31659281 DOI: 10.1038/s41418-019-0445-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 01/20/2023] Open
Abstract
Apart from its well-known prodeath activity, p53 is also implicated in promoting cell survival. How p53 can mediate such seemingly opposing effects is largely unclear. We report here a novel mechanism in which p53-mediated proapoptosis is switched to antiapoptosis via its interaction with a p53 isoform, Δ133p53. We show that the expression of Δ133p53 is induced by mild or a moderate level of stress via an HIF1-dependent mechanism. Increased Δ133p53 levels contribute to the adaptive response by shifting the p53 binding at the Bcl2 promoter from suppressive responsive elements (RE) to activating REs, resulting in induction of Bcl2. In accordance with this mode of action, pretreatment of mice with mild stress induces Δ133p53 and Bcl2, which is associated with protection of animals from toxicity caused by high doses of DNA damage agents. Collectively, our work uncovers a novel functional interplay between p53 and Δ133p53 determining cell fate; survival or death in response to stress.
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7
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Naryzhny SN, Legina OK. [Structural-functional diversity of p53 proteoforms]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2019; 65:263-276. [PMID: 31436168 DOI: 10.18097/pbmc20196504263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Protein p53 is one of the most studied proteins. This attention is primarily due to its key role in the cellular mechanisms associated with carcinogenesis. Protein p53 is a transcription factor involved in a wide variety of processes: cell cycle regulation and apoptosis, signaling inside the cell, DNA repair, coordination of metabolic processes, regulation of cell interactions, etc. This multifunctionality is apparently determined by the fact that p53 is a vivid example of how the same protein can be represented by numerous proteoforms bearing completely different functional loads. By alternative splicing, using different promoters and translation initiation sites, the TP53 gene gives rise to at least 12 isoforms, which can additionally undergo numerous (>200) post-translational modifications. Proteoforms generated due to numerous point mutations in the TP53 gene are adding more complexity to this picture. The proteoforms produced are involved in various processes, such as the regulation of p53 transcriptional activity in response to various factors. This review is devoted to the description of the currently known p53 proteoforms, as well as their possible functionality.
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Affiliation(s)
- S N Naryzhny
- Petersburg Nuclear Physics Institute NRC Kurchatov Institute, Leningrad region, Gatchina, Russia
| | - O K Legina
- Petersburg Nuclear Physics Institute NRC Kurchatov Institute, Leningrad region, Gatchina, Russia
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8
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Zhang B, Cui B, Du J, Shen X, Wang K, Chen J, Xiao L, Sun C, Li Y. ATR activated by EB virus facilitates chemotherapy resistance to cisplatin or 5-fluorouracil in human nasopharyngeal carcinoma. Cancer Manag Res 2019; 11:573-585. [PMID: 30666155 PMCID: PMC6331066 DOI: 10.2147/cmar.s187099] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Purpose Epstein-Barr virus (EBV) infection is closely associated with nasopharyngeal carcinoma (NPC) and increases the chemotherapy resistance of tumor cells. Although the mechanism by which EBV manipulates ataxia telangiectasia mutation (ATM)-mediated DNA damage response in NPC has been extensively studied, the relationship between ATR (ATM and Rad-3 related) and EBV infection is largely unexplored, and also the role of ATR in chemotherapy resistance in EBV-positive NPC has not been specifically reported. Materials and methods Levels of γ-H2AX, latent membrane protein 1 (LMP1), and EBV-encoded RNA in clinical NPC and nasopharyngeal inflammation (NPI) specimens were examined using immunohistochemistry and in situ hybridization. The effects of EBV infection, chemotherapy drugs cisplatin (CDDP) and 5-fluorouracil (5-FU) treatment, and ATR silencing were assessed in NPC cells in vitro using immunofluorescence, Western blot, and flow cytometry. Results A notable increase of γ-H2AX expression was examined in the EBV-positive NPC clinical specimens. Additionally, we observed that the phosphorylation of ATR/checkpoint kinase 1 (CHK1) pathway protein was gradually activated along with the duration of EBV exposure in NPC cell lines, which was obviously inhibited after ATR depletion. Moreover, EBV infection promoted the resistance of NPC cells to CDDP and 5-FU, whereas the chemosensitivity of cells was significantly enhanced following ATR knockdown. Furthermore, ATR depletion caused both S-phase cell arrest and apoptosis, enhanced p53 phosphorylation, and impaired the formation of Rad51. Conclusion Our data suggest that EBV activation of ATR-mediated DNA damage response might result in chemotherapy resistance to CDDP and 5-FU in NPC. Accordingly, ATR knockdown may serve as an effective treatment strategy for chemotherapy-resistant, EBV-positive NPC.
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Affiliation(s)
- Bo Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Bomiao Cui
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Jintao Du
- Department of Otorhinolaryngology-Head and Neck Surgery, West China Hospital, Chengdu 610041, Sichuan, China
| | - Xin Shen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Kun Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Jiao Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Liying Xiao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Chongkui Sun
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
| | - Yan Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China, ;
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9
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Li H, Guan H, Guo Y, Liang W, Liu L, He X, Ke W, Cao X, Xiao H, Li Y. CITED1 promotes proliferation of papillary thyroid cancer cells via the regulation of p21 and p27. Cell Biosci 2018; 8:57. [PMID: 30450190 PMCID: PMC6219258 DOI: 10.1186/s13578-018-0256-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 10/26/2018] [Indexed: 12/17/2022] Open
Abstract
Background It has been reported that CBP/p300-Interacting Transactivator with glutamic acid [E]/aspartic acid [D]-rich C-terminal domain 1 (CITED1) is overexpressed in papillary thyroid cancer (PTC). However, the functional significance and underlying mechanisms of CITED1 in PTC are largely unknown. Methods The Cancer Genome Atlas dataset and real-time PCR were used to determine the expression of CITED1 in PTC. The role of CITED1 in PTC cell proliferation was determined conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and flow cytometry assays in vitro, and a subcutaneous xenotransplantation tumor model in nude mice was established to analyze tumor growth in vivo. We studied the potential mechanisms underlying the contribution of CITED1 to PTC proliferation using western blotting and luciferase assays. Results We found that CITED1 was highly expressed in PTC. In vitro and in vivo experiments demonstrated that CITED1 was involved in PTC cell proliferation and tumorigenesis. Then, gain- and loss-of-function experiments revealed that CITED1 decreased the expression of p21 and p27, and thereby increased the phosphorylation of pRb as well as E2F1 transcriptional activity. Conclusions Our results suggest that CITED1 is overexpressed in PTC and that CITED1 promotes the proliferation of PTC cells via the regulation of p21 and p27, which indicates that CITED1 might be a potential therapeutic target in the treatment of PTC.
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Affiliation(s)
- Hai Li
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Hongyu Guan
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Yan Guo
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Weiwei Liang
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Liehua Liu
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Xiaoying He
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Weijian Ke
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Xiaopei Cao
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Haipeng Xiao
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
| | - Yanbing Li
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, 510080 Guangdong China
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10
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Assi R, Gur HD, Loghavi S, Konoplev SN, Konopleva M, Daver N, Tashakori M, Kadia T, Routbort M, Salem A, Kanagal-Shamanna R, Quesada A, Jabbour EJ, Kornblau SM, Medeiros LJ, Kantarjian H, Khoury JD. P53 protein overexpression in de novo acute myeloid leukemia patients with normal diploid karyotype correlates with FLT3 internal tandem duplication and worse relapse-free survival. Am J Hematol 2018; 93:1376-1383. [PMID: 30117185 DOI: 10.1002/ajh.25255] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/09/2018] [Accepted: 08/13/2018] [Indexed: 12/30/2022]
Abstract
Although ~50% of acute myeloid leukemia (AML) patients have a normal diploid karyotype by conventional cytogenetics at diagnosis, this patient subset has a variable disease course and outcome. Aberrant overexpression of the p53 protein is usually associated with TP53 alterations and a complex karyotype, but the prevalence and impact of p53 overexpression in AML with diploid cytogenetics is unknown. We examined 100 newly diagnosed AML patients to evaluate the impact of p53 expression status quantified in bone marrow core biopsy samples using immunohistochemistry and computer-assisted image analysis. A total of 24 patients had p53 overexpression defined as 3+ staining intensity in ≥5% of cells; this finding correlated with lower platelet counts (P = .002), absence of CD34 expression in blasts (P = .009), higher bone marrow blast counts (P = .04), and a higher frequency of FLT3 internal tandem duplication (P = .007). Overexpression of p53 independently predicted for shorter leukemia-free survival in patients who underwent allogeneic stem cell transplantation by univariate (P = .021) and multivariate analyses (P = .004). There was no correlation between MDM2 and p53 protein expression in this cohort. We conclude that p53 expression evaluated by immunohistochemistry in bone marrow biopsy specimens at the time of AML diagnosis may indicate distinct clinical characteristics in patients with normal diploid cytogenetics and is a potentially valuable tool that can enhance risk-stratification.
