Abstract
Fangchinoline is a bisbenzylisoquinoline alkaloid isolated from Radix Stephaniae tetrandrae S. Moore. Fangchinoline and its structure analogue, tetrandrine, exhibited direct binding affinity with recombinant human proteasome β1 subunit and also inhibited its activity in vitro. In cultured prostate PC-3 cells and LnCap cells, fangchinoline could dose-dependently inhibit cell proliferation and caspase-like activity of cellular proteasome which was mediated by proteasome β1 subunit. The inhibitive effect of fangchinoline on caspase-like activity of proteasome was also observed in purified human erythrocyte 20S proteasome. In PC-3 cells, fangchinoline induced cell cycle arrest at G0/G1 phase and apoptosis. Treatment of PC-3 tumor-bearing nude mice with fangchinoline inhibited tumor growth, induced apoptosis and also caused decrease in proteasome activities in tumor xenografts. Dose-dependent and time-dependent accumulation of ubiquitinated proteins and important proteasome substrates such as p27, Bax and IκB-α were observed in fangchinoline-treated cells. Over-expression of proteasome β1 subunit by plasmid transfection increased sensitivity of cells to the cytotoxicity of fangchinoline while knockdown of proteasome β1 subunit ameliorated cytotoxicity of fangchinoline in PC-3 cells. Results of the present study suggested that proteasome inhibition was involved in the anti-cancer effects of fangchinoline. Fangchinoline and its structure analogues might be new natural proteasome inhibitors targeting β1 subunit.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antineoplastic Agents, Phytogenic / pharmacology*
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Apoptosis / drug effects
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Benzylisoquinolines / pharmacology*
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Catalytic Domain
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Cell Cycle Checkpoints / drug effects
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Cell Line, Tumor
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Cell Proliferation / drug effects
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Cyclin-Dependent Kinase Inhibitor p27 / metabolism
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Disease Models, Animal
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Enzyme Activation
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Gene Expression
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Gene Knockdown Techniques
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Humans
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I-kappa B Proteins / metabolism
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Male
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Mice
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Prostatic Neoplasms / drug therapy
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Prostatic Neoplasms / metabolism
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Prostatic Neoplasms / pathology
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Proteasome Endopeptidase Complex / chemistry
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Proteasome Endopeptidase Complex / genetics
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Proteasome Endopeptidase Complex / metabolism*
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Proteasome Inhibitors / pharmacology*
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Protein Binding
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Protein Subunits / antagonists & inhibitors*
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Recombinant Proteins
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Ubiquitination
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Xenograft Model Antitumor Assays
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bcl-2-Associated X Protein / metabolism
Substances
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Antineoplastic Agents, Phytogenic
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Benzylisoquinolines
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I-kappa B Proteins
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Proteasome Inhibitors
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Protein Subunits
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Recombinant Proteins
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bcl-2-Associated X Protein
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Cyclin-Dependent Kinase Inhibitor p27
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fangchinoline
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PSMB6 protein, human
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Proteasome Endopeptidase Complex
Grants and funding
This work was supported in part by Shanghai Science & Technology Support Program (13431900401), the National Nature Science Foundation of China (81373964), Shanghai Science & Technology Innovation Action program (15140904800), the National Science & Technology Major Project of China (2014ZX09301-306-03), and the Twelfth Five-Year National Science & Technology Support Program (2012BAI29B06). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Nanjing Tianyi Bioscience Co. Ltd, provided support in the form of salaries for authors YL, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.