Radiation responses of 2D and 3D glioblastoma cells: a novel, 3D-specific radioprotective role of VEGF/Akt signaling through functional activation of NHEJ

Gomez-Roman, N. , Chong, M. Y., Chahal, S. K., Caragher, S. P., Jackson, M. R. , Stevenson, K. H., Dongre, S. A. and Chalmers, A. J. (2020) Radiation responses of 2D and 3D glioblastoma cells: a novel, 3D-specific radioprotective role of VEGF/Akt signaling through functional activation of NHEJ. Molecular Cancer Therapeutics, 19(2), pp. 575-589. (doi: 10.1158/1535-7163.MCT-18-1320) (PMID:31672763)

Abstract

Glioblastoma is resistant to conventional treatments and has dismal prognosis. Despite promising in vitro data, molecular targeted agents have failed to improve outcomes in patients, indicating that conventional two-dimensional (2D) in vitro models of GBM do not recapitulate the clinical scenario. Responses of primary glioblastoma stem-like cells (GSC) to radiation in combination with EGFR, VEGF and Akt inhibition were investigated in conventional 2D cultures and a 3-dimensional (3D) in vitro model of GBM that recapitulates key GBM clinical features. VEGF deprivation had no effect on radiation responses of 2D GSC but enhanced radiosensitivity of GSC cultures in 3D. The opposite effects were observed for EGFR inhibition. Detailed analysis of VEGF and EGF signalling demonstrated a radioprotective role of Akt that correlates with VEGF in 3D and with EGFR in 2D. In all cases, positive correlations were observed between increased radiosensitivity, markers of unrepaired DNA damage and persistent phospho-DNA-PK nuclear foci. Conversely, increased numbers of Rad51 foci were observed in radioresistant populations, indicating a novel role for VEGF/Akt signalling in influencing radiosensitivity by regulating the balance between non-homologous end-joining and homologous recombination mediated DNA repair. Differential activation of tyrosine kinase receptors in 2D and 3D models of GBM explains the well documented discrepancy between pre-clinical and clinical effects of EGFR inhibitors. Data obtained from our 3D model identify novel determinants and mechanisms of DNA repair and radiosensitivity in GBM, and confirm Akt as a promising therapeutic target in this cancer of unmet need.

• Item Type: Articles
• Additional Information: This research was funded by a Chief Scientist Office (CSO, grant number ETM/405) to A.Chalmers. We also thank the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) for funding this work (grant reference NC/P001335/1) to A.Chalmers and N. Gomez-Roman.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Dongre, Dr Sidhartha and Davis, Mrs Sandeep and Gomez-Roman, Dr Maria and Jackson, Dr Mark and Stevenson, Mrs Katrina and Chalmers, Professor Anthony
• Authors: Gomez-Roman, N., Chong, M. Y., Chahal, S. K., Caragher, S. P., Jackson, M. R., Stevenson, K. H., Dongre, S. A., and Chalmers, A. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Molecular Cancer Therapeutics
• Publisher: American Association for Cancer Research
• ISSN: 1535-7163
• ISSN (Online): 1538-8514
• Published Online: 31 October 2019
• Copyright Holders: Copyright © 2019 American Association for Cancer Research
• First Published: First published in Molecular Cancer Therapeutics 19(2):575-589
• Publisher Policy: Reproduced in accordance with the publisher copyright policy

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
171214		Mitochondrial poisoning as a novel strategy to overcome radiation resistance of glioblastoma	Anthony Chalmers	Chief Scientist Office (CSO)	ETM/405	CS - Clinical Trials Research