Dual roles of oxostephanine as an Aurora kinase inhibitor and angiogenesis suppressor

The Aurora kinases, including Aurora A, B and C, play critical roles in cell division. They have been found overexpressed in a number of types of cancer and may thus be potential targets in cancer therapy. Several Aurora kinase inhibitors have been identified and developed. Some of these have been used in clinical trials and have exhibited certain efficacy in cancer treatment. However, none of these has yet been applied clinically due to the poor outcomes. Oxostephanine is an aporphine alkaloid isolated from several plants of the genus Stephania. This compound has been reported to inhibit Aurora kinase activity in kinase assays and in cancer cells. The present study aimed to investigate the real-time effects of oxostephanine extracted from Stephania dielsiana Y.C. Wu leaves on the growth of an ovarian cancer cell line (OVCAR-8, human ovarian carcinoma); these effects were compared to those of the well-known Aurora kinase inhibitor, VX-680. The effects of oxostephanine on stromal cells, as well as endothelial cells were also examined. The results demonstrated that oxostephanine was an Aurora kinase inhibitor through the prevention of histone H3 phosphorylation at serine 10, the mislocalization of Aurora B and the induction of aneuploidy. Moreover, this substance was selectively cytotoxic to human umbilical vein endothelial cells (hUVECs), whereas it was less cytotoxic to human fibroblasts and umbilical cord-derived mesenchymal stem cells. In addition, this compound significantly attenuated the migration and tube formation ability of hUVECs. Taken together, the present study demonstrates that oxostephanine plays dual roles in inhibiting Aurora kinase activity and angiogenesis. Thus, it may have potential for use as a drug in cancer treatment.