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Biochem Biophys Res Commun. 2012 Oct 12;427(1):24-9. doi: 10.1016/j.bbrc.2012.08.133. Epub 2012 Sep 12.

Withaferin A inhibits JAK/STAT3 signaling and induces apoptosis of human renal carcinoma Caki cells.

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  • 1Department of Immunology, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.


Withaferin A, the active component of Withania somnifera, causes cytotoxicity in a variety of tumor cell lines. In this study, we show that withaferin A inhibits constitutive and IL-6-induced phosphorylation of STAT3 (on Tyr705), but not IFN-γ-induced STAT1 phosphorylation. Withaferin A-induced down-regulation of STAT3 activation is associated with a reduction in Janus-activated kinase 2 (JAK2) activity. Withaferin A also down-regulates the expression of STAT3 regulated genes such as Bcl-xL, Bcl-2, cyclin D1 and survivin. The apoptotic effect of withaferin A in Caki human renal cancer cells was investigated. Withaferin A induced dose-dependent apoptotic cell death in Caki cells, as measured by FACS analysis and PARP cleavage. Furthermore, overexpression of STAT3 attenuated withaferin A-induced apoptosis. Taken together, the present study provides strong evidence that down-regulation of the STAT3 signaling pathway mediates withaferin A-induced apoptosis.

Copyright © 2012 Elsevier Inc. All rights reserved.

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