A copper chelate of thiosemicarbazone NSC 689534 induces oxidative/ER stress and inhibits tumor growth in vitro and in vivo

Abstract

In this study, a Cu 2+ chelate of the novel thiosemicarbazone NSC 689534 was evaluated for in vitro and in vivo anti-cancer activity. Results demonstrated that NSC 689534 activity (low µM range) was enhanced 4-5 fold by copper chelation and completely attenuated by iron. Importantly, once formed, the NSC 689534/Cu 2+ complex retained activity in the presence of additional iron or iron-containing biomolecules. NSC 689534/Cu 2+ mediated its effects primarily through the induction of ROS, with depletion of cellular glutathione and protein thiols. Pre-treatment of cells with the antioxidant L-NAC impaired activity, whereas NSC 689534/Cu 2+ effectively synergized with the glutathione biosynthesis inhibitor, buthionine sulphoximine. Microarray analysis of NSC 689534/Cu 2+ -treated cells highlighted activation of pathways involved in oxidative and ER-stress/ UPR, autophagy and metal metabolism. Further scrutiny of the role of ER-stress and autophagy indicated that NSC 689534/Cu 2+ -induced cell death was ER-stress dependent and autophagyindependent. Lastly, NSC 689534/Cu 2+ was shown to have activity in an HL60 xenograft model. These data suggest that NSC 689534/Cu 2+ is a potent oxidative stress inducer worthy of further preclinical investigation.

Selective induction of oxidative stress in cancer cells via synergistic combinations of agents targeting redox homeostasis

“…19 A similar difference in activity between the ligand and its copper complex was, however, reported by C.N. Hancock et al, 25 regarding the activity of NSC 689534 on HL-60 (Human promyelocytic leukemia). Hancock concluded that NSC689534 and its copper complex act via distinctively different mechanisms on HL-60.…”

Copper(II) thiosemicarbazonate molecular modifications modulate apoptotic and oxidative effects on U937 cell line

“…On one hand several lines of evidence support the hypothesis that thiosemicarbazone metal complexes induce toxic effects through generation of active oxygen species, due to the presence of metal ions that potentially can activate O 2 and generate radicals [2,[27][28][29][30]. In particular, the binding of Cu-complexes to thiols, the interaction with the cellular reducing agent glutathione, together with the oxidation-reduction reactions of the adducts have been confirmed in both chemical and cellular model systems [28,31].…”

Triapine and a More Potent Dimethyl Derivative Induce Endoplasmic Reticulum Stress in Cancer Cells

“…The UPR can be triggered by a wide variety of causes, including accumulation of misfolded/ unfolded proteins, imbalances in ER lipids and glycolipids, changes in the redox environment of the ER caused by ROS, and disruption of Ca 21 homeostasis. Recent studies showed that Cu 21 thiosemicarbazone complexes generate oxidative stress in cell-based assays, whereas the metal-free compounds do not (Hancock et al, 2011;Lovejoy et al, 2011;Kowol et al, 2012). Furthermore, the Cu 21 complex of the thiosemicarbazone NSC 689534 [2-pyridinecarbaldehyde N,N-bis(2-pyridinylmethyl) thiosemicarbazone] was shown to induce ER stress in a ROSdependent manner, whereas the metal-free NSC 689534 does not induce oxidative or ER stress (Hancock et al, 2011).…”

“…Recent studies showed that Cu 21 thiosemicarbazone complexes generate oxidative stress in cell-based assays, whereas the metal-free compounds do not (Hancock et al, 2011;Lovejoy et al, 2011;Kowol et al, 2012). Furthermore, the Cu 21 complex of the thiosemicarbazone NSC 689534 [2-pyridinecarbaldehyde N,N-bis(2-pyridinylmethyl) thiosemicarbazone] was shown to induce ER stress in a ROSdependent manner, whereas the metal-free NSC 689534 does not induce oxidative or ER stress (Hancock et al, 2011). By contrast, our study revealed that the metal-free thiosemicarbazones 3-AP and 3-AP-Me induce ER stress in a ROSindependent manner.…”