To gain further insight into alterations in cellular pathways,
tumor profiling, and marker discovery in
colorectal cancer (CRC) we used a new antibody microarray specific for cell signaling. Soluble
protein extracts were prepared from paired
tumor/normal biopsies of 11 patients diagnosed with
colorectal carcinoma at different stages; four liver
carcinomas were used as a reference. Antibody microarray analysis identified 46
proteins that were differentially expressed between normal colorectal epithelium and
adenocarcinoma. These
proteins gave a specific signature for CRC, different from other
tumors, as well as a panel of novel markers and potential targets for CRC. Twenty-four
proteins were validated by using a specific
colorectal cancer tissue microarray and immunoblotting analysis. Together with some previously well known deregulated
proteins in CRC (
beta-catenin, c-MYC, or p63), we found new potential markers preferentially expressed in CRC
tumors:
cytokeratin 13,
calcineurin, CHK1,
clathrin light chain, MAPK3, phospho-PTK2/
focal adhesion kinase (Ser-910), and MDM2. CHK1
antibodies were particularly effective in discriminating between tumoral and normal mucosa in CRC. Moreover a global picture of alterations in signaling pathways in CRC was observed, including a significant up-regulation of different components of the
epidermal growth factor receptor and Wnt/
beta-catenin pathways and the down-regulation of
p14(ARF). The experimental approach described here should be applicable to other pathologies and
neoplastic processes.