OBJECTIVE: Multiple myeloma (MM) is the second most prevalent hematologic malignancy worldwide.The development of innovative therapies and the identification of more effective drugs for MM have high priority.Lycorine,a natural alkaloid,has widely been reported to possess potential efficacy against cancer.The purpose of this work is to elucidate the new mechanism by which lycorine induces MM.METHODS: To assess the anti-MM effect of lycorine,cell proliferation was analyzed by CCK-8 assay.MM cell lines MM.1S,ARH-77,KM3 and H-929 were treated with 0,2.5,5 and 10 μM lycorine for 24 hours.The effect of lycorine on cell cycle distribution of ARH-77 cells was examined by flow cytometric analysis after PI staining.To measure the ROS level,cell permeable fluorogenic probe dichloro-fluorescin diacetate (DCF-DA) was used.Nuclear was stained with DNA binding dye Hoechst 33258.The Comet assay was used to investigate DNA damage.Necrosis and mitochondrion changes were observed by transmission electron microscope.The protein expression levels of Cyclin D1,Cyclin-dependent kinase 4 (CDK4),γH2AX,PARP-1,RIP-l,and RIP-3 were determined by Westem blotting.RESULTS: Quantitative analysis showed that lycorine was effective against all the tested MM cell lines.Among the cell lines,ARH-77 was proved to be the most sensitive to lycorine.The percentage of G0/G1 phase cells increased significantly in different lycorine-treated group.Western blot analysis revealed a dose dependent decrease in the Cyclin D1 and CDK4 protein levels.ARH-77 cells treated with lycorine showed aberrant mitochondria on the micrographs.DCF-DA fluorescence staining and flow cytometry revealed a significant increase in ROS production by lycorine.Nuclear staining with Hoechst 33258 revealed DNA damage characteristics on lycorine treated cells.The Comet assay shows that there is a significant increase tail area after lycorine treatment.And lycorine caused significant increases in the phosphorylation of γH2AX and cleavage of PARP-1 in a concentration-dependent manner.Using a transmission electron microscope to detect necrosis,lycorine-treated ARH-77 cells presented necrosis characteristics.Dramatically up-regulation of RIP-1 and RIP-3 that are thought to play a crucial role in necrosis in ARH-77 cells after lycorine treatment.CONCLUSION: In this report,the results show that lycorine can induce cell cycle inhibition and lead cell death by programmed necrosis,which indicates that lycorine can be a potential therapeutic agent against MM.