Effects of Nontoxic Heat Shock Protein 90 Inhibitor Peptide Derivatives on Reversal of MDR of Tumor Cells

Abstract

Novel heat shock protein 90 inhibitor peptide derivatives [D-Trp-Phe-D-Trp-Leu-AMB (1), p-HOPA-D-Trp-Phe-D-Trp-Leu-Ψ(CH₂NH)-Leu-NH₂ (2), D-Trp-Phe-D-Trp-OH (3), Suc-D-Trp-Phe-D-Trp-Leu-AMB (4), D-Tyr-Phe-D-Trp-Leu-AMB (5), D-Arg-D-Trp-Phe-D-Trp-Leu-Leu-NH₂ (6), Leu-Ψ(CH₂NH)-Leu-NH₂x2HCl (7), Phe-Trp-Phe-Trp-Leu-Leu-NH₂ (8), Tyr-Trp-Phe-Trp-Leu-Leu-NH2 (9) and Tyr-D-Trp-Phe-D-Trp-Leu-Leu-NH₂ (10)] were synthetized, and their ability to reverse multidrug resistance (MDR) was studied. Peptide derivatives 1, 4 and 5, with D-Trp or D-Tyr residues in the N-terminal position caused a marked inhibition of MDR in cancer cells. These MDR inhibitor compounds and epirubicin were demonstrated to have additive and synergistic antiproliferative effects in checkerboard experiments on human MDR1 gene-transfected mouse lymphoma cells in vitro. It is suggested that the MDR reversal effects of these anticancer peptide derivatives, together with their antiproliferative effects on lung cancer cells, may open up new horizons in cancer chemotherapy.