The synthesis and biological evaluation of novel 1-aryl-3-[2-, 3- or 4-(thieno[3,2-b]pyridin-7-ylthio)phenyl]ureas 3, 4 and 5 as VEGFR-2 tyrosine kinase inhibitors, are reported. The 1-aryl-3-[3-(thieno[3,2-b]pyridin-7-ylthio)phenyl]ureas 4a-4h, with the arylurea in the meta position to the thioether, showed the lowest IC₅₀ values in enzymatic assays (10-206 nM), the most potent compounds 4d-4h (IC₅₀ 10-28 nM) bearing hydrophobic groups (Me, F, CF₃ and Cl) in the terminal phenyl ring. A convincing rationalization was achieved for the highest potent compounds 4 as type II VEGFR-2 inhibitors, based on the simultaneous presence of: (1) the thioether linker and (2) the arylurea moiety in the meta position. For compounds 4, significant inhibition of Human Umbilical Vein Endothelial Cells (HUVECs) proliferation (BrdU assay), migration (wound-healing assay) and tube formation were observed at low concentrations. These compounds have also shown to increase apoptosis using the TUNEL assay. Immunostaining for total and phosphorylated (active) VEGFR-2 was performed by Western blotting. The phosphorylation of the receptor was significantly inhibited at 1.0 and 2.5 μM for the most promising compounds. Altogether, these findings point to an antiangiogenic effect in HUVECs.

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New fluorescent methoxylated di(hetero)arylethers in the thieno [3,2-b]pyridine series were prepared by a copper-catalyzed Ullmann-type C-O coupling of the methyl 3-amino-6-bromothieno[3,2b]pyridine-2-carboxylate with ortho, meta and para-methoxyphenols, using N,N-dimethylglycine as the ligand and Cs 2 CO 3 as the base. The compounds obtained were tested for their inhibitory growth activity in three human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer). The di(hetero)arylethers bearing a methoxy group in the ortho and meta positions showed very low GI 50 values (1.1−2.5 µM) in all the three tumor cell lines. Their fluorescence properties in solution and when encapsulated in different nanoliposome formulations, composed either by egg-yolk phosphatidylcholine (Egg-PC), dipalmitoyl phosphatidylcholine (DPPC), dimyristoyl phosphatidylglycerol (DMPG), dioctadecyldimethylammonium bromide (DODAB), distearoyl phosphatidylcholine (DSPC), with or without cholesterol (Ch), or distearoyl phosphatidylethanolamine-(polyethylene glycol)2000 (DSPE-PEG), were studied. All compounds can be carried in the hydrophobic region of the liposome membrane. The liposomes with incorporated compounds are nanometric in size (diameter lower than 150 nm) and have generally low polydispersity.

Breast cancer is the most frequently diagnosed cancer and the second leading cause of cancer related deaths among women worldwide. The purpose of this study is to evaluate the cytotoxic effects and possible molecular mechanisms of the antiproliferative properties of the antiangiogenic 1-aryl-3-[3-(thieno[3,2-b]pyridin-7-ylthio)phenyl]ureas 1a-e, prepared earlier by us, on two human breast cancer cell lines of distinct histological types: hormone-dependent MCF-7 (ER positive), and hormone independent MDA-MB-231 (ER/PR/HER2 negative), this latter being the most aggressive and difficult to treat. Our findings clearly demonstrated that compounds 1a-e suppress breast cancer cell survival, proliferation, migration, and colony formation at very low concentrations, not showing cytotoxicity in normal human mammary cells (MCF-10A). TUNEL assay demonstrated that compounds 1a-e induced apoptosis in MDA-MB-231, but not in MCF-7 at the concentrations tested. PI3K/Akt and MAPK/Erk cell signaling pathways were investigated using Western blot analysis, revealing that these compounds decrease their activity in both breast cancer cell lines. Compounds 1b (R = F), 1c (R = Me), and 1e (R = Cl, R = CF ) were the most effective particularly in MDA-MB-231 cells. Overall, 1c and 1e compounds are the most promising antitumor compounds. These findings, together with the antiangiogenic activity previously described by us, render these compounds a relevant breakthrough for cancer therapy. J. Cell. Biochem. 117: 2791-2799, 2016. © 2016 Wiley Periodicals, Inc.