Fig. 4
Inhibition of both MAPK and IGF-1R signaling impairs drug resistance. a Growth inhibition curves for BRAFi (top) and BRAFi + MEKi (bottom) in the indicated conditions (µM) after 72 h, n = 3. Data are mean ± SEM. b The effects of BRAFi or BRAFi + IGF-1R/IRi treatment on components of IGF-1R, AKT, and ERK signaling pathways in the indicated CRISPR cell lines. Levels of pIGF-1R, total IGF-1R, pAKT, total AKT, pMEK, total MEK, pERK, and total ERK shown after 4 days ± 0.5 µM BRAFi or 0.5 µM BRAFi + 0.5 µM IGF-1R/IRi. GAPDH used as a loading control. c Indicated cell lines were seeded at the same density and cultured for 1 week in presence of the indicated compounds (top). Relative cell proliferation (percentage) of the same cells, n = 3. Data are mean ± SEM; ****P < 0.0001; Paired two-tailed Student’s t-test was performed for comparisons (bottom). d L-C-B and SIRT6.2–7 cells were treated with DMSO, IGF-1R/IRi (2 µM), BRAFi (0.5 µM), or both at 0.5 µM for 72 h. Percentages of Annexin-V positive cells indicated, n = 3. Data are mean ± SEM; *P < 0.05, **P < 0.01 Paired two-tailed Student’s t-test was performed for comparisons. e Quantification of tumor volume in nude mice bearing xenograft tumors of SIRT6.2–7 cells and that were fed a control, vemurafenib (PLX)-containing diet (100 mg/Kg), linsitinib (50 mg/Kg for 2 days, then 25 mg/Kg), or vemurafenib (PLX) + linsitinib (100 mg/Kg + 50 mg/Kg for 2 days, then 100 mg/Kg + 25 mg/Kg). Mann–Whitney test was performed for comparison between the three groups of mice treated. Data are mean ± SEM. *P < 0.05, **P < 0.01. n = 5–7
