Objective: To investigate the effect of polysaccharide extract obtained from the Cestrum nocturnum(PCN)on the apoptosis of human osteosarcoma cell line MG-63 as well as it possible mechanism. Method: PCN was separated

and MG-63 cells in logarithmic phase were processed using PCN with the final concentration of 2.5

5

10 mg·L-1. Blank group was established with MG-63 cells. After 72 h of PCN (different mass concentration) action

MTT assay was used to determine the inhibition of cell proliferation. After 46 h of PCN (different mass concentration) action

transmission electron microscope was used to observe the morphological changes of processed cells. Its effect on apoptosis of MG-63 cells was detected by flow cytometry

and the protein expression of Caspase-3

Caspase-8

Caspase-9 and Bcl-2 were detected by Western blot. Result: PCN significantly inhibited the proliferation of MG-63 cells in a time and dose-dependent manner. It could significantly inhibit cells proliferation within the concentration range of 5-10 mg·L-1. Under electron microscopy

it could be found that PCN can induce cell apoptosis

with a large number of vacuoles in cytoplasm

and chromatin pyknosis was present for cell nucleus

and villus on cell nucleus surface was reduced. Flow cytometry indicated that 5 mg·L-1 can make MG-63 cells blocked in G0/G1. PCN induced apoptosis of MG-63 cells in a dose dependent manner

reduced Bcl-2 expression and increased Caspase-8 expression in a concentration dependent manner (P<0.05

P<0.01). Conclusion: PCN could effectively inhibit cell proliferation and induce MG-63 cells apoptosis

with a direct relation to the dose and time. This process may be associated with down-regulating protein expressions of Bcl-2 and activating the expressions of Caspases-8.