[Mechanism of apoptosis induced by trichostatin A in leukemia Molt-4 cells analyzed by microarray]

Histone deacetylase is overexpressed in a variety of cancers and is closely correlated with oncogenic factors. A histone-deacetylase inhibitor, trichostatin A (TSA), has been shown to induce apoptosis in many cancer cells at submicromolar concentrations. However, the mechanism remains unknown. This study was to investigate the underlying mechanism of trichostatin A on apoptosis of Molt-4 cells by characterizing the global gene expression profiles before and after TSA treatment.

PI single-labeled flow cytometry, MTT and DNA ladder were used to observe the effect of TSA on apoptosis of MOLT-4 cells and normal human peripheral blood mononuclear cells (PBMC). Microarray and reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were used to detect the differentially expressed genes of Molt-4 cells after incubation with TSA.

TSA could induce apoptosis in Molt-4 cells in a dose and time-dependent manner. Besides, the dose of TSA within the time duration which could induce significant apoptosis in Molt-4 cells did not demonstrate apparent cytotoxicity to PBMCs. After incubation with TSA for 9 hours, 313 genes were detected down-regulated by microarray. Proteins encoded by these genes included signal transduction molecules, transcription factors, enzymes etc., which were involved in the regulation of cell growth, differentiation and survival. STAT5A, MYC and ikaros were down-regulated by 80.4%, 77.3% and 83.1%, respectively. The changes of the three genes were confirmed by RT-PCR and the changes of STAT5A and MYC were further confirmed by Western blot.

The inhibition of cell growth and induction of apoptosis by TSA in Molt-4 cells may be due to the changes of pro-proliferation genes and anti-apoptosis genes.