Fig. 4

Resistance to BET inhibitors is linked to activation of RAF/MEK/ERK signaling pathway by FBXW7 mutants. a RPPA was used to comprehensively analyze the protein expression in MT1 cells expressing FBXW7 WT and S462P. BRAF is up-regulated in MT1 FBXW7 S462P expressing cells compared to MT1 cells expressing FBXW7 WT. b Cell signaling pathways affected by wild-type or mutant FBXW7 S462P. (c) Gene ontology fold enrichment from MT1 cells expressing FBXW7 WT, S462P, R465C, R505C and R479Q. d MT1 cells stably expressing doxycycline inducible FBXW7 WT or S462P mutant were treated with DMSO or JQ1 in the presence or absence of Dox and analyzed for expression of BRAF, p-MEK, p-ERK, c-MYC and STAT3 by Western blot using actin as a loading control. e The expression of Myc and BRAF in HTLV-I/ATL-lines was analyzed by WB. Correlation between Myc/BRAF expression and IC50 was calculated by Pearson correlation calculations. JQ1 IC50 in relation to c-MYC or BRAF expression was calculated in ATL-lines treated with different concentration of JQ1 or dimethyl sulfoxide (DMSO) for 72 h. Each cell line was treated at least twice for standard deviation. Cell proliferation was analyzed by XTT assay (Roche)