Acute myeloid leukemia (AML) is a disease characterized by a block of maturation. Genes coding for core binding factors are rearranged in a considerable subset of AML cases and result in the altered interaction of CBF subunits with transcriptional co-regulators (NCoR/SMRT). Recruitment of HDAC is also altered in this subtype of AML, and a subsequent transcriptional repression of target genes involved in myeloid maturation is determined. We recently demonstrated that sodium butyrate and the stable prodrug xylitol butyrate derivative (D1) as single drugs restore histone acetylation and granulocytic maturation in the t(8;21)-positive Kasumi-1 cell line, as well as primary CBF-AML blasts. These effects are paralleled by massive apoptosis as well as reduction of cell number. The mitogen-activated protein kinases (MAPK) have been shown to regulate a wide variety of cellular processes, such as cell proliferation, differentiation and apoptosis. D1 induced ERK activation (peaks at 2-6h and 48-72h) and a transient activation of p38.JNK activity was also modulated following D1 treatment, with differences among the JNK isoforms. Specific inhibitors of the ERK, p38 and JNK pathways (PD98059, SB203580 and SP600125, respectively) were then used to investigate the role of MAPK in the biological effects determined by D1 administration to Kasumi-1 cells. Inhibition of ERK 1/2 and JNK determined a significant decreased in cell number. P38 inhibition did not affect cell number while inhibiting the D1-induced decrease. Inhibition of ERK and JNK were ineffective in the D1- induced decrease. Decrease of cell number was caused by induction of apoptosis, as determined by the Annexin V test. In particular, ERK and p38 inhibition did not determine significant apoptosis. JNK inhibition determined a marked apoptosis which was similar to that induced by D1, while the treatment with both D1 and SP600125 induced an additive effect. Inhibition of the ERK and p38 pathways did not interfere with D1-induced apoptosis. These results were confirmed by western blotting evaluation of caspase-3 activation. Indeed, caspase-3 precursor decreased and the active caspase form appeared after a 24 h treatment with D1 and SP600125 alone, while the combination of D1 with SP600125 determined maximal effects. Caspase-3 activation was unchanged by the treatment with PD98059 or SB203580, alone or in combination with D1.PD98059 and SP600125 were able to induce a conspicuous maturation, as revealed by morphological analysis. These data were not supported by immunophenotype data. None of MAPKs inhibitors interfered with D1-induced maturation. It is worth pointing out that none of the above MAPK inhibitors modulated histone acetylation which occurs after D1 treatment of these cells. D1-induced modulation of MAPK, which seems to be involved in Kasumi 1 survival and maturation, suggests that the butyrate derivative exerts its action also via HDAC-unrelated pathways.
|Titolo:||MAPKS ARE INVOLVED IN THE SURVIVAL AND DIFFERENTIATION OF A T(8;21) ACUTE MYELOID LEUKEMIA CELL LINE AND ARE MODULATED BY THE HDAC INHIBITOR D1|
|Anno di registrazione:||2004|
|Autori di Ateneo:|
|Autori:||E. Rovida; A. Gozzini; V. Barbetti; S. Giuntoli; V. Santini; P. Dello Sbarba|
|Appare nelle tipologie:||1c - Abstract su rivista|
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|Haematologica_2004_S6p96.pdf||Altro||DRM non definito||Administrator|