Fig. 1
CREB5 is upregulated in cisplatin-resistant HNSCC cells and promotes cisplatin resistance. A MTT assay was used to analyze IC50cisplatin in parent and cisplatin-resistant cells. B Venn diagram shows the expression of 241 genes upregulated simultaneously in HN4/DDP and HN30/DDP cells; the log FC (fold change) value is greater than 2. C Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of 241 genes upregulated in HN4/DDP and HN30/DDP cells compared to control cells. D, E Immunoblotting was used to detect the correlation of AKT phosphorylation level with cisplatin-stimulated concentration and time. F List of genes in PI3K-Akt signaling pathway. G RT-PCR analysis of the gene expression contained in the PI3K-Akt signaling pathway in parent and cisplatin-resistant cells. H Immunoblotting analysis of CREB5 expression in parent and cisplatin-resistant cells. I Immunoblotting was used to detect the correlation of CREB5 expression with cisplatin-stimulated concentration. J Immunoblotting analysis of phosphor-AKT (Ser 473) and nuclear CREB5 expression in parent cells and untreated or MK2206-treated (10 μM for 24 h) cisplatin-resistant cells. K RT-PCR analysis of CREB5 expression in 40 CR-HNSCC samples and 32 non-CR-HNSCC tissues. L Kaplan-Meier analysis of the correlation between CREB5 expression and overall survival. M, N RT-PCR and immunoblotting were used to detect the overexpression or knockout efficiency of CREB5. O, P MTT assay was used to analyze the correlation of IC50cisplatin with CREB5 expression in parent and cisplatin-resistant cells. Q The tumor volume and weight in nude mice subcutaneously inoculated with un-transfected or CREB5-transfected HN30 cells at the end of the experiment are shown. R The tumor volume of control or CREB5-transfected HN30 cells was calculated every 3–4 days; cisplatin was injected intraperitoneally every 6 days for a total of four times. S Immunoblotting and RT-PCR analysis of CREB5 expression in subcutaneous tumor tissues of nude mice. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001