Silencing of R-Spondin1 increases radiosensitivity of glioma cells.

Although radiation therapy is the most effective postoperative adjuvant treatment, it does not substantially improve the long-term outcomes of glioma patients because of the characteristic radioresistance of glioma. We found that R-Spondin1 (Rspo1) expression was elevated in high-grade gliomas and was associated with worse overall survival and disease-free survival. Rspo1 expression was also associated with reduced survival rates in glioma patients after treatment with radiotherapy and temozolomide (RT-TMZ). Importantly, Rspo1 was dramatically upregulated after radiation treatment in patients with glioma. Rspo1 silencing by shRNA potentiated glioma cell death upon radiation treatment. In a xenograft nude mouse model, combining radiation and silencing of Rspo1 potentiated tumor growth inhibition. Thus, combining radiotherapy with silencing of Rspo1 is a potential therapeutic approach.