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

• Published in: Free radical biology & medicine 2011-01, Vol.50 (1), p.110-121
• Main Authors: Hancock, Chad N., Stockwin, Luke H., Han, Bingnan, Divelbiss, Raymond D., Jun, Jung Ho, Malhotra, Sanjay V., Hollingshead, Melinda G., Newton, Dianne L.
• Format: Article
• Language: English
• Subjects: acetylcysteine; Animals; anticarcinogenic activity; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; antioxidants; autophagy; biosynthesis; Cell Proliferation - drug effects; Chelating Agents - metabolism; Chelating Agents - pharmacology; chelation; Copper; Copper - metabolism; Down-Regulation - drug effects; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - metabolism; ER stress; Female; Free radicals; glutathione; HL-60 Cells; Humans; iron; Macroautophagy; Mice; Mice, Nude; microarray technology; Neoplasms - metabolism; Neoplasms - pathology; Organometallic Compounds - pharmacology; Organometallic Compounds - therapeutic use; Oxidants - pharmacology; Oxidants - therapeutic use; Oxidative stress; Oxidative Stress - drug effects; thiols; Thiosemicarbazone; Thiosemicarbazones - pharmacology; Thiosemicarbazones - therapeutic use; Tumor Cells, Cultured; Unfolded Protein Response - drug effects; Up-Regulation - drug effects; UPR; Xenograft Model Antitumor Assays
• ISSN: 0891-5849; 1873-4596; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2010.10.696

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 micromolar range) was enhanced four- to fivefold 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. Pretreatment of cells with the antioxidant N-acetyl-l-cysteine impaired activity, whereas NSC 689534/Cu 2+ effectively synergized with the glutathione biosynthesis inhibitor buthionine sulfoximine. 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 autophagy independent. Last, 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.