Objective      To determine the effects of tetrandrine (Tet) on the growth in human hepatoma 3b (Hep3b) cells.       Methods       Flow cytometry

MTT assay

and Western blotting were used to investigate the effects of Tet （0.33 to 1.0 μg/ml） on the growth of Hep3b and Hep3b/5-Fu cells.       Results        Tet resulted in a decreased survival rate of Hep3b cells in a dose-dependent manner. Tet of 0.5 and 1.0 μg/ml significantly increased the IC

50

of 5-fluo

rouracil (5-Fu) to Hep3b cells

whereas reduced the IC

50

of 5-FU to Hep3b/5-Fu cells. Tet of 0.33μg/ml significantly increased the IC

50

of Cisplatin (cDDP) to Hep3b/5-Fu cells

but that of 0.5 and 1.0 μg/ml significantly reduced its IC

50

to Hep3b/5-Fu cells. Treatment of 1.0 μg/ml Tet for 48 h obviously resulted in an up-regulation of P-gp and MRP1 in the Hep3b cells （P0.05）. Our results indicated that Tet exerted inhibitory effect on Hep3b growth

and it at high concentration reversed the resistance of Hep3b/5-Fu cells to 5-Fu and enhanced the cytotoxic effect of cDDP on these Hep3b/5-Fu cells.       Conclusion        Tet shows a dose-related dualistic effects on the growth of Hep3b and Hep3b/5-Fu cells

which might be related with the up-regulating of P-gp and MRP1.