Tanshinone IIA-based imidazole compounds exert dual anti-angiogenic and anti-tumor effects in hepatocellular carcinoma by modulating VEGFR2.

Tanshinone IIA, a bioactive lipophilic diterpenoid from Salvia miltiorrhiza Bunge (Lamiaceae), exhibits anti-tumor effects but is limited by poor pharmacokinetic properties. Building on our previously reported tanshinone IIA-derived imidazole analogue (1), we systematically evaluated its anti-hepatocellular carcinoma (HCC) activity and investigated its effects on VEGFR2 signaling in relation to autophagy. In vitro, compound 1 inhibited HepG2 colony formation and migration while inducing minimal apoptosis. Immunofluorescence revealed altered paxillin distribution and reduced FAK expression. In VEGF-induced and tumor-induced angiogenesis models using transgenic zebrafish (Tg-fli1a: EGFP), compound 1 suppressed ectopic vessel sprouting and reduced HepG2 xenograft growth. Notably, compound 1 treatment dose-dependently suppressed VEGFR2 phosphorylation without altering total VEGFR2 expression in both HepG2 cells and VEGF-stimulated endothelial cells. Concurrently, compound 1 induced autophagic features (LC3-II accumulation and autolysosome formation) and downregulated the PI3K/AKT/mTOR pathway. These findings indicate that compound 1 exerts dual anti-angiogenic and anti-tumor effects in HCC, with VEGFR2 phosphorylation inhibition as a key contributing pathway.