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Nguele Meke F, Bai Y, Ruiz-Avila D, Carlock C, Ayub J, Miao J, Hu Y, Li Q, Zhang ZY. Inhibition of PRL2 Upregulates PTEN and Attenuates Tumor Growth in Tp53-deficient Sarcoma and Lymphoma Mouse Models. CANCER RESEARCH COMMUNICATIONS 2024; 4:5-17. [PMID: 38047587 PMCID: PMC10764713 DOI: 10.1158/2767-9764.crc-23-0308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/22/2023] [Accepted: 11/28/2023] [Indexed: 12/05/2023]
Abstract
The phosphatases of regenerating liver (PRL) are oncogenic when overexpressed. We previously found that PRL2 deletion increases PTEN, decreases Akt activity, and suppresses tumor development in a partial Pten-deficient mouse model. The current study aims to further establish the mechanism of PTEN regulation by PRL2 and expand the therapeutic potential for PTEN augmentation mediated by PRL2 inhibition in cancers initiated without PTEN alteration. The TP53 gene is the most mutated tumor suppressor in human cancers, and heterozygous or complete deletion of Tp53 in mice leads to the development of sarcomas and thymic lymphomas, respectively. There remains a lack of adequate therapies for the treatment of cancers driven by Tp53 deficiency or mutations. We show that Prl2 deletion leads to PTEN elevation and attenuation of Akt signaling in sarcomas and lymphomas developed in Tp53 deficiency mouse models. This results in increased survival and reduced tumor incidence because of impaired tumor cell proliferation. In addition, inhibition of PRL2 with a small-molecule inhibitor phenocopies the effect of genetic deletion of Prl2 and reduces Tp53 deficiency-induced tumor growth. Taken together, the results further establish PRL2 as a negative regulator of PTEN and highlight the potential of PRL2 inhibition for PTEN augmentation therapy in cancers with wild-type PTEN expression. SIGNIFICANCE Prl2 deletion attenuates Tp53 deficiency-induced tumor growth by increasing PTEN and reducing Akt activity. Targeting Tp53-null lymphoma with PRL inhibitors lead to reduced tumor burden, providing a therapeutic approach via PTEN augmentation.
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Affiliation(s)
- Frederick Nguele Meke
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Yunpeng Bai
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Diego Ruiz-Avila
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Colin Carlock
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Jinan Ayub
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Jinmin Miao
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Yanyang Hu
- Department of Chemistry, Purdue University, West Lafayette, Indiana
| | - Qinglin Li
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
- Department of Chemistry, Purdue University, West Lafayette, Indiana
- Institute for Cancer Research, Purdue University, West Lafayette, Indiana
- Institute for Drug Discovery, Purdue University, West Lafayette, Indiana
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2
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Zhou Y, Nakajima R, Shirasawa M, Fikriyanti M, Zhao L, Iwanaga R, Bradford AP, Kurayoshi K, Araki K, Ohtani K. Expanding Roles of the E2F-RB-p53 Pathway in Tumor Suppression. BIOLOGY 2023; 12:1511. [PMID: 38132337 PMCID: PMC10740672 DOI: 10.3390/biology12121511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023]
Abstract
The transcription factor E2F links the RB pathway to the p53 pathway upon loss of function of pRB, thereby playing a pivotal role in the suppression of tumorigenesis. E2F fulfills a major role in cell proliferation by controlling a variety of growth-associated genes. The activity of E2F is controlled by the tumor suppressor pRB, which binds to E2F and actively suppresses target gene expression, thereby restraining cell proliferation. Signaling pathways originating from growth stimulative and growth suppressive signals converge on pRB (the RB pathway) to regulate E2F activity. In most cancers, the function of pRB is compromised by oncogenic mutations, and E2F activity is enhanced, thereby facilitating cell proliferation to promote tumorigenesis. Upon such events, E2F activates the Arf tumor suppressor gene, leading to activation of the tumor suppressor p53 to protect cells from tumorigenesis. ARF inactivates MDM2, which facilitates degradation of p53 through proteasome by ubiquitination (the p53 pathway). P53 suppresses tumorigenesis by inducing cellular senescence or apoptosis. Hence, in almost all cancers, the p53 pathway is also disabled. Here we will introduce the canonical functions of the RB-E2F-p53 pathway first and then the non-classical functions of each component, which may be relevant to cancer biology.
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Affiliation(s)
- Yaxuan Zhou
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
| | - Rinka Nakajima
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
| | - Mashiro Shirasawa
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
| | - Mariana Fikriyanti
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
| | - Lin Zhao
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
| | - Ritsuko Iwanaga
- Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA; (R.I.); (A.P.B.)
| | - Andrew P. Bradford
- Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA; (R.I.); (A.P.B.)
| | - Kenta Kurayoshi
- Division of Molecular Genetics, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan;
| | - Keigo Araki
- Department of Morphological Biology, Ohu University School of Dentistry, 31-1 Misumido Tomitamachi, Koriyama, Fukushima 963-8611, Japan;
| | - Kiyoshi Ohtani
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan; (Y.Z.); (R.N.); (M.S.); (M.F.); (L.Z.)
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Baker NE, Montagna C. Reducing the aneuploid cell burden - cell competition and the ribosome connection. Dis Model Mech 2022; 15:dmm049673. [PMID: 36444717 PMCID: PMC10621665 DOI: 10.1242/dmm.049673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Aneuploidy, the gain or loss of chromosomes, is the cause of birth defects and miscarriage and is almost ubiquitous in cancer cells. Mosaic aneuploidy causes cancer predisposition, as well as age-related disorders. Despite the cell-intrinsic mechanisms that prevent aneuploidy, sporadic aneuploid cells do arise in otherwise normal tissues. These aneuploid cells can differ from normal cells in the copy number of specific dose-sensitive genes, and may also experience proteotoxic stress associated with mismatched expression levels of many proteins. These differences may mark aneuploid cells for recognition and elimination. The ribosomal protein gene dose in aneuploid cells could be important because, in Drosophila, haploinsufficiency for these genes leads to elimination by the process of cell competition. Constitutive haploinsufficiency for human ribosomal protein genes causes Diamond Blackfan anemia, but it is not yet known whether ribosomal protein gene dose contributes to aneuploid cell elimination in mammals. In this Review, we discuss whether cell competition on the basis of ribosomal protein gene dose is a tumor suppressor mechanism, reducing the accumulation of aneuploid cells. We also discuss how this might relate to the tumor suppressor function of p53 and the p53-mediated elimination of aneuploid cells from murine embryos, and how cell competition defects could contribute to the cancer predisposition of Diamond Blackfan anemia.
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Affiliation(s)
- Nicholas E. Baker
- Departments of Genetics, Developmental and Molecular Biology, and Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Cristina Montagna
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08901, USA
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4
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Marney CB, Anderson ES, Baum R, Schmitt AM. A Unique Spectrum of Spontaneous Tumors in Dino Knockout Mice Identifies Tissue-Specific Requirements for Tumor Suppression. Cells 2022; 11:cells11111818. [PMID: 35681513 PMCID: PMC9180304 DOI: 10.3390/cells11111818] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/27/2022] [Accepted: 05/29/2022] [Indexed: 02/05/2023] Open
Abstract
Here, we report that Dino, a lncRNA required for p53 signaling, suppresses spontaneous tumorigenesis in mice. Dino−/− mice develop significantly more malignant tumors than Dino+/+ littermate controls, consisting predominantly of sarcomas, B cell lymphomas and additional rare tumors. While the prevalence of lymphomas and sarcomas in Dino−/− mice is similar to that of mice with p53 loss, important distinctions emerged. p53-null mice predominantly develop T cell lymphomas; however, no spontaneous T cell lymphoma was observed in Dino−/− mice. Rather than being a phenocopy of the p53-null tumor spectrum, spontaneous tumors in Dino−/− mice resemble the spectrum of human cancers in which DINO is recurrently silenced by methylation in a manner that is mutually exclusive with TP53 alterations, suggesting that similar tissues in human and mouse require DINO for tumor suppression. Consistent with a tissue-specific role for Dino in tumor suppression, loss of Dino had no impact on the development of radiation-induced T cell lymphoma and oncogene-driven medulloblastoma, tumors that are accelerated by the loss of p53. Taken together, these data indicate that Dino serves as a potent tumor suppressor molecule specific to a select subset of tissues in mice and humans.
