Targeted inhibition of mTORC1 and mTORC2 by active-site mTOR inhibitors has cytotoxic effects in T-cell acute lymphoblastic leukemia.
Leukemia
; 25(5): 781-91, 2011 May.
Article
en En
| MEDLINE
| ID: mdl-21331075
The mammalian Target Of Rapamycin (mTOR) serine/threonine kinase belongs to two multi-protein complexes, referred to as mTORC1 and mTORC2. mTOR-generated signals have critical roles in leukemic cell biology by controlling mRNA translation of genes that promote proliferation and survival. However, allosteric inhibition of mTORC1 by rapamycin has only modest effects in T-cell acute lymphoblastic leukemia (T-ALL). Recently, ATP-competitive inhibitors specific for the mTOR kinase active site have been developed. In this study, we have explored the therapeutic potential of active-site mTOR inhibitors against both T-ALL cell lines and primary samples from T-ALL patients displaying activation of mTORC1 and mTORC2. The inhibitors affected T-ALL cell viability by inducing cell-cycle arrest in G(0)/G(1) phase, apoptosis and autophagy. Western blot analysis demonstrated a Ser 473 Akt dephosphorylation (indicative of mTORC2 inhibition) and a dephosphorylation of mTORC1 downstream targets. Unlike rapamycin, we found a marked inhibition of mRNA translation in T-ALL cell lines treated with active-site mTOR inhibitors. The inhibitors strongly synergized with both vincristine and the Bcl-2 inhibitor, ABT-263. Remarkably, the drugs targeted a putative leukemia-initiating cell sub-population (CD34(+)/CD7(-)/CD4(-)) in patient samples. In conclusion, the inhibitors displayed remarkable anti-leukemic activity, which emphasizes their future development as clinical candidates for therapy in T-ALL.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Autofagia
/
Factores de Transcripción
/
Proteínas
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Apoptosis
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Inhibidores de Proteínas Quinasas
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Leucemia-Linfoma Linfoblástico de Células T Precursoras
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Leukemia
Asunto de la revista:
HEMATOLOGIA
/
NEOPLASIAS
Año:
2011
Tipo del documento:
Article
País de afiliación:
Italia
Pais de publicación:
Reino Unido