The anti-HER3 (ErbB3) therapeutic antibody 9F7-F11 induces HER3 ubiquitination and degradation in tumors through JNK1/2- dependent ITCH/AIP4 activation
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Christophe Le Clorennec1,2,3,4, Yassamine Lazrek1,2,3,4,5,8, Olivier Dubreuil5,9, Christel Larbouret1,2,3,4, Marie-Alix Poul1,2,3,4, Philippe Mondon5,10, Gerry Melino6,7, André Pèlegrin1,2,3,4, Thierry Chardès1,2,3,4
1IRCM, Institut de Recherche en Cancérologie de Montpellier, Montpellier, F-34298, France
2INSERM, U1194 Montpellier, Montpellier, F-34298, France
3Université de Montpellier, Montpellier, F-34298, France
4ICM, Institut Régional du Cancer Montpellier, Montpellier, F-34298, France
5Millegen SA, Labège, F-31670, France
6Biochemistry Laboratory, Instituto Dermopatico Dell'Immacolata, Department of Experimental Medicine and Surgery, University of Rome “Tor Vergata,” 00133 Rome, Italy
7Toxicology Unit, Medical Research Council, Leicester University, Leicester LE1 9HN, United Kingdom
8Institut Pasteur de Guyane, BP 6010, 97306, Cayenne Cedex, France
9GamaMabs Pharma SA, Centre Pierre Potier, ONCOPOLE, BP 50624, France
10LFB Biotechnologies, 59000, Lille, France
Thierry Chardès, email: email@example.com
Keywords: cancer, HER3, ITCH/AIP4, antibody, treatment
Received: January 06, 2016 Accepted: April 16, 2016 Published: May 18, 2016
We characterized the mechanism of action of the neuregulin-non-competitive anti-HER3 therapeutic antibody 9F7-F11 that blocks the PI3K/AKT pathway, leading to cell cycle arrest and apoptosis in vitro and regression of pancreatic and breast cancer in vivo. We found that 9F7-F11 induces rapid HER3 down-regulation. Specifically, 9F7-F11-induced HER3 ubiquitination and degradation in pancreatic, breast and prostate cancer cell lines was driven mainly by the itchy E3 ubiquitin ligase (ITCH/AIP4). Overexpression of the ITCH/AIP4 inhibitor N4BP1 or small-interfering RNA-mediated knockdown of ITCH/AIP4 inhibited HER3 ubiquitination/degradation and PI3K/AKT signaling blockade induced by 9F7-F11. Moreover, 9F7-F11-mediated JNK1/2 phosphorylation led to ITCH/AIP4 activation and recruitment to HER3 for receptor ubiquitination and degradation. ITCH/AIP4 activity was activated by the deubiquitinases USP8 and USP9X, as demonstrated by RNA interference. Taken together, our results suggest that 9F7-F11-induced HER3 ubiquitination and degradation in cancer cells mainly occurs through JNK1/2-dependent ITCH/AIP4 activation.
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