Fig. 1.

In vivo tumor mouse model of TMZ-resistant GBM cells shows enhanced P4HB expression. (A) Mouse tumor xenografts (n = 4) developed from TMZ-sensitive (U87-S) and TMZ-resistant (U87-R) GBM cells were treated with Ora Plus (Ctrl) or TMZ in Ora Plus (TMZ) for 2 cycles when the tumor volume reached 50 mm³. Tumor xenografts isolated from U87-R group substantiate resistance to TMZ after 2 cycles of treatment. (B) In vivo tumor growth curves in response to TMZ treatment. Tumor volume (mm³) were expressed as: tumor volume (mm³) = (tumor length (mm) × tumor width (mm)²)/2. Each data point represents the mean ± SD of 4 animals. **P = .01. (C) Kaplan-Meier survival curves were defined by end-point of tumor volume reaching four times (200 mm³) the initial implanted tumor volume (50 mm³). Prolonged survival was seen in animals implanted with U87-R cells after treatment with TMZ when compared to those with U87-S cells (P = .0002). (D) H&E staining of xenografts from mice developed from U87-R cells shows enhanced vascular densities. Scale bar, 20 µm. Original magnification: 100×; 400× (insets). (E) Western blots show increased P4HB levels in xenografts from mice developed from U87-R cells (M1: mouse 1; M2: mouse 2).