[Effect of tetrandrine and droloxifene on the reversion of drug resistance of K562/A02 cell line and induction of apoptosis].

OBJECTIVE: To study the reversal effect of tetrandrine (Tet) and droloxifene (Drol) on multidrug resistant cell line K562/A02 and apoptosis induction. METHODS: The cytotoxicity of daunorubicin (DNR) was assayed by MTT method. The effects of Tet and DRL, alone or combined were detected through the apoptosis of K562/A02 by agarose gel electrophoresis. RESULTS: The cytotoxicity of DNR to K562/A02 was enhanced by 0.62 microg/ml Tet or 1.94 microg/ml Drol with IC(50) 7.28 +/- 2.06 microg/ml, 7.58 +/- 3.44 microg/ml, giving a reversal effect of 2.94 and 2.82. But IC(50) of combined Tet and Drol was 1.66 +/- 0.41 microg/ml with the reversal effect markedly increased to 12.9. Neither 0.62 microg/ml Tet nor 1.94 microg/ml Drol could induce apoptosis of K562/A02 cells. CONCLUSION: Multidrug resistance (MDR) can be partially reversed by Tet or Drol, of which the combination shows a great synergistic reversal effect. The mechanism of Tet and Drol reversing multidrug resistance is not correlated with the apoptosis of K562/A02 cells.