Techniques to reverse or circumvent drug-resistance in vitro.

In this study, we report that membrane-active agents can reverse or circumvent multidrug resistance in tumor cells through alteration of membrane permeability. Two different cell lines are used to assay the drug-sensitivity: colchicine-resistant clone derived from human cancer KB cell line with multidrug resistance and P388 leukemia cells resistant to many anticancer agents such as adriamycin, vincristine and other agents. In the latter system, circumvention effect can be tested with mice bearing drug-sensitive or -resistant P388 leukemia in vivo. Thioridazine (calmodulin inhibitor), N-(p-methylbenzyl)decaprenylamine, N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine and amphotericin B (a sterol-binding polyene antibiotic) have been screened with these two drug-resistant cell systems. They overcome the multidrug resistance in Chr-24 as well as P388 leukemia cells resistant to adriamycin or vincristine. N-solanesyl-N,N'-bis(3,4-dimethoxylbenzyl)ethylenediamine can reverse the drug-resistance in vivo against mice bearing resistant leukemia. Mechanism to reverse the drug-resistance is to be discussed in relation with altered membrane permeability of the anticancer agents.