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Chaturvedi NK, Mahapatra S, Kesherwani V, Kling MJ, Shukla M, Ray S, Kanchan R, Perumal N, McGuire TR, Sharp JG, Joshi SS, Coulter DW. Role of protein arginine methyltransferase 5 in group 3 (MYC-driven) Medulloblastoma. BMC Cancer 2019; 19:1056. [PMID: 31694585 PMCID: PMC6836472 DOI: 10.1186/s12885-019-6291-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 10/25/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND MYC amplification or overexpression is common in Group 3 medulloblastoma and is associated with the worst prognosis. Recently, protein arginine methyl transferase (PRMT) 5 expression has been closely associated with aberrant MYC function in various cancers, including brain tumors such as glioblastoma. However, the role of PRMT5 and its association with MYC in medulloblastoma have not been explored. Here, we report the role of PRMT5 as a novel regulator of MYC and implicate PRMT5 as a potential therapeutic target in MYC-driven medulloblastoma. METHODS Expression and association between PRMT5 and MYC in primary medulloblastoma tumors were investigated using publicly available databases. Expression levels of PRMT5 protein were also examined using medulloblastoma cell lines and primary tumors by western blotting and immunohistochemistry, respectively. Using MYC-driven medulloblastoma cells, we examined the physical interaction between PRMT5 and MYC by co-immunoprecipitation and co-localization experiments. To determine the functional role of PRMT5 in MYC-driven medulloblastoma, PRMT5 was knocked-down in MYC-amplified cells using siRNA and the consequences of knockdown on cell growth and MYC expression/stability were investigated. In vitro therapeutic potential of PRMT5 in medulloblastoma was also evaluated using a small molecule inhibitor, EPZ015666. RESULTS We observed overexpression of PRMT5 in MYC-driven primary medulloblastoma tumors and cell lines compared to non-MYC medulloblastoma tumors and adjacent normal tissues. We also found that high expression of PRMT5 is inversely correlated with patient survival. Knockdown of PRMT5 using siRNA in MYC-driven medulloblastoma cells significantly decreased cell growth and MYC expression. Mechanistically, we found that PRMT5 physically associated with MYC by direct protein-protein interaction. In addition, a cycloheximide chase experiment showed that PRMT5 post-translationally regulated MYC stability. In the context of therapeutics, we observed dose-dependent efficacy of PRMT5 inhibitor EPZ015666 in suppressing cell growth and inducing apoptosis in MYC-driven medulloblastoma cells. Further, the expression levels of PRMT5 and MYC protein were downregulated upon EPZ015666 treatment. We also observed a superior efficacy of this inhibitor against MYC-amplified medulloblastoma cells compared to non-MYC-amplified medulloblastoma cells, indicating specificity. CONCLUSION Our results reveal the regulation of MYC oncoprotein by PRMT5 and suggest that targeting PRMT5 could be a potential therapeutic strategy for MYC-driven medulloblastoma.
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Affiliation(s)
- Nagendra K Chaturvedi
- Department of Pediatrics, Division of Hematology and Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
| | - Sidharth Mahapatra
- Department of Pediatrics, Division of Hematology and Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Varun Kesherwani
- Child Health Research Institute Cancer, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Matthew J Kling
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Mamta Shukla
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Sutapa Ray
- Department of Pediatrics, Division of Hematology and Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Ranjana Kanchan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Naveenkumar Perumal
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Timothy R McGuire
- Department of Pharmacy Practice, University of Nebraska Medical Center, Omaha, NE, 69198, USA
| | - J Graham Sharp
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Shantaram S Joshi
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Don W Coulter
- Department of Pediatrics, Division of Hematology and Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
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