Resibufogenin Suppresses Triple-Negative Breast Cancer Angiogenesis by Blocking VEGFR2-Mediated Signaling Pathway

Abstract

Resibufogenin (RBF), an active compound from Bufo bufonis, has been used for the treatment of multiple malignant cancers, including pancreatic cancer, colorectal cancer, and breast cancer. However, whether RBF could exert its antitumor effect by inhibiting angiogenesis remains unknown. Here, we aimed to explore the antiangiogenic activity of RBF and its underlying mechanism on human umbilical vein endothelial cell (HUVEC), and the therapeutic efficacy with regard to antiangiogenesis in vivo using two triple-negative breast cancer (TNBC) models. Our results demonstrated that RBF can inhibit the proliferation, migration, and tube formation of HUVECs in a dose-dependent manner. Spheroid sprouts were thinner and shorter after RBF treatment in vitro 3D spheroid sprouting assay. RBF also significantly suppressed VEGF-mediated vascular network formation in vivo Matrigel plug assay. In addition, Western blot analysis was used to reveal that RBF inhibited the phosphorylation of VEGFR2 and its downstream protein kinases FAK and Src in endothelial cells (ECs). Molecular docking simulations showed that RBF affected the phosphorylation of VEGFR2 by competitively binding to the ATP-bound VEGFR2 kinase domain, thus preventing ATP from providing phosphate groups. Finally, we found that RBF exhibited promising antitumor effect through antiangiogenesis in vivo without obvious toxicity. The present study first revealed the high antiangiogenic activity and the underlying molecular basis of RBF, suggesting that RBF could be a potential antiangiogenic agent for angiogenesis-related diseases.

Resibufogenin inhibits the malignant characteristics of multiple myeloma cells by blocking the PI3K/Akt signaling pathway

“…Different concentrations of RBG (2, 4 and 8 µM) were used to treat RPMI8226 cells for 12, 24 and 48 h at 37˚C. The doses for RBG treatment were selected according to previous reports ( 10 , 12 , 27 ). In addition, RPMI8226 cells also received the treatments of 8 µM RBG combined with 50 ng/ml insulin-like growth factor 1 (IGF-1; an activator of the PI3K/AKT signaling pathway) ( 14 , 28 ) for 12, 24 and 48 h at 37˚C in feedback verification assays.…”

Toad venom-derived bufadienolides and their therapeutic application in prostate cancers: Current status and future directions

“…There are several prominent members that are categorized as bufadienolides ( Figure 2 ) ( Cunha-Filho et al, 2010 ; Zhang et al, 2014 ), including Bufalin, (3β,14-dihydroxy-5β-bufa-20,22-dienolide, shown as compound 1 ) ( Zhang et al, 2020a ), bufatalin [(3β,14,16β-Trihydroxy-5β-bufa-20,22-dienolide) 16-acetate, shown as compound 2 ] ( Zhang et al, 2022b ), cinobufagin, (3β-Hydroxy-14,15β-epoxy-5β-bufa-20,22-dienolid-16β-yl acetate, shown as 3 ) ( Toma et al, 1987 ), resibufogenin [(3β,5β,15β)-14,15-epoxy-3-hydroxy-bufa-20,22-dienolide, shown as 4 ] ( Yang et al, 2021a ), and arenobufagin [(3β,5β,11α)-3,11,14-Trihydroxy-12-oxobufa-20,22-dienolide, shown as 5 ] ( Zhang et al, 2013 ). These compounds are structurally related, and specially, all of them can be regarded as bufalin’s derivatives, with minor differences at certain position, which are shown and highlighted in Figure 2 .…”