Cabozantinib and Tivantinib, but Not INC280, Induce Antiproliferative and Antimigratory Effects in Human Neuroendocrine Tumor Cells in vitro: Evidence for ‘Off-Target' Effects Not Mediated by c-Met Inhibition

Abstract

Background/Aims: The hepatocyte growth factor/transmembrane tyrosine kinase receptor c-Met has been defined as a potential target in antitumoral treatment of various carcinomas. We aimed to investigate the direct effect of c-Met inhibition on neuroendocrine tumor cells in vitro. Methods: The effects of the multi-tyrosine kinase inhibitors cabozantinib and tivantinib and of the highly specific c-Met inhibitor INC280 were investigated in human pancreatic neuroendocrine BON1, bronchopulmonary NCI-H727 and midgut GOT1 cells in vitro. Results: INC280, cabozantinib and tivantinib inhibited c-Met phosphorylation, respectively. However, while equimolar concentrations (10 μ<smlcap>M</smlcap>) of cabozantinib and tivantinib inhibited cell viability and cell migration, INC280 had no inhibitory effect. Knockdown experiments with c-Met siRNA also did not demonstrate effects on cell viability. Cabozantinib and tivantinib caused a G2 arrest in neuroendocrine tumor cells. Conclusions: Our in vitro data suggest that c-Met inhibition alone is not sufficient to exert direct antitumoral or antimigratory effects in neuroendocrine tumor cells. The multi-tyrosine kinase inhibitors cabozantinib and tivantinib show promising antitumoral and antimigratory effects in neuroendocrine tumor cells, which are most probably ‘off-target' effects, not mediated by c-Met.

Proliferation Markers Are Associated with MET Expression in Hepatocellular Carcinoma and Predict Tivantinib Sensitivity In Vitro

“…Initially, tivantinib was identified as an MET inhibitor in a kinase assay (5), but subsequent work showed that it was able to bind only to the inactive unphosphorylated-MET and has no direct effect on the MET kinase activity (26). Next, several studies (5,(27)(28)(29)(30), performed in cellulo, have shown a decreased phosphorylation of MET after a long-time exposure (24 hours) to tivantinib contrasting with our results and others that were obtained with a short-time (4-6 hours) exposure in hepatocellular or other types of tumor cells (11)(12)(13). Indeed, after 24 hours of tivantinib exposure, a decrease in both phospho-and total MET proteins was shown by Western blot analysis in most of the cell models (27)(28)(29).…”

The MTH1 inhibitor TH588 demonstrates anti-tumoral effects alone and in combination with everolimus, 5-FU and gamma-irradiation in neuroendocrine tumor cells

“…Then medium was replaced by fresh medium and cells were incubated with different concentrations of TH588 (5 μM and 10 μM), either alone or in combination with 5-FU (5 μM) or everolimus (10 nM). The incubation times were up to 96 h. Western blotting was conducted as described previously [23]. The following primary antibodies used were: pAKT (Ser473) (#4060), AKT (#2920), pERK1/2 (Thr202/Tyr204) (#4370), p4EBP1 (Ser65) (#9451), 4EBP1 (#9644), pRb (Ser780) (#9307), pCDK1 (Tyr15) (#4539), CDK1 (#9116), Cyclin B1 (#12231), Cyclin D1 (# 2926), Cyclin D3 (#2936), CDK4 (#12790), CDK6 (#13331), Chk1 (#2360), pChk2 (Ser19) (#2666), pChk2 (Thr68) (#6334), Chk2 (#6334), Parp (#9542), PCNA (#2586) (all from CellSignaling, Danvers, USA), p16 INK4A (ab151303) (abcam, Cambridge, UK), Rb (#614602) (Biolegend, San Diego, USA), Actin (A5441) (Sigma, St.Louis, USA), ERK1/2 (06–182) (Merck-Millipore, Darmstadt, Germany).…”

Emerging multitarget tyrosine kinase inhibitors in the treatment of neuroendocrine neoplasms

“…Its kinase-inhibiting profile was reported to affect in vitro proliferation and migration of human NEN cell lines (pancreatic BON1, bronchopulmonary NCI-H727 and midgut GOT1 cells), causing arrest in the G2 phase of cell cycle (Reuther et al 2016). In vivo, using RIP1-Tag2 transgenic mice, cabozantinib reduced not only pancreatic tumor burden but also invasion and metastasis, an effect related to the simultaneous inhibition of c-MET and VEGF signaling (Sennino et al 2012).…”