MEK inhibition induces caspases activation, differentiation blockade and PML/RARα degradation in acute promyelocytic leukaemia.

Autor: Barbarroja, Nuria, Siendones, Emilio, Torres, Luis Arístides, Luque, Ma. Jose, Martinez, Julio Manuel, Dorado, Gabriel, Velasco, Francisco, Torres, Antonio, López-Pedrera, Chary
Předmět:
Zdroj: British Journal of Haematology; Jul2008, Vol. 142 Issue 1, p27-35, 9p, 1 Chart, 5 Graphs
Abstrakt: The hallmark of acute promyelocytic leukaemia (APL) is the reciprocal translocation t(15;17), which leads to the expression of the promyelocytic leukaemia/retinoic acid receptor α (PML/RARα) fusion protein and a cell differentiation blockade at the promyelocytic stage. PML/RARα is directly targeted by all- trans-retinoic acid (ATRA), which degrades the oncoprotein and induces complete remission of malignancies. The aberrant function of PML/RARα, together with the constitutive activation of the mitogen-activated protein/extracellular signal-regulated kinase (MEK/ERK) signalling pathway, regulates the ability of haematopoietic cells to proliferate, differentiate, and escape from apoptotic episodes. The role of the MEK/ERK pathway in PML/RARα expression, differentiation, proliferation and apoptosis in APL cells was analysed using specific MEK inhibitors. The blockade of MEK/ERK pathway resulted in caspase-dependent degradation of PML/RARα, and attenuation of the cell differentiation induction. To our knowledge, this is the first report to show that PML/RARα was suppressed by MEK/ERK inhibition, through a mechanism dependent on caspase activation. ATRA co-operated with MEK inhibitor to increase degradation of PML/RARα and exhibited a convergence point in caspase activation with MEK inhibitors. Taken together, our data suggest a new role of MEK/ERK pathway in the pathogenesis of APL, thus supporting the use of MEK/ERK inhibitors as an efficient therapeutic strategy for this haematological malignancy. [ABSTRACT FROM AUTHOR]
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