HL-60 Cell Death Induced by Lycorine Is Due to p21-Mediated Cell Cycle Arrest and TNF-α Signaling Stimulation.

Abstract 4158

Lycorine displays various biological functions including remarkable anti-tumor effect. We previously reported that lycorine induced anti-leukemia effect via arresting cell cycle and inducing apoptosis on human acute promyelocytic leukemia (APL) cell line HL-60. To explore the molecular mechanism how lycorine induced HL-60 cell apoptosis, cDNA microarray was used to investigate the expression profile of 494 apoptosis-associated genes. Real-time RT-PCR, Western blotting and immunocytochemistry were used to analyze the expression of related genes, as well as the modification and distribution of related proteins in the presence of lycorine. The results showed that 89 differential genes were expressed significantly (Cy3:Cy5 > 2 or < 0.5) among all the 494 apoptosis-related genes. 78 genes were up-regulated and 11 genes were down-regulated. We are particularly interested in the expression increase of p21 (9.271 folds) and TNF-α (8.242 folds). Furthermore, we found that lycorine could down-regulate p21-related gene expression including Cdc2, Cyclin B, Cdk2 and Cyclin E, promote the truncation of Bid protein and the release of cytochrome c from mitochondria, decrease the phosphorylation of IκB, block the nuclear import of NF-κB and down-regulate expression of survivin. This study revealed that lycorine decreased HL-60 cells survival through p21-mediated cell cycle arrest and stimulation of TNF-α signaling pathway which induced apoptosis.