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Affiliation(s)
- Rita Assi
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Hatice D. Gur
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Sanam Loghavi
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Sergej N. Konoplev
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Marina Konopleva
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Naval Daver
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Mehrnoosh Tashakori
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Tapan Kadia
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Mark Routbort
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Alireza Salem
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Rashmi Kanagal-Shamanna
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Andres Quesada
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Elias J. Jabbour
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Steven M. Kornblau
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - L. Jeffrey Medeiros
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Hagop Kantarjian
- Departments of Leukemia; The University of Texas MD Anderson Cancer Center; Houston Texas
| | - Joseph D. Khoury
- Department of Hematopathology; The University of Texas MD Anderson Cancer Center; Houston Texas
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11
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Guo H, Fu X, Lin Q, Liu L, Liang H, Huang Z, Li N, Su J. Mandarin fish p53: Genomic structure, alternatively spliced variant and its mRNA expression after virus challenge. FISH & SHELLFISH IMMUNOLOGY 2017; 70:536-544. [PMID: 28923524 DOI: 10.1016/j.fsi.2017.09.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/08/2017] [Accepted: 09/14/2017] [Indexed: 06/07/2023]
Abstract
A number of size variants of the p53 protein have been described in mammal, but little is known about alternative splicing of p53 expression and function in the fish. In our previous study, the immune defense and antiviral responses of p53 had been determined in mandarin fish (Siniperca chuatsi). However, the role of its splicing variants remains unknown. In the present study, the organization of mandarin fish p53 (Sc-p53) genome sequence was determined and a novel splice variant was characterized. The Sc-p53 genomic sequence was composed of 5543 bp, containing 11 exons and 10 introns, which was similar to other species. Then, a 1106 bp full-length cDNA of a novel splice variant p53 from mandarin fish (designed as Sc-p53I6) was cloned and characterized. Quantitative real-time PCR assays revealed that Sc-p53I6 was expressed in all tissues examined, and it was most abundant in the gill, hemocyte and hind kidney. Western blotting analysis revealed that Sc-p53I6 protein was abundant in liver, trunk kidney, hind kidney, stomach and heart. In addition, the regulation of Sc-p53I6 gene expression after virus infection was determined and characterized. The results showed twice rise expression pattern of Sc-p53I6 in CPB cells and spleen of mandarin fish in response to infectious kidney and spleen necrosis virus (ISKNV). However, a different expression pattern, once rise, of Sc-p53I6 in response to Siniperca chuatsi rhabdovirus (SCRV) infection was found. The mRNA expression of Sc-p53I6 was significantly up-regulated in CPB at 4 h and spleen of mandarin fish at 12 h post-infection. These results will shed a new light on antiviral response mechanisms of p53 in mandarin fish.
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Affiliation(s)
- Huizhi Guo
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Xiaozhe Fu
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Qiang Lin
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Lihui Liu
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Hongru Liang
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Zhibin Huang
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China
| | - Ningqiu Li
- Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of Fishery Drug Development, Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology, Guangdong Provinces, Guangzhou 510380, China.
| | - Jianguo Su
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
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12
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Zhang X, Zhang L, Du Y, Zheng H, Zhang P, Sun Y, Wang Y, Chen J, Ding P, Wang N, Yang C, Huang T, Yao X, Qiao Q, Gu H, Cai G, Cai S, Zhou X, Hu W. A novel FOXM1 isoform, FOXM1D, promotes epithelial-mesenchymal transition and metastasis through ROCKs activation in colorectal cancer. Oncogene 2017; 36:807-819. [PMID: 27399334 PMCID: PMC5311249 DOI: 10.1038/onc.2016.249] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 05/23/2016] [Accepted: 06/01/2016] [Indexed: 12/13/2022]
Abstract
Epithelial-mesenchymal transition (EMT) is a critical event in metastasis of colorectal cancer (CRC). Rho/ROCKs signaling has a pivotal role in orchestrating actin cytoskeleton, leading to EMT and cancer invasion. However, the underlying mechanisms for ROCKs activation are not fully understood. Here, we identified FOXM1D, a novel isoform of Forkhead box M1 (FOXM1) that has a pivotal role in ROCKs activation by directly interacting with coiled-coil region of ROCK2. FOXM1D overexpression significantly polymerizes actin assembly and impairs E-cadherin expression, resulting in EMT and metastasis in xenograft mouse model and knockdown of FOXM1D has the opposite effect. Moreover, a high FOXM1D level correlates closely with clinical CRC metastasis. FOXM1D-induced ROCKs activation could be abrogated by the ROCKs inhibitors Y-27632 and fasudil. These observations indicate that the FOXM1D-ROCK2 interaction is crucial for Rho/ROCKs signaling and provide novel insight into actin cytoskeleton regulation and therapeutic potential for CRC metastasis.
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Affiliation(s)
- X Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - L Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Y Du
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - H Zheng
- Department of Colorectal Surgery, Shanghai Medical College, Fudan University, Shanghai, China
| | - P Zhang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Y Sun
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Y Wang
- Department of Colorectal Surgery, Shanghai Medical College, Fudan University, Shanghai, China
| | - J Chen
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - P Ding
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - N Wang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - C Yang
- Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - T Huang
- Department of Urology, Shanghai Tenth People's Hospital, Shanghai, China
| | - X Yao
- Department of Urology, Shanghai Tenth People's Hospital, Shanghai, China
| | - Q Qiao
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - H Gu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - G Cai
- Department of Colorectal Surgery, Shanghai Medical College, Fudan University, Shanghai, China
| | - S Cai
- Department of Colorectal Surgery, Shanghai Medical College, Fudan University, Shanghai, China
| | - X Zhou
- Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - W Hu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Collaborative Innovation Center of Cancer Medicine, Shanghai Medical College, Fudan University; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Department of Immunology, Shanghai Medical College, Fudan University, Shanghai, China
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13
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p53 Specifically Binds Triplex DNA In Vitro and in Cells. PLoS One 2016; 11:e0167439. [PMID: 27907175 PMCID: PMC5131957 DOI: 10.1371/journal.pone.0167439] [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: 07/23/2016] [Accepted: 11/14/2016] [Indexed: 11/30/2022] Open
Abstract
Triplex DNA is implicated in a wide range of biological activities, including regulation of gene expression and genomic instability leading to cancer. The tumor suppressor p53 is a central regulator of cell fate in response to different type of insults. Sequence and structure specific modes of DNA recognition are core attributes of the p53 protein. The focus of this work is the structure-specific binding of p53 to DNA containing triplex-forming sequences in vitro and in cells and the effect on p53-driven transcription. This is the first DNA binding study of full-length p53 and its deletion variants to both intermolecular and intramolecular T.A.T triplexes. We demonstrate that the interaction of p53 with intermolecular T.A.T triplex is comparable to the recognition of CTG-hairpin non-B DNA structure. Using deletion mutants we determined the C-terminal DNA binding domain of p53 to be crucial for triplex recognition. Furthermore, strong p53 recognition of intramolecular T.A.T triplexes (H-DNA), stabilized by negative superhelicity in plasmid DNA, was detected by competition and immunoprecipitation experiments, and visualized by AFM. Moreover, chromatin immunoprecipitation revealed p53 binding T.A.T forming sequence in vivo. Enhanced reporter transactivation by p53 on insertion of triplex forming sequence into plasmid with p53 consensus sequence was observed by luciferase reporter assays. In-silico scan of human regulatory regions for the simultaneous presence of both consensus sequence and T.A.T motifs identified a set of candidate p53 target genes and p53-dependent activation of several of them (ABCG5, ENOX1, INSR, MCC, NFAT5) was confirmed by RT-qPCR. Our results show that T.A.T triplex comprises a new class of p53 binding sites targeted by p53 in a DNA structure-dependent mode in vitro and in cells. The contribution of p53 DNA structure-dependent binding to the regulation of transcription is discussed.
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14
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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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15
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Wild-type p53 binds to MYC promoter G-quadruplex. Biosci Rep 2016; 36:BSR20160232. [PMID: 27634752 PMCID: PMC5064454 DOI: 10.1042/bsr20160232] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 09/15/2016] [Indexed: 12/19/2022] Open
Abstract
G-quadruplexes are four-stranded nucleic acid structures that are implicated in the regulation of transcription, translation and replication. Genome regions enriched in putative G-quadruplex motifs include telomeres and gene promoters. Tumour suppressor p53 plays a critical role in regulatory pathways leading to cell cycle arrest, DNA repair and apoptosis. In addition to transcriptional regulation mediated via sequence-specific DNA binding, p53 can selectively bind various non-B DNA structures. In the present study, wild-type p53 (wtp53) binding to G-quadruplex formed by MYC promoter nuclease hypersensitive element (NHE) III1 region was investigated. Wtp53 binding to MYC G-quadruplex is comparable to interaction with specific p53 consensus sequence (p53CON). Apart from the full-length wtp53, its isolated C-terminal region (aa 320-393) as well, is capable of high-affinity MYC G-quadruplex binding, suggesting its critical role in this type of interaction. Moreover, wtp53 binds to MYC promoter region containing putative G-quadruplex motif in two wtp53-expressing cell lines. The results suggest that wtp53 binding to G-quadruplexes can take part in transcriptional regulation of its target genes.
