Volume 121, Issue 2 pp. 431-441
Cancer Therapy

TNF potentiates anticancer activity of bortezomib (Velcade®) through reduced expression of proteasome subunits and dysregulation of unfolded protein response

Dominika Nowis

Dominika Nowis

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

Dominika Nowis: On leave from the Department of Immunology, Center of Biostructure, Medical University of Warsaw, Warsaw, Poland.

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Elizabeth J. McConnell

Elizabeth J. McConnell

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

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Lindsey Dierlam

Lindsey Dierlam

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

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Alla Palamarchuk

Alla Palamarchuk

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

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Agnieszka Lass

Agnieszka Lass

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

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Cezary Wójcik

Corresponding Author

Cezary Wójcik

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN

Fax: +1-812-4651184.

Department of Anatomy and Cell Biology, Indiana University School of Medicine–Evansville, 8600 University Boulevard, Evansville, IN 47712, USASearch for more papers by this author
First published: 18 May 2007
Citations: 21

Abstract

Bortezomib (Velcade®) exploits proteasome inhibition as a unique mechanism of anticancer activity. The effectiveness of bortezomib is, however, limited, therefore, the search for therapeutic regimens combining bortezomib with other agents. In the present work we demonstrate enhanced anticancer activity of bortezomib by its combination with tumor necrosis factor (TNF) in the experimental model of C-26 colon carcinoma in mice. This interaction likely relies on the induction of a dysregulated response to ER stress, leading to apoptosis of cancer cells, evidenced by caspase-3 cleavage, p53 accumulation as well as increased SAPK/JNK phosphorylation. ER stress induced by the combination of TNF and bortezomib is corroborated by upregulation of BiP, PDI and calnexin as well as cleavage of caspase-12; however, in contrast to the classic pathway, it is also associated with decreased phosphorylation of eIF2α and prevention of XBP-1 splicing. TNF prevented the upregulation of Hsp27 induced by bortezomib, which may contribute to enhanced ER stress. Moreover, TNF interfered with bortezomib-induced upregulation of distinct subunits of the 26S proteasome. Bortezomib concentration used in this study was not sufficient to prevent TNF from inducing nuclear translocation of p65/RelA; however, the combination of both agents reduced total p65/RelA levels. Combined treatment of tumor-bearing mice with bortezomib and TNF not only inhibited tumor growth but also significantly prolonged animal survival. Therefore, combination of bortezomib with TNF is an attractive option for further clinical studies. © 2007 Wiley-Liss, Inc.

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