CYCLOSPORINE INHIBITED CALCIUM-MEDIATED APOPTOSIS OF HL-60 CELLS

AIM: To study the effects of cyclosporine (Cyc) on apoptosis of HL-60 cells. METHODS: Apoptotic cells induced by harringtonine (Har), campto thecin (Cam), or calcimycin (Gal), thapsigargin (Tha) were identified with DNA electrophoresis, morphology, and flow cytometry. Relative [Ca 2+](i) alteration of apoptotic HL-60 cells were determined with flow c ytometry. RESULTS: Cal 1 mg.L-1 or Tha 0.5 mg.L-1 induced apoptosis of HL-60 cells. This effect was inhibited by nontoxic concentration of C yc 1 mg.L-1. Cyc did not inhibit Har- or Cam-induced apoptosis of HL-6 0 cells. Both Cal and Tha increased intracellular calcium, whereas Har or Cam did not. CONCLUSION: Cyc inhibited apoptosis only induced by c alcium increasement in HL-60 cells. The mechanism of apoptosis induced by Cal or Tha was different from that by Har or Cam.