Molecular manipulations of the multidrug transporter: a new role for transgenic mice.

Multidrug resistance in human cancer is associated with overexpression of the MDR1 gene which encodes a 170,000 molecular weight membrane glycoprotein that transports cytotoxic drugs out of cancer cells. The MDR1 gene is normally expressed in intestine, kidney, liver, and adrenal glands, and in tumors derived from these tissues, but it is not expressed in normal bone marrow. Transgenic mice that express the MDR1 gene in their bone marrow have been developed, and because of this expression these mice are resistant to the bone marrow-suppressive effects of daunomycin, doxorubicin, taxol, and several other anticancer drugs. These mice can be used in several different ways to develop new types of drugs to treat human cancer.--Pastan, I.; Willingham, M. C.; Gottesman, M. Molecular manipulations of the multidrug transporter: a new role for transgenic mice.