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5
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Wang M, Attardi LD. A Balancing Act: p53 Activity from Tumor Suppression to Pathology and Therapeutic Implications. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2021; 17:205-226. [PMID: 34699262 DOI: 10.1146/annurev-pathol-042320-025840] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
TP53, encoding the p53 transcription factor, is the most frequently mutated tumor suppressor gene across all human cancer types. While p53 has long been appreciated to induce antiproliferative cell cycle arrest, apoptosis, and senescence programs in response to diverse stress signals, various studies in recent years have revealed additional important functions for p53 that likely also contribute to tumor suppression, including roles in regulating tumor metabolism, ferroptosis, signaling in the tumor microenvironment, and stem cell self-renewal/differentiation. Not only does p53 loss or mutation cause cancer, but hyperactive p53 also drives various pathologies, including developmental phenotypes, premature aging, neurodegeneration, and side effects of cancer therapies. These findings underscore the importance of balanced p53 activity and influence our thinking of how to best develop cancer therapies based on modulating the p53 pathway. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Mengxiong Wang
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California 94305, USA;
| | - Laura D Attardi
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California 94305, USA; .,Department of Genetics and Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305, USA
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6
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Gopalan V, Singh A, Rashidi Mehrabadi F, Wang L, Ruppin E, Arda HE, Hannenhalli S. A Transcriptionally Distinct Subpopulation of Healthy Acinar Cells Exhibit Features of Pancreatic Progenitors and PDAC. Cancer Res 2021; 81:3958-3970. [PMID: 34049974 PMCID: PMC8338776 DOI: 10.1158/0008-5472.can-21-0427] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/19/2021] [Accepted: 05/26/2021] [Indexed: 12/30/2022]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) tumors can originate either from acinar or ductal cells in the adult pancreas. We re-analyze multiple pancreas and PDAC single-cell RNA-seq datasets and find a subset of nonmalignant acinar cells, which we refer to as acinar edge (AE) cells, whose transcriptomes highly diverge from a typical acinar cell in each dataset. Genes upregulated among AE cells are enriched for transcriptomic signatures of pancreatic progenitors, acinar dedifferentiation, and several oncogenic programs. AE-upregulated genes are upregulated in human PDAC tumors, and consistently, their promoters are hypomethylated. High expression of these genes is associated with poor patient survival. The fraction of AE-like cells increases with age in healthy pancreatic tissue, which is not explained by clonal mutations, thus pointing to a nongenetic source of variation. The fraction of AE-like cells is also significantly higher in human pancreatitis samples. Finally, we find edge-like states in lung, liver, prostate, and colon tissues, suggesting that subpopulations of healthy cells across tissues can exist in pre-neoplastic states. SIGNIFICANCE: These findings show "edge" epithelial cell states with oncogenic transcriptional activity in human organs without oncogenic mutations. In the pancreas, the fraction of acinar cells increases with age.
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Affiliation(s)
- Vishaka Gopalan
- Cancer Data Science Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland.
| | - Arashdeep Singh
- Cancer Data Science Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland
| | - Farid Rashidi Mehrabadi
- Cancer Data Science Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland
- Department of Computer Science, Indiana University, Bloomington, Indiana
| | - Li Wang
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Eytan Ruppin
- Cancer Data Science Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland
| | - H Efsun Arda
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Sridhar Hannenhalli
- Cancer Data Science Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland.
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7
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Imran SAM, Yazid MD, Idrus RBH, Maarof M, Nordin A, Razali RA, Lokanathan Y. Is There an Interconnection between Epithelial-Mesenchymal Transition (EMT) and Telomere Shortening in Aging? Int J Mol Sci 2021; 22:ijms22083888. [PMID: 33918710 PMCID: PMC8070110 DOI: 10.3390/ijms22083888] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022] Open
Abstract
Epithelial–Mesenchymal Transition (EMT) was first discovered during the transition of cells from the primitive streak during embryogenesis in chicks. It was later discovered that EMT holds greater potential in areas other than the early development of cells and tissues since it also plays a vital role in wound healing and cancer development. EMT can be classified into three types based on physiological functions. EMT type 3, which involves neoplastic development and metastasis, has been the most thoroughly explored. As EMT is often found in cancer stem cells, most research has focused on its association with other factors involving cancer progression, including telomeres. However, as telomeres are also mainly involved in aging, any possible interaction between the two would be worth noting, especially as telomere dysfunction also contributes to cancer and other age-related diseases. Ascertaining the balance between degeneration and cancer development is crucial in cell biology, in which telomeres function as a key regulator between the two extremes. The essential roles that EMT and telomere protection have in aging reveal a potential mutual interaction that has not yet been explored, and which could be used in disease therapy. In this review, the known functions of EMT and telomeres in aging are discussed and their potential interaction in age-related diseases is highlighted.
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Affiliation(s)
- Siti A. M. Imran
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
| | - Muhammad Dain Yazid
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
| | - Ruszymah Bt Hj Idrus
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia
| | - Manira Maarof
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
| | - Abid Nordin
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia
| | - Rabiatul Adawiyah Razali
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia
| | - Yogeswaran Lokanathan
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia; (S.A.M.I.); (M.D.Y.); (R.B.H.I.); (M.M.); (A.N.); (R.A.R.)
- Correspondence: ; Tel.: +60-391457704
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8
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Valente LJ, Tarangelo A, Li AM, Naciri M, Raj N, Boutelle AM, Li Y, Mello SS, Bieging-Rolett K, DeBerardinis RJ, Ye J, Dixon SJ, Attardi LD. p53 deficiency triggers dysregulation of diverse cellular processes in physiological oxygen. J Cell Biol 2021; 219:152074. [PMID: 32886745 PMCID: PMC7594498 DOI: 10.1083/jcb.201908212] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 06/17/2020] [Accepted: 07/28/2020] [Indexed: 12/20/2022] Open
Abstract
The mechanisms by which TP53, the most frequently mutated gene in human cancer, suppresses tumorigenesis remain unclear. p53 modulates various cellular processes, such as apoptosis and proliferation, which has led to distinct cellular mechanisms being proposed for p53-mediated tumor suppression in different contexts. Here, we asked whether during tumor suppression p53 might instead regulate a wide range of cellular processes. Analysis of mouse and human oncogene-expressing wild-type and p53-deficient cells in physiological oxygen conditions revealed that p53 loss concurrently impacts numerous distinct cellular processes, including apoptosis, genome stabilization, DNA repair, metabolism, migration, and invasion. Notably, some phenotypes were uncovered only in physiological oxygen. Transcriptomic analysis in this setting highlighted underappreciated functions modulated by p53, including actin dynamics. Collectively, these results suggest that p53 simultaneously governs diverse cellular processes during transformation suppression, an aspect of p53 function that would provide a clear rationale for its frequent inactivation in human cancer.
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Affiliation(s)
- Liz J Valente
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Amy Tarangelo
- Department of Biology, Stanford University, Stanford, CA
| | - Albert Mao Li
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Marwan Naciri
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.,École Normale Supérieure de Lyon, Université Claude Bernard Lyon I, Université de Lyon, Lyon, France
| | - Nitin Raj
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Anthony M Boutelle
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Yang Li
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Stephano Spano Mello
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.,Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY
| | - Kathryn Bieging-Rolett
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jiangbin Ye
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
| | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA.,Department of Genetics, Stanford University School of Medicine, Stanford, CA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA
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9
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Kon N, Churchill M, Li H, Mukherjee S, Manfredi JJ, Gu W. Robust p53 Stabilization Is Dispensable for Its Activation and Tumor Suppressor Function. Cancer Res 2021; 81:935-944. [PMID: 33323382 PMCID: PMC8026563 DOI: 10.1158/0008-5472.can-20-1804] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 11/06/2020] [Accepted: 12/10/2020] [Indexed: 11/16/2022]
Abstract
p53 is a short-lived protein with low basal levels under normal homeostasis conditions. However, upon DNA damage, levels of p53 dramatically increase for its activation. Although robust stabilization of p53 serves as a "trademark" for DNA damage responses, the requirement for such dramatic protein stabilization in tumor suppression has not been well addressed. Here we generated a mutant p53KQ mouse where all the C-terminal domain lysine residues were mutated to glutamines (K to Q mutations at K367, K369, K370, K378, K379, K383, and K384) to mimic constitutive acetylation of the p53 C-terminus. Because of p53 activation, p53KQ/KQ mice were perinatal lethal, yet this lethality was averted in p53KQ/- mice, which displayed normal postnatal development. Nevertheless, p53KQ/- mice died prematurely due to anemia and hematopoiesis failure. Further analyses indicated that expression of the acetylation-mimicking p53 mutant in vivo induces activation of p53 targets in various tissues without obviously increasing p53 levels. In the well-established pancreatic ductal adenocarcinoma (PDAC) mouse model, expression of the acetylation-mimicking p53-mutant protein effectively suppressed K-Ras-induced PDAC development in the absence of robust p53 stabilization. Together, our results provide proof-of-principle evidence that p53-mediated transcriptional function and tumor suppression can be achieved independently of its robust stabilization and reveal an alternative approach to activate p53 function for therapeutic purposes. SIGNIFICANCE: Although robust p53 stabilization is critical for acute p53 responses such as DNA damage, this study underscores the important role of low basal p53 protein levels in p53 activation and tumor suppression.
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Affiliation(s)
- Ning Kon
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Michael Churchill
- Department of Medicine and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Huan Li
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - Siddhartha Mukherjee
- Department of Medicine and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York
| | - James J Manfredi
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Wei Gu
- Institute for Cancer Genetics, Department of Pathology and Cell Biology, and Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons, Columbia University, New York, New York.
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10
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Boutelle AM, Attardi LD. p53 and Tumor Suppression: It Takes a Network. Trends Cell Biol 2021; 31:298-310. [PMID: 33518400 DOI: 10.1016/j.tcb.2020.12.011] [Citation(s) in RCA: 149] [Impact Index Per Article: 49.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 02/07/2023]
Abstract
The TP53 tumor suppressor is the most frequently mutated gene in human cancer. p53 suppresses tumorigenesis by transcriptionally regulating a network of target genes that play roles in various cellular processes. Though originally characterized as a critical regulator for responses to acute DNA damage (activation of apoptosis and cell cycle arrest), recent studies have highlighted new pathways and transcriptional targets downstream of p53 regulating genomic integrity, metabolism, redox biology, stemness, and non-cell autonomous signaling in tumor suppression. Here, we summarize our current understanding of p53-mediated tumor suppression, situating recent findings from mouse models and unbiased screens in the context of previous studies and arguing for the importance of the pleiotropic effects of the p53 transcriptional network in inhibiting cancer.
