PT - JOURNAL ARTICLE AU - Maria J. Abad-Merin AU - Nuria Cortés AU - Isabel Masip AU - Enrique Pérez-Payá AU - José A. Ferragut AU - Angel Messeguer AU - Antonio Ferrer-Montiel TI - Trimers of <em>N</em>-Alkylglycines Are Potent Modulators of the Multidrug Resistance Phenotype AID - 10.1124/jpet.104.078014 DP - 2005 Apr 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 112--120 VI - 313 IP - 1 4099 - http://jpet.aspetjournals.org/content/313/1/112.short 4100 - http://jpet.aspetjournals.org/content/313/1/112.full SO - J Pharmacol Exp Ther2005 Apr 01; 313 AB - The multidrug resistance (MDR) phenotype is considered a major cause of the failure of cancer chemotherapy. The acquisition of MDR is usually mediated by the overexpression of drug efflux pumps such as glycoprotein P (P-gp) or multidrug resistance-related protein 1 (MRP1). Thus, the identification, validation, and development of compounds that mitigate the MDR phenotype by modulating the activity of these transport proteins is an important yet elusive target. Here, we have addressed this issue and screened an N-trialkylglycine-based combinatorial library composed of 5120 compounds to search for modulators of the MDR phenotype. The screening identified 20 trimers of N-alkylglycine that increased the intracellular accumulation of daunomycin (DNM) in drug-resistant L1210R tumor cells that overexpressed the P-gp. These compounds seem to act as P-gp antagonists, as evidenced by the augmentation of DNM accumulation in the L1210P-gp cell line, a drug-sensitive L1210 cell stably expressing the murine P-gp protein. Similarly, several of the active N-trialkylglycines also produced an increment in DNM uptake in human HL60R cells, which primarily express the MRP1 protein. Trialkylglycines notably sensitized L1210R and HL60R tumor cells to DNM with a potency that rivaled that of verapamil. These findings provide new molecular scaffolds for the development of effective chemosensitizers against the MDR phenotype that, in due turn, could be used as adjuvant drugs in cancer chemotherapy. The American Society for Pharmacology and Experimental Therapeutics