Fig. 3

TCF4 functions as an essential transcription factor in the regulation of ER stress. A The top 10 transcription factors (right table) regulating the expression of ER stress genes from the AmiGO 2 database (left panel) were analyzed by PWMs software. B Kaplan–Meier survival analysis in colorectal cancer GEO database (GSE14333, GSE17538, GSE33114) finding three transcription factors regulating ER stress genes. C qRT-PCR assay revealing the levels of TCF4, NFIC, and STAT3 in RKO cells treated with or without oridonin (n = 3). Normalized to β-actin. D-E Western blot and qRT-PCR assays showing the levels of TCF4 in different cell lines (n = 3). Normalized to β-actin. F Correlation analysis of TCF4 and target genes in colorectal cancer GEO database. G-I Western blot and qRT-PCR assays revealing the expression of TCF4, CFTR, FYN, YOD1 in RKO or LoVo cells stably transfected with empty vector pCMV-Mock (Mock), TCF4 eukaryotic expression plasmid pCMV-TCF4 (TCF4) or knockdown control plasmid pLV3-U6-sh-Scb (sh-Scb), RNA interference plasmid pLV3-U6-shTCF4 #1 (sh-TCF4 #1) and pLV3-U6-shTCF4 #2 (sh-TCF4 #2) (n = 3). Normalized to β-actin. The statistical results were presented as mean ± SD. Student’s t-test compared the difference in C-E and G-I; Linear regression analysis in F. * P < 0.05, ** P < 0.01 compared with Control, NCM460, Mock in C, D, E, G, and I; # P < 0.05 compared with sh-Scb in G and I; ns compared with Control in C. TFs: transcription factors; PWMs: Position Weight Matrices; GEO: Gene Expression Omnibus database; qRT-PCR: reverse transcription-quantitative polymerase chain reaction; TCF4: transcription factor 4; NFIC: nuclear factor 1 C-type; STAT3: signal transducer and activator of transcription 3; CFTR: Cystic fibrosis transmembrane conductance regulator; FYN: Tyrosine-protein kinase Fyn; YOD1: YOD1 deubiquitinase; ns: not statistically significant