title: Targeting activating mutations of EZH2 leads to potent cell growth inhibition in human melanoma by derepression of tumor suppressor genes.
abstract: The epigenetic modifier EZH2 is part of the polycomb repressive complex that suppresses gene expression via histone methylation. Activating mutations in EZH2 are found in a subset of melanoma that contributes to disease progression by inactivating tumor suppressor genes. In this study we have targeted EZH2 with a specific inhibitor (GSK126) or depleted EZH2 protein by stable shRNA knockdown. We show that inhibition of EZH2 has potent effects on the growth of both wild-type and EZH2 mutant human melanoma in vitro particularly in cell lines harboring the EZH2Y646 activating mutation. This was associated with cell cycle arrest, reduced proliferative capacity in both 2D and 3D culture systems, and induction of apoptosis. The latter was caspase independent and mediated by the release of apoptosis inducing factor (AIFM1) from mitochondria. Gene expression arrays showed that several well characterized tumor suppressor genes were reactivated by EZH2 inhibition. This included activating transcription factor 3 (ATF3) that was validated as an EZH2 target gene by ChIP-qPCR. These results emphasize a critical role for EZH2 in the proliferation and viability of melanoma and highlight the potential for targeted therapy against EZH2 in treatment of patients with melanoma.
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Jessamy C
authors: JC
authors: Tiffen
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Dilini
authors: D
authors: Gunatilake
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Stuart J
authors: SJ
authors: Gallagher
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Kavitha
authors: K
authors: Gowrishankar
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Anja
authors: A
authors: Heinemann
authors: Translational Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.
authors: Carleen
authors: C
authors: Cullinane
authors: Oncogenomics Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
authors: Ken
authors: K
authors: Dutton-Regester
authors: Center for Cancer Research, University of Sydney at Westmead Millennium Institute, Westmead, NSW, Australia.
authors: Gulietta M
authors: GM
authors: Pupo
authors: School of Mathematics and Statistics, University of Sydney, NSW, Australia.
authors: Dario
authors: D
authors: Strbenac
authors: School of Mathematics and Statistics, University of Sydney, NSW, Australia.
authors: Jean Y
authors: JY
authors: Yang
authors: Sydney Medical School, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Jason
authors: J
authors: Madore
authors: Center for Cancer Research, University of Sydney at Westmead Millennium Institute, Westmead, NSW, Australia.|School of Mathematics and Statistics, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Graham J
authors: GJ
authors: Mann
authors: Oncogenomics Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
authors: Nicholas K
authors: NK
authors: Hayward
authors: Translational Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.|Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.
authors: Grant A
authors: GA
authors: McArthur
authors: Systems Biology and Cancer Metabolism, Program for Quantitative Systems Biology, University of California Merced, Merced, CA, USA.
authors: Fabian V
authors: FV
authors: Filipp
authors: Melanoma Immunology and Oncology Group, Centenary Institute, University of Sydney, NSW, Australia.|Melanoma Research Group, Kolling Institute of Medical Research, University of Sydney, NSW, Australia.|Melanoma Institute Australia, Crows Nest, Sydney, NSW, Australia.
authors: Peter
authors: P
authors: Hersey
mesh_terms: D051700:Activating Transcription Factor 3 / Q000235:genetics; D017209:Apoptosis; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D018450:Disease Progression; D000071221:Enhancer of Zeste Homolog 2 Protein; D057890:Epigenomics; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D005838:Genotype; D006657:Histones / Q000737:chemistry; D006801:Humans; D007211:Indoles / Q000737:chemistry; D020128:Inhibitory Concentration 50; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D063151:Polycomb Repressive Complex 2 / Q000235:genetics*; D011728:Pyridones / Q000737:chemistry; D012878:Skin Neoplasms / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C490449:ATF3 protein, human; D051700:Activating Transcription Factor 3; C577920:GSK-2816126; D006657:Histones; D007211:Indoles; D011728:Pyridones; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2
keywords: EZH2; H3K27me3; epigenetics; melanoma; targeted therapy