Replication Stress Drives Constitutive Activation of the DNA Damage Response and Radioresistance in Glioblastoma Stem-like Cells

Carruthers, Ross D., Ahmed, Shafiq, Ramachandran, Shaliny, Strathdee, Karen, Kurian, Kathreena M., Hedley, Ann, Gomez-Roman, Natividad, Kalna, Gabriela, Neilson, Mathew, Gilmour, Lesley, Stevenson, Katrina H., Hammond, Ester M. and Chalmers, Anthony J. (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. ISSN 0008-5472

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Abstract

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: Article
Subjects: Sciences > Pharmacy and Pharmacology
Divisions: Faculty of Health Sciences and Wellbeing
Faculty of Health Sciences and Wellbeing > School of Pharmacy and Pharmaceutical Sciences
Depositing User: Barry Hall
Date Deposited: 05 Sep 2018 08:00
Last Modified: 19 Feb 2020 16:09
URI: http://sure.sunderland.ac.uk/id/eprint/9953
ORCID for Shafiq Ahmed: ORCID iD orcid.org/0000-0001-8701-6889

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