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Molecular Biology - Oncology - Surgery


Engagement of Overexpressed Her2 with GEP100 Induces Autonomous Invasive Activities and Provides a Biomarker for Metastases of Lung Adenocarcinoma
Published: Thursday, September 22, 2011
Author: Toshi Menju et al.

by Toshi Menju, Shigeru Hashimoto, Ari Hashimoto, Yutaro Otsuka, Haruka Handa, Eiji Ogawa, Yoshinobu Toda, Hiromi Wada, Hiroshi Date, Hisataka Sabe

Overexpression of Her2/ErbB2/Neu in cancer is often correlated with recurrent distant metastasis, although the mechanism still remains largely elusive. We have previously shown that EGFR, when tyrosine-phosphorylated, binds to GEP100/BRAG2 to activate Arf6, which induces cancer invasion and metastasis. We now show that overexpressed Her2 in lung adenocarcinoma cells also employs GEP100. Like EGFR-GEP100 binding, this association is primarily mediated by the pleckstrin homology (PH) domain of GEP100 and Tyr1139/Tyr1196 of Her2. Tyr1139/Tyr1196 are autonomously phosphorylated, when Her2 is overexpressed. Accordingly, invasive activities mediated by the Her2-GEP100 pathway are not dependent on external factors. Blocking Her2-GEP100 binding, as well as its signaling pathway all inhibit cancer invasive activities. Moreover, our clinical study indicates that co-overexpression of Her2 with GEP100 in primary lung adenocarcinomas of patients is correlated with the presence of their node-metastasis with a statistical significance. Since the GEP100 PH domain interacts with both Her2 and EGFR, targeting this domain may provide novel cancer therapeutics.
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