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Affiliation(s)
- Anthony M Boutelle
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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11
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Shi T, Dansen TB. Reactive Oxygen Species Induced p53 Activation: DNA Damage, Redox Signaling, or Both? Antioxid Redox Signal 2020; 33:839-859. [PMID: 32151151 DOI: 10.1089/ars.2020.8074] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Significance: The p53 tumor suppressor has been dubbed the "guardian of genome" because of its various roles in the response to DNA damage such as DNA damage repair, cell cycle arrest, senescence, and apoptosis, all of which are in place to prevent mutations from being passed on down the lineage. Recent Advances: Reactive oxygen species (ROS), for instance hydrogen peroxide derived from mitochondrial respiration, have long been regarded mainly as a major source of cellular damage to DNA and other macromolecules. Critical Issues: More recently, ROS have been shown to also play important physiological roles as second messengers in so-called redox signaling. It is, therefore, not clear whether the observed activation of p53 by ROS is mediated through the DNA damage response, redox signaling, or both. In this review, we will discuss the similarities and differences between p53 activation in response to DNA damage and redox signaling in terms of upstream signaling and downstream transcriptional program activation. Future Directions: Understanding whether and how DNA damage and redox signaling-dependent p53 activation can be dissected could be useful to develop anti-cancer therapeutic p53-reactivation strategies that do not depend on the induction of DNA damage and the resulting additional mutational load.
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Affiliation(s)
- Tao Shi
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tobias B Dansen
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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12
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Abstract
The growth and survival of cells within tissues can be affected by 'cell competition' between different cell clones. This phenomenon was initially recognized between wild-type cells and cells with mutations in ribosomal protein (Rp) genes in Drosophila melanogaster. However, competition also affects D. melanogaster cells with mutations in epithelial polarity genes, and wild-type cells exposed to 'super-competitor' cells with mutation in the Salvador-Warts-Hippo tumour suppressor pathway or expressing elevated levels of Myc. More recently, cell competition and super-competition were recognized in mammalian development, organ homeostasis and cancer. Genetic and cell biological studies have revealed that mechanisms underlying cell competition include the molecular recognition of 'different' cells, signalling imbalances between distinct cell populations and the mechanical consequences of differential growth rates; these mechanisms may also involve innate immune proteins, p53 and changes in translation.
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13
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Ho T, Tan BX, Lane D. How the Other Half Lives: What p53 Does When It Is Not Being a Transcription Factor. Int J Mol Sci 2019; 21:ijms21010013. [PMID: 31861395 PMCID: PMC6982169 DOI: 10.3390/ijms21010013] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/07/2019] [Accepted: 12/16/2019] [Indexed: 12/31/2022] Open
Abstract
It has been four decades since the discovery of p53, the designated ‘Guardian of the Genome’. P53 is primarily known as a master transcription factor and critical tumor suppressor, with countless studies detailing the mechanisms by which it regulates a host of gene targets and their consequent signaling pathways. However, transcription-independent functions of p53 also strongly define its tumor-suppressive capabilities and recent findings shed light on the molecular mechanisms hinted at by earlier efforts. This review highlights the transcription-independent mechanisms by which p53 influences the cellular response to genomic instability (in the form of replication stress, centrosome homeostasis, and transposition) and cell death. We also pinpoint areas for further investigation in order to better understand the context dependency of p53 transcription-independent functions and how these are perturbed when TP53 is mutated in human cancer.
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14
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New Insights into the Role of Epithelial⁻Mesenchymal Transition during Aging. Int J Mol Sci 2019; 20:ijms20040891. [PMID: 30791369 PMCID: PMC6412502 DOI: 10.3390/ijms20040891] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 02/08/2019] [Accepted: 02/15/2019] [Indexed: 12/29/2022] Open
Abstract
Epithelial–mesenchymal transition (EMT) is a cellular process by which differentiated epithelial cells undergo a phenotypic conversion to a mesenchymal nature. The EMT has been increasingly recognized as an essential process for tissue fibrogenesis during disease and normal aging. Higher levels of EMT proteins in aged tissues support the involvement of EMT as a possible cause and/or consequence of the aging process. Here, we will highlight the existing understanding of EMT supporting the phenotypical alterations that occur during normal aging or pathogenesis, covering the impact of EMT deregulation in tissue homeostasis and stem cell function.
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15
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Luo G, Liu N. An integrative theory for cancer (Review). Int J Mol Med 2018; 43:647-656. [PMID: 30483756 PMCID: PMC6317675 DOI: 10.3892/ijmm.2018.4004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/21/2018] [Indexed: 12/24/2022] Open
Abstract
In the integrative theory, chronic irritations induce tumors with genetic alterations and rapid proliferative ability. Tumor cells reprogram the metabolism and employ aerobic glycolysis to sustain rapid growth. The host provides both the nutrients and exhaust system to support tumor growth via the tumor microenvironment. Under certain conditions, such as aging, diabetes, obesity and a high‑fat diet, the exhaust system is impaired, triggering a metabolic imbalance between the tumor and host. This is similar to a problematic car with an advanced motor with an out‑of‑date exhaust system. The metabolic imbalance causes a metabolic catastrophe, making tumor cells reside in a dismal environment and forcing them to invade, metastasize and undergo necrosis. Tumor necrosis, particularly in metastases, leads to non‑specific systemic inflammation, which is the major cause of cancer‑related mortality. On the whole, the integrative theory views cancer in an integrative manner and proposes that both genetic alterations and tumor‑host interaction as regards metabolism and immunology determine the destiny of the tumor and host. Although cancer is a genetic disease, tumor biology is basically the nature of the host.
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Affiliation(s)
- Guopei Luo
- Department of Pancreatic Surgery, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Na Liu
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, P.R. China
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16
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Two-Step Senescence-Focused Cancer Therapies. Trends Cell Biol 2018; 28:723-737. [PMID: 29776716 DOI: 10.1016/j.tcb.2018.04.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/15/2018] [Accepted: 04/23/2018] [Indexed: 01/07/2023]
Abstract
Damaged cells at risk of neoplastic transformation can be neutralized by apoptosis or engagement of the senescence program, which induces permanent cell-cycle arrest and a bioactive secretome that is implicated in tumor immunosurveillance. While from an evolutionary perspective senescence is beneficial in that it protects against malignancies, the accumulation of senescent cells in tissues and organs with aging and at sites of various pathologies is largely detrimental. Because induction of senescence in cancer cells is emerging as a therapeutic concept, it will be important to consider these detrimental effects, including tumor-promoting properties that may drive the formation of secondary tumors or cancer relapse. In this review we discuss the complex relationship between senescence and cancer, and highlight important considerations for therapeutics.
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17
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A Reassessment of Genes Modulating Aging in Mice Using Demographic Measurements of the Rate of Aging. Genetics 2018; 208:1617-1630. [PMID: 29444805 PMCID: PMC5887152 DOI: 10.1534/genetics.118.300821] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 02/07/2018] [Indexed: 02/07/2023] Open
Abstract
Many studies have reported genetic interventions that have an effect on mouse life span; however, it is crucial to discriminate between manipulations of aging and aging-independent causes of life extension. Here, we used the Gompertz equation to determine whether previously reported aging-related mouse genes statistically affect the demographic rate of aging. Of 30 genetic manipulations previously reported to extend life span, for only two we found evidence of retarding demographic aging: Cisd2 and hMTH1. Of 24 genetic manipulations reported to shorten life span and induce premature aging features, we found evidence of five accelerating demographic aging: Casp2, Fn1, IKK-β, JunD, and Stub1. Overall, our reassessment found that only 15% of the genetic manipulations analyzed significantly affected the demographic rate of aging as predicted, suggesting that a relatively small proportion of interventions affecting longevity do so by regulating the rate of aging. By contrast, genetic manipulations affecting longevity tend to impact on aging-independent mortality. Our meta-analysis of multiple mouse longevity studies also reveals substantial variation in the controls used across experiments, suggesting that a short life span of controls is a potential source of bias. Overall, the present work leads to a reassessment of genes affecting the aging process in mice, with broad implications for our understanding of the genetics of mammalian aging and which genes may be more promising targets for drug discovery.
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18
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Mello SS, Attardi LD. Deciphering p53 signaling in tumor suppression. Curr Opin Cell Biol 2017; 51:65-72. [PMID: 29195118 DOI: 10.1016/j.ceb.2017.11.005] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/07/2017] [Accepted: 11/09/2017] [Indexed: 12/20/2022]
Abstract
The p53 transcription factor is mutated in over half of human cancers, and p53-null mice are highly predisposed to cancer, highlighting p53s essential role in tumor suppression. Studies in mouse models have revealed that p53 cell cycle arrest and apoptosis responses to acute DNA damage signals are dispensable for tumor suppression, prompting a search for new mechanisms underlying p53-mediated cancer suppression. p53 responds to other types of stress signals and regulates a host other cellular processes, including maintenance of genomic stability, metabolism, stemness, non-apoptotic cell death, migration/invasion, and cell signaling, any or all of which could be fundamental for suppressing carcinogenesis. The ability of p53 to govern numerous transcriptional programs and cellular functions likely explains its potent tumor suppressor activity.
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Affiliation(s)
- Stephano S Mello
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
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19
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Kaiser AM, Attardi LD. Deconstructing networks of p53-mediated tumor suppression in vivo. Cell Death Differ 2017; 25:93-103. [PMID: 29099489 DOI: 10.1038/cdd.2017.171] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/18/2017] [Accepted: 08/31/2017] [Indexed: 02/07/2023] Open
Abstract
The transcription factor p53 is a vital tumor suppressor. Upon activation by diverse stresses including oncogene activation, DNA damage, hypoxia and nutrient deprivation, p53 activates a panoply of target genes and orchestrates numerous downstream responses that suppress tumorigenesis. Although early studies of p53 suggested that its ability to induce cell cycle arrest, senescence and apoptosis programs accounted for its tumor-suppressor activity, more recent studies have challenged this notion. Moreover, p53 regulates a suite of additional processes, such as metabolism, stem cell function, invasion and metastasis. The processes p53 coordinately regulates to enact tumor suppression, and how such regulation occurs, thus remain elusive. In this review, we will summarize our current knowledge of p53-mediated tumor-suppressive mechanisms gleaned from in vivo studies in mouse models.
