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Abstract
Apoptosis has been established as a mechanism of anti-cancer defense. Members of the BCL-2 family are critical mediators of apoptotic cell death in health and disease, often found to be deregulated in cancer and believed to lead to the survival of malignant clones. However, over the years, a number of studies pointed out that a model in which cell death resistance unambiguously acts as a barrier against malignant disease might be too simple. This is based on paradoxical observations made in tumor patients as well as mouse models indicating that apoptosis can indeed drive tumor formation, at least under certain circumstances. One possible explanation for this phenomenon is that apoptosis can promote proliferation critically needed to compensate for cell loss, for example, upon therapy, and to restore tissue homeostasis. However, this, at the same time, can promote tumor development by allowing expansion of selected clones. Usually, tissue resident stem/progenitor cells are a major source for repopulation, some of them potentially carrying (age-, injury- or therapy-induced) genetic aberrations deleterious for the host. Thereby, apoptosis might drive genomic instability by facilitating the emergence of pathologic clones during phases of proliferation and subsequent replication stress-associated DNA damage. Tumorigenesis initiated by repeated cell attrition and repopulation, as confirmed in different genetic models, has parallels in human cancers, exemplified in therapy-induced secondary malignancies and myelodysplastic syndromes in patients with congenital bone marrow failure syndromes. Here, we aim to review evidence in support of the oncogenic role of stress-induced apoptosis.
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Affiliation(s)
- V Labi
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin 13125, Germany
- Immune Regulation and Cancer, Max-Delbrück-Center for Molecular Medicine, Robert Rössle-Strasse 10, 13125 Berlin, Germany. Tel: +49 30 9406 3462; Fax: +49 30 9406 2390; E-mail:
| | - M Erlacher
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, University Medical Center of Freiburg, Freiburg 79106, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg 79104, Germany
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Kollek M, Voigt G, Bertele D, Garcia A, Maurer U, Krombholz F, Labi V, Fischer N, Niemeyer C, Geley S, Villunger A, Erlacher M. Transient apoptosis inhibition in donor cells increases efficacy of hematopoietic stem cell transplantation without increasing the risk of leukemogenesis. Klin Padiatr 2014. [DOI: 10.1055/s-0034-1374838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kollek M, Voigt G, Bertele D, Labi V, Fischer N, Geley S, Villunger A, Erlacher M. Improvement of hematopoietic stem cell transplantations by ex vivo manipulation of donor stem and progenitor cells. Klin Padiatr 2013. [DOI: 10.1055/s-0033-1343639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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4
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Manzl C, Peintner L, Krumschnabel G, Bock F, Labi V, Drach M, Newbold A, Johnstone R, Villunger A. PIDDosome-independent tumor suppression by Caspase-2. Cell Death Differ 2012; 19:1722-32. [PMID: 22595758 PMCID: PMC3438502 DOI: 10.1038/cdd.2012.54] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The PIDDosome, a multiprotein complex constituted of the ‘p53-induced protein with a death domain (PIDD), ‘receptor-interacting protein (RIP)-associated ICH-1/CED-3 homologous protein with a death domain' (RAIDD) and pro-Caspase-2 has been defined as an activating platform for this apoptosis-related protease. PIDD has been implicated in p53-mediated cell death in response to DNA damage but also in DNA repair and nuclear factor kappa-light-chain enhancer (NF-κB) activation upon genotoxic stress, together with RIP-1 kinase and Nemo/IKKγ. As all these cellular responses are critical for tumor suppression and deregulated expression of individual PIDDosome components has been noted in human cancer, we investigated their role in oncogenesis induced by DNA damage or oncogenic stress in gene-ablated mice. We observed that Pidd or Caspase-2 failed to suppress lymphoma formation triggered by γ-irradiation or 3-methylcholanthrene-driven fibrosarcoma development. In contrast, Caspase-2 showed tumor suppressive capacity in response to aberrant c-Myc expression, which did not rely on PIDD, the BH3-only protein Bid (BH3 interacting domain death agonist) or the death receptor ligand Trail (TNF-related apoptosis-inducing ligand), but associated with reduced rates of p53 loss and increased extranodal dissemination of tumor cells. In contrast, Pidd deficiency associated with abnormal M-phase progression and delayed disease onset, indicating that both proteins are differentially engaged upon oncogenic stress triggered by c-Myc, leading to opposing effects on tumor-free survival.
