Effects of retinoic acid and histone deacetylase inhibitor Bml-210 on protein expression in NB4 cells

Abstract

The acute promyelocytic leukemia cell line NB4 can differentiate to granulomytes in response to retinoic acid (RA) or to monocytes / macrophages in response to 1.25 dihydroxyvitamin D3 (1.25 D3) and phorbol esters. We have examined changes in protein levels during granulocytic differentiation of NB4 cells treated with RA alone or in combination with the histone deacetylase inhibitor (HDACI), Bml-210. By MALDI-TOF MS analysis we identified proteins that displayed significant changes in the expression level with indicated treatments. One of the identified proteins whose expression levels underwent significant changes is β-dystrobrevin, a splice isoform of α-dystrobrevin. We further demonstrated changes in the expression of α-dystrobrevin in total soluble and insoluble protein fractions of NB4 cells treated with RA or Bml-210 alone or in combination. We found increased levels of α-dystrobrevin in the insoluble fraction of NB4 cells exposed to RA or in combination with Bml-210 for 24–48 h. The current results indicate an association between the increased level of dystrobrevin expression and induction of differentiation by RA. In the present work we also characterised some proteins that are present in proliferating leukemia cells and may be involved in the differentiation process in response to RA and combination of RA with HDAC inhibitor. Our results suggest that HDACI Bml-210 may be a promising agent in leukemia therapy. Keywords: differentiation, NB4 cells, dystrobrevin, histone deacetylase inhibitor