title: Effect of valproic acid and antiapoptotic cytokines on differentiation and apoptosis induction of human leukemia cells.
abstract: This work compares effect of histondeacetylase inhibitor, valproic acid (VA), on proliferation, differentiation and apoptosis induction in two human leukemic cell lines: HL-60 (human promyleocytic leukemia, p53 negative) and MOLT-4 (human T-lymphocyte leukemia, p53 wild type). Incubation with VA caused decrease in percentage of cells in S phase of cell cycle. The decrease was more intensive in HL-60 cells, where the cells in S phase were absent 6 days after the beginning of incubation with VA (4 mmol/l). 3-day-long incubation of HL-60 cells with 4 mmol/l VA caused differentiation of these cells, marked by increase in CD11b and co-stimulatory/adhesion molecule CD86, and induction of a significant apoptosis. Annexin V positive cells lost the CD11b antigen. 3-day-long incubation of MOLT-4 cells with VA (1-2 mmol/l) inhibited proliferation and decreased percentage of cells in S phase of the cell cycle. 90% of MOLT-4 cells are CD7 positive. This CD7 positivity is not changed during apoptosis induction (detected as Annexin V positivity). On the other hand, CD4 marker expression decreases after incubation with 1-2 mmol/l VA, but during apoptosis induction by 4 mmol/l VA, most of the apoptotic Annexin V positive cells were also CD4 positive. Using a clonogenic survival assay EC(50) for 3-day-long incubation with VA was determined. For HL-60 cells, the established EC(50) was 1.84 mmol/l, for MOLT-4 cells it was 1.76 mmol/l. Ability of VA to induce differentiation in HL-60 cells thus does not affect final cell killing. However, the elimination of the cells was considerably affected by presence of hematopoietic growth factors. 14-day-long incubation of HL-60 cells with VA in conditioned medium (source of IL-3, SCF, G-CSF) caused increase in EC(50) to 4 mmol/l, while in MOLT-4 cells (cultivation without conditioned medium), the EC(50) decreased to 0.63 mmol/l.
authors.affiliation: Department of Medical Biochemistry, Charles University in Prague, Faculty of Medicine in Hradec Králové, Hradec Králové, Czech Republic. rezacovam@lfhk.cuni.cz
authors.forename: M
authors.initials: M
authors.lastname: Rezácová
authors.forename: J
authors.initials: J
authors.lastname: Vávrová
authors.forename: D
authors.initials: D
authors.lastname: Vokurková
authors.forename: D
authors.initials: D
authors.lastname: Záskodová
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002470:Cell Survival; D016207:Cytokines / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D018922:HL-60 Cells / Q000473:pathology; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D015458:Leukemia, T-Cell / Q000378:metabolism / Q000473:pathology*; D014410:Tumor Stem Cell Assay; D014635:Valproic Acid / Q000494:pharmacology*
chemical_list: D017304:Annexin A5; D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; D016207:Cytokines; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D014635:Valproic Acid