Figure 4.

PF403 blocked the Hedgehog signaling pathway in T98G cells and downregulated MGMT expression. (A) Protein levels of Gli1, Smo, and MGMT were detected via immunoblotting in T98G cells exposed to various concentrations of PF403 for 48 hours. (B) Cell inhibition curve of T98G cells treated with various concentrations of PF403 alone or in combination with Lom for 72 hours. (C) Cell inhibition curve of T98G cells treated with various concentrations of TMZ alone, or in combination with Lom for 72 hours. (D) T98G cells were pretreated with Lom (10 µM) for 1 hour, following the addition of TMZ (250 µM) over 48 hours. Protein levels of MGMT were detected via immunoblotting. (E) T98G cells were pretreated with PF403 (5 nM) for 1 hour, following the addition of Shh (500 ng/mL) over 48 hours. Protein levels of Gli1 and MGMT were detected via immunoblotting. (F) U251/TMZ cells were transfected with pLenti-CMV-hMGMT and treated with various concentrations of PF403. Protein levels of Gli1, MGMT, and cyclin D1 were detected via immunoblotting.

Abbreviations: Lom, lomeguatrib; MGMT, O⁶-methylguanine DNA methyltransferase; PF403, 13a(S)-3-hydroxyl-6,7-dimethoxyphenanthro[9,10-b]-indolizidine; Shh, sonic Hedgehog; Smo, smoothened; TMZ, temozolomide.