Synergism of EGFR and c-Met pathways, cross-talk and inhibition, in non-small cell lung cancer

Abstract

Backgroundc-Met and EGFR receptors are widely expressed on cancer cells; they are implicated in the development and progression of cancer through a plethora of effects on cell cycle progression, apoptosis, motility and metastasis and are potential targets for combination therapy. EGFR receptor tyrosine kinases are currently being targeted in a number of malignancies.MethodsApoptosis was studied by FACS analysis using propidium iodide. EGF and HGF signaling intermediates were studied by western blotting. Cell proliferation was determined by MTT assays. Cell motility was done by time lapse confocal microscopy.Resultsc-Met and EGFR were both expressed in A549, H1838, H2170, SW900, SW1573, H358, SKLU-1, and H1993 non small cell lung cancer (NSCLC) cell lines. Both EGF and HGF at 100 ng/ml in medium showed a synergistic effect on cell proliferation at 48–72 h as seen by a proliferation assay in A549, H1838, and SKMES cells. In A549 and H1838 cell lines, HGF (40 ng/ml) and EGF (5 ng/ml) induced synergistic phosphorylation on c-Met (Tyr 1003/1230/1234/1235). Additionally, synergistic phosphorylation of Akt (Ser-473) and phospho-ERK1+ERK2 (Thr202/Tyr204) was also seen indicating that EGF and HGF could induce synergistic phosphorylation of important signaling intermediates. Treatment with EGF and HGF at 100 ng/ml for 2 h also leads to an additive effect in inducing cell motility (especially membrane ruffling) in H1993 cells. A novel c-Met small molecule tyrosine kinase inhibitor SU11274 and EGFR tyrosine kinase inhibitors Tyrphostin AG1478 and gefitinib (Iressa) were tested to study their effect in combination on proliferation and apoptosis in lung cancer cells. Interestingly, a synergistic effect on inhibition of cell proliferation was seen in the presence of SU11274 and Tyrphostin AG1478. 0.5 µM Tyrphostin AG1478 and 2 µM SU11274 inhibited growth by 21% and 25%, respectively; a combination of both tyrosine kinase inhibitors inhibited growth by 65%. Interestingly, EGFR inhibitor (gefitinib, Iressa) and c-Met inhibitor (SU11274) also had a synergistic effect on apoptosis in H358 cells.ConclusionThere was a synergistic effect of EGF and HGF on proliferation, downstream activation of signal transduction and an additive effect seen on motility. These studies show that a combination of HGF and EGF tyrosine kinase inhibitors on NSCLC, could potentially be targeted in a synergistic fashion.

MET in Lung Cancer: Biomarker Selection Based on Scientific Rationale

“…These preclinical studies suggested that the combination of inhibitors for MET and EGFR RTKs could potentially produce synergistic antitumor effects (24). Indeed, a synergistic effect on inhibition of cell proliferation and apoptosis was seen when a novel first-generation MET inhibitor, SU11274, was combined with EGFR inhibitors such as AG1478 or gefitinib (24). The synergism and cross-talk of EGFR and MET pathways in NSCLC, and the potential of simultaneous inhibition, were thus recognized in these studies.…”

“…Indeed, synergistic effects of epidermal growth factor (EGF) and HGF on proliferation, and additive effects on motility, were noted in preclinical studies in NSCLC cells. For example, increased membrane ruffling to form a motile cell surface was observed when cells were stimulated with HGF and EGF independently, and when these growth factors were combined, an additive effect was observed (24). These preclinical studies suggested that the combination of inhibitors for MET and EGFR RTKs could potentially produce synergistic antitumor effects (24).…”

“…For example, increased membrane ruffling to form a motile cell surface was observed when cells were stimulated with HGF and EGF independently, and when these growth factors were combined, an additive effect was observed (24). These preclinical studies suggested that the combination of inhibitors for MET and EGFR RTKs could potentially produce synergistic antitumor effects (24). Indeed, a synergistic effect on inhibition of cell proliferation and apoptosis was seen when a novel first-generation MET inhibitor, SU11274, was combined with EGFR inhibitors such as AG1478 or gefitinib (24).…”

Effects of bufalin on the proliferation of human lung cancer cells and its molecular mechanisms of action

“…The activated receptors such as VEGFR, EGFR, and c-Met play very important roles in the proliferation of cancer cells including lung cancer cells (Colon et al 2009;Kim et al 2008;Morelli et al 2006;Naumov et al 2009;Puri and Salgia 2008). In order to clarify the bufalin-targeted receptors in A549 cells, we studied the effects of bufalin on the related receptor phosphorylation and expressions in A549 cells.…”

“…Suppression of the activated EGFR and ERK1/2 and p38 MAPKs as well as Akt signaling pathways led to inhibition of the proliferation of A549 cells (Baldys et al 2007;Nguyen et al 2004;Recchia et al 2009;Su et al 2010). There has been the cross-talk in EGFR and c-Met pathways in A549 cells which is related to the A549 cell proliferation (Puri and Salgia 2008). Suppression of EGFR, VEGFR, and c-Met led to inhibition of A549 cell proliferation in vitro and in vivo (Colon et al 2009;Kim et al 2008;Morelli et al 2006;Naumov et al 2009).…”