Fig. 5.

Radiosensitization of GSCs by bevacizumab and temozolomide is determined by growth conditions. (A) Representative immunohistochemistry images of phospho-VEGFR2 in G7 and E2 orthotopic tumors grown from 3D GSC. (B) Clonogenic survival efficiency of G7 and E2 cells treated with either vehicle (PBS) or bevacizumab (0.1 µg/mL) 20 hours following seeding and left for the duration of the experiment (18 days). Graph depicts mean±SD. (C and D) Clonogenic survival of G7, E2, and R10 cells grown in 3D (C) and 2D (D) conditions and irradiated with single doses of X-rays (0–6 Gy; n = 3) 2 hours after treatment with bevacizumab (0.1 µg/ mL) or vehicle (PBS). Bevacizumab treatment significantly increased the radiosensitivity of G7 and E2 GSCs under 3D conditions (ANOVA; control vs bevacizumab P < .01 and P < .05, respectively). (E) Protein extracts of G7 GSCs grown in 2D or 3D conditions in the absence or presence of VEGF-A (30ng/mL) were analyzed for total and phospho-VEGFR2 by western blot. (F) Clonogenic survival efficiency of G7 and E2 cells treated with either vehicle (dimethyl sulfoxide; DMSO) or temozolomide (10 µM) as in (B). Statistical significance (t-test) *P < .05, **P < 0.05.