Fig. 6

PRDM15 regulates FGFR4 expression by binding its promoter. A Venn diagram displays METTL16-regulated genes (from RNA-seq data in CCLP1 and HuCCT1 cells with or without METTL16 knockout) and genes that positively correlated with PRDM15 in CCA from the TCGA database. B Depletion of PRDM15 decreased the mRNA level of FGFR4. RT-qPCR analysis of FGFR4 expression in CCLP1 and HuCCT1 cells transfected with siPRDM15 or siNC. C Depletion of PRDM15 decreased the protein level of FGFR4. CCLP1 and HuCCT1 cells were transfected with siPRDM15 or siNC for 48 h. FGFR4 protein expression was measured by immunoblotting. D Putative binding sites of PRDM15 in the promoter region of FGFR4 (top). ChIP-qPCR was performed in CCLP1 cells transfected with PRDM15-HA construct (bottom). E Forced overexpression of PRDM15 reversed FGFR4 expression in METTL16-depleted cells. CCLP1 and HuCCT1 cells were transfected with the PRDM15 expression construct for 48 h. PRDM15 and FGFR4 protein expression was determined by immunoblotting. F Inhibition of METTL16 by next generation GampeR ASO reduced PRDM15 and FGFR4 protein expression. CCLP1 cells were transfected with METTL16-specific GampeR ASO for 72 h. The levels of PRDM15 and FGFR4 proteins were determined by immunoblotting. G Depletion of METTL16 by next generation GampeR ASO enhances the tumor inhibitory effect of the FGFR4 inhibitor BLU-554. CCLP1 cells were transfected with METTL16 GampeR ASO and treated with the FGFR4 inhibitor BLU-554 for 72 h. Cell viability was determined by WST1 assay. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Mean ± SD, Two-way ANOVA test in B, D, and G