Abstract 4464: C-erbB3 protein modifications are secondary to severe cell membrane alterations induced by Irvalec treatment in CHO cells

• Published in: Cancer research (Chicago, Ill.) Ill.), 2010-04, Vol.70 (8_Supplement), p.4464-4464
• Main Authors: Váradi, Tímea, Guijarro, José Manuel Molina, Vereb, György, Galmarini, Carlos M., Szöllõsi, János, Nagy, Peter
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM10-4464

Irvalec® is a marine-derived antitumor agent that is currently undergoing phase II clinical trials. The compound induces a necrotic cell death associated with the appearance of membrane blebs and severe cell swelling reflecting a serious membrane damage caused by the drug. Indirect evidence has also suggested a possible role of ErbB proteins, in particular ErbB3, and lipid rafts in conferring sensitivity to Irvalec treatment. In order to assess the role of ErbB protein expression in the mechanism of action of Irvalec, and to measure the effect of drug treatment on the clustering properties of these proteins, we generated CHO cell lines stably transfected with ErbB2 (CHO-ErbB2) or with ErbB2 and ErbB3 (CHO-ErbB2-3). The IC50 values of the three cell lines for Irvalec did not differ significantly from each other. On the other hand treatment with Irvalec induced a significant increase in the binding of a conformational sensitive antibody to ErbB3 (ErbB3.105.5) without modifying the binding of other ErbB3 antibodies or antibodies against ErbB2. In addition, Irvalec treatment decreased the homoassociation of ErbB2 and ErbB3 measured by flow cytometric FRET. A431 cells transfected with GPI-anchored GFP or ErbB3-citrine showed significant Irvalec-induced patching of the GPI-anchor and ErbB3, whereas the distribution of ErbB1 and ErbB2 were not affected in cells transfected with ErbB1-GFP or ErbB2-mYFP. In conclusion, our data do not support a role for ErbB proteins in determining sensitivity to Irvalec, but show that these receptors are indirectly affected by exposing cells to the compound. These alterations should be ascribed to cell membrane modifications induced by Irvalec treatment Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4464.