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Affiliation(s)
- Alyssa M Kaiser
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
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20
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Lemon JA, Phan N, Boreham DR. Multiple CT Scans Extend Lifespan by Delaying Cancer Progression in Cancer-Prone Mice. Radiat Res 2017; 188:495-504. [DOI: 10.1667/rr14575.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Jennifer A. Lemon
- Medical Sciences, Northern Ontario School of Medicine, Sudbury, Canada, P3E 2C6
| | - Nghi Phan
- Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Canada, L8S 4K1
| | - Douglas R. Boreham
- Medical Sciences, Northern Ontario School of Medicine, Sudbury, Canada, P3E 2C6
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21
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Castle KD, Chen M, Wisdom AJ, Kirsch DG. Genetically engineered mouse models for studying radiation biology. Transl Cancer Res 2017; 6:S900-S913. [PMID: 30733931 PMCID: PMC6363345 DOI: 10.21037/tcr.2017.06.19] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genetically engineered mouse models (GEMMs) are valuable research tools that have transformed our understanding of cancer. The first GEMMs generated in the 1980s and 1990s were knock-in and knock-out models of single oncogenes or tumor suppressors. The advances that made these models possible catalyzed both technological and conceptual shifts in the way cancer research was conducted. As a result, dozens of mouse models of cancer exist today, covering nearly every tissue type. The advantages inherent to GEMMs compared to in vitro and in vivo transplant models are compounded in preclinical radiobiology research for several reasons. First, they accurately and robustly recapitulate primary cancers anatomically, histopathologically, and genetically. Reliable models are a prerequisite for predictive preclinical studies. Second, they preserve the tumor microenvironment, including the immune, vascular, and stromal compartments, which enables the study of radiobiology at a systems biology level. Third, they provide exquisite control over the genetics and kinetics of tumor initiation, which enables the study of specific gene mutations on radiation response and functional genomics in vivo. Taken together, these facets allow researchers to utilize GEMMs for rigorous and reproducible preclinical research. In the three decades since the generation of the first GEMMs of cancer, advancements in modeling approaches have rapidly progressed and expanded the mouse modeling toolbox with techniques such as in vivo short hairpin RNA (shRNA) knockdown, inducible gene expression, site-specific recombinases, and dual recombinase systems. Our lab and many others have utilized these tools to study cancer and radiobiology. Recent advances in genome engineering with CRISPR/Cas9 technology have made GEMMs even more accessible to researchers. Here, we review current and future approaches to mouse modeling with a focus on applications in preclinical radiobiology research.
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Affiliation(s)
- Katherine D. Castle
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Mark Chen
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Medical Scientist Training Program, Duke University Medical Center, Durham, North Carolina, USA
| | - Amy J. Wisdom
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Medical Scientist Training Program, Duke University Medical Center, Durham, North Carolina, USA
| | - David G. Kirsch
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, USA
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22
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Palacio L, Krishnan V, Le NLO, Sharpless NE, Beauséjour CM. Sustained p16 INK4a expression is required to prevent IR-induced tumorigenesis in mice. Oncogene 2016; 36:1309-1314. [PMID: 27568978 PMCID: PMC5336385 DOI: 10.1038/onc.2016.298] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 06/29/2016] [Accepted: 07/17/2016] [Indexed: 12/17/2022]
Abstract
Exposure of murine and human tissues to ionizing radiation (IR) induces the expression of p16INK4a, a tumor suppressor gene and senescence/aging biomarker. Increased p16INK4a expression is often delayed several weeks post exposure to IR. In this context, it remains unclear if it occurs to suppress aberrant cellular growth of potentially transformed cells or is simply a result of IR-induced loss of tissue homeostasis. To address this question, we used a conditional p16INK4a null mouse model and determined the impact of p16INK4a inactivation long-term post exposure to IR. We found that, in vitro, bone marrow stromal cells exposed to IR enter DNA replication following p16INK4a inactivation. However, these cells did not resume growth; instead, they mostly underwent cell cycle arrest in G2. Similarly, delayed inactivation of p16INK4a in mice several weeks post exposure to IR resulted in increased BrdU incorporation and cancer incidence. In fact, we found that the onset of tumorigenesis was similar whether p16INK4a was inactivated before or after exposure to IR. Overall, our results suggest that IR-induced p16INK4a dependent growth arrest is reversible in mice and that sustained p16INK4a expression is necessary to protect against tumorigenesis.
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Affiliation(s)
- L Palacio
- Centre de Recherche du Centre Hospitalier Universitaire Ste-Justine, Montréal, Canada.,Département de Pharmacologie, Université de Montréal, Montréal, Canada
| | - V Krishnan
- Centre de Recherche du Centre Hospitalier Universitaire Ste-Justine, Montréal, Canada.,Département de Pharmacologie, Université de Montréal, Montréal, Canada
| | - N L O Le
- Centre de Recherche du Centre Hospitalier Universitaire Ste-Justine, Montréal, Canada
| | - N E Sharpless
- Departments of Medicine and Genetics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - C M Beauséjour
- Centre de Recherche du Centre Hospitalier Universitaire Ste-Justine, Montréal, Canada.,Département de Pharmacologie, Université de Montréal, Montréal, Canada
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23
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Yang L, Rodriguez B, Mayle A, Park HJ, Lin X, Luo M, Jeong M, Curry CV, Kim SB, Ruau D, Zhang X, Zhou T, Zhou M, Rebel VI, Challen GA, Gottgens B, Lee JS, Rau R, Li W, Goodell MA. DNMT3A Loss Drives Enhancer Hypomethylation in FLT3-ITD-Associated Leukemias. Cancer Cell 2016; 29:922-934. [PMID: 27300438 PMCID: PMC4908977 DOI: 10.1016/j.ccell.2016.05.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 02/29/2016] [Accepted: 05/10/2016] [Indexed: 10/21/2022]
Abstract
DNMT3A, the gene encoding the de novo DNA methyltransferase 3A, is among the most frequently mutated genes in hematologic malignancies. However, the mechanisms through which DNMT3A normally suppresses malignancy development are unknown. Here, we show that DNMT3A loss synergizes with the FLT3 internal tandem duplication in a dose-influenced fashion to generate rapid lethal lymphoid or myeloid leukemias similar to their human counterparts. Loss of DNMT3A leads to reduced DNA methylation, predominantly at hematopoietic enhancer regions in both mouse and human samples. Myeloid and lymphoid diseases arise from transformed murine hematopoietic stem cells. Broadly, our findings support a role for DNMT3A as a guardian of the epigenetic state at enhancer regions, critical for inhibition of leukemic transformation.
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Affiliation(s)
- Liubin Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Benjamin Rodriguez
- Dan L. Duncan Cancer Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Allison Mayle
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Hyun Jung Park
- Dan L. Duncan Cancer Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Xueqiu Lin
- Dan L. Duncan Cancer Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Bioinformatics, School of Life sciences and Technology, Tongji University, Shanghai 20092, China
| | - Min Luo
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Mira Jeong
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Choladda V. Curry
- Department of Pathology and Immunology, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Sang-Bae Kim
- Department of Systems Biology, Division of Cancer Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - David Ruau
- Wellcome Trust/MRC Stem Cell Institute, Cambridge CB2 0XY, UK
| | - Xiaotian Zhang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Ting Zhou
- Greehey Children's Cancer Research Institute and Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | | | - Vivienne I. Rebel
- Greehey Children's Cancer Research Institute and Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Grant A. Challen
- Division of Oncology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | - Ju-Seog Lee
- Department of Systems Biology, Division of Cancer Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Rachel Rau
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Wei Li
- Dan L. Duncan Cancer Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Margaret A. Goodell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Dan L. Duncan Cancer Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Systems Biology, Division of Cancer Medicine, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
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24
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p19(Arf) is required for the cellular response to chronic DNA damage. Oncogene 2016; 35:4414-21. [PMID: 26725325 PMCID: PMC4931997 DOI: 10.1038/onc.2015.490] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 11/03/2015] [Accepted: 11/09/2015] [Indexed: 01/13/2023]
Abstract
The p53 tumor suppressor is a stress sensor, driving cell-cycle arrest or apoptosis in response to DNA damage or oncogenic signals. p53 activation by oncogenic signals relies on the p19Arf tumor suppressor, while p53 activation downstream of acute DNA damage is reported to be p19Arf-independent. Accordingly, p19Arf-deficient mouse embryo fibroblasts (MEFs) arrest in response to acute DNA damage. However, p19Arf is required for replicative senescence, a condition associated with an activated DNA damage response, as p19Arf−/− MEFs do not senesce after serial passage. A possible explanation for these seemingly disparate roles for p19Arf is that acute and chronic DNA damage responses are mechanistically distinct. Replicative senescence may result from chronic, low-dose DNA damage responses in which p19Arf has a specific role. We therefore examined the role of p19Arf in cellular responses to chronic, low-dose DNA damaging agent treatment by maintaining MEFs in low oxygen and administering 0.5 Gy γ-irradiation daily or 150μM hydroxyurea, a replication stress-inducer. In contrast to their response to acute DNA damage, p19Arf−/− MEFs exposed to chronic DNA damage do not senesce, revealing a selective role for p19Arf in senescence upon low-level, chronic DNA damage. We show further that p53 pathway activation in p19Arf−/− MEFs exposed to chronic DNA damage is attenuated relative to wild-type MEFs, suggesting a role for p19Arf in fine-tuning p53 activity. However, combined Nutlin3a and chronic DNA damaging agent treatment is insufficient to promote senescence in p19Arf−/− MEFs, suggesting that the role of p19Arf in the chronic DNA damage response may be partially p53-independent. These data suggest the importance of p19Arf for the cellular response to the low-level DNA damage incurred in culture or upon oncogene expression, providing new insight into how p19Arf serves as a tumor suppressor. Moreover, our study helps reconcile reports suggesting crucial roles for both p19Arf and DNA damage signaling pathways in tumor suppression.
