mediates Src invasive activity in advanced colon carcinoma cells.

ABSTRACT The non-receptor tyrosine kinase Src is freque ntly overexpressed and/or activated in human colon carcinoma (CRC) and its increased activity has been associated with a poor clinical outcome. Src has been then implicated in growth and invasion of these can cer cells by still not well known mechanisms. Here we addressed thes e Src oncogenic signaling using quantitative phosphoproteomics. Src overexpression increased gr owth and invasiveness of the metastatic SW620 CRC cells. Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC) in combination with LC-MS/MS allowed the iden tification of 136 proteins which exhibited a significant increased and/or association with tyrosine phosphorylation upon Src expression. These mainly include signaling, cytoskeleton and vesicular-associated pr oteins. Interestingly, Src also phosphorylated a cluster of tyrosine kinases, ie the receptors Met and EphA2, the cytoplasmic tyrosine kinase Fa k and pseudo-tyrosine kinase Sg K223, which were required for its invasive activity. Similar re sults were obtained with the me tastatic Colo205 CRC cells that exhibit high endogenous Sr c activity. We concluded that Src uses a tyrosine kinases network to promote its invasive activity in CRC and this implicates a reverse signaling via tyrosine kinase receptors. Targeting thes e tyrosine kinases may be of si gnificant therapeutic value in hal-00367875, version 1 - 12 Mar 2009 this cancer.