Withaferin A inhibits the proteasome activity in mesothelioma in vitro and in vivo

• Published in: PloS one Vol. 7; no. 8; p. e41214
• Main Authors: Yang, Huanjie, Wang, Ying, Cheryan, Vino T, Wu, Wenjuan, Cui, Cindy Qiuzhi, Polin, Lisa A, Pass, Harvey I, Dou, Q Ping, Rishi, Arun K, Wali, Anil
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 17-08-2012; Public Library of Science (PLoS)
• Subjects: Adenosine diphosphate; Angiogenesis; Animals; Anticancer properties; Anticarcinogenic Agents - pharmacology; Apoptosis; Apoptosis - drug effects; Asbestos; BAX protein; bcl-2-Associated X Protein - metabolism; Bioactive compounds; Biology; Blockage; Blood proteins; c-Myc protein; Cancer; Cancer therapies; Carp; Caspase; Caspase 3 - metabolism; Caspase 7 - metabolism; Caspase-3; Cell cycle; Cell growth; Cell Line, Tumor; Cell Proliferation - drug effects; Chemistry; Departments; Dingell, John D; Enzyme Activation - drug effects; Female; Gene expression; Gene Expression Regulation, Neoplastic - drug effects; Growth factors; Herbal medicine; Humans; In vivo methods and tests; Inflammation; Kinases; Medicinal plants; Medicine; Mesothelioma; Mesothelioma - enzymology; Mesothelioma - pathology; Metastases; Mice; Mice, Inbred BALB C; Molecular modelling; Myc protein; Neoplasm Metastasis; Oncology; p38 Mitogen-Activated Protein Kinases - metabolism; Penicillin; Peritoneum; Poly(ADP-ribose) polymerase; Proteasome Endopeptidase Complex - metabolism; Proteasome Inhibitors - pharmacology; Proteasomes; Protein kinase; Protein kinases; Proteins; Ribose; Signaling; Tumors; Withania somnifera; Withanolides - pharmacology; Xenograft Model Antitumor Assays; New York; United States > US; Detroit Michigan; Michigan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0041214

The medicinal plant Withania somnifera has been used for over centuries in Indian Ayurvedic Medicine to treat a wide spectrum of disorders. Withaferin A (WA), a bioactive compound that is isolated from this plant, has anti-inflammatory, immuno-modulatory, anti-angiogenic, and anti-cancer properties. Here we investigated malignant pleural mesothelioma (MPM) suppressive effects of WA and the molecular mechanisms involved. WA inhibited growth of the murine as well as patient-derived MPM cells in part by decreasing the chymotryptic activity of the proteasome that resulted in increased levels of ubiquitinated proteins and pro-apoptotic proteasome target proteins (p21, Bax, IκBα). WA suppression of MPM growth also involved elevated apoptosis as evidenced by activation of pro-apoptotic p38 stress activated protein kinase (SAPK) and caspase-3, elevated levels of pro-apoptotic Bax protein and cleavage of poly-(ADP-ribose)-polymerase (PARP). Our studies including gene-array based analyses further revealed that WA suppressed a number of cell growth and metastasis-promoting genes including c-myc. WA treatments also stimulated expression of the cell cycle and apoptosis regulatory protein (CARP)-1/CCAR1, a novel transducer of cell growth signaling. Knock-down of CARP-1, on the other hand, interfered with MPM growth inhibitory effects of WA. Intra-peritoneal administration of 5 mg/kg WA daily inhibited growth of murine MPM cell-derived tumors in vivo in part by inhibiting proteasome activity and stimulating apoptosis. Together our in vitro and in vivo studies suggest that WA suppresses MPM growth by targeting multiple pathways that include blockage of proteasome activity and stimulation of apoptosis, and thus holds promise as an anti-MPM agent.