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16
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Wang S, Chen Y, Bai Y. p21 participates in the regulation of anaplastic thyroid cancer cell proliferation by miR-146b. Oncol Lett 2016; 12:2018-2022. [PMID: 27602131 DOI: 10.3892/ol.2016.4874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 05/18/2016] [Indexed: 01/28/2023] Open
Abstract
Anaplastic thyroid carcinoma (ATC) originates from completely undifferentiated cells, and is the most lethal type of thyroid-derived tumor. Numerous microRNAs have significant roles in tumorigenesis by targeting relevant genes. The role of microRNA 146b (miR-146b) in ATC remains to be elucidated. In order to characterize the role of miR-146b in ATC, overexpression or interference of miR-146b was induced in ATC cell lines, and cell proliferation and migration were evaluated. The potential targets of miR-146b were searched in the Gene Expression Omnibus database for ATC and matched non-tumor control samples. The expression level of potential targets was detected following overexpression or interference of miR-146b in ATC cell lines. In the present study, cell proliferation was promoted when overexpression of miR-146b was induced in ATC, and inhibited when interference of miR-146b was induced, which indicated that miR-146b affects the proliferation of ATC cells in vitro. In addition, cell migration of ATC was also affected by miR-146b. During the search for potential targets of miR-146b in ATC, p21 (also known as p21Waf1/Cip1 or CDKN1A) was noted for its role in cell cycle progression and tumor pathogenesis. The expression level of p21 was influenced by the level of miR-146b, and the results of the present study demonstrated that the level of p21 was increased when FRO cells were transformed with miR-146b mimic, and p21 was downregulated when FRO cells transformed with anti-miR-146b. In conclusion, p21 may participate in the regulation of ATC cell proliferation by miR-146b.
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Affiliation(s)
- Shiyang Wang
- Department of Otorhinolaryngology - Head and Neck Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yangjing Chen
- Department of Otorhinolaryngology - Head and Neck Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yanxia Bai
- Department of Otorhinolaryngology - Head and Neck Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
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17
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Hou Q, Lin J, Huang W, Li M, Feng J, Mao X. CTRP3 Stimulates Proliferation and Anti-Apoptosis of Prostate Cells through PKC Signaling Pathways. PLoS One 2015. [PMID: 26218761 PMCID: PMC4517796 DOI: 10.1371/journal.pone.0134006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
C1q/TNF-related protein-3 (CTRP3) is a novel adipokine with roles in multiple cellular processes. However, little is known about its function in prostate cells. This study investigated the effects and mechanisms of CTRP3 in prostate cells. We first generated and purified CTRP3 protein in HEK 293T cells. Proliferation of RWPE-1 prostate cells was evaluated by MTT analyses under treatment with different concentrations of CTRP3 for various exposure times. The results revealed maximum enhancement of proliferation with 10 μg/mL CTRP3 for 72 h. Cell apoptosis and cell cycle were determined by TUNEL staining and flow cytometry analysis. TUNEL assay showed decreased TUNEL-positive cells in RWPE-1 prostate cells treated with CTRP3, and flow cytometry showed significantly decreased apoptotic cells upon CTRP3 treatment (treated cells, 8.34±1.175 vs. controls, 20.163±0.35) (P < 0.01). Moreover, flow cytometry analysis also showed a significant decrease of cells in the G1 phase and an increase of cells in the S and G2 phase upon CTRP3 treatment (treated cells, 42.85±1.40 vs. control, 52.77±0.90; 28.41±0.57 vs. 23.49±1.13; 27.08±1.97 vs. 22.20±1.32, respectively) (all P < 0.05). Two-dimensional gel electrophoresis and mass spectrometry identified differentially expressed proteins, including cytokeratin-19, GLRX3 and DDAH1, which were upregulated in CTRP3 treated cells, and cytokeratin-17 and 14-3-3 sigma, which were downregulated. GLRX3, DDAH1 and 14-3-3 sigma were confirmed using western blot analysis. A PKC inhibitor, staurosporine, was used to inhibit PKC activity in CTRP3 treated RWPE-1 cells. Staurosporine completely abolished the CTRP3-induced increased phosphorylation of intracellular PKC substrates and CTRP3-stimulated effect by RWPE-1 cells. Our results provide the first evidence for a physiological role of the novel adipokine, CTRP3, in prostate cells. Our findings suggest that CTRP3 could improve proliferation and anti-apoptosis of prostate cells through protein kinase C signaling pathways.
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Affiliation(s)
- Qi Hou
- Department of Urology, Longgang District Central Hospital, Shenzhen, China
| | - Jinyan Lin
- Health management center, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Wentao Huang
- Department of Urology, Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Maoyin Li
- Department of Urology, Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jianhua Feng
- Department of Urology, Longgang District Central Hospital, Shenzhen, China
- * E-mail: (JF); (XM)
| | - Xiangming Mao
- Department of Urology, Peking University Shenzhen Hospital, Shenzhen, China
- * E-mail: (JF); (XM)
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18
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Abstract
The Janus tyrosine kinases JAK1-3 and tyrosine kinase-2 (TYK2) are frequently hyperactivated in tumors. In lung cancers JAK1 and JAK2 induce oncogenic signaling through STAT3. A putative role of TYK2 in these tumors has not been reported. Here, we show a previously not recognized TYK2-STAT3 signaling node in lung cancer cells. We reveal that the E3 ubiquitin ligase seven-in-absentia-2 (SIAH2) accelerates the proteasomal degradation of TYK2. This mechanism consequently suppresses the activation of STAT3. In agreement with these data the analysis of primary non-small-cell lung cancer (NSCLC) samples from three patient cohorts revealed that compared to lung adenocarcinoma (ADC), lung squamous cell carcinoma (SCC) show significantly higher levels of SIAH2 and reduced STAT3 phosphorylation levels. Thus, SIAH2 is a novel molecular marker for SCC. We further demonstrate that an activation of the oncologically relevant transcription factor p53 in lung cancer cells induces SIAH2, depletes TYK2, and abrogates the tyrosine phosphorylation of STAT1 and STAT3. This mechanism appears to be different from the inhibition of phosphorylated JAKs through the suppressor of cytokine signaling (SOCS) proteins. Our study may help to identify molecular mechanisms affecting lung carcinogenesis and potential therapeutic targets.
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19
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Guichard A, Humbert P, Tissot M, Muret P, Courderot-Masuyer C, Viennet C. Effects of topical corticosteroids on cell proliferation, cell cycle progression and apoptosis: in vitro comparison on HaCaT. Int J Pharm 2014; 479:422-9. [PMID: 25556056 DOI: 10.1016/j.ijpharm.2014.12.066] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/26/2014] [Indexed: 11/27/2022]
Abstract
Topical-corticosteroids are mainly used for the treatment of inflammatory or hyperproliferative skin diseases. The in vivo assay to rank topical-corticosteroids potency, based on the skin blanching, is not adapted to compare their anti-proliferative efficacy. We have compared the antiproliferative effect of six topical-corticosteroids on a model of hyperproliferant keratinocytes (HaCaT). Betamethasone-dipropionate; clobetasol-propionate; betamethasone-valerate; desonide; hydrocortisone-butyrate and hydrocortisone-base, at different concentrations (10(-8)-10(-4)M) have been compared. HaCaT proliferation has been evaluated by MTT-assay and the mechanism of the death was evaluated by annexin V/propidium iodide staining and cell cycle phases analysis. Topical corticosteroids reduced cell growth in a dose-dependent manner. At 10(-4)M, betamethasone dipropionate was the most antiproliferative compound while hydrocortisone-butyrate was the less. Hydrocortisone-base which is usually considered as the less potent topical-corticosteroids showed a clear cytotoxic effect. Betamethasone-dipropionate and betamethasone-valerate induced more apoptosis than necrosis whereas the reverse has been observed for other topical-corticosteroids. All topical-corticosteroids, except clobetasol-propionate, arrested cell cycle mainly in G2-phase. Clobetasol-propionate arrested cell cycle in S-phase population. At 10(-8)M, topical-corticosteroids induced HaCaT proliferation. In terms of antiproliferative effect at 10(-4)M, we propose to rank topical corticosteroids as follow: betamethasone-dipropionate>desonide≥betamethasone-valerate=hydrocortisone-base=clobetasol-propionate>hydrocortisone-butyrate. This classification differs from the current ranking, based on the vasoconstrictive effect, but is more adapted for hyperproliferative disease treatment.