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25
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Abstract
p53 has been studied intensively as a major tumour suppressor that detects oncogenic events in cancer cells and eliminates them through senescence (a permanent non-proliferative state) or apoptosis. Consistent with this role, p53 activity is compromised in a high proportion of all cancer types, either through mutation of the TP53 gene (encoding p53) or changes in the status of p53 modulators. p53 has additional roles, which may overlap with its tumour-suppressive capacity, in processes including the DNA damage response, metabolism, aging, stem cell differentiation and fertility. Moreover, many mutant p53 proteins, termed 'gain-of-function' (GOF), acquire new activities that help drive cancer aggression. p53 is regulated mainly through protein turnover and operates within a negative-feedback loop with its transcriptional target, MDM2 (murine double minute 2), an E3 ubiquitin ligase which mediates the ubiquitylation and proteasomal degradation of p53. Induction of p53 is achieved largely through uncoupling the p53-MDM2 interaction, leading to elevated p53 levels. Various stress stimuli acting on p53 (such as hyperproliferation and DNA damage) use different, but overlapping, mechanisms to achieve this. Additionally, p53 activity is regulated through critical context-specific or fine-tuning events, mediated primarily through post-translational mechanisms, particularly multi-site phosphorylation and acetylation. In the present review, I broadly examine these events, highlighting their regulatory contributions, their ability to integrate signals from cellular events towards providing most appropriate response to stress conditions and their importance for tumour suppression. These are fascinating aspects of molecular oncology that hold the key to understanding the molecular pathology of cancer and the routes by which it may be tackled therapeutically.
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26
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Lee CL, Castle KD, Moding EJ, Blum JM, Williams N, Luo L, Ma Y, Borst LB, Kim Y, Kirsch DG. Acute DNA damage activates the tumour suppressor p53 to promote radiation-induced lymphoma. Nat Commun 2015; 6:8477. [PMID: 26399548 PMCID: PMC4586051 DOI: 10.1038/ncomms9477] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 08/26/2015] [Indexed: 11/10/2022] Open
Abstract
Genotoxic cancer therapies, such as chemoradiation, cause haematological toxicity primarily by activating the tumour suppressor p53. While inhibiting p53-mediated cell death during cancer therapy ameliorates haematologic toxicity, whether it also impacts carcinogenesis remains unclear. Here we utilize a mouse model of inducible p53 short hairpin RNA (shRNA) to show that temporarily blocking p53 during total-body irradiation (TBI) not only ameliorates acute toxicity, but also improves long-term survival by preventing lymphoma development. Using KrasLA1 mice, we show that TBI promotes the expansion of a rare population of thymocytes that express oncogenic KrasG12D. However, blocking p53 during TBI significantly suppresses the expansion of KrasG12D-expressing thymocytes. Mechanistically, bone marrow transplant experiments demonstrate that TBI activates p53 to decrease the ability of bone marrow cells to suppress lymphoma development through a non-cell-autonomous mechanism. Together, our results demonstrate that the p53 response to acute DNA damage promotes the development of radiation-induced lymphoma. p53 can be activated by oncogenic stress to suppress tumourigenesis, but its role in radiation carcinogenesis has not been studied in p53 wild-type mice. Here, Lee et al. show that knocking down p53 during total-body irradiation not only reduces acute toxicity, but prevents the formation of radiation-induced lymphoma.
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Affiliation(s)
- Chang-Lung Lee
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Katherine D Castle
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Everett J Moding
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Jordan M Blum
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Nerissa Williams
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Lixia Luo
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Yan Ma
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Luke B Borst
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA
| | - Yongbaek Kim
- Laboratory of Veterinary Clinical Pathology, College of Veterinary Medicine, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-742, South Korea
| | - David G Kirsch
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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27
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Speidel D. The role of DNA damage responses in p53 biology. Arch Toxicol 2015; 89:501-17. [PMID: 25618545 DOI: 10.1007/s00204-015-1459-z] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 01/08/2015] [Indexed: 12/16/2022]
Abstract
The tumour suppressor p53 is a central player in cellular DNA damage responses. P53 is upregulated and activated by genotoxic stress and induces a transcriptional programme with effectors promoting apoptosis, cell cycle arrest, senescence and DNA repair. For the best part of the last three decades, these DNA damage-related programmes triggered by p53 were unequivocally regarded as the major if not sole mechanism by which p53 exerts its tumour suppressor function. However, this interpretation has been challenged by a number of recent in vivo studies, demonstrating that mice which are defective in inducing p53-dependent apoptosis, cell cycle arrest and senescence suppress thymic lymphoma as well as wild-type p53 expressing animals. Consequently, the importance of DNA damage responses for p53-mediated tumour suppression has been questioned. In this review, I summarize current knowledge on p53-controlled DNA damage responses and argue that these activities, while their role has certainly changed, remain an important feature of p53 biology with relevance for cancer therapy and tumour suppression.
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Affiliation(s)
- Daniel Speidel
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia,
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28
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Li-Weber M. Molecular mechanisms and anti-cancer aspects of the medicinal phytochemicals rocaglamides (=flavaglines). Int J Cancer 2014; 137:1791-9. [PMID: 24895251 DOI: 10.1002/ijc.29013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/29/2014] [Accepted: 06/02/2014] [Indexed: 01/08/2023]
Abstract
Rocaglamides (= flavaglines) are potent natural anti-cancer phytochemicals that inhibit cancer growth at nanomolar concentrations by the following mechanisms: (1) inhibition of translation initiation via inhibition of phosphorylation of the mRNA cap-binding eukaryotic translation initiation factor eIF4E and stabilization of RNA-binding of the translation initiation factor eIF4A in the eIF4F complex; (2) blocking cell cycle progression by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway; (3) inactivation of the heat shock factor 1 (HSF1) leading to up-regulation of thioredoxin-interacting protein (TXNIP) and consequent reduction of glucose uptake and (4) induction of apoptosis through activation of the MAPK p38 and JNK and inhibition of the Ras-CRaf-MEK-ERK signaling pathway. Besides the anti-cancer activities, rocaglamides are also shown to protect primary cells from chemotherapy-induced cell death and alleviate inflammation- and drug-induced injury in neuronal tissues. This review will focus on the recently discovered molecular mechanisms of the actions of rocaglamides and highlights the benefits of using rocaglamides in cancer treatment.
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Affiliation(s)
- Min Li-Weber
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), D-69120, Heidelberg, Germany
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29
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Abstract
p53 is a crucial tumour suppressor that responds to diverse stress signals by orchestrating specific cellular responses, including transient cell cycle arrest, cellular senescence and apoptosis, which are all processes associated with tumour suppression. However, recent studies have challenged the relative importance of these canonical cellular responses for p53-mediated tumour suppression and have highlighted roles for p53 in modulating other cellular processes, including metabolism, stem cell maintenance, invasion and metastasis, as well as communication within the tumour microenvironment. In this Opinion article, we discuss the roles of classical p53 functions, as well as emerging p53-regulated processes, in tumour suppression.
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Affiliation(s)
- Kathryn T Bieging
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, CCSR-South, Room 1255, 269 Campus Drive, Stanford, California 94305, USA
| | - Stephano Spano Mello
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, CCSR-South, Room 1255, 269 Campus Drive, Stanford, California 94305, USA
| | - Laura D Attardi
- 1] Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, CCSR-South, Room 1255, 269 Campus Drive, Stanford, California 94305, USA. [2] Department of Genetics, Stanford University School of Medicine, CCSR-South, Room 1255, 269 Campus Drive, Stanford, California 94305, USA
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30
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Donehower LA. Insights into Wild-Type and Mutant p53 Functions Provided by Genetically Engineered Mice. Hum Mutat 2014; 35:715-27. [DOI: 10.1002/humu.22507] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/02/2014] [Indexed: 01/17/2023]
Affiliation(s)
- Lawrence A. Donehower
- Departments of Molecular Virology and Microbiology, Molecular and Cellular Biology, and Pediatrics; Baylor College of Medicine; Houston Texas 77030
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31
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Becker MS, Schmezer P, Breuer R, Haas SF, Essers MA, Krammer PH, Li-Weber M. The traditional Chinese medical compound Rocaglamide protects nonmalignant primary cells from DNA damage-induced toxicity by inhibition of p53 expression. Cell Death Dis 2014; 5:e1000. [PMID: 24434508 PMCID: PMC4040689 DOI: 10.1038/cddis.2013.528] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 12/14/2022]
Abstract
One of the main obstacles of conventional anticancer therapy is the toxicity of chemotherapeutics to normal tissues. So far, clinical approaches that aim to specifically reduce chemotherapy-mediated toxicities are rare. Recently, a number of studies have demonstrated that herbal extracts derived from traditional Chinese medicine (TCM) may reduce chemotherapy-induced side effects. Thus, we screened a panel of published cancer-inhibiting TCM compounds for their chemoprotective potential and identified the phytochemical Rocaglamide (Roc-A) as a candidate. We show that Roc-A significantly reduces apoptotic cell death induced by DNA-damaging anticancer drugs in primary human and murine cells. Investigation of the molecular mechanism of Roc-A-mediated protection revealed that Roc-A specifically blocks DNA damage-induced upregulation of the transcription factor p53 by inhibiting its protein synthesis. The essential role of p53 in Roc-A-mediated protection was confirmed by siRNA knockdown of p53 and by comparison of the effects of Roc-A on chemoprotection of splenocytes isolated from wild-type and p53-deficient mice. Importantly, Roc-A did not protect p53-deficient or -mutated cancer cells. Our data suggest that Roc-A may be used as an adjuvant to reduce the side effects of chemotherapy in patients with p53-deficient or -mutated tumors.
