Abstract

To investigate the role of ERK1, c-Jun, c-Myc and Cyclin D1 in the suppressive effect of ursolic acid (UA) on the proliferation of human umbilical vein endothelial cells (HUVECs), HUVECs were treated in vitro with UA at various concentrations (31.5, 62.5, 125, 250 and 500 μg/ml) for different durations (12, 24 and 48 h) and the proliferation inhibition rate of HUVECs was determined by MTT method. Then, HUVECs were treated with 125 μg/ml UA or 100 μmol/L PD98059 (an ERK inhibitor) for 48 h, or with various concentrations of UA for 24 h; or with 125 μg/ml UA for different durations and the protein and mRNA expressions of ERK1, c-Jun, c-Myc and Cyclin D1 were determined by RT-PCR and Western blot assay, respectively. UA exerted a suppressive effect on the proliferation of HUVECs in a time and concentration dependent manner. The protein and mRNA expressions of ERK1, c-Jun, c-Myc and Cyclin D1 in HUVECs were significantly decreased following treatment with UA and PD98059, which was also in a concentration and time dependent manner. UA can inhibit the proliferation of HUVECs by inhibiting the ERK signaling pathway.

Key words: Ursolic acid, endothelial cells, cell proliferation, extracellular-signal-regulated kinase.