Fig. 6
From: ERK5 is activated by oncogenic BRAF and promotes melanoma growth
Combined pharmacological inhibition of the ERK5 pathway and BRAFV600E reduces melanoma cell growth in vitro and in vivo. a Cytoplasmic and nuclear extracts of A375 or SK-Mel-5 melanoma cells showing the effect of vemurafenib (1 μM), BIX02189 (10 μM) or the combination on the expression of endogenous ERK5. GAPDH and Lamin A were used as cytoplasmic or nuclear markers, respectively. Quantification of cytoplasmic and nuclear endogenous ERK5 normalized for loading control from three independent experiments is shown in histograms (mean ± SD). *p < 0.05 as determined by Student's t-test. b, c 2D colony forming assay in A375 (b) and SK-Mel-5 (c) cells treated with DMSO (Control) or IC50 concentration of XMD8-92 (A375: 2.5 μM; SK-Mel-5: 2.0 μM), BIX02189 (A375: 2.5 μM; SK-Mel-5: 5.5 μM) or vemurafenib (A375: 0.5 μM; SK-Mel-5: 0.45 μM) alone or in combination. Histograms represent mean ± SD from four independent experiments. **p < 0.01 treatment vs Control; ##p < 0.01 between indicated samples. P values were determined using one-way ANOVA. Below are representative images of plates (left) or colonies (right). d, e Number of viable A375 (d) and SK-Mel-5 (e) cells treated for 72 h with DMSO (Control), vemurafenib, XMD8-92, or the combination (Vem + XMD) at the indicated concentrations. Histograms represent mean ± SD from one representative experiment out of three performed in triplicate. Bliss independence indicates additive effects in Vem + XMD vs Vem or XMD. *p < 0.05, **p < 0.01, ***p < 0.001 as determined by one-way ANOVA. f In vivo tumor growth of A375 melanoma cells subcutaneously injected (1 × 104). Mice were treated at tumor appearance with vemurafenib (20 mg/kg), XMD8-92 (25 mg/kg) or the combination. After 19 days of treatment mice were sacrificed. Data shown are mean ± SEM. Combined treatment increased the efficacy of XMD8-92 or vemurafenib alone. Number of tumors for each group is indicated. *p ≤ 0.05; **p < 0.01 as determined by one-way ANOVA. g Representative images of A375 xenografts in athymic nude mice. Bar = 10 mm
