Figure 5. Decreased sensitivity of CD133+ subpopulations to MAPK pathway inhibition.
Alamar Blue viability assay using FACS-enriched CD133+, NG2+ and marker-negative (−/−) cells from SF188 GBM cell lines (A) treated for 5 consecutive days with 0.5μM PD901 (MAPK inhibitor) and vehicle (VEH) (B) DBTRG-05MG treated for 5 consecutive days with 1μM PLX4720 and vehicle (VEH) (n=3 individual experiments per cell line; 2-way ANOVA with Bonferroni post-hoc test; error bars represent SEM).
Flow cytometry analyses of (C) CD133−NG2+ (NG2) and (D) CD133+NG2− (CD133) cell frequency in SF188 and DBTRG-05MG GBM cell lines following treatment with 0.5μM PD901 (SF188) or 1μM PLX4720 (DBTRG-05MG) for four passages (P0=passage 0; P4= passage 4; n=2 individual experiments per cell line, 1-way ANOVA with Tukey post-hoc test; error bars represent SEM; *p≤0.05 in B and C).
(E) Flow cytometry analyses of CD133+ and CD133−NG2+ (NG2) cell frequency in subcutaneous DBTRG-05MG xenografts; established tumors were transplanted into new hosts on average every 6 weeks and received 186-days of continuous treatment with vehicle or PLX4720 (10mg/kg/day). (N=4 individual tumor specimen; 2-way ANOVA with Bonferroni post-hoc test; error bars represent SEM; **p≤0.01).