THERAPEUTIC APPROACH TO DRUG-RESISTANT TUMORS

Drug resistance is a major problem in cancer chemotherapy. P-glycoprot ein plays a major role in multidrug resistance in cancer cells. P-glyc oprotein is expressed in some normal tissues and has physiological fun ctions. These include protecting the brain against toxic substances at the blood-brain barrier site, excreting toxic substances from the liv er, kidney, and gastrointestinal tracts, and transporting steroidal ho rmones in the adrenal grand. Once expressed in cancer cells, P-glycopr otein effluxes a variety of anticancer drugs, such as doxorubicin, vin ca alkaloids, etoposide and taxol, and thereby allows cancer cells to show resistance to these drugs.