Figure 2

Targeting PI3K-Akt-mTOR signaling. (A) U251 and T98G cells were pretreated with rapamycin (RPM) plus TMZ for 24 h and subjected to western blot analysis using the indicated antibodies. Pretreatment with rapamycin (100 nM) plus TMZ (25 μM) did not have a synergistic radiosensitizing effect compared to TMZ alone treatment on U251 and T98G cells. (B) U251 and T98G cells were pretreated with a dual inhibitor of class I PI3K and mTOR signaling, PI103 (0.4 μM), and TMZ (25 μM) for 24 h. PI103 effectively enhanced the radiosensitizing effect of TMZ in both U251 and T98G cells. (C) U251 and T98G cells were pretreated with the HSP90 inhibitor 17-DMAG (25nM) and TMZ (25 μM) for 24 h. 17-DMAG enhanced the radiosensitizing effect of TMZ in U251 and T98G cells. (D) U251 and T98G cells were pretreated with TMZ (25 μM) and LBH589 (20 nM) for 24 h. LBH589 effectively potentiated the radiosensitizing effect of TMZ. Points on survival curves represent mean surviving fractions from minimum three experiments performed in triplicate.