ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells.
Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the "MDR1" gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate [3H]vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent Km of 38 microM for ATP and of approximately equal to 2 microM for vinblastine. The nonhydrolyzable analog adenosine 5'-[beta, gamma-imido]triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, an ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport of vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine greater than actinomycin D greater than daunomycin greater than colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process.
Horio
M
M
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892.
Gottesman
M M
MM
Pastan
I
I
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D004351:Drug Resistance; D006801:Humans; D006868:Hydrolysis; D007624:KB Cells; D007700:Kinetics; D011802:Quinidine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D014747:Vinblastine / Q000378:metabolism*
D000970:Antineoplastic Agents; D014747:Vinblastine; D000255:Adenosine Triphosphate; D014700:Verapamil; D011802:Quinidine