Abstract 2479: Bz-423: A novel benzodiazephine mitochondrial-targeted drug, cytotoxic to human ovarian cancer cells.

Abstract

Abstract Objectives: Bz-423 is a chemically synthesized 1,4-benzodiazepine with cytotoxic activity in several cell types. We sought to determine the anti-neoplastic potential and mechanism of action in human ovarian cancer cells. Methods: A total of 12 human ovarian cancer cell lines were used. Cultured cells were treated with Bz-423 or vehicle control in dose-response and time-course experiments. Viability was determined on the basis of plasma membrane integrity using flow cytometry. The mechanism leading to death in these cells was characterized ultrastructurally using electron micrscopy and by determining changes in reaction oxygen species, glutathione, mitochondrial function, caspase and Bak activation. Cytochrome c release from mitochondria was analyzed by immunofluorescence. Apoptosome complex formation was monitored by gel filtration chromatography. Results: Bz-423 induced apoptosis in all ovarian cell lines at low micromolar concentrations by generating an intracellular superoxide signal from the mitochondria. The apoptotic response was associated with the release of cytochrome c from the mitochondria, collapse of the mitochondrial transmembrane gradient, and formation of the apoptosome complex containing Apaf-1 and caspase-9. The release of cytochrome c and a decrease in mitochondria glutathione within 2 hours of treatment was identified by ultrastructural evidence of mitochondrial swelling. Furthermore, Bak activation was necessary for apoptosis. Bz-423 effectively induced apoptosis in chemoresistant ovarian cancer cells overexpressing Bcl-2 and Bcl-xL. Conclusion: Bz-423 is a novel compound that effectively kills human ovarian cancer cells, including cells that are resistant to conventional chemotherapies such as Cisplatinum. This compound has cytotoxic qualities that are unique among benzodiazepines. The mechanism of action involves both proximal and direct effects on the cell mitochondria that lead to apoptosis. Bz-423 is a novel compound that may have broad clinical impact in the treatment of ovarian cancer patients. Citation Format: Gong He, Lijun Tan, Weimin Wang, Anthony E. Boitano, Natalie A. Vandeven, Anthony W. Opipari, J Rebecca Liu. Bz-423: A novel benzodiazephine mitochondrial-targeted drug, cytotoxic to human ovarian cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2479. doi:10.1158/1538-7445.AM2013-2479 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.