Cell Reports - A Truncated Form of IKKα Is Responsible for Specific Nuclear IKK Activity in Colorectal Cancer
A Truncated Form of IKKα Is Responsible for Specific Nuclear IKK Activity in Colorectal Cancer
Cell Reports, 04 October 2012
Copyright © 2012 The Authors
10.1016/j.celrep.2012.08.028
Authors
Pol Margalef, Vanessa Fernández-Majada, Alberto Villanueva, Ricard Garcia-Carbonell, Mar Iglesias, Laura López, María Martínez-Iniesta, Jordi Villà-Freixa, Mari Carmen Mulero, Montserrat Andreu, Ferran Torres, Marty W. Mayo, Anna Bigas, Lluis Espinosa
See Affiliations - Highlights
- A truncated active form of IKKα is found in colorectal cancer cells
- Nuclear complex containing p45-IKKα phosphorylates SMRT and histone H3
- Cleavage of IKK(alpha) into p45-IKKα is required for cancer cell growth
Summary
Nuclear IKKα regulates gene transcription by phosphorylating specific substrates and has been linked to cancer progression and metastasis. However, the mechanistic connection between tumorigenesis and IKKα activity remains poorly understood. We have now analyzed 288 human colorectal cancer samples and found a significant association between the presence of nuclear IKK and malignancy. Importantly, the nucleus of tumor cells contains an active IKKα isoform with a predicted molecular weight of 45 kDa (p45-IKKα) that includes the kinase domain but lacks several regulatory regions. Active nuclear p45-IKKα forms a complex with nonactive IKKα and NEMO that mediates phosphorylation of SMRT and histone H3. Proteolytic cleavage of FL-IKKα into p45-IKKα is required for preventing the apoptosis of CRC cells in vitro and sustaining tumor growth in vivo. Our findings identify a potentially druggable target for treating patients with advance refractory CRC.
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