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Affiliation(s)
- Alexandre Guichard
- Research and Studies Center on the Integument (CERT), Department of Dermatology, Clinical Investigation Center (CIC INSERM 1431), Besançon University Hospital, France; Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Philippe Humbert
- Research and Studies Center on the Integument (CERT), Department of Dermatology, Clinical Investigation Center (CIC INSERM 1431), Besançon University Hospital, France; Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Marion Tissot
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | - Patrice Muret
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
| | | | - Céline Viennet
- Engineering and Cutaneous Biology Laboratory, INSERM UMR 1098, SFR FED 4234, University of Franche-Comte, Besançon, France.
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20
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Tang X, Amar S. p53 suppresses CCL2-induced subcutaneous tumor xenograft. Tumour Biol 2014; 36:2801-8. [PMID: 25492482 DOI: 10.1007/s13277-014-2906-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/27/2014] [Indexed: 11/30/2022] Open
Abstract
Chemokine (C-C motif) ligand 2 (CCL2) has recently been found to be a key player in the pathology of many human glomerular and tubulointerstitial diseases. CCL2 has also been found to be expressed in various cancers, including human hepatoma cells, human cancer progression, and human multiple myeloma cells. Thus, the inhibition of elevated CCL2 production may provide a new avenue for therapeutic intervention in CCL2-mediated cancer diseases. A previous study has indicated that knockdown of human p53 has a strong negative impact on CCL2 induction. We therefore are interested in how p53 regulates CCL2 gene expression. In the following study, our findings indicate that p53 binds to CCL2, consequently significantly downregulating CCL2 promoter activity. Furthermore, injection of CCL2-promoting cancer cells (CCL2/A549) in p53-deficient mice for 3 weeks strongly induced subcutaneous xenograft tumor growth compared with the control. Overall, the research results support the novel role of p53 in suppression of chemokine (such as CCL2)-mediated cancer diseases.
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Affiliation(s)
- Xiaoren Tang
- Center for Anti-Inflammatory Therapeutics, Department of Molecular & Cell Biology, Boston University Goldman School of Dental Medicine, 650 Albany Street, X-343, Boston, MA, 02118, USA
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21
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Identification of p53 and its isoforms in human breast carcinoma cells. ScientificWorldJournal 2014; 2014:618698. [PMID: 24511294 PMCID: PMC3913390 DOI: 10.1155/2014/618698] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/12/2013] [Indexed: 02/03/2023] Open
Abstract
In breast carcinoma, disruption of the p53 pathway is one of the most common genetic alterations. The observation that the p53 can express multiple protein isoforms adds a novel level of complexity to the outcome of p53 mutations. p53 expression was analysed by Western immunoblotting and immunohistochemistry using monoclonal antibodies DO-7, Pab240, and polyclonal antiserum CM-1. The more frequently p53-positive nuclear staining has been found in the invasive breast tumors. One of the most intriguing findings is that mutant p53 appears as discrete dot-shaped regions within the nucleus of breast cancer cells. In many malignant cells, the nucleolar sequestration of p53 is evident. These observations support the view that the nucleolus is involved directly in the mediation of p53 function or indirectly by the control of the localization of p53 interplayers. p53 expressed in the nuclear fraction of breast cancer cells revealed a wide spectrum of isoforms. p53 isoforms ΔNp53 (47 kDa) and Δ133p53 β (35 kDa), known as dominant-negative repressors of p53 function, were detected as the most predominant variants in nuclei of invasive breast carcinoma cells. The isoforms expressed also varied between individual tumors, indicating potential roles of these p53 variants in human breast cancer.
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Surget S, Khoury MP, Bourdon JC. Uncovering the role of p53 splice variants in human malignancy: a clinical perspective. Onco Targets Ther 2013; 7:57-68. [PMID: 24379683 PMCID: PMC3872270 DOI: 10.2147/ott.s53876] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Thirty-five years of research on p53 gave rise to more than 68,000 articles and reviews, but did not allow the uncovering of all the mysteries that this major tumor suppressor holds. How p53 handles the different signals to decide the appropriate cell fate in response to a stress and its implication in tumorigenesis and cancer progression remains unclear. Nevertheless, the uncovering of p53 isoforms has opened new perspectives in the cancer research field. Indeed, the human TP53 gene encodes not only one but at least twelve p53 protein isoforms, which are produced in normal tissues through alternative initiation of translation, usage of alternative promoters, and alternative splicing. In recent years, it became obvious that the different p53 isoforms play an important role in regulating cell fate in response to different stresses in normal cells by differentially regulating gene expression. In cancer cells, abnormal expression of p53 isoforms contributes actively to cancer formation and progression, regardless of TP53 mutation status. They can also be associated with response to treatment, depending on the cell context. The determination of p53 isoform expression and p53 mutation status helps to define different subtypes within a particular cancer type, which would have different responses to treatment. Thus, the understanding of the regulation of p53 isoform expression and their biological activities in relation to the cellular context would constitute an important step toward the improvement of the diagnostic, prognostic, and predictive values of p53 in cancer treatment. This review aims to summarize the involvement of p53 isoforms in cancer and to highlight novel potential therapeutic targets.
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Affiliation(s)
- Sylvanie Surget
- Dundee Cancer Centre, University of Dundee, Dundee, UK ; Jacqui Wood Cancer Centre, Ninewells Hospital, University of Dundee, Dundee, UK
| | - Marie P Khoury
- Dundee Cancer Centre, University of Dundee, Dundee, UK ; Jacqui Wood Cancer Centre, Ninewells Hospital, University of Dundee, Dundee, UK
| | - Jean-Christophe Bourdon
- Dundee Cancer Centre, University of Dundee, Dundee, UK ; Jacqui Wood Cancer Centre, Ninewells Hospital, University of Dundee, Dundee, UK
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Hasty P, Christy BA. p53 as an intervention target for cancer and aging. PATHOBIOLOGY OF AGING & AGE RELATED DISEASES 2013; 3:22702. [PMID: 24124625 PMCID: PMC3794078 DOI: 10.3402/pba.v3i0.22702] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 09/13/2013] [Accepted: 09/13/2013] [Indexed: 12/30/2022]
Abstract
p53 is well known for suppressing tumors but could also affect other aging processes not associated with tumor suppression. As a transcription factor, p53 responds to a variety of stresses to either induce apoptosis (cell death) or cell cycle arrest (cell preservation) to suppress tumor development. Yet, the effect p53 has on the non-cancer aspects of aging is complicated and not well understood. On one side, p53 could induce cellular senescence or apoptosis to suppress cancer but as an unintended consequence enhance the aging process especially if these responses diminish stem and progenitor cell populations. But on the flip side, p53 could reduce growth and growth-related stress to enable cell survival and ultimately delay the aging process. A better understanding of diverse functions of p53 is essential to elucidate its influences on the aging process and the possibility of targeting p53 or p53 transcriptional targets to treat cancer and ameliorate general aging.
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Affiliation(s)
- Paul Hasty
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA ; Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA ; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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Terrier O, Bourdon JC, Rosa-Calatrava M. p53 protein isoforms: key regulators in the front line of pathogen infections? PLoS Pathog 2013; 9:e1003246. [PMID: 23592981 PMCID: PMC3616980 DOI: 10.1371/journal.ppat.1003246] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Olivier Terrier
- Laboratoire de Virologie et Pathologie Humaine EA4610 VirPath, Equipe VirCell, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France.
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Preferential binding of hot spot mutant p53 proteins to supercoiled DNA in vitro and in cells. PLoS One 2013; 8:e59567. [PMID: 23555710 PMCID: PMC3608670 DOI: 10.1371/journal.pone.0059567] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 02/19/2013] [Indexed: 11/21/2022] Open
Abstract
Hot spot mutant p53 (mutp53) proteins exert oncogenic gain-of-function activities. Binding of mutp53 to DNA is assumed to be involved in mutp53-mediated repression or activation of several mutp53 target genes. To investigate the importance of DNA topology on mutp53-DNA recognition in vitro and in cells, we analyzed the interaction of seven hot spot mutp53 proteins with topologically different DNA substrates (supercoiled, linear and relaxed) containing and/or lacking mutp53 binding sites (mutp53BS) using a variety of electrophoresis and immunoprecipitation based techniques. All seven hot spot mutp53 proteins (R175H, G245S, R248W, R249S, R273C, R273H and R282W) were found to have retained the ability of wild-type p53 to preferentially bind circular DNA at native negative superhelix density, while linear or relaxed circular DNA was a poor substrate. The preference of mutp53 proteins for supercoiled DNA (supercoil-selective binding) was further substantiated by competition experiments with linear DNA or relaxed DNA in vitro and ex vivo. Using chromatin immunoprecipitation, the preferential binding of mutp53 to a sc mutp53BS was detected also in cells. Furthermore, we have shown by luciferase reporter assay that the DNA topology influences p53 regulation of BAX and MSP/MST1 promoters. Possible modes of mutp53 binding to topologically constrained DNA substrates and their biological consequences are discussed.
