Structure-activity relationships of di-2-pyridylketone, 2-benzoylpyridine and 2-acetylpyridine thiosemicarbazones for overcoming Pgp-mediated drug resistance

Alexandra E Stacy, Duraippandi Palanimuthu, Paul V Bernhardt, Danuta Kalinowski, Patric J Jansson, Des Richardson

Research output: Contribution to journalArticlepeer-review

83 Citations (Scopus)

Abstract

Multidrug resistance (MDR) mediated by P-glycoprotein (Pgp) represents a significant impediment to successful cancer treatment. The compound, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), has been shown to induce greater cytotoxicity against resistant cells than their nonresistant counterparts. Herein, the structure–activity relationships of selected thiosemicarbazones are explored and the novel mechanism underlying their ability to overcome resistance is further elucidated. Only thiosemicarbazones with electron-withdrawing substituents at the imine carbon mediated Pgp-dependent potentiated cytotoxicity, which was reversed by Pgp inhibition. Treatment of resistant cells with these thiosemicarbazones resulted in Pgp-dependent lysosomal membrane permeabilization (LMP) that relied on copper (Cu) chelation, reactive oxygen species generation, and increased relative lipophilicity. Hence, this study is the first to demonstrate the structural requirements of these thiosemicarbazones necessary to overcome MDR. We also demonstrate the mechanism that enables the targeting of resistant tumors, whereby thiosemicarbazones “hijack” lysosomal Pgp and form redox-active Cu complexes that mediate LMP and potentiate cytotoxicity.
Original languageEnglish
Pages (from-to)8601-8620
Number of pages20
JournalJournal of Medicinal Chemistry
Volume59
Issue number18
DOIs
Publication statusPublished - 2016

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