Replication stress drives constitutive activation of the DNA damage response and radioresistance in glioblastoma stem-like cells

Carruthers, R. D. et al. (2018) Replication stress drives constitutive activation of the DNA damage response and radioresistance in glioblastoma stem-like cells. Cancer Research, 78(17), pp. 5060-5071. (doi: 10.1158/0008-5472.CAN-18-0569) (PMID:29976574) (PMCID:PMC6128404)

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Glioblastoma (GBM) is a lethal primary brain tumor characterized by treatment resistance and inevitable tumor recurrence, both of which are driven by a subpopulation of GBM cancer stem-like cells (GSC) with tumorigenic and self-renewal properties. Despite having broad implications for understanding GSC phenotype, the determinants of upregulated DNA damage response (DDR) and subsequent radiation resistance in GSC are unknown and represent a significant barrier to developing effective GBM treatments. In this study, we show that constitutive DDR activation and radiation resistance are driven by high levels of DNA replication stress (RS). CD133+ GSC exhibited reduced DNA replication velocity and a higher frequency of stalled replication forks than CD133- non-GSC in vitro; immunofluorescence studies confirmed these observations in a panel of orthotopic xenografts and human GBM specimens. Exposure of non-GSC to low-level exogenous RS generated radiation resistance in vitro, confirming RS as a novel determinant of radiation resistance in tumor cells. GSC exhibited DNA double strand breaks (DSB) which co-localized with 'replication factories' and RNA: DNA hybrids. GSC also demonstrated increased expression of long neural genes (>1Mbp) containing common fragile sites, supporting the hypothesis that replication/transcription collisions are the likely cause of RS in GSC. Targeting RS by combined inhibition of ATR and PARP (CAiPi) provided GSC-specific cytotoxicity and complete abrogation of GSC radiation resistance in vitro. These data identify RS as a cancer stem cell-specific target with significant clinical potential.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Carruthers, Dr Ross and Gilmour, Dr Lesley and Ahmed, Dr Shafiq and Stevenson, Mrs Katrina and Strathdee, Mrs Karen and Kalna, Dr Gabriela and Neilson, Dr Matthew and Chalmers, Professor Anthony
Authors: Carruthers, R. D., Ahmed, S. U., Ramachandran, S., Strathdee, K., Kurian, K. M., Hedley, A., Gomez-Roman, N., Kalna, G., Neilson, M. P., Gilmour, L., Stevenson, K. H., Hammond, E. M., and Chalmers, A. J.
College/School:College of Medical Veterinary and Life Sciences > School of Cancer Sciences
Journal Name:Cancer Research
Publisher:American Association for Cancer Research
ISSN (Online):1538-7445
Published Online:05 July 2018
Copyright Holders:Copyright © 2018 American Association for Cancer Research
First Published:First published in Cancer Research 78(17): 5060-5071
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
737161Investigating elevated DNA replication stress in glioblastoma stem cells and neural stem cells and exploiting its therapeutic potential.Ross CarruthersCancer Research UK (CRUK)C52808/A23920RI CANCER SCIENCES