CS-05MUTATION SPECIFIC FUNCTIONS OF EGFR RESULT IN A MUTATION-SPECIFIC DOWNSTREAM PATHWAY ACTIVATION

BACKGROUND: EGFR is frequently mutatedin various types of cancer. Although all oncogenic mutationsare considered activating, different tumor types have different mutationspectra. It is possible that functional differences underlie this tumor-type specific mutationspectrum. METHODS: We have determined whether specific mutationsin EGFR (EGFR, EGFRvIII and EGFR-L858R) have differences in binding partners, differences in downstream pathway activation (gene expression and phosphoproteins), and have functional consequences on cellular growth and migration. RESULTS: Using biotin pulldown and subsequent mass spectrometry we were able to detect mutationspecific binding partners for EGFR. Differential binding was confirmed using a proximilty ligation assay and/or Western Blot for the dedicator of cytokinesis4 ( DOCK4), UDP-glucose glycoprotein glucosyltransferase1 (UGGT1), MYC binding protein 2 (MYCBP2) and Smoothelin (SMTN). We also demonstrate that each mutationinduces the expression of a specific set of genes, and that each mutationis associated with specific phosphorylation patterns. Finally, we demonstrate using stably expressing cell lines that EGFRvIII and EGFL858R display reduced growth and migration compared to EGFR wildtype expressing cells. CONCLUSION: Our results indicate that there are distinct functional differencesbetween differentEGFR mutations. The functional differencesbetween different mutationsargue for the development of mutationspecific targeted therapies.