[Induction of apoptosis by proteasome inhibitor MG-132 in human erythroleukemia cell line K562].

ABSTRACT

OBJECTIVE: To investigate whether proteasome inhibitor MG-132 induces apoptosis of human erythroleukemia cell line K562 and possible mechanisms. METHODS: K562 cells were incubated with RPMI 1640 and exposed to 0, 1, 5, 10, 15 micromol/L of MG-132 for 24 hrs, respectively. The apoptosis of cells were detected by fluorescence microscope, DNA fragments and flow cytometry. The NF-kappaB mRNA expression was quantified by reverse transcription-polymerase chain reaction (RT-PCR). Expression of NF-kappaB and caspase-3 was semiquantitatively analyzed with SABC techniques. Caspase-3 activities were measured with a colorimetric method. RESULTS: The growth of K562 cells was inhibited and the apoptosis of the cells increased after MG-132 treatment in a dose-dependent manner. After 24 hrs of 15 micromol/L MG-132 treatment, the percentage of apoptotic cells (26.5+/-0.6%) increased significantly when compared with the untreated controls (1.2+/-0.1%) (P<0.01). MG-132 treatment decreased the mRNA and protein expression of NF-kappaB, and increased the protein expression of caspase-3. CONCLUSIONS: MG-132 can induce apoptosis of human erythroleukemia cell line K562 through the down-regulation of NF-kappaB expression and up-regulation of caspase-3 expression.