Objective:To investigate the effects of vorinostat(suberoylanilide hydroxamic acid

SAHA)on the proliferation and apoptosis of human osteosarcoma 143 B cells in vitro and to explore its underlying mechanisms. Methods:143B cells were treated with SAHA at various concentrations(2-32 μmol/L)and the cell viability was measured by MTT assay. The optimal concentration and time point of SAHA function were chosen for subsequent research

and the group adding the maximum dose of 1 ml/L DMSO was taken as blank control. Flow cytometry(FCM)was used to evaluate the level of cell cycle and apoptosis rate;the expression levels of Cyclin D1

Bax

Bcl-2

and HDACs m RNAs were examined by RT-PCR;the HDACs activity of 143 B cells was measured by chemical colorimetry. The probable signaling pathways activation after SAHA treatment was tested by luciferase reporter assay. Western blot was used to detect the protein expression levels of Cyclin D1

Bax

Bcl-2

cleaved-Caspase-3

cleaved-PARP and AP1. Results:The cell viability of 143 B cells was inhibited by SAHA(2-32 μmol/L)in a dose- and time-dependent manner

and the concentration of IC50 at 48 h was 8 μmol/L. Compared with that of control group

SAHA arrest the cell cycle at G0/G1 phase and induce apoptosis of 143 B cells. SAHA treatment inhibited the expression level of cyclin D1

bax

bcl-2 and HDACs while induced the bax expression

both in m RNA and protein levels. HDAC activity of 143 B cells treated with SAHA was reduced. Luciferase reporter assay indicated that AP1 transcription factor expression can be promoted by SAHA treatment. At the same time

the expression level of cleaved-Caspase-3

cleaved-PARP and AP1 protein were elevated significantly in 143 B cells after SAHA treatment. Conclusion:SAHA can induce apoptosis and cell cycle arrest of 143 B cells in vitro

which may be possibly via inhibition of the activity of HDACs and activation of the AP1 signaling pathways.