A HIF-independent, CD133-mediated mechanism of cisplatin resistance in glioblastoma cells

Ahmed, Eroje M.; Bandopadhyay, Gagori; Coyle, Beth; Grabowska, Anna M.

Abstract

Purpose


Glioblastoma Multiforme (GBM) is the commonest brain tumour in adults. A population of cells, known as cancer stem cells (CSCs), is thought to mediate chemo/radiotherapy resistance. CD133 is a cell surface marker to identify and isolate CSCs. However, its functional significance and the relevant microenvironment in which to study CD133 remain unknown. We examined the influence of hypoxia on CD133 expression and the potential functional significance of CD133 in glioblastoma chemoresistance.

Methods

Gene expression was analysed by qRT-PCR. siRNA technique was used to downregulate genes and confirmed by flow cytometry. IC50 values was evaluated with the Alamar blue assay.

Results

CD133 expression was upregulated in hypoxia in 2D and 3D models. There was increased resistance to chemotherapeutics, cisplatin, temozolomide and etoposide, in cells cultured in hypoxia compared to normoxia. siRNA knockdown of either HIF1a or HIF2a resulted in reduced CD133 mRNA expression with HIF2a having a more prolonged effect on CD133 expression. HIF2a downregulation sensitized GBM cells to cisplatin to a greater extent than HIF1a but CD133 knockdown had a much more marked effect on cisplatin sensitisation than knockdown of either of the HIFs suggesting a HIF-independent mechanism of cisplatin resistance mediated via CD133. The same mechanism was not involved in temozolomide resistance since downregulation of HIF1a but not HIF2a or CD133 sensitized GBM cells to temozolomide.

Conclusion

Knowledge of the mechanisms involved in the novel hypoxia-induced CD133-mediated resistance to cisplatin observed might lead to identification of new strategies that enable more effective use of current therapeutic agents.

Citation

Ahmed, E. M., Bandopadhyay, G., Coyle, B., & Grabowska, A. M. (2018). A HIF-independent, CD133-mediated mechanism of cisplatin resistance in glioblastoma cells. Cellular Oncology, 41(3), https://doi.org/10.1007/s13402-018-0374-8

• Journal Article Type: Article
• Acceptance Date: Feb 12, 2018
• Online Publication Date: Feb 28, 2018
• Publication Date: Jun 30, 2018
• Deposit Date: Feb 19, 2018
• Publicly Available Date: Feb 28, 2018
• Journal: Cellular Oncology
• Electronic ISSN: 2211-3436
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 41
• Issue: 3
• DOI: https://doi.org/10.1007/s13402-018-0374-8
• Keywords: Hypoxia; Cisplatin; Temozolomide; Chemoresistance; CD133; HIFs
• Public URL: https://nottingham-repository.worktribe.com/output/943702
• Publisher URL: https://link.springer.com/article/10.1007/s13402-018-0374-8