Fig. 1.
Development of TMZ-resistant D54-MG malignant glioma cells. a Survival curves of D54-C0 (parental D54-MG), D54-C10 (passage control, 10 months in culture), D54-P5 (TMZ-resistant variant, 5 months in culture) and D54-P10 (TMZ-resistant variant, 10 months in culture) cells, determined by drug sensitivity assay. IC50 of TMZ of each cell lines is tabulated underneath the graph. b Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay revealed more D54-C0 cells undergoing apoptosis when compared with its resistant D54-P10 counterpart after treatment with TMZ at different concentrations for 96 h. The above representative images show treatment of both D54-C0 and D54-P10 cells with 500 μM TMZ. Data were analysed by Student’s t-test and are reported as mean ± standard deviation (SD). *P < 0.05; **P < 0.01