Role of organelle pH in tumor cell biology and drug resistance

Multidrug resistance is a generic term for the variety of strategies that t umor cells develop to evade the cytotoxic effects of anticancer drugs. It i s characterized by decreased cellular sensitivity, not only to the drug(s) employed in chemotherapy but also to a broad spectrum of drugs with neither obvious common targets nor structural homology, it is one of the major obs tacles to the successful treatment of tumors. This review concentrates on s ome of the physiological changes observed in drug-sensitive and drug-resist ant tumor cell lines that could account for their relative sensitivities to chemotherapeutics. These changes suggest alternative strategies for combat ing tumor cells in general and multidrug-resistant cells in particular.