Abstract 5281: Role of SHP-2 tyrosine phosphatase in colorectal carcinogenesis

Abstract

Abstract SHP-2 (Src homology-2 domain-containing phosphatase 2) is a tyrosine phosphatase ubiquitously expressed. Previous work done in SHP-2-/- fibroblasts demonstrated its implication in proliferation and migration as well as in the regulation of many signaling pathways including the Ras-Raf/MEK/ERK, the PI3K/AKT and the Jak/STAT pathways(1). Importantly, gain-of-function mutations were discovered in some colorectal cancers (CRCs)(2). However, the role of SHP-2 in intestinal tumorigenesis has never been investigated. Methods: SHP-2 expression and catalytic activity were analyzed by Western blot, qPCR and immunohistochemistry in human CRC cells and in human tumours from different stages. SHP-2 expression was also analyzed in polyps (adenomas) from mice bearing a mutation in Apc gene (APCMin/+ mice). To elucidate the role of SHP-2, RNA interference was used to specifically downregulate its expression in intestinal epithelial cells transformed or not by the oncogenic form of KRASG12V (IEC/KRas). Proliferation (cell counting), invasion (through Matrigel in Boyden chamber), anchorage-independent growth (soft agar) and tumor formation in nude mice (xenograft assays) were analyzed. Results: 1- SHP-2 mRNA and protein levels were significantly increased in human CRC cells and tumors, especially in adenomas, in comparison to healthy adjacent tissues. 2- Interestingly, polyps from APCMin/+ mice also exhibited marked increase in SHP-2 protein expression in comparison to normal adjacent intestinal epithelium. 3- SHP-2 silencing in IEC/KRAS cells markedly reduced their proliferation rate, their growth in soft agar, their capacity to migrate and invade Matrigel and finally, their capacity to form tumor in vivo, in nude mice. 4- Of note, phosphorylated and activated levels of MEK and ERK kinases were significantly decreased following SHP-2 silencing in IECs particularly in those expressing the mutated form of KRAS. Conclusion: Our data suggest that SHP-2 promotes malignancy of intestinal epithelial cells by sustaining the oncogenic activation of MEK/ERK signalling during intestinal tumorigenesis. (1)Shi ZQ, Lu W, Feng GS., J Biol Chem. 1998 Feb 27;273(9):4904-8. (2)Bentires-Alj M. et al., Cancer Res. 2004 Dec 15;64(24):8816-20. Citation Format: Jessica Gagne Sansfacon, Geneviève Coulombe, Nadia Bourdages, Nathalie Rivard. Role of SHP-2 tyrosine phosphatase in colorectal carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5281. doi:10.1158/1538-7445.AM2014-5281