OBJECTIVETo study the effect of pseudolaric acid B (PLAB) on cell proliferation and cycle of human prostate carcinoma DU-145 cells. method: Its inhibitory effect on the cell growth was measured by MTT method. Characteristics of cell death were determined by Hoechest 33342 staining. The cell cycle was detected by flow cytometry. The expressions of cyclin B1, cyclin D1 and CDK1 were detected by Real time-PCR and Western blot, respectively.

RESULTPLAB notably inhibited DU-145 cell growth in a dose- and time dependent manner (P < 0.05). Its IC50 values of PLAB for DU-145 cells for 24, 48 and 72 h were 4.53, 2.39 and 2.08 micromol x L(-1), respectively. Having been treated with 5 micromol x L(-1) PLAB for 24 h, the cells showed such apoptosis characteristics as nuclei chromatin condensation and apoptotic body. With the increase in PLAB concentration, the proportion of G2/M phase cells strikingly increased in a dose- and time dependent manner (P < 0.05), meanwhile cyclin B1 and CDK1 showed over-expressions (P < 0.05), and the cyclin D1 showed under-expression (P < 0.05).

CONCLUSIONPLAB can inhibit the growth of DU-145 cells and induce the cell cycle G2/M arrest, accompanied with the over-expression of cyclin B1 and CDK1, which may be related with its regulation cycle-associated protein degradation.