Abstract: AIM:To study the effect of proteasome inhibitor MG132 on the expression of caspase 3 and the apoptosis in cultured human umbilical vascular smooth muscle cells. METHODS:Human umbilical vascular smooth muscle cells were treated with MG132 (2. 5, 5, 10 μmol/L) for 24 hours and for 48 hours. The apoptotic cells were determined by flow cytometric analysis. The levels of Ub, E1, E₂, E₃, 26S and caspase 3 mRNA expression were detected by reverse transcription- polymerase chain reaction (RT-PCR). The expression of caspase 3 protein was detected by immunocytochemistry. RESULTS: The results showed that the expressions of Ub, E1, E₂, E₃, 26S genes were decreased in treatment group and the apoptosis rates were increased obviously. MG132 could up-regulate the gene/protein expression of caspase 3. CONCLUSION: The results implicate that proteasome inhibitor MG132 could dose-dependently induce human umbilical vascular smooth muscle cells apoptosis, the apoptosis of human umbilical vascular smooth muscle cells induced by MG132 probably is relates to the decreases of Ub, E1, E₂, E₃ and 26S expressions and the increase of caspase 3 expression.

Key words: human umbilical vascular smooth muscle cells, ubiquitin-proteasome pathway, inhibitor, apoptosis, caspase 3