Knockdown of circSMAD2 inhibits the tumorigenesis of gallbladder cancer through binding with eIF4A3

BACKGROUND: Gallbladder cancer (GBC) is the seventh most common gastrointestinal cancer worldwide. This study aimed to investigate the function of circSMAD2 in GBC. METHODS: To investigate the function of circSMAD2 in GBC, the level of circSMAD2 in GBC cells was detected by RT-qPCR. CCK-8 assay was performed to investigate the cell viability. Cell apoptosis was tested by flow cytometry. In addition, transwell assay was used to detect the cell migration and invasion. RIP and RNA pull-down were used to explore the relation among circSMAD2, eIF4A3 and SMAD2. Meanwhile, xenograft mice model was established to investigate the function of circSMAD2 in GBC. RESULTS: The data revealed that circSMAD2 was upregulated in GBC, and circSMAD2 knockdown significantly inhibited the viability of GBC cells. In addition, circSMAD2 siRNA notably induced the apoptosis in GBC cells. The migration and invasion of GBC cells were obviously suppressed in the presence of circSMAD2 siRNA. Meanwhile, circSMAD2 suppressed the binding between eukaryotic translation initiation factor 4A3 (eIF4A3) and SMAD2 through binding with eIF4A3. Knockdown of circSMAD2 notably inhibited the expression of SMAD2 in GBC cells, and SMAD2 overexpression partially reversed the anti-tumor effect of circSMAD2 knockdown. Finally, circSMAD2 siRNA significantly inhibited the tumor growth of GBC in vivo. CONCLUSION: Knockdown of circSMAD2 inhibits the tumorigenesis of gallbladder cancer through binding with eIF4A3. Thus, our study provided a new strategy for the treatment of GBC. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-021-08895-1.