Abstract
BackgroundLycorine, a natural alkaloid extracted from Amaryllidaceae, has shown various pharmacological effects. Recent studies have focused on the potential antitumor activity of lycorine. In our previous study, we found that lycorine decrease the cell viability of leukemia HL-60 cells and multiple myeloma KM3 cells and induces cell apoptosis. However, the effect and molecular mechanism of lycorine on human chronic myelocytic leukemia cells has yet to be determined.MethodsHuman chronic myelocytic leukemia cells K562 were treated with lycorine. Cell viability was monitored using the method of CCK-8. The histone deacetylase (HDAC) enzymatic activity was detected by HDAC colorimetric assay, and the cell cycle was analyzed by flow cytometry. The expression of cell-cycle related proteins were identified using Western blot.ResultsIn the present study, we further revealed that lycorine can inhibit the proliferation of K562 cells. Analysis of HDAC activity showed that lycroine decreases HDAC enzymatic activities in K562 cells in a dose-dependent manner. Inhibition of HDAC activity has been associated with cell-cycle arrest and growth inhibition. We evaluated the cell cycle distribution after lycorine treatment and found that lycorine causes cell-cycle arrest in the G0/G1 phase. To investigate the mechanism behind this cell cycle arrest, G1-related proteins were assayed by Western blot. After lycorine treatment, cyclin D1 and cyclin-dependent kinase 4 expressions were inhibited and retinoblastoma protein phosphorylation was reduced. Lycorine treatment also significantly upregulated the expression of p53 and its target gene product, p21.ConclusionsThese results suggest that inhibition of HDAC activity is responsible for at least part of the induction of cell-cycle arrest in the G0/G1 phase by lycorine and provide a mechanistic framework for further exploring the use of lycorine as a novel antitumor agent.
Highlights
Lycorine, a natural alkaloid extracted from Amaryllidaceae, has shown various pharmacological effects
We show that lycorine inhibits the proliferation of K562 cells through G0/G1 phase arrest, which is mediated by the regulation of G1-related proteins
Lycorine treatment significantly upregulates the expression of p53 and its target gene product, p21. These results suggest that inhibition of histone deacetylase (HDAC)
Summary
A natural alkaloid extracted from Amaryllidaceae, has shown various pharmacological effects. The effect and molecular mechanism of lycorine on human chronic myelocytic leukemia cells has yet to be determined. Histone acetylation is catalyzed by histone acetyltransferases (HATs) and associated with transcriptional activation, whereas histone deacetylation is mediated by histone deacetylases (HDACs) and correlated with chromatin condensation and transcriptional repression [3]. Both of these processes play crucial roles in various biological functions, including cell growth, differentiation, and apoptosis. Dysregulation of these pathways contributes to human cancer development. Two HDAC inhibitors, suberoylanilide hydroxamic acid (Vorinostat) and romidepsin (Depsipeptide, FK228), were recently approved by the U.S Food and Drug Administration (USA) for the treatment of cutaneous T-cell lymphoma [5]
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