We have previously shown that four hydroxamic acids: butyric and propionic hydroxamic acids, subericbishydroxamic acid (SBHA) and suberoylanilide hydroxamic acid (SAHA) are potent inhibitors of histone deacetylase and strong inducers of fetal hemoglobin expression in vitro (

Exp Hematol.
31
:
197
,
2003
). In the present study we tested their effect on fetal hemoglobin synthesis in vivo. Transgenic mice carrying the human μLCR Aγ construct continue to express the human γ gene in the adult stage of development ( γ/α mRNA ratio ~ 5%,
Blood.
77
:
1326
,
1991
). These mice were crossed to mice heterozygous for a thalassemia gene due to β globin gene deletion (
PNAS.
92
:
11608
,
1995
). The β thalassemia/μLCR Aγ mice represent an appropriate moderately anemic animal model for testing the effects of Hb F inducers. Compounds were administered subcutaneously with a mini-osmotic pump continuously for 7days in a high and a low concentration. Concentrations were: for butyric hydroxamic acid: 500mg/kg/day/100mg/kg/day; for propionic hydroxamic acid: 500mg/kg/day/100mg/kg/day; for SAHA: 100mg/kg/day/20mg/kg/day; and for SBHA: 200mg/kg/day/40mg/kg/day. Two test groups were studied. In group 1, 70μL mice blood was drawn every other day up to 20 days; in group 2, 70μL mice blood was drawn only on days 0 and 21. Reticulocytes and F reticulocytes were measured using flow cytometry, while γ globin gene expression was quantitated by RNase protection assay. Butyric and propionate hydroxamic acids increased reticulocytes by 70.52% (from 13.96% to 23.81%) and 172.52% (from 10.34% to 28.20%) respectively. There was only small increase in reticulocytes in the mice treated with SAHA (from 13.33% to 15.36%), SBHA (from 14.24% to 16.27%) and the PBS control (11.06% to 14.11%). All the compounds increased the level of γ mRNA: butyric hydroxamate by 53.07%; propionic hydroxamate by 40.05%; SAHA by 49.87%, and SBHA by 34.05%. These results suggest first that all the hydroxamic acid derivatives we used increase fetal hemoglobin in vivo in the thalassemia animal model; second butyric and propionic hydroxanic acids are in addition inducers of in vivo erythropoiesis.

Topics:
animal model, gene expression, globins, hydroxamic acids, vorinostat, fetal hemoglobin, thalassemia, rna, messenger, anemia, flow cytometry

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2005, The American Society of Hematology
2004
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