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Tang X, Asano M, O'Reilly A, Farquhar A, Yang Y, Amar S. p53 is an important regulator of CCL2 gene expression. Curr Mol Med 2013; 12:929-43. [PMID: 22804246 DOI: 10.2174/156652412802480844] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/20/2012] [Accepted: 02/21/2012] [Indexed: 12/11/2022]
Abstract
The p53 protein is a sequence-specific DNA-binding factor that regulates inflammatory genes such as CCL2/MCP-1 that may play a role in various diseases. A recent study has indicated that the knockdown of human p53 leads to a strong negative regulation of CCL2 induction. We are therefore interested in how p53 regulates CCL2 gene expression. In the following study, our findings indicate that UV-induced p53 accumulation in mouse macrophages significantly decreases LPS-induced CCL2 production, and that p53 binds to CCL2 5'UTR in the region (16-35). We also found that a p53 domain (p53pep170) mimics full length p53 to down-regulate CCL2 promoter activity. Treatment of p53-deficient mouse primary macrophages with synthetic p53pep170 was found to decrease LPS-induced production of CCL2 without association with cellular endogenous p53. CCL2 production induced by lentiCLG in human monocytes or mouse primary macrophages was blocked in the presence of p53pep170. Overall, these results demonstrate that p53 or its derived peptide (p53pep170) is an important regulator of CCL2 gene expression via its binding activity, and acts as a novel model for future studies linking p53 and its short peptide to pave the way to possible pharmaceutical intervention of CCL2-mediated inflammatory and cancer diseases.
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Affiliation(s)
- X Tang
- Center for Anti- Inflammatory Therapeutics, Boston University, 650 Albany Street, X- 343, Boston, MA 02118, USA.
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Guan X, Liu Z, Wang L, Wang LE, Sturgis EM, Wei Q. Functional repeats (TGYCC)n in the p53-inducible gene 3 (PIG3) promoter and susceptibility to squamous cell carcinoma of the head and neck. Carcinogenesis 2012; 34:812-7. [PMID: 23241165 DOI: 10.1093/carcin/bgs388] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A polymorphic pentanucleotide microsatellite sequence (TGYCC)n within the p53-inducible gene 3 (PIG3) promoter is correlated with the extent of transcriptional activation by p53 and thought to modulate susceptibility to cancer. Using a PCR-silver staining-based single-strand conformation assay, we visualized variant genotypes of the PIG3 promoter (TGYCC)n motif in a subset of 100 subjects for each of four ethnic groups: non-Hispanic whites, African Americans, Hispanic Americans and Native Chinese. We found that PIG3 (TGYCC)15 was the most common allele but less frequent in non-Hispanic whites (0.660) than in Chinese (0.785) (P = 0.016). In an additional study of 616 patients with squamous cell carcinoma of the head and neck (SCCHN) and 623 cancer-free controls in a non-Hispanic white population, we found that compared with those who were PIG3 (TGYCC)15 homozygotes, subjects without the PIG3 (TGYCC)15 allele had a significantly increased SCCHN risk [adjusted odds ratio (OR) = 1.34; 95% CI = 1.04-1.73 for heterozygotes and OR = 1.69; 95% CI = 1.18-2.44 for variant homozygotes] in an allele-dose response manner (P = 0.002). Consistently, subsequent luciferase reporter assay revealed that the wild-type (TGYCC)15 allele had the highest p53-mediated transcriptional activity, compared with the other (TGYCC)n motifs. Our data suggest that the PIG3 variant polymorphic repeats alleles other than (TGYCC)15 may affect p53 binding and thus may be a marker for susceptibility to SCCHN, but our findings need to be validated in larger studies.
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Affiliation(s)
- Xiaoxiang Guan
- Department of Medical Oncology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
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Almazi JG, Mactier S, Best OG, Crossett B, Mulligan SP, Christopherson RI. Fludarabine nucleoside induces accumulations of p53, p63 and p73 in the nuclei of human B-lymphoid cell lines, with cytosolic and mitochondrial increases in p53. Proteomics Clin Appl 2012; 6:279-90. [PMID: 22641291 DOI: 10.1002/prca.201200003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE Human Raji cells treated with fludarabine nucleoside (2-FaraA, 3 μM) undergo apoptosis with accumulation of p53 in the nuclei as multiple phosphorylated isoforms and C-terminal truncated derivatives. Changes induced by 2-FaraA in the levels of p53, p63 and p73 in the nuclear, cytosolic and mitochondrial fractions have been determined in four human B-lymphoid cell lines that are TP53-functional (Raji and IM9) and TP53-mutated (MEC1 and U266). EXPERIMENTAL DESIGN The B-lymphoid cell lines were treated with 2-FaraA (3 μM, 24 h, 48 h) and viability determined. Protein extracts of subcellular fractions from 2-FaraA-treated cells were analysed by 1D and 2D electrophoresis; multiple phosphorylated isoforms and truncated derivatives were identified by Western blots for p53, p63 and p73. RESULTS p53 and p63 were present in all three fractions, while p73 was only detected in nuclei. After treatment with 2-FaraA, nuclear p53, p63 and p73 accumulated as multiple phosphorylated isoforms and truncated derivatives. The association of p63 with mitochondria in human cells is novel. CONCLUSIONS AND CLINICAL RELEVANCE Comprehensive information on the subcellular distributions and responses of p53, p63 and p73 to 2-FaraA provides additional insight into mechanisms for induction of apoptosis in the treatment of B-lymphoproliferative disorders with fludarabine.
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Affiliation(s)
- Juhura G Almazi
- School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia
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Mund A, Schubert T, Staege H, Kinkley S, Reumann K, Kriegs M, Fritsch L, Battisti V, Ait-Si-Ali S, Hoffbeck AS, Soutoglou E, Will H. SPOC1 modulates DNA repair by regulating key determinants of chromatin compaction and DNA damage response. Nucleic Acids Res 2012; 40:11363-79. [PMID: 23034801 PMCID: PMC3526275 DOI: 10.1093/nar/gks868] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Survival time-associated plant homeodomain (PHD) finger protein in Ovarian Cancer 1 (SPOC1, also known as PHF13) is known to modulate chromatin structure and is essential for testicular stem-cell differentiation. Here we show that SPOC1 is recruited to DNA double-strand breaks (DSBs) in an ATM-dependent manner. Moreover, SPOC1 localizes at endogenous repair foci, including OPT domains and accumulates at large DSB repair foci characteristic for delayed repair at heterochromatic sites. SPOC1 depletion enhances the kinetics of ionizing radiation-induced foci (IRIF) formation after γ-irradiation (γ-IR), non-homologous end-joining (NHEJ) repair activity, and cellular radioresistance, but impairs homologous recombination (HR) repair. Conversely, SPOC1 overexpression delays IRIF formation and γH2AX expansion, reduces NHEJ repair activity and enhances cellular radiosensitivity. SPOC1 mediates dose-dependent changes in chromatin association of DNA compaction factors KAP-1, HP1-α and H3K9 methyltransferases (KMT) GLP, G9A and SETDB1. In addition, SPOC1 interacts with KAP-1 and H3K9 KMTs, inhibits KAP-1 phosphorylation and enhances H3K9 trimethylation. These findings provide the first evidence for a function of SPOC1 in DNA damage response (DDR) and repair. SPOC1 acts as a modulator of repair kinetics and choice of pathways. This involves its dose-dependent effects on DNA damage sensors, repair mediators and key regulators of chromatin structure.
