Objective        To determine  the effect of tetrandrine (Tet) on the growth of human leukemia K562 and K562/ADM cells.       Methods        The K562 and K562/ADM cells were cultured in RPMI1640 containing 10% newborn bovine serum (NBS) under the condition of 37 ℃ and 5% CO

2

. MTT assay and Western blot analysis were used to investigate the effect of Tet on the growth of K562 and K562/ADM cells after the cells were treated with Tet for 48 h.       Results        Tet (0.33-1.0 μg/ml) decreased the survival of K56

2 and K562/ADM cells to 75%-80%. The low dose of Tet (0.33 μg/ml) significantly increased the IC

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of doxorubicin (ADM) on K562/ADM cells and the IC

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of cisplatin (cDDP) on K562 cells (P0.01)

whereas the 1.0 μg/ml of Tet reduced the IC

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of cDDP on K562 cells (P0.01). The IC

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of cDDP on K562/ADM cells was not affected. The expression of P-gp and multidrug resistance-related protein 1 (MRP1) was significantly increased by 0.33 μg/ml of Tet in K562 and K562/ADM cells (P0.05). The expression of lung resistance-related protein (LRP) in K562 and K562/ADM cells was not affected by varied concentrations of Tet.       Conclusion        The growth inhibition of K562 and K562/ADM cells by Tet is in a dose-dependent manner. Low dose Tet (0.33 μg/ml) promotes the drug resistance of K562 and K562/AMD cells to doxorubicin and cisplatin

and the mechanism is related to the upregulation of P-gp and MRP1.