Cyclin E/Cdk2-dependent phosphorylation of Mcl-1 determines its stability and cellular sensitivity to BH3 mimetics.
Oncotarget
; 6(19): 16912-25, 2015 Jul 10.
Article
em En
| MEDLINE
| ID: mdl-26219338
ABSTRACT
Cyclin E/Cdk2 kinase activity is frequently deregulated in human cancers, resulting in impaired apoptosis. Here, we show that cyclin E/Cdk2 phosphorylates and stabilizes the pro-survival Bcl-2 family protein Mcl-1, a key cell death resistance determinant to the small molecule Bcl-2 family inhibitors ABT-199 and ABT-737, mimetics of the Bcl-2 homology domain 3 (BH3). Cyclin E levels were elevated and there was increased association of cyclin E/Cdk2 with Mcl-1 in ABT-737-resistant compared to parental cells. Cyclin E depletion in various human tumor cell-lines and cyclin E-/- mouse embryo fibroblasts showed decreased levels of Mcl-1 protein, with no change in Mcl-1 mRNA levels. In the absence of cyclin E, Mcl-1 ubiquitination was enhanced, leading to decreased protein stability. Studies with Mcl-1 phosphorylation mutants show that cyclin E/Cdk2-dependent phosphorylation of Mcl-1 residues on its PEST domain resulted in increased Mcl-1 stability (Thr92, and Thr163) and Bim binding (Ser64). Cyclin E knock-down restored ABT-737 sensitivity to acquired and inherently resistant Mcl-1-dependent tumor cells. CDK inhibition by dinaciclib resulted in Bim release from Mcl-1 in ABT-737-resistant cells. Dinaciclib in combination with ABT-737 and ABT-199 resulted in robust synergistic cell death in leukemic cells and primary chronic lymphocytic leukemia patient samples. Collectively, our findings identify a novel mechanism of cyclin E-mediated Mcl-1 regulation that provides a rationale for clinical use of Bcl-2 family and Cdk inhibitors for Mcl-1-dependent tumors.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Leucemia Linfocítica Crônica de Células B
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Ciclina E
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Quinase 2 Dependente de Ciclina
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Proteína de Sequência 1 de Leucemia de Células Mieloides
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article