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Affiliation(s)
- Andreas Mund
- Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Department of General Virology, Martinistrasse 52, 20251 Hamburg, Germany
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Tang Y, Horikawa I, Ajiro M, Robles AI, Fujita K, Mondal AM, Stauffer JK, Zheng ZM, Harris CC. Downregulation of splicing factor SRSF3 induces p53β, an alternatively spliced isoform of p53 that promotes cellular senescence. Oncogene 2012; 32:2792-8. [PMID: 22777358 DOI: 10.1038/onc.2012.288] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Most human pre-mRNA transcripts are alternatively spliced, but the significance and fine-tuning of alternative splicing in different biological processes is only starting to be understood. SRSF3 (SRp20) is a member of a highly conserved family of splicing factors that have critical roles in key biological processes, including tumor progression. Here, we show that SRSF3 regulates cellular senescence, a p53-mediated process to suppress tumorigenesis, through TP53 alternative splicing. Downregulation of SRSF3 was observed in normal human fibroblasts undergoing replicative senescence, and was associated with the upregulation of p53β, an alternatively spliced isoform of p53 that promotes p53-mediated senescence. Knockdown of SRSF3 by short interfering RNA (siRNA) in early-passage fibroblasts induced senescence, which was associated with elevated expression of p53β at mRNA and protein levels. Knockdown of p53 partially rescued SRSF3-knockdown-induced senescence, suggesting that SRSF3 acts on p53-mediated cellular senescence. RNA pulldown assays demonstrated that SRSF3 binds to an alternatively spliced exon uniquely included in p53β mRNA through the consensus SRSF3-binding sequences. RNA crosslinking and immunoprecipitation assays (CLIP) also showed that SRSF3 in vivo binds to endogenous p53 pre-mRNA at the region containing the p53β-unique exon. Splicing assays using a transfected TP53 minigene in combination with siRNA knockdown of SRSF3 showed that SRSF3 functions to inhibit the inclusion of the p53β-unique exon in splicing of p53 pre-mRNA. These data suggest that downregulation of SRSF3 represents an endogenous mechanism for cellular senescence that directly regulates the TP53 alternative splicing to generate p53β. This study uncovers the role for general splicing machinery in tumorigenesis, and suggests that SRSF3 is a direct regulator of p53.
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Affiliation(s)
- Y Tang
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4258, USA
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Splicing of mouse p53 pre-mRNA does not always follow the "first come, first served" principle and may be influenced by cisplatin treatment and serum starvation. Mol Biol Rep 2012; 39:9247-56. [PMID: 22740133 DOI: 10.1007/s11033-012-1798-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 06/09/2012] [Indexed: 10/28/2022]
Abstract
Transcription of a pre-mRNA in eukaryotic cells elongates from the 5' to the 3' end, but intron removal during a pre-mRNA splicing does not always proceed in this orientation. In this study, we identified eight mouse p53 transcripts that retained one or more of introns 6, 7 and 8. The 5' part of intron 9 was also retained while the 3' part was not studied. These intron-containing transcripts, abbreviated as p53-ICTs, were detected at low abundance in many mouse embryonic fibroblasts (MEF) as well as cancer cell lines and tissues, and the highest ratio of these p53-ICTs to the mature p53 mRNA was seen in the normal pancreas. Serum starvation decreased those p53-ICTs that retained introns 6 and 7 but increased the levels of those lacking these introns while the level of the mature p53 mRNA was unaffected. Treatment of several cancer cell lines with cisplatin increased the mature p53 mRNA level but decreased these p53-ICTs. Transfection of p53(-/-) MEF with the p53 cDNA or several p53-ICT mini-genes slightly increased the cell viability and rendered the cells resistant to cisplatin. These data also suggest that p53 pre-mRNA splicing may have multiple orders of intron removal, some of which may not follow the "first come, first served" principle. It remains possible that these p53-ICTs are splicing intermediates existing as a mechanism for the cell to respond more promptly to a demand for more p53 and that p53 protein may be required for a normal life of MEF.
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Abstract
Mutations of the TP53 gene and dysregulation of the TP53 pathway are important in the pathogenesis of many human cancers, including lymphomas. Tumor suppression by p53 occurs via both transcription-dependent activities in the nucleus by which p53 regulates transcription of genes involved in cell cycle, DNA repair, apoptosis, signaling, transcription, and metabolism; and transcription-independent activities that induces apoptosis and autophagy in the cytoplasm. In lymphoid malignancies, the frequency of TP53 deletions and mutations is lower than in other types of cancer. Nonetheless, the status of TP53 is an independent prognostic factor in most lymphoma types. Dysfunction of TP53 with wild-type coding sequence can result from deregulated gene expression, stability, and activity of p53. To overcome TP53 pathway inactivation, therapeutic delivery of wild-type p53, activation of mutant p53, inhibition of MDM2-mediated degradation of p53, and activation of p53-dependent and -independent apoptotic pathways have been explored experimentally and in clinical trials. We review the mechanisms of TP53 dysfunction, recent advances implicated in lymphomagenesis, and therapeutic approaches to overcoming p53 inactivation.
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Stegh AH. Targeting the p53 signaling pathway in cancer therapy - the promises, challenges and perils. Expert Opin Ther Targets 2012; 16:67-83. [PMID: 22239435 DOI: 10.1517/14728222.2011.643299] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Research over the past three decades has identified p53 as a multi-functional transcription factor. p53 influences myriad, highly diverse cellular processes, and represents one of the most important and extensively studied tumor suppressors. Activated by various stresses, p53 blocks cancer progression by provoking transient or permanent growth arrest, by enabling DNA repair, or by advancing cellular death programs. This anti-cancer activity profile, together with genomic and mutational analyses documenting inactivation of p53 in more than 50% of human cancers, motivated drug development efforts to (re-) activate p53 in established tumors. AREAS COVERED The complexities of p53 signaling in cancer are summarized, including current strategies and challenges to restore p53's tumor suppressive function in established tumors, to inactivate p53 inhibitors, and to restore wild type function of p53 mutant proteins. EXPERT OPINION p53 represents an attractive target for the development of anti-cancer therapies. Whether p53 is 'druggable', however, remains an area of active research and discussion, as p53 has pro-survival functions and chronic p53 activation accelerates aging, which may compromise the long-term homeostasis of an organism. The complex biology and dual functions of p53 in cancer prevention and age-related cellular responses pose significant challenges to the development of p53-targeting cancer therapies.
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Affiliation(s)
- Alexander H Stegh
- Feinberg School of Medicine, The Robert H. Lurie Comprehensive Cancer Center, Davee Department of Neurology, Chicago, IL 60611, USA.
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Vigneron AM, Vousden KH. An indirect role for ASPP1 in limiting p53-dependent p21 expression and cellular senescence. EMBO J 2011; 31:471-80. [PMID: 22068052 DOI: 10.1038/emboj.2011.402] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 10/17/2011] [Indexed: 12/31/2022] Open
Abstract
In addition to acting as a transcriptional cofactor for p53, ASPP1 has been shown to function in the cytoplasm to regulate the nuclear localization and activity of YAP/TAZ. We show here that the ability of ASPP1 to activate YAP results in the decreased expression of LATS2, which lowers the ability of p53 to induce p21, cell-cycle arrest and senescence. ASPP1 expression peaks in S-phase, and down-regulation of ASPP1 leads to a reduction in DNA synthesis and enhanced senescence in response to drugs that impede DNA replication. These activities of cytoplasmic ASPP1 in opposing p53-mediated p21 expression are in contrast to the role of nuclear ASPP1 in cooperating with p53 to induce the expression of apoptotic target genes, and may help to dampen p53 activity in normal cells.
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Affiliation(s)
- Arnaud M Vigneron
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
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35
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Candeias MM. The can and can’t dos of p53 RNA. Biochimie 2011; 93:1962-5. [DOI: 10.1016/j.biochi.2011.06.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 06/07/2011] [Indexed: 11/16/2022]
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Hafsi H, Hainaut P. Redox control and interplay between p53 isoforms: roles in the regulation of basal p53 levels, cell fate, and senescence. Antioxid Redox Signal 2011; 15:1655-67. [PMID: 21194382 DOI: 10.1089/ars.2010.3771] [Citation(s) in RCA: 223] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The p53 tumor suppressor protein has achieved stardom in molecular oncology owing to frequent inactivation in a large range of cancers. Known as a factor activated by multiple forms of stress and causing a broad suppressive response to DNA damage, its regulation and functions in basal (non-stress) conditions has received relatively little attention. We summarize recent findings highlighting roles of p53 in physiological processes such as stem cell maintenance, development, aging and senescence, and regulation of basal oxidative cell metabolism. We suggest that these properties are regulated through two integrated biochemical systems: the redox-sensing capacity of the p53 protein (due to its structural features and its regulation by redox factors such as thioredoxin, metallothioneins, or the redox-repair enzyme APE1/ref-1), and the expression of p53 as multiple isoforms with antagonist effects. We propose that interactions between p53 and its isoforms Δ40p53 or Δ133p53 play critical roles in intracellular signaling by reactive oxygen species. We also discuss evidence that p53 controls energy production by repressing glycolysis and enhancing mitochondrial oxidative metabolism. Together, these mechanisms suggest that p53 acts not only as a "guardian of the genome" against DNA damage but also as a finely-tuned regulator of redox-dependent physiological processes.
