Drug transporters as targets for cancer chemotherapy.

Transporter proteins play an important role in taking up nutrients into and effluxing xenobiotics out of cells to sustain cell survival. Transporters that affect drug absorption, distribution and excretion are the so-called drug transporters. In the last decade, a number of studies revealed interactions between drug transporters and clinically important anticancer agents. Utilizing the knowledge of transporter functions offers us the possibility of delivering a drug to the target tissues, avoiding distribution to other tissues and improving oral bioavailability. Many transporters have been reported to be differentially up-regulated in cancer cells compared to normal tissues, suggesting that the differential expression of transporters in cancer cells may provide good targets for enhancing drug delivery as well as diagnostic markers for cancer therapy. This review will focus on the role of drug transporters in the adaptation and growth of tumors and in their potential usefulness as therapeutic targets in cancer.