Two natural eudesmane-type sesquiterpenes from Laggera alata inhibit angiogenesis and suppress breast cancer cell migration through VEGF- and Angiopoietin 2-mediated signaling pathways

Eudesmane-type Sesquiterpenes are natural Sesquiterpenes with anti-inflammatory properties, but their anti-angiogenic activities are not known. The present study demonstrated that 5α-hydroxycostic acid and hydroxyisocostic acid, two eudesmane-type Sesquiterpenes (ETSs), isolated from the herb Laggera alata, possessed anti-angiogenic effects. Under non-toxic dosage, ETSs suppressed VEGF‑induced proliferation in human umbilical vein endothelial cells (HUVECs) and vessel formation in zebrafish embryos. Moreover, ETSs inhibited VEGF-stimulated HUVEC migration, stress fibers and tube formation. Results from real‑time PCR analysis involving in vivo and in vitro experiments indicated that pro-angiogenic-related mRNA levels were downregulated, including VEGFA, VEGFR2/KDR/Flk-1 and Tie2 genes after ETS treatments. Western blot analysis showed that ETSs suppressed VEGF-stimulated VEGFR2/KDR/Flk-1 phosphorylation and activation of its downstream molecules, such as Src/Akt/eNOS, FAK, PLCγ/ERK1/2 and p38. Moreover, the VEGF-stimulation of angiopoietin 2 (Ang2) mRNA level increase was significantly downregulated in the presence of ETSs. ETSs inhibited Ang2-induced phosphorylation of the receptor Tie2 in HUVECs, which indicated that ETSs not just suppressed VEGF/VEGFR2/KDR/Flk-1 axis, but also the Ang2/Tie2 one. Furthermore, the wound-healing assay revealed that ETSs reduced the migration of Ang2-stimulated human breast Cancer (MCF-7) cells. Mechanistically, the anti-migration effect of ETSs correlated with the blockade of Ang2-induced E-cadherin loss and Akt activation. Collectively, the present study suggests that ETSs possess anti-angiogenic ability by interfering the VEGF- and Ang2-related pathways, and they may be good drug candidates.