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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: M700119-MCP200v1 6/11/1842    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Glossary Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Com, E. Articles by Hondermarck, H. Search for Related Content PubMed PubMed Citation Articles by Com, E. Articles by Hondermarck, H. Social Bookmarking                      What's this?

Molecular & Cellular Proteomics 6:1842-1854, 2007.
© 2007 by The American Society for Biochemistry and Molecular Biology, Inc.

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Research

Nerve Growth Factor Receptor TrkA Signaling in Breast Cancer Cells Involves Ku70 to Prevent Apoptosis^*,S

Emmanuelle Com^,, Chann Lagadec^,¶, Adeline Page^||, Ikram El Yazidi-Belkoura, Christian Slomianny^**, Ambre Spencer, Djilali Hammache, Brian B. Rudkin and Hubert Hondermarck^,

From the INSERM ERI-8 (JE-2488), "Growth factor signaling in breast cancer. Functional proteomics," ^|| Mass spectrometry facility, ^** INSERM U800, IFR 147, University of Sciences and Technologies Lille, 59655 Villeneuve d'Ascq, France and Differentiation and Cell Cycle Group, Laboratory for Molecular Biology of the Cell, UMR 5239/CNRS/ENS Lyon/Université Lyon 1, IFR 128, Ecole Normale Supérieure de Lyon, 69364 cedex 07 Lyon, France

The nerve growth factor (NGF)-tyrosine kinase receptor TrkA plays a critical role in various neuronal and non-neuronal cell types by regulating cell survival, differentiation, and proliferation. In breast cancer cells, TrkA stimulation results in the activation of cellular growth, but downstream signaling largely remains to be described. Here we used a proteomics-based approach to identify partners involved in TrkA signaling in breast cancer cells. Wild type and modified TrkA chimeric constructs with green fluorescent protein were transfected in MCF-7 cells, and co-immunoprecipitated proteins were separated by SDS-PAGE before nano-LC-MS/MS analysis. Several TrkA putative signaling partners were identified among which was the DNA repair protein Ku70, which is increasingly reported for its role in cell survival and carcinogenesis. Physiological interaction of Ku70 with endogenous TrkA was induced upon NGF stimulation in non-transfected cells, and co-localization was observed with confocal microscopy. Mass spectrometry analysis and Western blotting of phosphotyrosine immunoprecipitates demonstrated the induction of Ku70 tyrosine phosphorylation upon NGF stimulation. Interestingly no interaction between TrkA and Ku70 was detected in PC12 cells in the absence or presence of NGF, suggesting that it is not involved in the initiation of neuronal differentiation. In breast cancer cells, RNA interference indicated that whereas Ku70 depletion had no direct effect on cell survival, it induced a strong potentiation of apoptosis in TrkA-overexpressing cells. In conclusion, TrkA signaling appears to be proapoptotic in the absence of Ku70, and this protein might therefore play a role in the long time reported ambivalence of tyrosine kinase receptors that can exhibit both anti- and eventually proapoptotic activities.

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