RESISTANCE TO APOPTOSIS OF HARRINGTONINE-RESISTANT HL60 CELLS INDUCEDBY TETRANDRINE

AIM: To study the mechanism of resistance to, apoptosis in the harring tonine (Har)-resistant HL60 cells with tetrandrine (Tet). METHODS: Gro wth inhibition, flow cytometry, DNA agarose gel electrophoresis, prote in phosphorylation, and RNA dot hybridization. RESULTS: The resistant cells had no cross resistance to Tet. Tet induced the sensitive but no t the Har-resistant HL60 cells to apoptosis. The high phosphorylation of protein <30 kDa occurred when the resistant cells were treated with Tet. Tet and Har increased the expression of c-myc mRNA in the sensit ive HL60 cells. The expression of c-myc mRNA in the resistant cells wa s obviously decreased and almost not changed in treatment with Tet and Har. CONCLUSION: Tet induced the sensitive but not the Har-resistant HL60 cells to apoptosis, and the resistance to apoptosis induced by Te t was associated with the high protein phosphorylation and reduction o f the expression of c-myc mRNA.