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), camptothecin (Cam), or calcimycin (Cal), thapsigargin (Tha) were identified with DNA electrophoresis, morphology, and flow cytometry. Relative [Ca2+]i alteration of apoptotic HL-60 cells were determined with flow cytometry. 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 Cyc 1 mg.L-1. Cyc did not inhibit Har- or Cam-induced apoptosis of HL-60 cells. Both Cal and Tha increased intracellular calcium, whereas Har or Cam did not. CONCLUSION: Cyc inhibited apoptosis only induced by calcium increasement in HL-60 cells. The mechanism of apoptosis induced by Cal or Tha was different from that by Har or Cam.