LBA3Novel pyrazolopyrimidine derivatives inhibit angiogenesis and tumor growth in a mouse Lewis lung carcinoma model

ABSTRACT Background: Vascular endothelial growth factor receptors (VEGFR) are tyrosine kinases (TK) known to promote angiogenesis and cancer. Since quinazoline and pyridopyrimidine derivatives have been proved to be potent and highly selective TK inhibitors, in this work we aimed to synthesize novel substituted pyrazolopyridines and explore their capability to modulate angiogenesis and tumor growth. Materials and methods: Pyrazolopyridine derivatives were synthesized using 2-amino-5-nitro-4-picoline as starting material, which upon suitable transformations was converted to 5-chloropyrazolo[3,4-c]pyridine. A 4-methoxybenzyl group was inserted at N1 of the heterocyclic ring system followed by a subsequent addition of a 3-phenyl group in certain derivatives. A second chlorine atom was introduced at position 7 via N-oxide metathesis and then 5- and 7-chlorine atoms were successively displaced by suitable amines. Twelve derivatives were isolated pure and their structure identified using 1D and 2D NMR and mass spectrometry. Compounds were assessed for their ability to modulate basal and/or VEGF-induced endothelial cell proliferation, migration and differentiation using MTT, transwell and matrigel tube-formation assays [ 1 ], respectively. The effect of active compounds on VEGFR2 signaling was determined by immunoblotting. In vivo activity was evaluated on a syngeneic Lewis lung carcinoma (LLC) transplantation mouse model [ 2 ] Results: Amongst test compounds, four (SC1117, SC1119, SC1123, SC1124) significantly inhibited at a concentration-dependent manner (0.2–2 µM), crucial pro-angiogenic attributes of endothelial cells related to proliferation, migration and differentiation capabilities, in part by targeting pathways downstream of VEGFR2. Moreover i.p. administration of SC1117, SC1119 and SC1124 (0.05-0.2 mg/kg body weight thrice/week, for 2 weeks) significantly reduced LLC tumor volume in mice without toxicity. Conclusions: We described three novel pyrazolopyrimidine derivatives targeting VEGFR2 as potential inhibitors of angiogenesis and tumor growth.