Microarray expression data of A375 eIF4B-knockout (KO; KO/LacZ) and eIF4B-rescued (KO/eIF4B) cells with or without vemurafenib treatment

Activating Transcription Factor 4 (ATF4) is a key transcription factor of the integrated stress response, which assists cells to survive in response to tumor microenvironmental and therapeutic stresses. BRAF inhibitors, such as vemurafenib, are also known to induce ATF4 in BRAF-mutated melanoma cells, but the mechanisms of ATF4 induction are not fully elucidated. Here, we show that ATF4 expression can be upregulated by eIF4B (eukaryotic initiation factor 4B) in BRAF-mutated A375 cells. In fact, knockout (KO) of eIF4B hindered ATF4 induction as well as ATF4 translation mechanism under vemurafenib treatment, which were effectively recovered by rescue of eIF4B. Transcriptome analysis revealed that eIF4B KO selectively affected ATF4-target gene expression among gene expression altered by vemurafenib. Our results indicate that eIF4B can contribute to cellular stress adaptation by regulating ATF4 expression. A375 eIF4B-knockout (KO) cells were established by CRISPR technology. Then, willdtype eIF4B gene or LacZ gene as a negative control was transduced by lentiviral system. The established stable cell lines (KO/eIF4B and KO/LacZ) were treated with 10 µM vemurafenib for 6 or 18 hours. Vehicle (DMSO) control samples were also preapred.