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Pinarbasi-Degirmenci N, Sur-Erdem I, Akcay V, Bolukbasi Y, Selek U, Solaroglu I, Bagci-Onder T. Chronically Radiation-Exposed Survivor Glioblastoma Cells Display Poor Response to Chk1 Inhibition under Hypoxia. Int J Mol Sci 2022; 23:ijms23137051. [PMID: 35806055 PMCID: PMC9266388 DOI: 10.3390/ijms23137051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/30/2022] [Accepted: 06/10/2022] [Indexed: 02/04/2023] Open
Abstract
Glioblastoma is the most malignant primary brain tumor, and a cornerstone in its treatment is radiotherapy. However, tumor cells surviving after irradiation indicates treatment failure; therefore, better understanding of the mechanisms regulating radiotherapy response is of utmost importance. In this study, we generated clinically relevant irradiation-exposed models by applying fractionated radiotherapy over a long time and selecting irradiation-survivor (IR-Surv) glioblastoma cells. We examined the transcriptomic alterations, cell cycle and growth rate changes and responses to secondary radiotherapy and DNA damage response (DDR) modulators. Accordingly, IR-Surv cells exhibited slower growth and partly retained their ability to resist secondary irradiation. Concomitantly, IR-Surv cells upregulated the expression of DDR-related genes, such as CHK1, ATM, ATR, and MGMT, and had better DNA repair capacity. IR-Surv cells displayed downregulation of hypoxic signature and lower induction of hypoxia target genes, compared to naïve glioblastoma cells. Moreover, Chk1 inhibition alone or in combination with irradiation significantly reduced cell viability in both naïve and IR-Surv cells. However, IR-Surv cells’ response to Chk1 inhibition markedly decreased under hypoxic conditions. Taken together, we demonstrate the utility of combining DDR inhibitors and irradiation as a successful approach for both naïve and IR-Surv glioblastoma cells as long as cells are refrained from hypoxic conditions.
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Affiliation(s)
- Nareg Pinarbasi-Degirmenci
- Brain Cancer Research and Therapy Laboratory, Koç University School of Medicine, Istanbul 34450, Turkey; (N.P.-D.); (V.A.)
- Research Center for Translational Medicine, Koç University, Istanbul 34450, Turkey;
| | - Ilknur Sur-Erdem
- Brain Cancer Research and Therapy Laboratory, Koç University School of Medicine, Istanbul 34450, Turkey; (N.P.-D.); (V.A.)
- Research Center for Translational Medicine, Koç University, Istanbul 34450, Turkey;
- Correspondence: (I.S.-E.); (T.B.-O.)
| | - Vuslat Akcay
- Brain Cancer Research and Therapy Laboratory, Koç University School of Medicine, Istanbul 34450, Turkey; (N.P.-D.); (V.A.)
- Research Center for Translational Medicine, Koç University, Istanbul 34450, Turkey;
| | - Yasemin Bolukbasi
- Department of Radiation Oncology, Koç University School of Medicine, Istanbul 34010, Turkey; (Y.B.); (U.S.)
- Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ugur Selek
- Department of Radiation Oncology, Koç University School of Medicine, Istanbul 34010, Turkey; (Y.B.); (U.S.)
- Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ihsan Solaroglu
- Research Center for Translational Medicine, Koç University, Istanbul 34450, Turkey;
- Department of Neurosurgery, Koç University School of Medicine, Istanbul 34010, Turkey
- Department of Basic Sciences, Loma Linda University, Loma Linda, CA 92354, USA
| | - Tugba Bagci-Onder
- Brain Cancer Research and Therapy Laboratory, Koç University School of Medicine, Istanbul 34450, Turkey; (N.P.-D.); (V.A.)
- Research Center for Translational Medicine, Koç University, Istanbul 34450, Turkey;
- Correspondence: (I.S.-E.); (T.B.-O.)
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