Visit our Expo - Redox and Inflammation signaling 2012

Session XIII : Cell signaling pathways leading to regulated chromatin modifications
Poster XIII, 7
Histone acetylation-targeted differential responses of leukemia cells HL-60 and NB4 to
histone deacetylase inhibitor FK228
Jurate Savickiene1, Grazina Treigyte1, Ruta Navakauskiene1 and Karl-Eric
Magnusson2
1Department of Developmental Biology, Institute of Biochemistry, LT-2600 Vilnius,
Lithuania. E-mail: grazina.treigyte@bchi.lt savickiene@bchi.lt
ruta.navakauskiene@bchi.lt
2Division of Medical Microbiology, Department of Molecular and Clinical Medicine,
Linköping University, SE-58185 Linköping, Sweden. E-mail: karma@imk.liu.se
The histone deacetylase inhibitor (HDACI), depsipeptide (FK228), was shown previously as a
chemopreventive agent for the treatment of adult T-cell lymphomas. In this report, we
investigated the in vitro antileukemic activity of FK228 alone, and in combination with alltrans
retinoic acid (RA), on the human leukemia cell lines, NB4 and HL-60. The results show
that FK228 induced a dose-dependent (0.2-1 ng/ml) cell growth arrest and death by apoptosis
in NB4 and HL-60. The combined treatment with RA accelerated and enhanced granulocytic
differentiation in both cell lines distinctly; the 6 h - pretreatment with HDACI had an additive
differentiating effect in HL-60 cells only. These effects were accompanied by a time- and
dose-dependent histone H4 hyper-acetylation and histone H3 dephosphorylation, occuring
after 2-8 h exposure to HDACI. FK228 up-regulated NF-!B binding to the FasL promoter,
and in combination with RA it altered the DNA binding of NF-!B linking the findings to cell
death and differentiation. Pifithrin-" (PFT), an inhibitor of p53 transcriptional activity,
protected from apoptosis only in NB4 cells with functional p53, i.e. when used 4 h before
treatment with FK228 only or together with HDACI. In NB4 cells, PFT inhibited p53 binding
to the p21 (Waf1/Cip1) promoter and induced DNA binding of NF-!B leading to enhanced
cell survival. Thus, FK228 may be a promising antileukemic agent in combination with RA,
since it exerts antiproliferative, differentiating and apoptotic effects in leukemia cells without
and with functional p53, acting via histone modifications and selective involvement of
transcription factors, like NF-!B and p53.
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