Abstract LB-143: ErbB2, EphrinB1, Src kinase and PTPN13 signaling complex regulates MAP kinase signaling in human cancers

Tyrosine kinases, like the ErbB and Src families, can mediate potent oncogenic growth and are successful therapeutic targets of human cancers. However, many cancer cells overcome or successfully modulate these downstream signaling cascades in the absence of growth factor or kinase over-expression. We have previously identified a cellular phosphatase, PTPN13 that significantly modulates mitogenic signaling and can function as tumor suppressors. Decreased PTPN13 expression enhances ErbB2-mediated MAP Kinase activation, and is also associated with decreased survival in breast cancer. Here we show that PTPN13 regulates a signaling complex consisting of ErbB2, Src, and EphrinB1. To our knowledge, this signaling complex has not been previously described. Co-immunoprecipitation, proximity ligation assay and immunofluoroscence studies demonstrate that EphrinB1, a PTPN13 substrate, interacts with ErbB2. In addition, the oncogenic V660E ErbB2 mutation enhances this interaction, while Src kinase mediates EphrinB1 phosphorylation and subsequent MAP Kinase signaling. Decreased PTPN13 function further potentiates these changes. The association of oncogene kinases (ErbB2, Src), a signaling transmembrane ligand (EphrinB1) and a phosphatase tumor suppressor (PTPN13) suggest that EphrinB1 may be a relevant therapeutic target in cancers harboring ErbB2-activating mutations and decreased PTPN13 expression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-143. doi:1538-7445.AM2012-LB-143