Chemosensitization to adriamycin by cyclosporin A and verapamil in human retinoblastoma cell lines.
The chemosensitizing effects of cyclosporin A and verapamil on the cytotoxicity of adriamycin were investigated using MTT assay against two human retinoblastoma cell lines, Y79 and WERI-Rb-1. Y79 and WERI-Rb-1 were totally resistant to doses up to 5.0 micrograms/ml of verapamil. Cyclosporin A inhibited the survival of Y79 and WERI-Rb-1 dose-dependently, however, the maximum inhibition at the highest concentration tested (5.0 micrograms/ml) was less than 50% (% survival at 5.0 micrograms/ml of cyclosporin A: 65.6% and 66.9% in Y79 and WERI-Rb-1, respectively). Combination of cyclosporin A and verapamil did not further inhibit the survival of Y79 and WERI-Rb-1 compared with cyclosporin A alone. Adramycin inhibited the survival of Y79 and WERI-Rb-1 dose-dependently. The chemosensitizing effects of cyclosporin A and verapamil on the cytotoxicity of adriamycin were evaluated in terms of sensitizing index (SI: the ratio of IC50 to adriamycin alone to IC50 to adriamycin in the presence of cyclosporin A and/or verapamil). Cyclosporin A significantly enhanced SI and the addition of verapamil enhanced SI further: SI values at 5.0 micrograms/ml of cyclosporin A, 5.0 micrograms/ml of cyclosporin A plus 1.5 micrograms/ml of cyclosporin A plus 1.5 micrograms/ml of verapamil, 5.0 micrograms/ml of cyclosporin A plus 3.0 micrograms/ml of verapamil were 2.0, 2.6 and 2.8 in Y79 and 2.6, 5.8 and 9.7 in WERI-Rb-1, respectively. These results suggest that cyclosporin A and verapamil are promising chemosensitizers to adriamycin in the treatment of retinoblastoma.
Lee
T W
TW
Department of Ophthalmology and Internal Medicine, Korea Cancer Center Hospital, Seoul.
Yang
S W
SW
Kim
C M
CM
Hong
W S
WS
Youn
D H
DH
D002470:Cell Survival / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology*; D005134:Eye Neoplasms / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D012175:Retinoblastoma / Q000188:drug therapy / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014700:Verapamil / Q000494:pharmacology*
D004317:Doxorubicin; D016572:Cyclosporine; D014700:Verapamil