Para-Coumaric Acid Suppresses Vascular Endothelial Growth Factor-Induced DLL4-NOTCH1 Signaling, Tumor Angiogenesis,...

DLL4-NOTCH1 signaling mediates juxtacrine communication between tip- and stalk-like endothelial cells during vascular sprouting, contributing to complementary aspects of endothelial function. Thus, simultaneous modulation of DLL4 and NOTCH1 may provide a strategy to broadly interfere with the endothelial functions involved in tumor angiogenesis. Accordingly, this study aimed to identify a novel natural compound capable of modulating DLL4-NOTCH1-mediated endothelial communication and to investigate how such modulation influences tumor angiogenesis and growth.

We screened 66 natural compounds to identify those that suppress DLL4 and NOTCH1 signaling in endothelial cells. Using a dual-reporter system that combines a DLL4 promoter-driven reporter and a CSL luciferase reporter, we simultaneously assessed ligand-associated activity and downstream transcriptional output of the DLL4-NOTCH1 axis. We confirmed VEGF-induced target gene expression via Western blotting and quantitative real-time polymerase chain reaction. We further performed in vitro angiogenesis assays and in vivo Lewis lung carcinoma (LLC) allograft tumor experiments.

Among the 66 screened natural compounds, para-coumaric acid (p-CA) dose-dependently suppressed DLL4 transcription and NOTCH1 signaling activity in endothelial cells, with IC₅₀ values of 4.57 and 8.34 µm, respectively. Furthermore, p-CA significantly suppressed VEGF-induced endothelial cell proliferation, migration, and tube formation. In the LLC allograft model, p-CA treatment suppressed tumor growth and vascular density, increased pericyte coverage, reduced tumor hypoxia, and enhanced CD3⁺ T-cell infiltration and tumor cell apoptosis.

In summary, p-CA is a natural compound that functionally suppresses VEGF-driven DLL4-NOTCH1 signaling in endothelial cells, exhibiting strong anti-angiogenic effects and promoting functional vascular normalization, resulting in marked tumor suppression and enhanced antitumor immunity in vivo. These findings suggest that p-CA warrants further investigation as an anti-angiogenic compound for cancer therapy.