Cinobufagin inhibits hepatocellular carcinoma EMT-like stemness via VEGF/VEGFR2 autocrine signaling.

Purpose: This study aimed to explore the role of the VEGFa/VEGFR2 autocrine pathway in cinobufagin-induced inhibition of hepatocellular carcinoma metastasis.

Methods: A CCK-8 assay was performed to assess cell viability. Scratch healing, Transwell, and sphere formation assays were used to measure the effects of cinobufagin on cell migration, invasion, and tumor sphere formation. An immunofluorescence double staining method was used to detect the localization of VEGFa and VEGFR2. The effects of inhibiting the VEGFa/VEGFR2 autocrine pathway on Huh7 cell metastasis and the effects of the VEGFa/VEGFR2 autocrine pathway on the regulation of PI3K/AKT-dependent migration, invasion, and epithelial‒mesenchymal transition were examined through use of the VEGFR2 inhibitor apatinib and the PI3K inhibitor LY294002. The effects of cinobufagin on the VEGFa/VEGFR2 autocrine pathway and tumor metastasis were assessed in transplanted tumors.

Results: Cinobufagin inhibited Huh7 cell viability, migration, invasion, and tumor sphere formation in a dose-dependent manner. In addition, colocalization between VEGFa and VEGFR2 was detected in Huh7 cells. The results revealed that apatinib treatment significantly inhibited PI3K/AKT-dependent migration, invasion, and epithelial‒mesenchymal transition. The VEGFa/VEGFR2 autocrine pathway, the PI3K/AKT pathway, and epithelial-mesenchymal transition-associated protein markers were attenuated by cinobufagin in Huh7 cells. Additionally, cinobufagin attenuated the growth of hepatocellular carcinoma tumors in the Huh7 xenograft model and significantly downregulated the VEGFa/VEGFR2 autocrine pathway, the PI3K/AKT pathway, and the epithelial‒mesenchymal transition.

Conclusion: Cinobufagin may attenuate the PI3K/AKT-dependent metastatic potential of hepatocellular carcinoma by inhibiting the VEGFa/VEGFR2 autocrine pathway.