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Affiliation(s)
- M S Becker
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), INF-280, D-69120 Heidelberg, Germany
| | - P Schmezer
- Division of Epigenomics and Cancer Risk Factors, German Cancer Research Centre (DKFZ), INF-280, D-69120 Heidelberg, Germany
| | - R Breuer
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), INF-280, D-69120 Heidelberg, Germany
| | - S F Haas
- Division of Stem Cells and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - M A Essers
- Division of Stem Cells and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - P H Krammer
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), INF-280, D-69120 Heidelberg, Germany
| | - M Li-Weber
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), INF-280, D-69120 Heidelberg, Germany
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32
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Garcia PB, Attardi LD. Illuminating p53 function in cancer with genetically engineered mouse models. Semin Cell Dev Biol 2014; 27:74-85. [PMID: 24394915 DOI: 10.1016/j.semcdb.2013.12.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 12/06/2013] [Accepted: 12/23/2013] [Indexed: 01/23/2023]
Abstract
The key role of the p53 protein in tumor suppression is highlighted by its frequent mutation in human cancers and by the completely penetrant cancer predisposition of p53 null mice. Beyond providing definitive evidence for the critical function of p53 in tumor suppression, genetically engineered mouse models have offered numerous additional insights into p53 function. p53 knock-in mice expressing tumor-derived p53 mutants have revealed that these mutants display gain-of-function activities that actively promote carcinogenesis. The generation of p53 knock-in mutants with alterations in different domains of p53 has helped further elucidate the cellular and biochemical activities of p53 that are most fundamental for tumor suppression. In addition, modulation of p53 post-translational modification (PTM) status by generating p53 knock-in mouse strains with mutations in p53 PTM sites has revealed a subtlety and complexity to p53 regulation. Analyses of mouse models perturbing upstream regulators of p53 have solidified the notion that the p53 pathway can be compromised by means other than direct p53 mutation. Finally, switchable p53 models that allow p53 reactivation in tumors have helped evaluate the potential of p53 restoration therapy for cancer treatment. Collectively, mouse models have greatly enhanced our understanding of physiological p53 function and will continue to provide new biological and clinical insights in future investigations.
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Affiliation(s)
- Patty B Garcia
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
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33
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Okazaki R, Ootsuyama A. p53-dependent delayed effects of radiation vary according to time of irradiation of p53 + / - mice. JOURNAL OF RADIATION RESEARCH 2014; 55:25-31. [PMID: 23764457 PMCID: PMC3885116 DOI: 10.1093/jrr/rrt083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We previously reported that in p53 (+ / -) mice that had been given a whole-body dose of 3 Gy at 8 weeks of age, p53-dependent delayed effects of radiation, as manifested in T-cell receptor (TCR) variant fractions (VF) instability in mouse splenocytes, were biphasic, namely, induction of TCR-VF mutation reappeared at 44 weeks. The manifestation of the delayed effects and the measures of biological markers varied according to the timing of irradiation. We also reported that the decrease in function of the p53 gene was related to the effects of a delayed mutation. In the present study, we investigated the functions and mutations of the p53 gene in old age for p53 (+ / -) mice following irradiation at various ages. p53 (+ / -) mice were given a whole-body dose of 3 Gy at 8, 28 or 40 weeks of age. There were significant differences for all variables tested at 8 weeks of age. This was similarly the case for mice irradiated at 28 weeks of age, in which there were also significant differences in TCR VF and the percentage of apoptosis. In mice irradiated at 40 weeks of age, there were significant differences for all considered variables except for the p53 allele. We demonstrated that the different patterns of delayed mutation of the p53 gene at 56 weeks of age depended on the age at which mice had undergone 3-Gy whole-body irradiation. Our conclusions are limited to variation in p53-dependent delayed effects according to the time of irradiation.
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Affiliation(s)
- Ryuji Okazaki
- Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka Yahatanishi-ku, Kitakyushu, 807-8555, Japan
- Corresponding author. Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka Yahatanishi-ku, Kitakyushu, 807-8555, Japan. Tel: +81-93-691-7549; Fax: +81-93-691-7552;
| | - Akira Ootsuyama
- Department of Radiation Biology and Health, School of Medicine, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka Yahatanishi-ku, Kitakyushu, 807-8555, Japan
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34
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Komarova EA, Antoch MP, Novototskaya LR, Chernova OB, Paszkiewicz G, Leontieva OV, Blagosklonny MV, Gudkov AV. Rapamycin extends lifespan and delays tumorigenesis in heterozygous p53+/- mice. Aging (Albany NY) 2013; 4:709-14. [PMID: 23123616 PMCID: PMC3517941 DOI: 10.18632/aging.100498] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The TOR (Target of Rapamycin) pathway accelerates cellular and organismal aging. Similar to rapamycin, p53 can inhibit the mTOR pathway in some mammalian cells. Mice lacking one copy of p53 (p53+/− mice) have an increased cancer incidence and a shorter lifespan. We hypothesize that rapamycin can delay cancer in heterozygous p53+/− mice. Here we show that rapamycin (given in a drinking water) extended the mean lifespan of p53+/− mice by 10% and when treatment started early in life (at the age less than 5 months) by 28%. In addition, rapamycin decreased the incidence of spontaneous tumors. This observation may have applications in management of Li-Fraumeni syndrome patients characterized by heterozygous mutations in the p53 gene.
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Affiliation(s)
- Elena A Komarova
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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35
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Abstract
The ageing of populations worldwide is leading to an unprecedented increase in cancer cases and fatalities. Understanding the links between cancer and ageing is therefore more important than ever. How the interplay of ageing-associated changes affects cancer initiation and progression is complex, however, and some ageing processes probably foster cancer development whereas others hinder it, possibly in a tissue-specific manner. In the emerging age of cancer, how can our growing understanding of the biology of ageing inform cancer biology?
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36
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Ganapathy S, Xiao S, Seo SJ, Lall R, Yang M, Xu T, Su H, Shadfan M, Ha CS, Yuan ZM. Low-dose arsenic induces chemotherapy protection via p53/NF-κB-mediated metabolic regulation. Oncogene 2013; 33:1359-66. [PMID: 23524579 PMCID: PMC4467814 DOI: 10.1038/onc.2013.81] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 01/02/2013] [Accepted: 01/11/2013] [Indexed: 02/08/2023]
Abstract
Most chemotherapeutical drugs kill cancer cells chiefly by inducing DNA damage, which unfortunately also causes undesirable injuries to normal tissues, mainly due to p53 activation. We report a novel strategy of normal tissue-protection that involves p53/NF-κB coordinated metabolic regulation. Pretreatment of untransformed cells with low doses of arsenic induced concerted p53 suppression and NF-κB activation, which elicited a marked induction of glycolysis. Significantly, this metabolic shift provided cells effective protection against cytotoxic chemotherapy, coupling the metabolic pathway to cellular resistance. Using both in vitro and in vivo models, we demonstrated an absolute requirement of functional p53 in arsenic-mediated protection. Consistently, a brief arsenic-pretreatment selectively protected only normal tissues but not tumors from toxicity of chemotherapy. An indispensable role of glycolysis in protecting normal tissues was demonstrated by using an inhibitor of glycolysis, 2-deoxyglucose, which almost totally abolished low-dose arsenic-mediated protection. Together, our work demonstrates that low-dose arsenic renders normal cells and tissues resistance to chemotherapy-induced toxicity by inducting glycolysis.
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Affiliation(s)
- S Ganapathy
- 1] Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA [2] Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA, USA
| | - S Xiao
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - S-J Seo
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - R Lall
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - M Yang
- 1] Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA [2] Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA, USA
| | - T Xu
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - H Su
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - M Shadfan
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - C S Ha
- Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Z-M Yuan
- 1] Department of Radiation Oncology, Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA [2] Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA, USA
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37
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Yadava N, Schneider SS, Jerry DJ, Kim C. Impaired mitochondrial metabolism and mammary carcinogenesis. J Mammary Gland Biol Neoplasia 2013; 18:75-87. [PMID: 23269521 PMCID: PMC3581737 DOI: 10.1007/s10911-012-9271-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 12/13/2012] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial oxidative metabolism plays a key role in meeting energetic demands of cells by oxidative phosphorylation (OxPhos). Here, we have briefly discussed (a) the dynamic relationship that exists among glycolysis, the tricarboxylic acid (TCA) cycle, and OxPhos; (b) the evidence of impaired OxPhos (i.e. mitochondrial dysfunction) in breast cancer; (c) the mechanisms by which mitochondrial dysfunction can predispose to cancer; and (d) the effects of host and environmental factors that can negatively affect mitochondrial function. We propose that impaired OxPhos could increase susceptibility to breast cancer via suppression of the p53 pathway, which plays a critical role in preventing tumorigenesis. OxPhos is sensitive to a large number of factors intrinsic to the host (e.g. inflammation) as well as environmental exposures (e.g. pesticides, herbicides and other compounds). Polymorphisms in over 143 genes can also influence the OxPhos system. Therefore, declining mitochondrial oxidative metabolism with age due to host and environmental exposures could be a common mechanism predisposing to cancer.
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Affiliation(s)
- Nagendra Yadava
- Pioneer Valley Life Sciences Institute, Springfield, MA 01107, USA.
