Wedelolactone Acts as Proteasome Inhibitor in Breast Cancer Cells

• Published in: International journal of molecular sciences 2017-04, Vol.18 (4), p.729-729
• Main Authors: Nehybová, Tereza, Šmarda, Jan, Daniel, Lukáš, Stiborek, Marek, Kanický, Viktor, Spasojevič, Ivan, Preisler, Jan, Damborský, Jiří, Beneš, Petr
• Format: Article
• Language: English
• Subjects: Breast cancer; Breast Neoplasms - metabolism; Caspase; Catalytic subunits; Cell Line, Tumor; Cell Survival - drug effects; Chymotrypsin; copper; Copper - metabolism; Coumarins - chemistry; Coumarins - pharmacology; Coumarins - toxicity; Cytotoxicity; Humans; Inhibitors; Molecular docking; Molecular Docking Simulation; Proteases; proteasome; Proteasome Endopeptidase Complex - chemistry; Proteasome Endopeptidase Complex - metabolism; Proteasome Inhibitors - chemistry; Proteasome Inhibitors - pharmacology; Proteasome Inhibitors - toxicity; Proteasomes; Protein Binding; Proteins; Proteolysis; Reactive oxygen species; Reactive Oxygen Species - metabolism; Redox properties; Trypsin; Tumor cells; Ubiquitination; wedelolactone
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms18040729

Wedelolactone is a multi-target natural plant coumestan exhibiting cytotoxicity towards cancer cells. Although several molecular targets of wedelolactone have been recognized, the molecular mechanism of its cytotoxicity has not yet been elucidated. In this study, we show that wedelolactone acts as an inhibitor of chymotrypsin-like, trypsin-like, and caspase-like activities of proteasome in breast cancer cells. The proteasome inhibitory effect of wedelolactone was documented by (i) reduced cleavage of fluorogenic proteasome substrates; (ii) accumulation of polyubiquitinated proteins and proteins with rapid turnover in tumor cells; and (iii) molecular docking of wedelolactone into the active sites of proteasome catalytic subunits. Inhibition of proteasome by wedelolactone was independent on its ability to induce reactive oxygen species production by redox cycling with copper ions, suggesting that wedelolactone acts as copper-independent proteasome inhibitor. We conclude that the cytotoxicity of wedelolactone to breast cancer cells is partially mediated by targeting proteasomal protein degradation pathway. Understanding the structural basis for inhibitory mode of wedelolactone might help to open up new avenues for design of novel compounds efficiently inhibiting cancer cells.