Objective:

2

To test the role of psoralidin in human liver cancer HepG2 cells in vitro.

Methods:

2

Cell viability was assessed by methylthiazolyldiphenyl-tetrazolum bromide assay and apoptotic cells were labeled by annexin V then sorted by flow cytometry. Protein expressions of caspase-3

caspase-8

caspase-9

Bax

Bid

Bcl-2

Bcl-xL and p53 were examined by western blot while activity of caspase-3

-8 and -9 were also determined.

Results:

2

Psoralidin reduces cell viability greatly in a time dependent manner (64%

40%

21%

12% at 2

6

24 and 48 h treatment with 64 μmol/L psoralidin respectively) and up-regulates activities of caspase-3

-8 and -9 in a concentration dependent manner (between 4 to 64 μmol/L). Psoralidin also increases the expression of pro-apoptosis genes Bax

Bid and p53 while decreases the expression of pro-survival genes Bcl-2 and Bcl-xL

both in a concentration dependent manner between 4 and 64 μmol/L (

P

<

0.05 at 16 and 64 μmol/L). Caspase-3 inhibitor (Ac-DEVD-CHO at concentrations between 10 to 20 μmol/L)

p53 inhibitor (pifithrin-α at 5 μmol/L) and cyclosporin A can attenuate the apoptotic effect of psoralidin.

Conclusion:

2

The cytotoxic role of psoralidin might work through both intrinsic and extrinsic apoptotic pathway.