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Affiliation(s)
- Hind Hafsi
- International Agency for Research on Cancer, 150 cours Albert Thomas, Lyon, France
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37
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Galluzzi L, Morselli E, Kepp O, Vitale I, Pinti M, Kroemer G. Mitochondrial liaisons of p53. Antioxid Redox Signal 2011; 15:1691-714. [PMID: 20712408 DOI: 10.1089/ars.2010.3504] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mitochondria play a central role in cell survival and cell death. While producing the bulk of intracellular ATP, mitochondrial respiration represents the most prominent source of harmful reactive oxygen species. Mitochondria participate in many anabolic pathways, including cholesterol and nucleotide biosynthesis, yet also control multiple biochemical cascades that contribute to the programmed demise of cells. The tumor suppressor protein p53 is best known for its ability to orchestrate a transcriptional response to stress that can have multiple outcomes, including cell cycle arrest and cell death. p53-mediated tumor suppression, however, also involves transcription-independent mechanisms. Cytoplasmic p53 can physically interact with members of the BCL-2 protein family, thereby promoting mitochondrial membrane permeabilization. Moreover, extranuclear p53 can suppress autophagy, a major prosurvival mechanism that is activated in response to multiple stress conditions. Thirty years have passed since its discovery, and p53 has been ascribed with an ever-increasing number of functions. For instance, p53 has turned out to influence the cell's redox status, by transactivating either anti- or pro-oxidant factors, and to regulate the metabolic switch between glycolysis and aerobic respiration. In this review, we will analyze the mechanisms by which p53 affects the balance between the vital and lethal functions of mitochondria.
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Affiliation(s)
- Lorenzo Galluzzi
- INSERM U848, Institut Gustave Roussy, Pavillon de Recherche 1, Villejuif (Paris), France
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Alternative splicings on p53, BRCA1 and PTEN genes involved in breast cancer. Biochem Biophys Res Commun 2011; 413:395-9. [DOI: 10.1016/j.bbrc.2011.08.098] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 08/20/2011] [Indexed: 01/08/2023]
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Correlation analysis of p53 protein isoforms with NPM1/FLT3 mutations and therapy response in acute myeloid leukemia. Oncogene 2011; 31:1533-45. [PMID: 21860418 DOI: 10.1038/onc.2011.348] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The wild-type tumor-suppressor gene TP53 encodes several isoforms of the p53 protein. However, while the role of p53 in controlling normal cell cycle progression and tumor suppression is well established, the clinical significance of p53 isoform expression is unknown. A novel bioinformatic analysis of p53 isoform expression in 68 patients with acute myeloid leukemia revealed distinct p53 protein biosignatures correlating with clinical outcome. Furthermore, we show that mutated FLT3, a prognostic marker for short survival in AML, is associated with expression of full-length p53. In contrast, mutated NPM1, a prognostic marker for long-term survival, correlated with p53 isoforms β and γ expression. In conclusion, p53 biosignatures contain useful information for cancer evaluation and prognostication.
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Tao L, Roberts AL, Dunphy KA, Bigelow C, Yan H, Jerry DJ. Repression of mammary stem/progenitor cells by p53 is mediated by Notch and separable from apoptotic activity. Stem Cells 2011; 29:119-27. [PMID: 21280161 DOI: 10.1002/stem.552] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Breast cancer is the most common tumor among women with inherited mutations in the p53 gene (Li-Fraumeni syndrome). The tumors represent the basal-like subtype, which has been suggested to originate from mammary stem/progenitor cells. In mouse mammary epithelium, mammosphere-forming potential was increased with decreased dosage of the gene encoding the p53 tumor suppressor protein (Trp53). Limiting dilution transplantation also showed a 3.3-fold increase in the frequency of long-term regenerative mammary stem cells in Trp53-/- mice. The repression of mammospheres by p53 was apparent despite the absence of apoptotic responses to radiation indicating a dissociation of these two activities of p53. The effects of p53 on progenitor cells were also observed in TM40A cells using both mammosphere-forming assays and the DsRed-let7c-sensor. The frequency of long-term label-retaining epithelial cells was decreased in Trp53-/- mammary glands indicating that asymmetric segregation of DNA is diminished and contributes to the expansion of the mammary stem cells. Treatment with an inhibitor of γ-secretase (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester) reduced the number of Trp53-/- mammospheres to the level found in Trp53+/+ cells. These results demonstrate that basal levels of p53 restrict mammary stem/progenitor cells through Notch and that the Notch pathway is a therapeutic target to prevent expansion of this vulnerable pool of cells.
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Affiliation(s)
- Luwei Tao
- Molecular and Cellular Biology Program, University of Massachusetts-Amherst, Massachusetts, USA
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41
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Hyperproliferation, cancer, and inflammation in mice expressing a Δ133p53-like isoform. Blood 2011; 117:5166-77. [PMID: 21411755 DOI: 10.1182/blood-2010-11-321851] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The p53 protein is a pivotal tumor suppressor that is frequently mutated in many human cancers, although precisely how p53 prevents tumors is still unclear. To add to its complexity, several isoforms of human p53 have now been reported. The Δ133p53 isoform is generated from an alternative transcription initiation site in intron 4 of the p53 gene (Tp53) and lacks the N-terminus. Elevated levels of Δ133p53 have been observed in a variety of tumors. To explore the functions of Δ133p53, we created a mouse expressing an N-terminal deletion mutant of p53 (Δ122p53) that corresponds to Δ133p53. Δ122p53 mice show decreased survival and a different and more aggressive tumor spectrum compared with p53 null mice, implying that Δ122p53 is a dominant oncogene. Consistent with this, Δ122p53 also confers a marked proliferative advantage on cells and reduced apoptosis. In addition to tumor development, Δ122p53 mice show a profound proinflammatory phenotype having increased serum concentrations of interleukin-6 and other proinflammatory cytokines and lymphocyte aggregates in the lung and liver as well as other pathologies. Based on these observations, we propose that human Δ133p53 also functions to promote cell proliferation and inflammation, one or both of which contribute to tumor development.
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Benatti P, Dolfini D, Viganò A, Ravo M, Weisz A, Imbriano C. Specific inhibition of NF-Y subunits triggers different cell proliferation defects. Nucleic Acids Res 2011; 39:5356-68. [PMID: 21415014 PMCID: PMC3141247 DOI: 10.1093/nar/gkr128] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Regulated gene expression is essential for a proper progression through the cell cycle. The transcription factor NF-Y has a fundamental function in transcriptional regulation of cell cycle genes, particularly of G2/M genes. In order to investigate common and distinct functions of NF-Y subunits in cell cycle regulation, NF-YA, NF-YB and NF-YC have been silenced by shRNAs in HCT116 cells. NF-YA loss led to a delay in S-phase progression, DNA damage and apoptosis: we showed the activation of the replication checkpoint, through the recruitment of Δp53 and of the replication proteins PCNA and Mcm7 to chromatin. Differently, NF-YB depletion impaired cells from exiting G2/M, but did not interfere with S-phase progression. Gene expression analysis of NF-YA and NF-YB inactivated cells highlighted a common set of hit genes, as well as a plethora of uncommon genes, unveiling a different effect of NF-Y subunits loss on NF-Y binding to its target genes. Chromatin extracts and ChIP analysis showed that NF-YA depletion was more effective than NF-YB in hitting NF-Y recruitment to CCAAT-promoters. Our data suggest a critical role of NF-Y expression, highlighting that the lack of the single subunits are differently perceived by the cells, which activate diverse cell cycle blocks and signaling pathways.
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Affiliation(s)
- Paolo Benatti
- Dipartimento di Biologia, Università di Modena e Reggio Emilia, via Campi 213/D, 41125 Modena, Italy
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Pekova S, Mazal O, Cmejla R, Hardekopf DW, Plachy R, Zejskova L, Haugvicova R, Jancuskova T, Karas M, Koza V, Smolej L, Bezdickova L, Kozak T. A comprehensive study of TP53 mutations in chronic lymphocytic leukemia: Analysis of 1287 diagnostic and 1148 follow-up CLL samples. Leuk Res 2011; 35:889-98. [PMID: 21232794 DOI: 10.1016/j.leukres.2010.12.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/19/2010] [Accepted: 12/19/2010] [Indexed: 11/28/2022]
Abstract
TP53 plays a pivotal role in the process of DNA repair and apoptosis. In 10-20% of patients with chronic lymphocytic leukemia (CLL), the TP53 pathway is affected. In this study, we analyzed the TP53 mutation status in 2435 consecutive CLL samples, including 1287 diagnostic samples and 1148 samples during follow-up, using FASAY (Functional Analysis of Separated Alleles in Yeast) and direct sequencing. In a cohort of 1287 diagnostic CLL samples, we identified 237 cases with TP53 variants, including mutations, temperature-sensitive variants, deletions, insertions and aberrant splicing variants (18.4%). In 1148 follow-up samples, no TP53 clonal evolution was observed.