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Affiliation(s)
- C Manzl
- Division of Developmental Immunology, BIOCENTER, Medical University Innsbruck, Austria
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Bertele D, Labi V, Woess C, Grothe G, Schwemmers S, Pahl HL, Geley S, Kunze M, Niemeyer CM, Villunger A, Erlacher M. Haematopoietic Stem Cell Survival and Transplantation Efficacy is Limited by the BH3-only Proteins Bim and Bmf. Klin Padiatr 2012. [DOI: 10.1055/s-0032-1310488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Baumgartner F, Woess C, Pedit V, Tzankov A, Labi V, Villunger A. Minor cell-death defects but reduced tumor latency in mice lacking the BH3-only proteins Bad and Bmf. Oncogene 2012; 32:621-30. [PMID: 22430207 PMCID: PMC3428852 DOI: 10.1038/onc.2012.78] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pro-apoptotic Bcl-2 family members of the BH3-only subgroup are critical for the establishment and maintenance of tissue homeostasis and can mediate apoptotic cell death in response to developmental cues or exogenously induced forms of cell stress and damage. Based on biochemical experiments as well as genetic studies in mice, the BH3-only proteins Bad and Bmf have been implicated in different proapoptotic events such as those triggered by glucose- or trophic factor-deprivation, glucocorticoids, or histone deacetylase inhibition in lymphocytes as well as suppression of B cell lymphomagenesis upon aberrant expression of c-Myc. To address possible redundancies in cell death regulation and tumor suppression, we generated compound mutant mice lacking both genes. Our studies revealed lack of redundancy in most paradigms of lymphocyte apoptosis tested in tissue culture. Only spontaneous cell death of thymocytes kept in low glucose or that of pre-B cells deprived of cytokines was significantly delayed when both genes were lacking. Of note, despite these minor apoptosis defects we observed compromised lymphocyte homeostasis in vivo that affected mainly the B cell lineage. Long-term follow up revealed significantly reduced latency to spontaneous tumor formation in aged mice when both genes were lacking. Together our study suggests that Bad and Bmf co-regulate lymphocyte homeostasis and limit spontaneous transformation by mechanisms that may not exclusively be limited to the induction of lymphocyte apoptosis.
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Affiliation(s)
- F Baumgartner
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
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Villunger A, Labi V, Bouillet P, Adams J, Strasser A. Can the analysis of BH3-only protein knockout mice clarify the issue of 'direct versus indirect' activation of Bax and Bak? Cell Death Differ 2011; 18:1545-6. [PMID: 21909118 PMCID: PMC3172109 DOI: 10.1038/cdd.2011.100] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- A Villunger
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - V Labi
- Division of Developmental Immunology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - P Bouillet
- Molecular Genetics of Cancer Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - J Adams
- Molecular Genetics of Cancer Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - A Strasser
- Molecular Genetics of Cancer Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
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Villunger A, Labi V, Frenzel A, Egle A, Pinon J. 3 Tumour suppression by BH3-only proteins, proapoptotic members of the Bcl-2 family. EJC Suppl 2010. [DOI: 10.1016/s1359-6349(10)70812-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Karlberg M, Ekoff M, Labi V, Strasser A, Huang D, Nilsson G. Pro-apoptotic Bax is the major and Bak an auxiliary effector in cytokine deprivation-induced mast cell apoptosis. Cell Death Dis 2010; 1:e43. [PMID: 21364649 PMCID: PMC3032311 DOI: 10.1038/cddis.2010.20] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The process of apoptosis in immune cells like mast cells is essential to regain homeostasis after an inflammatory response. The intrinsic pathway of apoptosis is ultimately controlled by the pro-apoptotic Bcl-2 family members Bax and Bak, which upon activation oligomerize to cause increased permeabilization of the mitochondria outer membrane leading to cell death. We examined the role of Bax and Bak in cytokine deprivation-induced apoptosis in mast cells using connective tissue-like mast cells and mucosal-like mast cells derived from bax−/−, bak−/− and bax−/−bak−/− mice. Although both Bax and Bak were expressed at readily detectable protein levels, we found a major role for Bax in mediating mast cell apoptosis induced by cytokine deprivation. We analyzed cell viability by propidium iodide exclusion and flow cytometry after deprivation of vital cytokines for each mast cell population. Upon cytokine withdrawal, bak−/− mast cells died at a similar rate as wild type, whereas bax−/− and bax−/−bak−/− mast cells were partially or completely resistant to apoptosis, respectively. The total resistance seen in bax−/−bak−/− mast cells is comparable with mast cells deficient of both pro-apoptotic Bim and Puma or mast cells overexpressing anti-apoptotic Bcl-2. These results show that Bax has a predominant and Bak a minor role in cytokine deprivation-induced apoptosis in both connective tissue-like and mucosal-like mast cells.
