HIGH CALCIUM CONTENT OF PLEIOTROPIC DRUG-RESISTANT P388 AND K562 LEUKEMIA AND CHINESE-HAMSTER OVARY CELLS

Abstract

The Ca content of pleiotropic drug-resistant tumor cells was estimated and compared with that of the parent tumor lines. P388 leukemia cells resistant to vincristine and Adriamycin contained more Ca (1.5- to 1.8-fold) in the cells and on the cell surface than the parent P388 cells. Similar results were obtained with human K562 myelogenous leukemia cells resistant to vincristine and also with Chinese hamster ovary cells resistant to colchicine. The Ca content of P388 cells resistant to 5-fluorouracil was almost the same as that of the parent P388 cells. The calmodulin content of pleiotropic resistant tumor lines and a 5-fluorouracil-resistant tumor line was almost the same as that of the corresponding parent lines. The isolated plasma membrane of K562 cells resistant to vincristine contained .apprx. 1.5-fold higher Ca than the parent cells. The higher cellular Ca content might be a characteristic phenotype of pleiotropic resistant tumor lines.