REDUCTION OF DOXORUBICIN RESISTANCE BY TETRANDRINE AND DAURICINE IN HARRINGTONINE-RESISTANT HUMAN LEUKEMIA (HL-60) CELLS

AIM: To study whether tetrandrine (Tet) and dauricine(Dau) can reduce doxorubicin (Dox) resistance in the harringtonine (Har)-resistant huma n leukemia cells. METHODS: The drug cytotoxities were determined by co unting cell numbers and colony formation. Cell cycle phases were assay ed by flow cytometry, Dox contents were quantified by Dox fluorescence . RESULTS: The non-cytotoxic concentrations of Tet and Dau potentiated the growth-inhibitory actions of Dox in the Har-resistant HL60 cells. The colony formation efficiencies were reduced from 60 % by Dox to 0. 2 % by Tet + Dox and 9.2 % by Dau + Dox. G(2)M phase cells was increas ed. did not potentiate Dox cytotoxities in the sensitive HL60 cells. D ox accumulation in the Har-resistant HL60 cells treated by Tet was inc reased. CONCLUSION: Dox resistance in the Har-resistant HL60 cells tre ated by Tet or Dau was reduced, due to the increase of Dox accumulatio n in the cells.