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Affiliation(s)
- Sona Pekova
- Laboratory for Molecular Diagnostics, Chambon Inc., Evropska 176/16, Prague 6, 160 00, Czech Republic.
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44
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Beno I, Rosenthal K, Levitine M, Shaulov L, Haran TE. Sequence-dependent cooperative binding of p53 to DNA targets and its relationship to the structural properties of the DNA targets. Nucleic Acids Res 2010; 39:1919-32. [PMID: 21071400 PMCID: PMC3061056 DOI: 10.1093/nar/gkq1044] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The prime mechanism by which p53 acts as a tumor suppressor is as a transcription factor regulating the expression of diverse downstream genes. The DNA-binding domain of p53 (p53DBD) interacts with defined DNA sites and is the main target for mutations in human primary tumors. Here, we show that the CWWG motif, found in the center of each consensus p53 half-site, is a key player in p53/DNA interactions. Gel-mobility-shift assays provide a unique opportunity to directly observe the various oligomeric complexes formed between p53DBD and its target sites. We demonstrate that p53DBD binds to p53 consensus sites containing CATG with relatively low cooperativity, as both dimers and tetramers, and with even lower cooperativity to such sites containing spacer sequences. p53DBD binds to sites containing CAAG and CTAG with measurable affinity only when imbedded in two contiguous p53 half-sites and only as tetramers (with very high cooperativity). There are three orders-of-magnitude difference in the cooperativity of interaction between sites differing in their non-contacted step, and further two orders-of-magnitude difference as a function of spacer sequences. By experimentally measuring the global structural properties of these sites, by cyclization kinetics of DNA minicircles, we correlate these differences with the torsional flexibility of the binding sites.
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Affiliation(s)
- Itai Beno
- Department of Biology, Technion, Technion City, Haifa 32000, Israel
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45
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Abstract
p53 is a transcription factor with a key role in the maintenance of genetic stability and therefore preventing cancer formation. It belongs to a family of genes composed of p53, p63, and p73. The p63 and p73 genes have a dual gene structure with an internal promoter in intron-3 and together with alternative splicing, can express 6 and 29 mRNA variants, respectively. Such a complex expression pattern had not been previously described for the p53 gene, which was not consistent with our understanding of the evolution of the p53 gene family. Consequently, we revisited the human p53 gene structure and established that it encodes nine different p53 protein isoforms because of alternative splicing, alternative promoter usage, and alternative initiation sites of translation. Therefore, the human p53 gene family (p53, p63, and p73) has a dual gene structure. We determined that the dual gene structure is conserved in Drosophila and in zebrafish p53 genes. The conservation through evolution of the dual gene structure suggests that the p53 isoforms play an important role in p53 tumor-suppressor activity. We and others have established that the p53 isoforms can regulate cell-fate outcome in response to stress, by modulating p53 transcriptional activity in a promoter and stress-dependent manner. We have also shown that the p53 isoforms are abnormally expressed in several types of human cancers, suggesting that they play an important role in cancer formation. The determination of p53 isoforms' expression may help to link clinical outcome to p53 status and to improve cancer patient treatment.
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Affiliation(s)
- Marie P Khoury
- University of Dundee, Ninewells Hospital, Centre for Oncology and Molecular Medicine, Inserm-European Associated Laboratory, Inserm U858, CR-UK Cell Transformation Research Group, Dundee, United Kingdom
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46
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Simian virus 40 activates ATR-Delta p53 signaling to override cell cycle and DNA replication control. J Virol 2010; 84:10727-47. [PMID: 20686026 DOI: 10.1128/jvi.00122-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During infection, simian virus 40 (SV40) attempts to take hold of the cell, while the host responds with various defense systems, including the ataxia-telangiectasia mutated/ATM-Rad3 related (ATM/ATR)-mediated DNA damage response pathways. Here we show that upon viral infection, ATR directly activates the p53 isoform Δp53, leading to upregulation of the Cdk inhibitor p21 and downregulation of cyclin A-Cdk2/1 (AK) activity, which force the host to stay in the replicative S phase. Moreover, downregulation of AK activity is a prerequisite for the generation of hypophosphorylated, origin-competent DNA polymerase α-primase (hypo-Polα), which is, unlike AK-phosphorylated Polα (P-Polα), recruited by SV40 large T antigen (T-Ag) to initiate viral DNA replication. Prevention of the downregulation of AK activity by inactivation of ATR-Δp53-p21 signaling significantly reduced the T-Ag-interacting hypo-Polα population and, accordingly, SV40 replication efficiency. Moreover, the ATR-Δp53 pathway facilitates the proteasomal degradation of the 180-kDa catalytic subunit of the non-T-Ag-interacting P-Polα, giving rise to T-Ag-interacting hypo-Polα. Thus, the purpose of activating the ATR-Δp53-p21-mediated intra-S checkpoint is to maintain the host in S phase, an optimal environment for SV40 replication, and to modulate the host DNA replicase, which is indispensable for viral amplification.
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47
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Bailey SG, Sanchez-Elsner T, Stephanou A, Cragg MS, Townsend PA. Regulating the genome surveillance system: miRNAs and the p53 super family. Apoptosis 2010; 15:541-52. [PMID: 20091234 DOI: 10.1007/s10495-010-0456-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The p53 gene super family consists of three members; TP53, TP63 and TP73, encoding proteins p53, p63 and p73. Whilst p63 appears to have an essential role in embryonic development with a less clear role in carcinogenesis, irregularities in p53 and p73 signalling are implicated in tumour formation. As such, p53 is a tumour suppressor which is mutated in over 50% cancers and p73 was recently formally classified as a tumour suppressor based on data showing p73 deficient mice generate spontaneous tumours similar to those observed in p53 null mice. Dysregulation of both p53 and p73 has been correlated with cancer progression in many cell types and although mutation of these genes is often observed, some form of p53/p73 deregulation likely occurs in all tumour cells. The discovery that complementary micro RNAs (miRNAs) are able to target both of these genes provides a potential new means of perturbing p53/p73 signalling networks in cancer cells. Here we summarise the current literature regarding the involvement of miRNAs in the modulation of p53 family proteins and cancer development and detail the use of in silico methods to reveal key miRNA targets.
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Affiliation(s)
- Sarah G Bailey
- School of Medicine, University of Southampton, Southampton, SO16 6YD, UK
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48
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Abstract
Apart from playing a crucial role in tumor suppression, the p53 signaling pathway also has important functions in the regulation of metabolism, organ development, and cellular senescence. A recent important advance in the p53 field is the uncovering of presence of various p53 isoforms in vivo. Although full-length p53 is well known to promote cell apoptosis and cell cycle arrest, the roles of p53 isoforms in these processes are still elusive. In this review, we summarized the recent studies on the p53 isoform Delta113p53 regarding its regulation and function in zebrafish and discussed the potential use of Tg(Delta113p53:gfp) transgenic fish for identification of novel factors involved in the p53 pathway and for screening of new compounds for cancer therapy.
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Affiliation(s)
- Jun Chen
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
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49
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Hollstein M, Hainaut P. Massively regulated genes: the example of TP53. J Pathol 2010; 220:164-73. [PMID: 19918835 DOI: 10.1002/path.2637] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Intensive study of the TP53 gene over the last three decades has revealed a highly complex network of factors that regulate its performance. The gene has several promoters, alternative splicing occurs and there are alternative translation initiation sites. Up to 10 p53 isoforms have been identified. At the post-translational level, p53 activity depends on its quantity in the cell and on qualitative changes in its structure, intracellular localization, DNA-binding activity and interactions with other proteins. Both accumulation and activation are regulated by an intricate pattern of post-translational modifications, including phosphorylation, acetylation, ubiquitination, sumoylation, neddylation, methylation and glycosylation. The Mdm2 protein, a negative regulator of p53, is the most important determinant of p53 abundance and subcellular localization. Enzymes that post-translationally modify p53 by phosphorylation, methylation and acetylation fine-tune p53 binding to recognition sequences in DNA and p53 interactions with transcription cofactors at promoters of target genes, thereby exerting a discriminatory role in p53 function. This multitude of parameters determining expression, modification, accumulation and localization of p53 proteins may explain how a single gene can display an extensive repertoire of activities. Presumably this is needed, because the p53 protein can have such profound consequences for a cell.
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Abstract
Among the 278,092 publications indexed into PubMed in 1979, a handful of articles stand out as the foundation of one of the most profound forays into the molecular basis of carcinogenesis: the discovery of the p53 tumour-suppressor protein. In the 30 years since then, understanding of p53 has progressed from obscure oncogene to key tumour-suppressor gene with clinical potential. Yet, p53 research has not followed a straight course. In this Historical Review, we describe how the 1979 discovery has shaped our view of the molecular basis of cancer, and identify some crucial steps ahead to transfer the wealth of knowledge accumulated on p53 into applications to cancer prevention and treatment.
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