METHODS TO DETECT P-GLYCOPROTEIN AND IMPLICATIONS FOR OTHER DRUG RESISTANCE-ASSOCIATED PROTEINS

The problem of tumor cell drug resistance remains a barrier to the suc cessful treatment of many neoplastic diseases. Problems of tumor cell heterogeneity and expression of multiple mechanisms of drug resistance complicate treatment strategies. Indeed, even that form of resistance to natural product anticancer agents, multidrug resistance (MDR), can have multiple mechanisms. Compounding these problems is the use of di fferent methodologies and different reagents to assess expression of t he most widely studied form of MDR, that due to increased expression o f the MDR1 gene end its product, P-glycoprotein (Pgp). In this paper, we discuss problems associated with assay variability and accurate mea surement of markers of drug resistance, and summarize consensus findin gs of the St Jude Workshop on methods to detect Pgp in tumors.