Abstract 4018: The role of c-MET/HGF signaling as a critical mediator of an invasive and resistant phenotype in colorectal cancer

Abstract

Abstract The c-MET proto-oncogene is frequently overexpressed (50-60%), amplified (5-10%), and mutated (5%) in colorectal cancer (CRC). Hepatocyte growth factor (HGF)-induced c-MET activation has been linked with migration, survival, invasion, and resistance to targeted therapy, and has been suggested as a possible prognostic biomarker for CRC. We are currently investigating the role of c-MET and microenvironment derived HGF in the acquisition of an invasive and migratory phenotype, and resistance to targeted therapy in CRC. In order to model CRC tumour cell invasion and metastasis, we have generated invasive subpopulations from CRC cells using Boyden Invasion chambers. Invasive cell lines were characterised for protein expression/activity by Western blotting, and analysed for migratory and invasive potential using the xCELLigence System (Roche). To model the CRC microenvironment, we have utilised a range of co-culture techniques with CRC cell lines and colon fibroblasts. c-MET expression in FFPE tissues was measured using IHC in a tissue microarray (TMA) derived from early stage CRC patients. HCT116 and LoVo invasive subpopulations showed an EMT-like, mesenchymal, migratory/invasive phenotype. In addition, increased expression and activation levels of c-MET were found in these sublines, which was determined to be ligand independent. Inhibition of c-MET using RNAi abrogated both basal and HGF-induced migration and invasion in CRC cell lines. Co-culture of CRC cells with HGF-expressing colon-derived fibroblasts leads to activation of c-MET, inducing CRC migration, invasion, and resistance to MEK inhibition, and this phenotype could be diminished using a HGF neutralising antibody. Significant increased expression levels of c-MET were also found in a CRC TMA compared to matched normal tissues, and also at the invasive edge of some CRC tumours, where it may be driving invasive biology. The identification of key pathways driving metastasis has a huge potential to change treatment strategies in CRC. We intend to further investigate the role of c-MET in regulation of migration, invasion, and resistance to therapy in CRC. We hypothesise that patients with high tumoural c-MET at the invasive front may benefit in particular from anti- c-MET therapies. Citation Format: Conor A. Bradley, Philip Dunne, Darragh McArt, Ken Arthur, Stephen McQuaid, Manuel Salto-Tellez, Patrick Johnston, Sandra Van Schaeybroeck. The role of c-MET/HGF signaling as a critical mediator of an invasive and resistant phenotype in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4018. doi:10.1158/1538-7445.AM2015-4018