Abstract 5559: Proteomic identification of activated, essential tyrosine kinases in human cancers

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Tyrosine kinases (TKs) are frequently, aberrantly activated in human cancers. Moreover, they could be easily inhibited by small molecules and thereby represent excellent therapeutic targets. Here, our project aims to systematically identify activated, essential TKs in human cancers. In our previously published study, we have developed a high-throughput, multiplex antibody-based assay capable of identifying activated tyrosine kinases regardless of their mode of activation. Using this approach, we profiled 130 established cancer cell lines and 31 primary patient samples. In particular, we found frequent SRC activation in glioblastomas in the absent of genomic alterations. Moreover, we determined SRC essentiality and demonstrated SRC being a relevant target of a FDA-approved drug, dasatinib, in this deadly disease. Since then, we have expanded the Luminex assay to include additional TKs, adaptors and other important signaling molecules. Specifically, the version 2 of this assay is capable of simultaneously analyzing the tyrosine phosphorylation levels on 71 out of the 90 TKs, 9 adaptor proteins, ERK1/2, PLCG1 in the human genome. In addition, we have established separate assays to measure activities of AKT1, GSK3B, p70S6K and RSK1/2. Besides expanding the panel of analytes, we have made significant improvement on assay setup and data analysis. In particular, we have fully automated assay setup in 96-well format. In addition, we have generated negative and positive control samples to enable more accurate background signal estimation and plate-to-plate comparison, respectively. Using the improved version o f the assay, we have profiled 200 additional cancer cell lines and 100 primary tumor specimens. We found that some TKs are frequently activated across multiple malignancies while other are restricted to a particular tumor type. Interestingly, majority of the TKs are activated at very low frequency. Together, these results stress the importance of personalized treatment (i.e. choosing kinase inhibitors based on kinase activation profile of a tumor). In parallel to our effort on identifying activated TKs, we are systematically assessing TK essentiality using the pharmacological approach. Specifically, we have collected 25 small molecules targeting all known oncogenic TKs and are in the process of measuring sensitivities towards these inhibitors in various cancer cell lines. By comparing TK activation status and sensitivity to inhibitors, we have identified potential targets and corresponding drug candidates for treating subsets of cancer patients. Together, we have gained a comprehensive view on aberrant TK activations and downstream signaling in human cancers. Beyond the mechanistic understanding of tyrosine kinase signaling, our study has identified potential targets for devising effective therapeutic strategies for treating cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5559.