Dexmedetomidine Promotes Angiogenesis and Vasculogenic Mimicry in Human Hepatocellular Carcinoma through α2-AR/HIF-1α/VEGFA Pathway*

Objective Dexmedetomidine (DEX), the most specific alpha 2-adrenergic receptor agonist widely used for its sedative and analgesic properties, has been reported to upregulate HIF-1 alpha expression to protect hypoxic and ischemic tissues. However, it is largely unclear whether DEX can also upregulate Hypoxia-inducible factor-1 alpha (HIF-1 alpha) expression and its downstream vascular endothelial growth factor-A (VEGFA) in cancer tissues with oxygen-deficient tumor microenvironment. Methods We used SMMC-7721 cells, MHCC97-H cells, and a mouse model of orthotopic hepatic carcinoma to explore the effect of DEX on angiogenesis and vasculogenic mimicry (VM) and its mechanism. Under normoxic (20% O2) and hypoxic (1% O2) conditions, DEX was used to intervene cells, and yohimbine was used to rescue them. Results The results showed that DEX promoted angiogenesis and VM in human liver cancer cells within a certain dose range, and the addition of yohimbine inhibited this effect. DEX could activate HIF-1 alpha/VEGFA pathway, which was further verified by silencing HIF-1 alpha. Consistently, in vivo results also showed that DEX can up-regulate HIF-1 alpha/VEGFA expression, and enhance the number of VM channels and microvessel density (MVD). Conclusion We believe that HIF-1 alpha/VEGFA might be an important signaling pathway by which DEX promotes angiogenesis and VM formation in human hepatocellular carcinoma, whereas alpha 2-adrenergic receptor mediation might be the critical mechanisms.