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38
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Beheshti A, Sachs RK, Peluso M, Rietman E, Hahnfeldt P, Hlatky L. Age and space irradiation modulate tumor progression: implications for carcinogenesis risk. Radiat Res 2013; 179:208-20. [PMID: 23289386 DOI: 10.1667/rr3100.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Age plays a major role in tumor incidence and is an important consideration when modeling the carcinogenesis process or estimating cancer risks. Epidemiological data show that from adolescence through middle age, cancer incidence increases with age. This effect is commonly attributed to a lifetime accumulation of cellular, particularly DNA, damage. However, during middle age the incidence begins to decelerate and, for many tumor sites, it actually decreases at sufficiently advanced ages. We investigated if the observed deceleration and potential decrease in incidence could be attributed to a decreased capacity of older hosts to support tumor progression, and whether HZE [high atomic number (Z), high energy (E)] radiation differentially modulates tumor progression in young vs. middle-age hosts, issues that are relevant to estimating carcinogenesis risk for astronauts. Lewis lung carcinoma (LLC) cells were injected into syngeneic mice (143 and 551 days old), which were then subject to whole-body (56)Fe irradiation (1 GeV/amu). Three findings emerged: (1) among unirradiated animals, substantial inhibition of tumor progression and significantly decreased tumor growth rates were seen for middle-aged mice compared to young mice, (2) whole-body (56)Fe irradiation inhibited tumor progression in both young and middle-aged mice (with greater suppression seen in case of young animals), with little effect on tumor growth rates, and (3) (56)Fe irradiation suppressed tumor progression in young mice to a degree that was not significantly different than transiting from young to middle-aged. Thus, (56)Fe irradiation acted similar to aging with respect to tumor progression. We further investigated the molecular underpinnings driving the radiation modulation of tumor dynamics in young and middle-aged mice. Through global gene expression analysis, the key players, FASN, AKT1 and the CXCL12/CXCR4 complex, were determined to be contributory. In sum, these findings demonstrated a reduced capacity of middle-aged hosts to support the progression phase of carcinogenesis and identify molecular factors that contribute to HZE radiation modulation of tumor progression as a function of age.
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Affiliation(s)
- Afshin Beheshti
- Center of Cancer Systems Biology, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA
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39
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Blagosklonny MV. Tumor suppression by p53 without apoptosis and senescence: conundrum or rapalog-like gerosuppression? Aging (Albany NY) 2012; 4:450-5. [PMID: 22869016 PMCID: PMC3433931 DOI: 10.18632/aging.100475] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
I discuss a very obscure activity of p53, namely suppression of senescence (gerosuppression), which is also manifested as anti-hypertrophic, anti-hypermetabolic, anti-inflammatory and anti-secretory effects of p53. But can gerossuppression suppress tumors?
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Affiliation(s)
- Mikhail V Blagosklonny
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
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40
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Corcos D. Unbalanced replication as a major source of genetic instability in cancer cells. AMERICAN JOURNAL OF BLOOD RESEARCH 2012; 2:160-9. [PMID: 23119227 PMCID: PMC3484411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 08/30/2012] [Indexed: 06/01/2023]
Abstract
The origin of genetic instability in tumors is a matter of debate: while the prevailing model postulates a mutator phenotype resulting from an alteration in a caretaker gene as a prerequisite for genetic alterations leading to tumor formation, there is evidence against this model in the majority of cancers. A model for chromosomal instability should take into account the role of oncogenes in directly stimulating DNA and cellular component replication, creating aberrant structures when overexpressed. I will distinguish here two distinct mechanisms for the genetic instability of tumors: primary and secondary. Primary genetic instability is dependent on the inactivation of genes involved in maintaining genetic stability (caretaker genes), whereas secondary genetic instability is dependent on genes involved in tumor progression, i.e. oncogenes and tumor suppressor genes of the gatekeeper type. Secondary genetic instability, the most frequent condition, can be explained by the fact that some of the genes involved in tumor progression control replication of cell structures from within, leading to replication unbalance.
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Affiliation(s)
- Daniel Corcos
- INSERM U955- Hôpital Henri Mondor 51 Avenue du Maréchal de Lattre de Tassigny, Faculté de Médecine, Paris 12, Créteil 94010
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41
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Abstract
Aberrations in the p53 tumor suppressor pathway are associated with hematologic malignancies. p53-dependent cell cycle control, senescence, and apoptosis functions are actively involved in maintaining hematopoietic homeostasis under normal and stress conditions. Whereas loss of p53 function promotes leukemia and lymphoma development in humans and mice, increased p53 activity inhibits hematopoietic stem cell function and results in myelodysplasia. Thus, exquisite regulation of p53 activity is critical for homeostasis. Most of our understanding of p53 function in hematopoiesis is derived from genetically engineered mice. Here we summarize some of these models, the various mechanisms that disrupt the regulation of p53 activity, and their relevance to human disease.
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42
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Haley VL, Barnes DJ, Sandovici I, Constancia M, Graham CF, Pezzella F, Bühnemann C, Carter EJ, Hassan AB. Igf2 pathway dependency of the Trp53 developmental and tumour phenotypes. EMBO Mol Med 2012; 4:705-18. [PMID: 22674894 PMCID: PMC3494071 DOI: 10.1002/emmm.201101105] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Revised: 04/24/2012] [Accepted: 04/27/2012] [Indexed: 01/22/2023] Open
Abstract
Insulin-like growth factor 2 (IGF2) and the transformation related protein 53 (Trp53) are potent regulators of cell growth and metabolism in development and cancer. In vitro evidence suggests several mechanistic pathway interactions. Here, we tested whether loss of function of p53 leads to IGF2 ligand pathway dependency in vivo. Developmental lethality occurred in p53 homozygote null mice that lacked the paternal expressed allele of imprinted Igf2. Further lethality due to post-natal lung haemorrhage occurred in female progeny with Igf2 paternal null allele only if derived from double heterozygote null fathers, and was associated with a specific gene expression signature. Conditional deletion of Igf2(fl/fl) attenuated the rapid tumour onset promoted by homozygous deletion of p53(fl/fl) . Accelerated carcinoma and sarcoma tumour formation in p53(+/-) females with bi-allelic Igf2 expression was associated with reductions in p53 loss of heterozygosity and apoptosis. Igf2 genetic dependency of the p53 null phenotype during development and tumour formation suggests that targeting the IGF2 pathway may be useful in the prevention and treatment of human tumours with a disrupted Trp53 pathway.
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Affiliation(s)
- Victoria L Haley
- CR-UK Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of OxfordOxford, UK
| | - David J Barnes
- CR-UK Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of OxfordOxford, UK
| | - Ionel Sandovici
- University of Cambridge Metabolic Research Laboratories, Department of Obstetrics & Gynaecology, The Rosie HospitalRobinson Way, Cambridge, UK
- Centre for Trophoblast Research, University of CambridgeCambridge, UK
- National Institute of Health Research, Cambridge Biomedical Research CentreCambridge, UK
| | - Miguel Constancia
- University of Cambridge Metabolic Research Laboratories, Department of Obstetrics & Gynaecology, The Rosie HospitalRobinson Way, Cambridge, UK
- Centre for Trophoblast Research, University of CambridgeCambridge, UK
- National Institute of Health Research, Cambridge Biomedical Research CentreCambridge, UK
| | | | - Francesco Pezzella
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe HospitalOxford, UK
| | - Claudia Bühnemann
- CR-UK Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of OxfordOxford, UK
| | - Emma J Carter
- CR-UK Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of OxfordOxford, UK
| | - A Bassim Hassan
- CR-UK Tumour Growth Group, Oxford Molecular Pathology Institute, Sir William Dunn School of Pathology, University of OxfordOxford, UK
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43
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Reinhardt HC, Schumacher B. The p53 network: cellular and systemic DNA damage responses in aging and cancer. Trends Genet 2012; 28:128-36. [PMID: 22265392 DOI: 10.1016/j.tig.2011.12.002] [Citation(s) in RCA: 327] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/12/2011] [Accepted: 12/12/2011] [Indexed: 12/16/2022]
Abstract
Genome instability contributes to cancer development and accelerates age-related pathologies as evidenced by a variety of congenital cancer susceptibility and progeroid syndromes that are caused by defects in genome maintenance mechanisms. DNA damage response (DDR) pathways that are mediated through the tumor suppressor p53 play an important role in the cell-intrinsic responses to genome instability, including a transient cell cycle arrest, senescence and apoptosis. Both senescence and apoptosis are powerful tumor-suppressive pathways preventing the uncontrolled proliferation of transformed cells. However, both pathways can potentially deplete stem and progenitor cell pools, thus promoting tissue degeneration and organ failure, which are both hallmarks of aging. p53 signaling is also involved in mediating non-cell-autonomous interactions with the innate immune system and in the systemic adjustments during the aging process. The network of p53 target genes thus functions as an important regulator of cancer prevention and aging.
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Affiliation(s)
- H Christian Reinhardt
- Cologne Excellence Cluster on Cellular Stress Response in Aging-Associated Diseases, University of Cologne, 50674 Cologne, Germany.
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44
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Bieging KT, Attardi LD. Deconstructing p53 transcriptional networks in tumor suppression. Trends Cell Biol 2011; 22:97-106. [PMID: 22154076 DOI: 10.1016/j.tcb.2011.10.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/26/2011] [Accepted: 10/27/2011] [Indexed: 12/16/2022]
Abstract
p53 is a pivotal tumor suppressor that induces apoptosis, cell-cycle arrest and senescence in response to stress signals. Although p53 transcriptional activation is important for these responses, the mechanisms underlying tumor suppression have been elusive. To date, no single or compound mouse knockout of specific p53 target genes has recapitulated the dramatic tumor predisposition that characterizes p53-null mice. Recently, however, analysis of knock-in mice expressing p53 transactivation domain mutants has revealed a group of primarily novel direct p53 target genes that may mediate tumor suppression in vivo. We present here an overview of well-known p53 target genes and the tumor phenotypes of the cognate knockout mice, and address the recent identification of new p53 transcriptional targets and how they enhance our understanding of p53 transcriptional networks central for tumor suppression.
