Knockdown of TBRG4 suppresses the migration, invasion, and epithelial-to-mesenchymal transition of pancreatic cancer cells via TGF-β/smad3 signaling.

Pancreatic cancer (PC) is one of the deadliest malignancies worldwide, with a low five-year survival rate of less than 10%. Transforming growth factor β regulator 4 (TBRG4) is differentially expressed in PC tissues, but its specific functions and regulatory role in PC have not been clarified. TBRG4 mRNA expression in PC cells was measured by qRT-PCR. Protein levels of TBRG4, key markers related to the epithelial-mesenchymal transition (EMT) process, and factors related to the TGF-β/smad3 pathway were quantified by western blot. The migratory and invasive abilities of PC cells were evaluated by wound healing and Transwell assays, respectively. Spearman's correlation analysis was performed to analyze the expression correlation between TBRG4 and TGF-β1 (or SMAD3). Xenograft mouse models were established to explore the in vivo role of TBRG4. The mRNA and protein expression of TBRG4 were elevated in PC cells. TBRG4 knockdown repressed PC cell migration, invasion, and the EMT process. Moreover, TBRG4 activated TGF-β/smad3 signaling in PC cells and positively correlated with TGF-β1 (or SMAD3) expression in PC tissues based on bioinformatics analysis. Furthermore, SRI-011381 (an agonist of TGF-β1) counteracted the inhibitory influence of TBRG4 knockdown on PC cellular behaviors, and SB431542 (an inhibitor of the TGF-β type I receptor) treatment countervailed the promoting influence of TBRG4 overexpression on PC cell invasion, migration, and EMT. Results of in vivo assays verified that TBRG4 silencing inhibited tumorigenesis and TGF-β/smad3 signaling. The silencing of TBRG4 inhibits PC cell invasion, migration, EMT, and tumorigenesis by inactivating TGF-β/smad3 signaling.