Figure 5
From: Combination of pan-RAF and MEK inhibitors in NRAS mutant melanoma
High endogenous activity of pro-survival signaling and low apoptotic response of resistant cell lines to the blockade of MAPK pathway. A) Higher levels of p-GSK3β and p-AKT in the resistant cell line M207, determined by antibody array analysis of 24 phosphoproteins. M207 and the sensitive cell line M296 were treated with the solvent, PRi, MEKi or their combination for 24 hours. The signal from solvent treated M296 was used as the reference (indicated as the value of 100) for all other samples. B) Induction of BIM RNA expression by the MAPK inhibitors, in the M296 but not in M207 determined by transcription microarray analysis. Different colors on the bars are the representation of signals from different probes for the same gene. C) Western blot analysis of three resistant cell lines (M202, M207, M311) and three sensitive cell lines (M243, M296, SKMEL173) indicating higher levels of p-GSK3B in the resistant cell lines and higher fold induction of BIM in sensitive cell line upon the treatments for 24 hours. D) Higher apoptotic response of the sensitive cell lines to the combination treatment determined by cleaved PARP flow cytometry assay. Cells were treated with PRi (500 nM), MEKi (25 nM) or the combination for 48 hours before the harvest, fixation and antibody staining.