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Paul PJ, Raghu D, Chan AL, Gulati T, Lambeth L, Takano E, Herold MJ, Hagekyriakou J, Vessella RL, Fedele C, Shackleton M, Williams ED, Fox S, Williams S, Haupt S, Gamell C, Haupt Y. Restoration of tumor suppression in prostate cancer by targeting the E3 ligase E6AP. Oncogene 2016; 35:6235-6245. [PMID: 27641331 DOI: 10.1038/onc.2016.159] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 03/22/2016] [Accepted: 03/31/2016] [Indexed: 12/20/2022]
Abstract
Restoration of tumor suppression is an attractive onco-therapeutic approach. It is particularly relevant when a tumor suppressor is excessively degraded by an overactive oncogenic E3 ligase. We previously discovered that the E6-associated protein (E6AP; as classified in the human papilloma virus context) is an E3 ligase that has an important role in the cellular stress response, and it directly targets the tumor-suppressor promyelocytic leukemia protein (PML) for proteasomal degradation. In this study, we have examined the role of the E6AP-PML axis in prostate cancer (PC). We show that knockdown (KD) of E6AP expression attenuates growth of PC cell lines in vitro. We validated this finding in vivo using cell line xenografts, patient-derived xenografts and mouse genetics. We found that KD of E6AP attenuates cancer cell growth by promoting cellular senescence in vivo, which correlates with restoration of tumor suppression by PML. In addition, we show that KD of E6AP sensitizes cells to radiation-induced death. Overall, our findings demonstrate a role for E6AP in the promotion of PC and support E6AP targeting as a novel approach for PC treatment, either alone or in combination with radiation.
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Affiliation(s)
- P J Paul
- The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia.,Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - D Raghu
- The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia.,Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - A-L Chan
- Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - T Gulati
- The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia.,Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - L Lambeth
- Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - E Takano
- Department of Pathology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - M J Herold
- Molecular Genetics of Cancer, The Walter and Eliza Hall Institute, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - J Hagekyriakou
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - R L Vessella
- Department of Urology, University of Washington, Seattle, WA, USA
| | - C Fedele
- Department of Pathology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Cancer Development and Treatment Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - M Shackleton
- Department of Pathology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Cancer Development and Treatment Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - E D Williams
- Australian Prostate Cancer Research Centre-Queensland University of Technology, Brisbane, Queensland, Australia
| | - S Fox
- Department of Pathology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - S Williams
- Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - S Haupt
- Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - C Gamell
- Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Y Haupt
- The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia.,Tumor Suppression Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia.,Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
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Wolyniec K, Carney DA, Haupt S, Haupt Y. New Strategies to Direct Therapeutic Targeting of PML to Treat Cancers. Front Oncol 2013; 3:124. [PMID: 23730625 PMCID: PMC3656422 DOI: 10.3389/fonc.2013.00124] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 05/03/2013] [Indexed: 01/16/2023] Open
Abstract
The tumor suppressor function of the promyelocytic leukemia (PML) protein was first identified as a result of its dysregulation in acute promyelocytic leukemia, however, its importance is now emerging far beyond hematological neoplasms, to an extensive range of malignancies, including solid tumors. In response to stress signals, PML coordinates the regulation of numerous proteins, which activate fundamental cellular processes that suppress tumorigenesis. Importantly, PML itself is the subject of specific post-translational modifications, including ubiquitination, phosphorylation, acetylation, and SUMOylation, which in turn control PML activity and stability and ultimately dictate cellular fate. Improved understanding of the regulation of this key tumor suppressor is uncovering potential opportunities for therapeutic intervention. Targeting the key negative regulators of PML in cancer cells such as casein kinase 2, big MAP kinase 1, and E6-associated protein, with specific inhibitors that are becoming available, provides unique and exciting avenues for restoring tumor suppression through the induction of apoptosis and senescence. These approaches could be combined with DNA damaging drugs and cytokines that are known to activate PML. Depending on the cellular context, reactivation or enhancement of tumor suppressive PML functions, or targeted elimination of aberrantly functioning PML, may provide clinical benefit.
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Affiliation(s)
- Kamil Wolyniec
- Tumour Suppression Laboratory, Peter MacCallum Cancer CentreEast Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneParkville, VIC, Australia
| | - Dennis A. Carney
- Tumour Suppression Laboratory, Peter MacCallum Cancer CentreEast Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneParkville, VIC, Australia
- Department of Haematology, Peter MacCallum Cancer CentreEast Melbourne, VIC, Australia
| | - Sue Haupt
- Tumour Suppression Laboratory, Peter MacCallum Cancer CentreEast Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneParkville, VIC, Australia
| | - Ygal Haupt
- Tumour Suppression Laboratory, Peter MacCallum Cancer CentreEast Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of MelbourneParkville, VIC, Australia
- Department of Pathology, The University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash UniversityClayton, VIC, Australia
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Haupt S, Mitchell C, Corneille V, Shortt J, Fox S, Pandolfi PP, Castillo-Martin M, Bonal DM, Cordon-Cardo C, Lozano G, Haupt Y. Loss of PML cooperates with mutant p53 to drive more aggressive cancers in a gender-dependent manner. Cell Cycle 2013; 12:1722-31. [PMID: 23656786 DOI: 10.4161/cc.24805] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED p53 mutations and downregulation of promyelocytic leukemia (PML) are common genetic alterations in human cancers. In healthy cells these two key tumor suppressors exist in a positive regulatory loop, promoting cell death and cellular senescence. However, the influence of their interplay on tumorigenesis has not been explored directly in vivo. The contribution of PML to mutant p53 driven cancer was evaluated in a mouse model harboring a p53 mutation (p53 (wild-type/R172H) ) that recapitulates a frequent p53 mutation (p53 (R175H) ) in human sporadic and Li-Fraumeni cancers. These mice with PML displayed perturbation of the hematopoietic compartment, manifested either as lymphoma or extramedullary hematopoiesis (EMH). EMH was associated with peripheral blood leucocytosis and macrocytic anemia, suggestive of myeloproliferative- myelodysplastic overlap. In contrast, a complete loss of PML from these mice resulted in a marked alteration in tumor profile. While the incidence of lymphomas was unaltered, EMH was not detected and the majority of mice succumbed to sarcomas. Further, males lacking PML exhibited a high incidence of soft tissue sarcomas and reduced survival, while females largely developed osteosarcomas, without impact on survival. Together, these findings demonstrate that PML is an important tumor suppressor dictating disease development in a pertinent mouse model of human cancer. KEY POINTS (1) A mutant p53 allele disrupts hematopoiesis in mice, by promoting lymphomas and myeloproliferative / myelodysplastic overlap. (2) Coincidental p53 allele mutation and PML loss shifts the tumor profile toward sarcoma formation, which is paralleled in human leiomyosarcomas (indicated by immunohistochemistry; IHC).
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Affiliation(s)
- Sue Haupt
- Research Division, Peter MacCallum Cancer Centre, East Melbourne, VIC Australia.
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