Abstract 4010: Identification of signaling pathways involved in colorectal adenoma-to-carcinoma progression using phosphoproteomics

Background Colorectal cancer (CRC) develops in a multi-step-process from normal epithelium, through a pre-malignant lesion (adenoma), into a malignant lesion (adenocarcinoma). A minority of about 5% of adenomas will ultimately progress into cancer. To improve clinical practice it is important to identify the subgroup of colorectal adenomas that is at risk of progressing to cancer. By extensive genomic analysis we have shown that specific copy number alterations are associated with risk of progression. An example of such an alteration is the gain of chromosome arm 20q and we identified AURKA and TPX2 as major drivers of this amplicon. Yet, the activation status of these and other genes during colorectal carcinogenesis and the downstream signaling pathways affected with gene (in)activation are not fully known. In order to better understand the biology of adenoma to carcinoma transition, we performed a comprehensive analysis of phosphoproteomes at different stages of colorectal carcinogenesis. Methods Phosphotyrosine containing peptides were immunoprecipitated from 5 mg of colorectal adenoma (n=81) and colorectal carcinoma tissues (n=50) using agarose bead-coupled phosphotyrosine antibody P-Tyr-1000. A Q Exactive HF mass spectrometer was used to perform NanoLC-MS/MS. Spectral counts of phosphoproteins and ion intensities of phosphopeptides were defined by MaxQuant for relative quantitation of protein phosphorylation. Results Phosphotyrosine-based phosphoproteomics of the 131 colorectal tissue samples yielded 6056 phosphopeptides, corresponding to 2745 unique phosphoproteins including 183 phosphokinases. Data analysis to identify regulated phosphorylation states and inference of kinase activity is ongoing. Conclusions and future plans This is the first large phosphoproteomics dataset of colorectal adenomas and carcinomas. Preliminary data analysis shows promising differences in kinase activities between adenomas and carcinomas. After further analysis, we will manipulate the activity of the driver kinases in adenoma-derived organoids and monitor tumor outgrowth in mice. Citation Format: Sanne Martens-de Kemp, Alex Henneman, Richard de Goeij-de Haas, Sander Piersma, Thang Pham, Gerrit Meijer, Beatriz Carvalho, Connie Jimenez. Identification of signaling pathways involved in colorectal adenoma-to-carcinoma progression using phosphoproteomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, I