Abstract C268: MET-inhibition using SU11274 and HER-inhibitions with lapatinib impair proliferation, motility and invasion in hepatocellular carcinoma (HCC) and exhibits an increased efficacy un sorafenib-tolerant model.

Introduction: Sorafenib significantly improved overall survival in advanced HCC. However patients may display primary resistance and a majority of them will develop acquired resistance over time when treated with sorafenib. Resistance to sorafenib has been correlated with upregulation of angiogenic pathways, including the c-MET pathway (Roskoski, 2007). In the SHARP study, patients exhibiting high HGF levels at baseline had a poor prognosis and appeared to benefit less from sorafenib in terms of survival than those with low levels of HGF (Pena, 2008). Therefore, MET appears to be a potential target to counteract sorafenib resistance. In this study we evaluate MET and EGFR expression and their sensitivity towards MET and EGFR inhibitors in terms of signaling, viability, and invasion in two HCC cell lines, one sensitive to sorafenib and with acquired sorafenib-tolerance. Methods: SU11274 is a specific inhibitor of overexpressed and activated MET. Antiproliferative effects of SU11274 (MET inhibitor) and lapatinib an (EGFR/HER2 inhibitor) (lapatinib) were evaluated in the human HCC cell lines, SK-HEP1 and its sorafenib-tolerant counterpart, SK-Sora, using MTT assays. mRNA expression and protein levels were assessed by qRT-PCR and Western blot, respectively. Cell motility was investigated by wound-healing and matrigel invasion assays. Results: SK-Sora was characterized by a 2-fold higher MET expression but a 3-fold lower EGFR expression respect to SK-HEP1. This differential expression of MET/EGFR between the two cell lines was associated with their sensitivity to SU11274 and lapatinib in proliferation assays. Whereas 5µM SU11274 or 20µM lapatinib induced 50 % growth inhibition of SK-HEP1 cells, SK-Sora cells displayed 86% and 27% of growth inhibition, respectively in the same conditions. These results indicated that baseline MET and EGFR expression levels may be good biomarkers to predict increased sensitivity or resistance to MET or EGFR inhibitors. Interestingly, SU11274 also more potently decreased HGF-dependent invasion in SK-Sora (80%) cells than in SK-HEP1 (50%) cells. To understand the differences observed regarding proliferation and invasion between SK-HEP1 and SK-Sora cells, we assessed MET-dependent signaling in both cell lines. HGF-induced MET activation was associated with differential pattern of p-METTyr1234/35, p-GAB1, p-ERK1/2, and p-AKTser473 between both cell lines, with higher phosphorylation of MET and GAB1 in SK-Sora than in SK-HEP1. Interestingly, we showed that SK-Sora cells were more sensitive to the inhibition of HGF-induced signaling by SU11274 than SK-HEP1 cells. Differential effects of lapatinib on cell signaling and invasion will be detailed. Conclusion: MET inhibition showed more potent effects in the sorafenib-tolerant cell line, which had increased MET expression levels, as compared to the parental cell line SK-HEP1. These results suggest that MET could be an attractive target in HCC patients particularly in the context of sorafenib resistance. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C268. Citation Format: Annemilai Tijeras-Raballand, Eugenia Riveiro, Maria Serova, Cindy Neuzillet, Matthieu Martinet, Valerie Paradis, Mohamed Bouattour, Eric Raymond, Sandrine Faivre, Armand de Gramont. MET-inhibition using SU11274 and HER-inhibitions with lapatinib impair proliferation, motility and invasion in hepatocellular carcinoma (HCC) and exhibits an increased efficacy un sorafenib-tolerant model. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C268.