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Affiliation(s)
- M Karlberg
- Department of Medicine, Karolinska Institutet, Stockholm, Sweden
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10
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Abstract
Among all BH3-only proteins known to date, most information is available on the biological role and function of Bim (Bcl-2 interacting mediator of cell death)/BOD (Bcl-2 related ovarian death agonist), whereas little is still known about its closest relative, Bcl-2 modifying factor (Bmf). Although Bim has been implicated in the regulation of cell death induction in multiple cell types and tissues in response to a large number of stimuli, including growth factor or cytokine deprivation, calcium flux, ligation of antigen receptors on T and B cells, glucocorticoid or loss of adhesion, Bmf seems to play a more restricted role by supporting Bim in some of these cell death processes. This review aims to highlight similarities between Bim and Bmf function in apoptosis signaling and their role in normal development and disease.
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Affiliation(s)
- J D Piñon
- Laboratory for Immunological and Molecular Cancer Research, University Hospital Salzburg, Salzburg, Austria
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Erlacher M, Labi V, Bertele D, Fischer N, Niemeyer CM, Villunger A. Displacement of wild type lymphopoiesis by bone marrow cells lacking the BH3-only proteins BIM or BMF but not puma. Klin Padiatr 2009. [DOI: 10.1055/s-0029-1222633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Labi V, Grespi F, Baumgartner F, Villunger A. Targeting the Bcl-2-regulated apoptosis pathway by BH3 mimetics: a breakthrough in anticancer therapy? Cell Death Differ 2008; 15:977-87. [PMID: 18369371 DOI: 10.1038/cdd.2008.37] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Induction of apoptosis in tumor cells by direct activation of the Bcl-2-regulated apoptosis pathway by small molecule drugs carries high hopes to overcome the shortcomings of current anticancer therapies. This novel therapy concept builds on emerging insights into how Bcl-2-like molecules maintain mitochondrial integrity and how pro-apoptotic BH3-only proteins lead to its disruption. Means to unleash the pro-apoptotic potential of BH3-only proteins in tumor cells, or to bypass the need for BH3-only proteins by directly blocking possible interactions of Bcl-2-like pro-survival molecules with Bax and/or Bak, constitute interesting options for the design of novel anticancer therapies. For the optimization and clinical implementation of these novel anticancer strategies, a detailed understanding of the role of individual BH3-only proteins in cell death signaling in healthy cells and during tumor suppression is required. In this review, we will touch on the latest findings on BH3-only protein function and attempts to define the molecular properties of the so-called 'BH3 mimetics,' a novel class of anticancer agents, able to prompt apoptosis in tumor cells, regardless of their p53 or Bcl-2 status.
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Affiliation(s)
- V Labi
- Division of Developmental Immunology, Department of Biocenter, Innsbruck Medical University, Innsbruck, Austria
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Manzl C, Labi V, Baumgartner F, Boeck G, Tschopp J, Villunger A. Role and function of the apoptosis-regulator PIDD. Comp Biochem Physiol A Mol Integr Physiol 2007. [DOI: 10.1016/j.cbpa.2007.01.373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Induction of apoptosis in tumour cells, either by direct activation of the death receptor pathway using agonistic antibodies or recombinant ligands, or direct triggering of the Bcl-2-regulated intrinsic apoptosis pathway by small molecule drugs, carries high hopes to overcome the shortcomings of current anticancer therapies. The latter therapy concept builds on a more detailed understanding of how Bcl-2-like molecules maintain mitochondrial integrity and how BH3-only proteins and Bax/Bak-like molecules can undermine it. Means to unleash the apoptotic potential of BH3-only proteins in tumour cells, or bypass the need for BH3-only proteins by blocking possible interactions of Bcl-2-like prosurvival molecules with Bax and/or Bak allowing their direct activation, constitute interesting options for the design of novel anticancer therapies.
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Affiliation(s)
- V Labi
- Division of Experimental Pathophysiology and Immunology, Biocenter, Innsbruck Medical University, Austria
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