Original ContributionA copper chelate of thiosemicarbazone NSC 689534 induces oxidative/ER stress and inhibits tumor growth in vitro and in vivo
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Cell lines and reagents
NSC 689534 was obtained from the Drug Synthesis and Chemistry Branch of the Developmental Therapeutics Program, National Cancer Institute (Rockville, MD, USA). All cell lines were from the Division of Cancer Treatment and Diagnosis Tumor Repository (Frederick, MD, USA). Materials were from the following: BCA protein assay, Pierce (Rockford, IL, USA); nitrocellulose membranes and polyacrylamide gels, Invitrogen (Carlsbad, CA, USA); Complete protease inhibitor tablets, Roche (Mannheim, Germany).
Cytotoxicity of the thiosemicarbazone NSC 689534 is differentially modulated by copper and iron
NSC 689534 (2-pyridinecarbaldehyde N,N-bis(2-pyridinylmethyl)thiosemicarbazone) is a member of the heterocyclic thiosemicarbazone family of compounds (for structure see Fig. 1A). This agent was first evaluated for cytotoxicity against HL60 (monocytic leukemia) and PC3 (prostate carcinoma) cell lines over the course of 3 days, using the [14C]leucine viability assay (Supplementary Fig. 1). Results showed that HL60 cells were more sensitive to NSC 689534 than PC3 cells after the first 2 days of
Discussion
Thiosemicarbazones, such as NSC 689534, are high-affinity metal-ion chelators, whose biological activity is markedly different between unconjugated and metal-bound forms [33], [34], [35]. In this study, we provide evidence that a copper chelate of NSC 689534 has properties worthy of further preclinical evaluation. Although NSC 689534 binds iron and copper, only the Cu2+ chelate has activity in the nanomolar range. Furthermore, once copper is chelated, exogenous free iron, transferrin, heme, or
Acknowledgments
We gratefully acknowledge the excellent technical assistance of Ms. Sherry Yu. This project has been funded in whole or in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract HHSN261200800001E. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. government. This
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