Hypofractionated Radiation Therapy Suppresses Radioresistance in U87 Human Glioma Cells by Inhibiting Yap1 and Hsp90 Proteins.

Background: Radiotherapy plays a vital role in the management of high-grade gliomas. However, the radio resistance of glioma cells limits the effect of radiation and drives recurrence inside the irradiated tumor volume leading to poor outcomes for patients.

Methods: High-grade glioma cell radioresistance significantly contributes to radiotherapy failure, highlighting the importance of identifying predictive biomarkers for radioresistance. An increasing body of evidence complies with the Yes Associated Protein 1 (Yap-1) and heat shock protein 90 (Hsp90) as biomarkers for radioresistance in glioma cells. A number of studies suggest the potential of radioresistance-associated factors as biomarkers and/ or novel therapeutic targets in glioma cells. Thus, it is essential for glioblastoma patients to identify robust druggable targets involved in radioresistance, optimizing irradiation protocol, and understanding their underlying molecular mechanisms.

Results: Therefore, in the present study, we hypothesized that hypofractionated Gamma Knife radiation therapy (HF-GKRT) could target Yap-1 and Hsp90 and downregulate the mechanism of radioresistance in high-grade glioma cells.

Conclusion: For this purpose, expression levels of radioresistance markers Yap-1 and Hsp90 were evaluated after treatment with HF-GKRT, and this was compared with single fraction Gamma Knife radiation therapy (SF-GKRT) in U87MG primary human glioblastoma cell line model. This would help design a novel radiation therapy regimen for glioblastoma patients by reducing the risk of radioresistance.