Evodiamine from Evodia rutaecarpa induces apoptosis via activation of JNK and PERK in human ovarian cancer cells

Background Evodiamine (EVO; 8,13,13b,14-tetrahydro-14-methylindolo[2′3′-3,4]pyrido[2,1-b]quinazolin-5-[7H]-one derived from the traditional herbal medicine Evodia rutaecarpa was reported to possess anticancer activity; however, the anticancer mechanism of EVO against the viability of human ovarian cancer cells is still unclear. Purpose A number of studies showed that chemotherapeutic benefits may result from targeting the endoplasmic reticular (ER) stress signaling pathway. The objective of the study is to investigate the mechanism by which ER stress protein PERK plays in EVO-induced apoptosis of human ovarian cancer cells. Methods Cell death analysis was performed by MTT assay, DNA fragmentation assay, and Giemsa staining. DiOC6 staining was used for mitochondrial membrane potential measurement. Protein levels were analyzed by Western blotting. Pharmacological studies using MAPK inhibitors and PERK inhibitor GSK2606414 were involved. Results The viability of human ovarian cancer cells A2780, A2780CP, ES-2, and SKOV-3 was inhibited by EVO at various concentrations in accordance with increases in the percentage of apoptotic cells, DNA ladders, and cleavage of caspase 3 and poly(ADP ribose) polymerase (PARP) proteins. Decreased viability of cells was reversed by adding caspase inhibitors VAD and DEVD in SKOV-3 and A2780CP cells, and incubation of cells with JNK inhibitor SP600125 (SP) and JNKI, but not other MAPK and AKT inhibitors including PD98059, SB203580, significantly prevented the apoptosis elicited by EVO in human ovarian cancer cells. Furthermore, increased expression of phospho-eIF2α (peIF2α) and phospho-PERK (pPERK) proteins was detected in EVO-treated human ovarian cancer cells, and that was inhibited by adding JNK inhibitors SP600125 and JNKI. Application of a PERK inhibitor GSK2606414 showed a significant protection of human ovarian cancer cells A2780 and A2780CP from EVO-induced apoptosis. EVO disruption of mitochondrial membrane potential (MMP) was also inhibited by adding JNK or PERK inhibitors. The structure-activity relationship study indicated that the alkyl group at position 14 in EVO is important for apoptosis induction via activation of JNK and PERK in human ovarian cancer cells. Conclusion Evidence supporting EVO induction of apoptosis via activation of JNK and PERK to disrupt MMP in human ovarian cancer cells is provided, and the alkyl at position 14 is a critical substitution for the apoptotic actions of EVO.