Quinolinone Derivatives Suppress Angiogenesis in Human Umbilical Vein Endothelial Cells by Blocking the VEGF‐Induced VEGFR2 Signaling Pathway

Targeting the vascular endothelial growth factor (VEGF) pathway is crucial for antiangiogenesis therapy in treating cancers and diseases with abnormal blood vessel growth. Human umbilical vein endothelial cells (HUVECs) activated by VEGF are widely used for exploring the impact of antiangiogenic agents on cellular functions. In this study, seven quinolinone derivatives were successfully synthesized and structurally confirmed through ¹H, ¹³C NMR, and HRMS spectra. Compounds 4 and 5 exhibited significant inhibition of VEGF-induced HUVEC proliferation, with IC₅₀ values of 84.8 and 58.1 μM for 48 h. Compounds 3‒6 effectively suppressed VEGF-induced HUVEC migration and invasion, demonstrating potent inhibitory effects in the Matrigel tube formation assay. Compounds 4 and 5 directly bind to vascular endothelial growth factor receptor 2 (VEGFR2), thereby inhibiting VEGFR2-mediated downstream angiogenic signaling pathways (PI3K/Akt, ERK1/2/p38 MAPK, and FAK). Cell-cycle analysis revealed that compounds 4 and 5 induced substantial G₂/M phase arrest in HUVECs, accompanied by increased p53 phosphorylation and upregulation of p21^cip1 expression. Compounds 3‒6 also induced apoptosis in HUVECs, as evidenced by nuclear condensation, DNA laddering, and increased Annexin V/PI staining. Western blot analysis showed that compounds 4 and 5 significantly increased the levels of apoptosis-related proteins, particularly cleaved caspase-3 and PARP. Through in vivo experiments utilizing the chicken embryo chorioallantoic membrane (CAM) assay, a marked decline in newly formed microvessels was observed posttreatment with both compounds. These results suggest that compounds 4 and 5 show promise as antiangiogenic agents, warranting further investigation into their therapeutic efficacy in conditions characterized by abnormal angiogenesis.