apicidin and Hypereosinophilic-Syndrome

Acetylation and deacetylation of proteins occur in cells in response to various stimuli, and are reversibly catalyzed by histone acetyltransferase and histone deacetylase (HDAC), respectively. EoL-1 cells have an FIP1L1-PDGFRA fusion gene that causes transformation of eosinophilic precursor cells into leukemia cells. The HDAC inhibitors apicidin and n-butyrate suppress the proliferation of EoL-1 cells and induce differentiation into eosinophils by a decrease in the protein level of FIP1L1-PDGFRalpha without affecting the mRNA level for FIP1L1-PDGFRA. In this study, we analyzed the mechanism by which the protein level of FIP1L1-PDGFRalpha is decreased by apicidin and n-butyrate.. EoL-1 cells were incubated in the presence of the HDAC inhibitors apicidin, trichostatin A or n-butyrate. The protein levels of FIP1L1-PDGFRalpha and phosphorylated eIF-2alpha were determined by Western blotting. Actinomycin D and cycloheximide were used to block RNA synthesis and protein synthesis, respectively, in the chasing experiment of the amount of FIP1L1-PDGFRalpha protein.. When apicidin- and n-butyrate-treated EoL-1 cells were incubated in the presence of actinomycin D, the decrease in the protein level of FIP1L1-PDGFRalpha was significantly enhanced when compared with controls. In contrast, the protein levels were not changed by cycloheximide among these groups. Apicidin and n-butyrate induced the continuous phosphorylation of eIF-2alpha for up to 8 days.. The decrease in the level of FIP1L1-PDGFRalpha protein by continuous inhibition of HDAC may be due to the decrease in the translation rate of FIP1L1-PDGFRA.

Topics: Acetylation; Blotting, Western; Butyrates; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Enzyme Inhibitors; Eosinophils; Eukaryotic Initiation Factor-2; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hypereosinophilic Syndrome; mRNA Cleavage and Polyadenylation Factors; Oncogene Proteins, Fusion; Peptides, Cyclic; Receptor, Platelet-Derived Growth Factor alpha

EoL-1 cells differentiate into eosinophils in the presence of n-butyrate, but the mechanism has remained to be elucidated. Because n-butyrate can inhibit histone deacetylases, we hypothesized that the inhibition of histone deacetylases induces the differentiation of EoL-1 cells into eosinophils. In this study, using n-butyrate and two other histone deacetylase inhibitors, apicidin and trichostatin A, we have analyzed the relationship between the inhibition of histone deacetylases and the differentiation into eosinophils in EoL-1 cells. It was demonstrated that apicidin and n-butyrate induced a continuous acetylation of histones H4 and H3, inhibited the proliferation of EoL-1 cells without attenuating the level of FIP1L1-PDGFRA mRNA, and induced the expression of markers for mature eosinophils such as integrin beta7, CCR1, and CCR3 on EoL-1 cells, while trichostatin A evoked a transient acetylation of histones and induced no differentiation into eosinophils. These findings suggest that the continuous inhibition of histone deacetylases in EoL-1 cells induces the differentiation into mature eosinophils.

Topics: Acetylation; Butyrates; Cell Differentiation; Cell Proliferation; Dose-Response Relationship, Drug; Enzyme Inhibitors; Eosinophils; Gene Expression Regulation, Enzymologic; Histone Deacetylase Inhibitors; Histone Deacetylases; Histones; HL-60 Cells; Humans; Hydroxamic Acids; Hypereosinophilic Syndrome; mRNA Cleavage and Polyadenylation Factors; Peptides, Cyclic; Platelet-Derived Growth Factor; RNA, Messenger

EoL-1 cells have a FIP1L1-PDGFRA fusion gene which causes the transformation of eosinophilic precursor cells into leukemia cells. Recently, we suggested that the induction of differentiation of EoL-1 cells into eosinophils by the HDAC inhibitors apicidin and n-butyrate is due to the continuous inhibition of HDACs. However, neither apicidin nor n-butyrate inhibited the expression of FIP1L1-PDGFRA mRNA, although both these inhibitors suppressed cell proliferation. Therefore, in this study, we analyzed whether the levels of FIP1L1-PDGFRalpha protein and phosphorylated-Stat5 involved in the signaling for the proliferation of EoL-1 cells are attenuated by HDAC inhibitors.. EoL-1 cells were incubated in the presence of apicidin, TSA or n-butyrate. FIP1L1-PDGFRalpha and phosphorylated-Stat5 were detected by Western blotting.. Treatment of EoL-1 cells with apicidin at 100 nM or n-butyrate at 500 microM decreased the levels of FIP1L1-PDGFRalpha protein and phosphorylated-Stat5, while that with trichostatin A at 30 nM did not.. The decrease in the level of FIP1L1-PDGFRalpha protein caused by apicidin and n-butyrate might be one of the mechanisms by which EoL-1 cells are induced to differentiate into eosinophils by these HDAC inhibitors.

Topics: Butyrates; Cell Differentiation; Cell Line, Tumor; Eosinophils; Gene Expression Regulation, Leukemic; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Hypereosinophilic Syndrome; mRNA Cleavage and Polyadenylation Factors; Neoplasm Proteins; Oncogene Proteins, Fusion; Peptides, Cyclic; Phosphorylation; Protein Processing, Post-Translational; Receptor, Platelet-Derived Growth Factor alpha; RNA, Messenger; STAT5 Transcription Factor