2. Academic Validation
  3. Structure-Activity Relationships of Di-2-pyridylketone, 2-Benzoylpyridine, and 2-Acetylpyridine Thiosemicarbazones for Overcoming Pgp-Mediated Drug Resistance

Structure-Activity Relationships of Di-2-pyridylketone, 2-Benzoylpyridine, and 2-Acetylpyridine Thiosemicarbazones for Overcoming Pgp-Mediated Drug Resistance

  • J Med Chem. 2016 Sep 22;59(18):8601-20. doi: 10.1021/acs.jmedchem.6b01050.
Alexandra E Stacy 1,  Duraippandi Palanimuthu 1,  Paul V Bernhardt 2,  Danuta S Kalinowski 1,  Patric J Jansson 1,  Des R Richardson 1
Affiliations

Affiliations

  • 1 Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, The University of Sydney , Level 5, Blackburn Building (D06), Sydney, New South Wales 2006, Australia.
  • 2 School of Chemistry and Molecular Biosciences, University of Queensland , Brisbane, Queensland 4072, Australia.
PMID: 27524608 DOI: 10.1021/acs.jmedchem.6b01050
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.

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