α-Cyperone, a sesquiterpene compound represents 25.23% of the total oil and is the most abundant compound in Cyperus rotundus oil. Endothelial cell protein C receptor (EPCR) is a main member in protein C (PC) anti-coagulation system. EPCR could be shed from cell surface, and is mediated by tumor necrosis factor-α converting enzyme (TACE). Nothing that EPCR is a marker of vascular barrier integrity in vascular inflammatory disease and takes part in systemic inflammatory disease. In this study, we investigated whether α-cyperone could inhibit EPCR shedding. To observe the effect, we investigated this issue by detection the effect of α-cyperone on phorbol-12-myristate 13-acetate (PMA)-induced EPCR shedding in human umbilical vein endothelial cells (HUVECs). The cells were pretreated with α-cyperone for 12 h, and then stimulated by PMA for 1 h. The solute EPCR (sEPCR) and expression of membrane EPCR (mEPCR) were measured by enzyme-linked immunosorbent assay (ELISA) and Western blot. The mRNA, protein level and activity of TACE were tested by quantitative (q)RT-PCR, Western blot and InnoZyme TACE activity assay kit. Furthermore, we measured the protein level of mitogen-activated protein kinase (MAPK) signaling and protein kinase C (PKC) pathway under this condition by Western blot. The results showed that α-cyperone could suppress PMA-induced EPCR shedding through inhibiting the expression and activity of TACE. In addition, α-cyperone could inhibit PKC translocation, but not have an effect on phosphorylation of c-Jun N-terminal kinase (JNK), p38 and extracellular regulated protein kinases (ERK) 1/2. Given these results, α-cyperone inhibits PMA-induced EPCR shedding through PKC pathway, which will provide an experimental basis for further research on α-cyperone.
Keywords: endothelial protein C receptor; protein kinase C pathway; shedding; α-cyperone.