Antitumor activity of metal-chelating compound Dp44mT is mediated by formation of a redox-active copper complex that accumulates in lysosomes

David B. Lovejoy, Patric J. Jansson, Ulf T. Brunk, Jacky Wong, Prem Ponka, Des R. Richardson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

195 Citations (Scopus)

Abstract

The metal-chelating compound Dp44mT is a di-2-pyridylketone thiosemicarbazone (DpT) which displays potent and selective antitumor activity. This compound is receiving translational attention, but its mechanism is poorly understood. Here, we report that Dp44mT targets lysosome integrity through copper binding. Studies using the lysosomotropic fluorochrome acridine orange established that the copper-Dp44mT complex (Cu[Dp44mT]) disrupted lysosomes. This targeting was confirmed with pepstatin A-BODIPY FL, which showed redistribution of cathepsin D to the cytosol with ensuing cleavage of the proapoptotic BH3 protein Bid. Redox activity of Cu[Dp44mT] caused cellular depletion of glutathione, and lysosomal damage was prevented by cotreatment with the glutathione precursor N-acetylcysteine. Copper binding was essential for the potent antitumor activity of Dp44mT, as coincubation with nontoxic copper chelators markedly attenuated its cytotoxicity. Taken together, our studies show how the lysosomal apoptotic pathway can be selectively activated in cancer cells by sequestration of redox-active copper. Our findings define a novel generalized strategy to selectively target lysosome function for chemotherapeutic intervention against cancer. Cancer Res; 71(17); 5871-80. (C) 2011 AACR.

Original languageEnglish
Pages (from-to)5871-5880
Number of pages10
JournalCancer Research
Volume71
Issue number17
DOIs
Publication statusPublished - 1 Sep 2011
Externally publishedYes

Keywords

  • IRON CHELATORS
  • CANCER-CELLS
  • TRANSFERRIN
  • INHIBITION
  • APOPTOSIS
  • POTENT
  • AGENTS
  • DEATH

Cite this