Résumé
The non receptor tyrosine kinase (TyrK) Src mediates signal transduction induced by growth factors and integrins. Src also exhibits oncogenic activity when deregulated, a situation frequently observed in colorectal cancer (CRC). Moreover, the extent of kinase deregulation often correlates with malignant potential, in agreement with an important role Src in this tumorigenic process. However, the exact role of Src in CRC is only partially elucidated. Src has been implicated in growth and invasiveness of various CRC cells. A previous SILAC quantitative phosphoproteomic analysis allowed the characterization of Src signaling leading to CRC cells growth and invasion (Leroy et al, Cancer Res, 2009, 15:2279-86). Interestingly, Src also increased tumor growth in nude mice engraft with human SW620 CRC cells. This biological effect correlated with a strong increase of tyrosine phosphorylation (pTyr) content in Src-positive tumors. Here, we wished to characterize Src oncogenic signaling in these xenograft tumor models. To this end, we have developed an innovative quantitative phosphoproteomic analysis coupled to stable isotope labeling in mice named SILAX for Stable Isotope Labeling in mouse Xenografts. This method is based on tumor heavy isotope labeling in nude mice by addition of [13C]-Lysine into the food. An incorporation level >87% was obtained in subcutaneous tumors after 30 days of heavy lysine diet. This approach allowed the identification of 61 proteins which exhibited a significant increase in and/or association with pTyr upon Src expression in tumors. These mainly include vesicular trafficking, signaling and RNA binding proteins. Interestingly, we identified the novel vesicular trafficking protein TOM1L1 (Franco et al, Mol Cell Biol, 2006, 26:1932-47) as a specific regulator of Src oncogenic signaling of CRC cells in vivo. While TOM1L1 depletion poorly affected Src-induced CRC proliferation in vitro, it significantly inhibited tumor growth in nude mice. This data suggests that vesicular trafficking plays an important role in Src-induced CRC tumor growth and validate SILAX as a valuable approach to decipher TyrK signaling in mouse xenograft models.
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 230. doi:1538-7445.AM2012-230