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Affiliation(s)
- Kathryn T Bieging
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Henry CJ, Marusyk A, DeGregori J. Aging-associated changes in hematopoiesis and leukemogenesis: what's the connection? Aging (Albany NY) 2011; 3:643-56. [PMID: 21765201 PMCID: PMC3164372 DOI: 10.18632/aging.100351] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aging is associated with a marked increase in a number of diseases, including many types of cancer. Due to the complex and multi-factorial nature of both aging and cancer, accurate deciphering of causative links between aging and cancer remains a major challenge. It is generally accepted that initiation and progression of cancers are driven by a process of clonal evolution. In principle, this somatic evolution should follow the same Darwinian logic as evolutionary processes in populations in nature: diverse heritable types arising as a result of mutations are subjected to selection, resulting in expansion of the fittest clones. However, prevalent paradigms focus primarily on mutational aspects in linking aging and cancer. In this review, we will argue that age-related changes in selective pressures are likely to be equally important. We will focus on aging-related changes in the hematopoietic system, where age-associated alterations are relatively well studied, and discuss the impact of these changes on the development of leukemias and other malignancies.
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Affiliation(s)
- Curtis J Henry
- Department of Biochemistry and Molecular Genetics, Integrated Department of Immunology, Program in Molecular Biology, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
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Abstract
Two functions of p53 are undisputed. Biologically, p53 is a potent tumor suppressor, whereas biochemically, it is a robust transcriptional activator of numerous target genes. Are these biological and biochemical functions of p53 related? The surprising answer, recently reported by Brady et al. (2011) in Cell, is minimally.
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Young NP, Crowley D, Jacks T. Uncoupling cancer mutations reveals critical timing of p53 loss in sarcomagenesis. Cancer Res 2011; 71:4040-7. [PMID: 21512139 DOI: 10.1158/0008-5472.can-10-4563] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is well accepted that cancer develops following the sequential accumulation of multiple alterations, but how the temporal order of events affects tumor initiation and/or progression remains largely unknown. Here, we describe a mouse model that allows for temporally distinct cancer mutations. By integrating a Flp-inducible allele of K-ras(G12D) with established methods for Cre-mediated p53 deletion, we were able to separately control the mutation of these commonly associated cancer genes in vitro and in vivo. We show that delaying p53 deletion relative to K-ras(G12D) activation reduced tumor burden in a mouse model of soft-tissue sarcoma, suggesting that p53 strongly inhibits very early steps of transformation in the muscle. Furthermore, using in vivo RNA interference, we implicate the p53 target gene p21 as a critical mediator in this process, highlighting cell-cycle arrest as an extremely potent tumor suppressor mechanism.
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Affiliation(s)
- Nathan P Young
- Koch Institute for Integrative Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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48
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Fleenor CJ, Marusyk A, DeGregori J. Ionizing radiation and hematopoietic malignancies: altering the adaptive landscape. Cell Cycle 2010; 9:3005-11. [PMID: 20676038 DOI: 10.4161/cc.9.15.12311] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Somatic evolution, which underlies tumor progression, is driven by two essential components: (1) diversification of phenotypes through heritable mutations and epigenetic changes and (2) selection for mutant clones which possess higher fitness. Exposure to ionizing radiation (IR ) is highly associated with increased risk of carcinogenesis. This link is traditionally attributed to causation of oncogenic mutations through the mutagenic effects of irradiation. On the other hand, potential effects of irradiation on altering fitness and increasing selection for mutant clones are frequently ignored. Recent studies bring the effects of irradiation on fitness and selection into focus, demonstrating that IR exposure results in stable reductions in the fitness of hematopoietic stem and progenitor cell populations. These reductions of fitness are associated with alteration of the adaptive landscape, increasing the selective advantages conferred by certain oncogenic mutations. Therefore, the link between irradiation and carcinogenesis might be more complex than traditionally appreciated: while mutagenic effects of irradiation should increase the probability of occurrence of oncogenic mutations, IR can also work as a tumor promoter, increasing the selective expansion of clones bearing mutations which become advantageous in the irradiation-altered environment, such as activated mutations in Notch1 or disrupting mutations in p53.
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Affiliation(s)
- Courtney J Fleenor
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
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Blagosklonny MV, Campisi J, Sinclair DA, Bartke A, Blasco MA, Bonner WM, Bohr VA, Brosh RM, Brunet A, Depinho RA, Donehower LA, Finch CE, Finkel T, Gorospe M, Gudkov AV, Hall MN, Hekimi S, Helfand SL, Karlseder J, Kenyon C, Kroemer G, Longo V, Nussenzweig A, Osiewacz HD, Peeper DS, Rando TA, Rudolph KL, Sassone-Corsi P, Serrano M, Sharpless NE, Skulachev VP, Tilly JL, Tower J, Verdin E, Vijg J. Impact papers on aging in 2009. Aging (Albany NY) 2010; 2:111-21. [PMID: 20351400 PMCID: PMC2871240 DOI: 10.18632/aging.100132] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 03/22/2010] [Indexed: 01/09/2023]
Abstract
The editorial board of Aging reviews research papers published in 2009, which they
believe have or will have a significant impact on aging research. Among many
others, the topics include genes that accelerate aging or in contrast promote
longevity in model organisms, DNA damage responses and telomeres, molecular
mechanisms of life span extension by calorie restriction and pharmacologic
interventions into aging. The emerging message in 2009 is that aging is not
random but determined by a genetically-regulated longevity network and can be
decelerated both genetically and pharmacologically.
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Marusyk A, Porter CC, Zaberezhnyy V, DeGregori J. Irradiation selects for p53-deficient hematopoietic progenitors. PLoS Biol 2010; 8:e1000324. [PMID: 20208998 PMCID: PMC2830447 DOI: 10.1371/journal.pbio.1000324] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 01/28/2010] [Indexed: 12/22/2022] Open
Abstract
While disruption of p53 is selectively neutral within non-stressed hematopoiesis, it confers a strong selective advantage upon irradiation, leading to expansion of p53 mutant clones and lymphoma development. Identification and characterization of mutations that drive cancer evolution constitute a major focus of cancer research. Consequently, dominant paradigms attribute the tumorigenic effects of carcinogens in general and ionizing radiation in particular to their direct mutagenic action on genetic loci encoding oncogenes and tumor suppressor genes. However, the effects of irradiation are not limited to genetic loci that encode oncogenes and tumor suppressors, as irradiation induces a multitude of other changes both in the cells and their microenvironment which could potentially affect the selective effects of some oncogenic mutations. P53 is a key tumor suppressor, the loss of which can provide resistance to multiple genotoxic stimuli, including irradiation. Given that p53 null animals develop T-cell lymphomas with high penetrance and that irradiation dramatically accelerates lymphoma development in p53 heterozygous mice, we hypothesized that increased selection for p53-deficient cells contributes to the causal link between irradiation and induction of lymphoid malignancies. We sought to determine whether ionizing irradiation selects for p53-deficient hematopoietic progenitors in vivo using mouse models. We found that p53 disruption does not provide a clear selective advantage within an unstressed hematopoietic system or in previously irradiated BM allowed to recover from irradiation. In contrast, upon irradiation p53 disruption confers a dramatic selective advantage, leading to long-term expansion of p53-deficient clones and to increased lymphoma development. Selection for cells with disrupted p53 appears to be attributable to several factors: protection from acute irradiation-induced ablation of progenitor cells, prevention of irradiation-induced loss of clonogenic capacity for stem and progenitor cells, improved long-term maintenance of progenitor cell fitness, and the disabling/elimination of competing p53 wild-type progenitors. These studies indicate that the carcinogenic effect of ionizing irradiation can in part be explained by increased selection for cells with p53 disruption, which protects progenitor cells both from immediate elimination and from long-term reductions in fitness following irradiation. Cancer progression can be understood through the framework of Darwinian evolution, which involves two major factors: genetic mutation and selection. Random mutations are thought to result in the initiation and phenotypic diversification of tumors, and environmental influences mediate selection for those mutations that increase tumor cell fitness. Since oncogenic mutations are necessary for the development of spontaneous malignancies and since experimental introduction of these mutations often leads to transformation and cancers, the causation of cancers by carcinogens is traditionally attributed to their induction of new mutations that are oncogenic. We instead asked whether selection for oncogenic mutations is affected by ionizing irradiation, an archetypal mutagenic carcinogen, by examining the selective effects of inactivation of the critical tumor suppressor gene p53. While disruption of p53 is selectively neutral in populations of unstressed hematopoietic progenitors, it provides a strong selective advantage upon irradiation. This selection of p53-deficient clones is attributable to protection from irradiation-induced cell death and loss of cellular fitness. Importantly, the selective expansion of irradiated cells bearing p53 disruption is blocked in the presence of non-irradiated wild-type competitors, indicating that the disabling of competing wild-type cells by irradiation is critical for selection of p53-deficient cells. Our results argue that induction of cancers by irradiation involves selection for mutations that confer radioresistance, and suggest that greater focus on how carcinogenic contexts impact on selection is warranted in understanding, preventing and treating cancers.
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Affiliation(s)
- Andriy Marusyk
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- Program in Molecular Biology, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
| | - Christopher C. Porter
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
| | - Vadym Zaberezhnyy
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- Program in Molecular Biology, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- Integrated Department of Immunology, University of Colorado Denver School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
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