title: Trisubstituted pyrazolopyrimidines as novel angiogenesis inhibitors.
abstract: Current inhibitors of angiogenesis comprise either therapeutic antibodies (e.g. bevacicumab binding to VEGF-A) or small molecular inhibitors of receptor tyrosin kinases like e.g. sunitinib, which inhibits PDGFR and VEGFR. We have recently identified cyclin-dependent kinase 5 (Cdk5) as novel alternative and pharmacologically accessible target in the context of angiogenesis. In the present work we demonstrate that trisubstituted pyrazolo[4,3-d]pyrimidines constitute a novel class of compounds which potently inhibit angiogenesis. All seven tested compounds inhibited endothelial cell proliferation with IC(50) values between 1 and 18 µM. Interestingly, this seems not to be due to cytotoxicity, since none of them showed acute cytotoxic effects on endothelial cells at a concentration of 10 µM,. The three most potent compounds (LGR1404, LGR1406 and LGR1407) also inhibited cell migration (by 27, 51 and 31%, resp.), chemotaxis (by 50, 70 and 60% in accumulative distance, resp.), and tube formation (by 25, 60 and 30% of total tube length, resp.) at the non-toxic concentration of 10 µM. Furthermore, angiogenesis was reduced in vivo in the CAM assay by these three compounds. A kinase selectivity profiling revealed that the compounds prevalently inhibit Cdk2, Cdk5 and Cdk9. The phenotype of the migrating cells (reduced formation of lamellipodia, loss of Rac-1 translocation to the membrane) resembles the previously described effects of silencing of Cdk5 in endothelial cells. We conclude that especially LGR1406 and LGR1407 are highly attractive anti-angiogenic compounds, whose effects seem to largely depend on their Cdk5 inhibiting properties.
authors: Department of Pharmacy, Ludwig-Maximilians-University, Munich, Germany.
authors: Sabine B
authors: SB
authors: Weitensteiner
authors: Johanna
authors: J
authors: Liebl
authors: Vladimir
authors: V
authors: Krystof
authors: Libor
authors: L
authors: Havlíček
authors: Tomáš
authors: T
authors: Gucký
authors: Miroslav
authors: M
authors: Strnad
authors: Robert
authors: R
authors: Fürst
authors: Angelika M
authors: AM
authors: Vollmar
authors: Stefan
authors: S
authors: Zahler
mesh_terms: D020533:Angiogenesis Inhibitors / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D016923:Cell Death / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D021381:Protein Transport / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D011743:Pyrimidines / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; C014175:pyrazolo(3,4-d)pyrimidine; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases; D020830:rac1 GTP-Binding Protein