Eugenol suppresses VEGF-dependent angiogenesis by JAK2/STAT3 pathway in non-small cell lung cancer

Background: Non-small cell lung cancer (NSCLC) is a highly vascularized solid tumor, and tumor angiogenesis is closely associated with the metastasis and progression of NSCLC. Antiangiogenic drugs can target the tumor microenvironment to degrade existing tumor blood vessels while inhibiting tumor angiogenesis and have become one of the indispensable treatments for patients with advanced NSCLC. Although various new drugs have been tested in different settings of NSCLC, none of them have shown the desired therapeutic effects so far. Therefore, the search for new and effective therapeutic modalities has become a new goal for treating NSCLC. Objective: Eugenol is a phenolic aromatic compound derived from Eugenia caryophyllata , Cinnamomum cassia , etc., which has historically been used for various medical purposes. Studies have shown that eugenol exhibits significant anticancer effects against several types of cancer; however, its therapeutic effect on angiogenesis remains a mystery. In this study, the in vitro and in vivo antiangiogenic effects of eugenol in NSCLC and the underlying molecular mechanism were explored, which could provide a promising strategy for the treatment of NSCLC. Methods: The effects of eugenol on the proliferative capacity of human umbilical vein endothelial cells (HUVECs) and A549 cells were examined by methyl thiazolyl tetrazolium assay. The migration and invasion of eugenol-treated HUVECs were evaluated by wounding-healing and transwell assay, and the angiogenesis was measured by tube formation assay. The expression of angiogenesis-related genes and proteins, as well as the JAK2/STAT3 pathway, was evaluated by real-time quantitative PCR and western blot. Flow cytometry was performed to detect the effect of eugenol on the apoptotic profile of A549 cells. Finally, the A549 tumor-bearing nude mice were constructed to evaluate the in vivo anti-NSCLC activity of eugenol. Results: Eugenol inhibited the migration, invasion, and tube formation of HUVECs. Meanwhile, eugenol blocked the phosphorylation of vascular endothelial growth factor reporter-2 and inhibited the expression of other angiogenesis-related proteins. In addition, eugenol suppressed the expression of p-JAK2 and p-STAT3 in HUVECs and A549 cells. Eugenol also suppressed the proliferation of A549 cells by promoting apoptosis and inhibited tumor growth and microvessel formation in A549 cell xenograft-bearing nude mice. Conclusions: Eugenol could be a potential lead compound for the treatment of NSCLC by blocking the vascular endothelial growth factor/vascular endothelial growth factor reporter-2 and JAK2/STAT3 signaling pathways.