【Objective】 To explore the effects of proteasome inhibitor MG132 on apoptosis

cell cycle distribution

and the expression of ubiquitin-activing enzyme 1 (UBE1) in human Burkitt’s lymphoma Raji cells. 【Methods】 Raji cells were cultured and treated with 5 μmol/L MG132 for 24 h

morphological changes of cells were observed under inverted microscope. Apoptosis and cell cycle distribution were assessed by flow cytometry. Expression of UBE1 mRNA and protein were determined by real-time RT-PCR and Western blot assay. 【Results】 Raji cells grew slowly after exposure to MG132

dead and apoptotic cells could be seen. The apoptosis rate in MG132 group was much higher than that in control group [(26.06 ± 1.10)% vs (0.30 ± 0.26)%

P < 0.05] and the cells in G2/M phases with MG132 treatment were significantly higher than those in control group [(33.2 ± 1.2)% vs (12.5 ± 1.1)%

P < 0.05]. The mRNA expression of UBE1 in MG132 group remarkably reduced compared to the control(0.35 ± 0.05 vs 1.00 ± 0.08

P < 0.05) with inhibition ratio of 65% and UBE1 protein was also down-regulated by MG132 (0.93±0.07 vs 1.62±0.22

P<0.05) with the protein expression ratio of (58±6)%. 【Conclusion】 MG132 can induce apoptosis and G2/M arrest of Raji cells

it can also inhibit the expression of UBE1 mRNA and protein of Raji cells significantly

the mechanisms involved needs further investigation.