Design,Synthesis And Anti-Tumor Activities Of Novel Small Molecule C-Met Kinase Inhibitors Bearing 4-Phenoxyquinoline Skeleton

The HGF/c-Met signal pathway,which exists widely in various kinds of cells,plays an important role in the growth of tissues and organs.However,the overexpression of HGF or c-Met usually leads to invasion and metastasis of tumor cells.Therefore,developing inhibitors of c-Met is a potential strategy for the treatment of human cancer.In this paper,we summarized the HGF,c-Met,the relationships between HGF/c-Met signal pathway and cancer,and recent developments in the discovery of small-molecule c-Met kinase inhibitors.Foretinib(XL880,GSK1363089),explored by Exelixis company,is a small molecule c-Met kinase inhibitor bearing 4-(2-fluorophenoxy)quinoline moiety.This compound,which is in Phase Ⅱ clinical trials,not only shows significant inhibition toward c-Met with an IC50 of 0.4 nM,but also exhibits strong inhibitory potency toward Ron,c-Kit,KDR and Flt-3 with IC50 values less than 10 nM.On the basis of summarizing the structural features and structure-activity relationships of Class Ⅱ c-Met inhibitors,taking Foretinib as the leading compound,three series of novel 4-(2-fluorophenoxy)quinoline derivatives were designed,in which the 4-(2-fluorophenoxy)quinoline framework was preserved,and substituted cinnolinone,quinolinone and 2-arylquinoline groups were introduced to the C-4 position of this framework,respectively.They include compounds bearing 1-aryl-4-oxo-1,4-dihydrocinnoline-3-carboxamide moiety(L-1～L-37),compounds bearing 1-aryl-4-oxo-1,4dihydroquinoline-3-carboxamide moiety(S-1～S-18),and compounds bearing 2-arylquinoline-4-carboxamide moiety(Y-1～Y-35).All the target compounds have not been reported in literatures and the chemical structures of all target compounds were confirmed by MS,1H NMR,and some were identified by 13C NMR and IR.The target compounds L-1～L-37 were evaluated for their antiproliferative activities on A549,H460,HT-29,MKN-45,U87 MG and SMMC-7721 cell lines by the MTT assay,using Foretinib as the positive control.Most compounds displayed moderate to strong antitumor activity,and higher selectivity against A549 and MKN-45 cells.In addition,33 of them were further screened for their c-Met activity by the Homogeneous Time Resolved Fluorescence(HTRF)assay,using c-Met inhibitor Foretinib as positive control.The results indicated that all of them showed obvious c-Met kinase inhibitory potency.Among them,the activity of compounds L-1、L-2、L-18、L-27 and L-28 was as excellent as Foretinib’s,with an IC50 value less than 2 nM.The antiproliferative activitiy of S-1～S-14 and Y-1～Y-35 was evaluated against H460,HT-29,MKN-45,U87 MG and SMMC-7721 cell lines by the MTT assay,using Foretinib as the positive control.Most compounds showed excellent potency and higher selectivity toward MKN-45 cells.7 more active compounds(S-2,S-5,S-9,Y-4,Y-5,Y-7 and Y-21)were further screened for their c-Met activity by the HTRF assay.The testing results indicated that they had strong c-Met inhibitory effect with IC50 values less than 10 nM,and deserved further research.The most promising compound L-18 was further evaluated for its inhibition toward c-Kit Flt-3,VEGFR-2,PDGF and EGFR kinases.The pharmacological data revealed that compound L-18 possessed obvious inhibition toward c-Kit,Flt-3,VEGFR-2 and PDGFR with IC50 values less than 30 nM,but no effect against EGFR.In addition,the binding mode of compound L-18 with c-Met displayed that this compound could form three hydrongen bonds with amino acid residues Lys58,Asp170 and Met108,respectively.Moreover,the Western-Blot assay of compound L-18 on A549 cell line revealed that this compound could inhibit p-c-Met obviously at a concentration of 2.5μg/mL,In the meanwhile,the Flow cytometric analysis suggested that compound L-18 could arrest the cell cycle at G2/M phase.The structure-activity relationships of these compounds were discussed,which would provide useful information for further study in this field.