Abstract 4797: Global phosphotyrosine survey reveals the evidence of activation of multiple tyrosine kinase signaling pathways in basal-like breast cancer cells

About 10-15% of all breast cancers are basal-like breast cancers (BLBCs) that are highly aggressive and lack effective targeted therapeutic options as they lack ER, PR and Her-2. Reversible phosphorylation of proteins is one the most important post-translational modifications and is involved in almost all kinds of cellular processes. Tyrosine phosphorylation (pY) accounts for a minority of total phosphorylation, less than 0.1% by overall abundance. However, pY plays a disproportionately large role in diseases especially in cancer. More than half of the 90 tyrosine kinasesidentified in the human proteome have been implicated in cancer through gain-of-function mutations, gene amplification, overexpression, or as tumor suppressors and become attractive therapeutic targets. To assess activated tyrosine kinasesignaling pathways in TNBCs, we collected a panel of 28 publicly available triple-negative breast cancercell lines and systematically analyzed the invasiveness and anchorage independent growth of this panel of cell lines. We carried out global quantitative phosphotyrosine profiling using high resolution Fourier transform mass spectrometry. In all, we identified 2,133 tyrosine-phosphorylated peptides from more than 800 proteins. A number of tyrosine kinaseswere found to be differentially phosphorylated in different sets of breast cancer cells. Pathway analysisrevealed that phosphorylation level of certain oncogenic kinases including EGFR, MET, FAK1 and SRC was elevated in a majority of basal-like breast cancer cells. Notably, multiple members of EPH receptor family, EPHA1, EPHA2, EPHA3, EPHB3and EPHB4, were hyper-phosphorylated in multiple basal-like breast cancer cells. Supervised clustering analysis of phosphorylated proteins identified specific phospho-signatures that correlated with invasiveness and anti- anoikiscolony formation ability. One of these hyper-phosphorylated proteins was DYRK2, a dual specificity tyrosine kinase. We observed that DYRK2 had an effect on colony formation and invasive ability on a subset of TNBC cell lines. Overall, our global phosphoproteomicstudy confirms high heterogeneity in the activation status of tyrosine kinasesacross triple negative breast cancercells and suggests that some of them are attractive candidates as therapeutic targets. 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 4797. doi:1538-7445.AM2012-4797