Abrogation of Mitogen-Activated Protein Kinase and Akt Signaling by Vandetanib Synergistically Potentiates Histone Deacetylase Inhibitor-Induced Apoptosis in Human Glioma Cells

• Published in: The Journal of pharmacology and experimental therapeutics 2009-10, Vol.331 (1), p.327-337
• Main Authors: Jane, Esther P, Premkumar, Daniel R, Addo-Yobo, Steven O, Pollack, Ian F
• Format: Article
• Language: English
• Subjects: Apoptosis - drug effects; Apoptosis - physiology; Cell Line, Tumor; Cellular and Molecular; Drug Synergism; Enzyme Inhibitors - pharmacology; Enzyme Inhibitors - therapeutic use; Glioma - drug therapy; Glioma - enzymology; Glioma - pathology; Histone Deacetylase Inhibitors; Histone Deacetylases - metabolism; Humans; Hydroxamic Acids - pharmacology; Hydroxamic Acids - therapeutic use; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - physiology; Mitogen-Activated Protein Kinases - antagonists & inhibitors; Mitogen-Activated Protein Kinases - metabolism; Piperidines - pharmacology; Piperidines - therapeutic use; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - physiology; Quinazolines - pharmacology; Quinazolines - therapeutic use; Vorinostat
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.109.155705

Vandetanib is a multitargeted tyrosine kinase inhibitor. Our initial studies demonstrated that this agent blocks vascular endothelial growth factor receptor, epidermal growth factor receptor, and platelet-derived growth factor receptor phosphorylation and mitogen-activated protein kinase (MAPK)-mediated signaling in glioma cell lines in a dose-dependent manner. Despite these effects, we observed that vandetanib had little effect on apoptosis induction at clinically achievable concentrations. Because histone deacetylase inhibitors (HDACIs) have been suggested to regulate signaling protein transcription and downstream interactions via modulation of protein chaperone function through the 90-kDa heat shock protein, we investigated whether combining vandetanib with an HDACI could synergistically potentiate signaling pathway inhibition and apoptosis induction in a panel of malignant human glioma cell lines. Proliferation assays, apoptosis induction studies, and Western immunoblot analysis were conducted in cells treated with vandetanib and HDACIs as single agents or in combination. Vandetanib and suberoylanalide hydroxamic acid reduced proliferation in all cell lines when used as single agents, and the combination produced marked potentiation of growth inhibition as assessed by combinatorial methods. These effects were paralleled by potentiation of Akt signaling inhibition and apoptosis induction. Our results indicate that inhibition of histone deacetylation enhances the antiproliferative effect of vandetanib in malignant human glioma cell lines by enhancing inhibition of MAPK, Akt, and other downstream effectors that may have application in combinatorial therapeutics for these tumors.