RT Journal Article SR Electronic T1 A Novel Roscovitine Derivative Potently Induces G1-Phase Arrest in Platelet-Derived Growth Factor-BB-Activated Vascular Smooth Muscle Cells JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 255 OP 261 DO 10.1124/mol.109.060327 VO 77 IS 2 A1 Irene M. Sroka A1 Elke H. Heiss A1 Libor Havlicek A1 Frank Totzke A1 Yasmin Aristei A1 Paul Pechan A1 Michael H. G. Kubbutat A1 Miroslav Strnad A1 Verena M. Dirsch YR 2010 UL http://molpharm.aspetjournals.org/content/77/2/255.abstract AB Abnormal vascular smooth muscle cell (VSMC) proliferation contributes to the pathogenesis of restenosis. Thus, drugs interfering with cell cycle progression in VSMC are promising candidates for an antirestenotic therapy. In this study, we pharmacologically characterize N-5-(2-aminocyclohexyl)-N-7-benzyl-3-isopropyl-1(2)H-pyrazolo[4,3-d]pyrimidine-5,7-di-amine (LGR1406), a novel derivative of the cyclin-dependent kinase (CDK) inhibitor roscovitine (ROSC), in PDGF-BB-activated VSMC. Cell proliferation was quantified measuring DNA synthesis via 5-bromo-2′-deoxyuridine incorporation. Analysis of cell cycle distribution was done by flow cytometry using propidium iodide-stained nuclei. Key regulators of the cell cycle and relevant signaling pathways were dissected by Western blot analyses. In addition, in vitro kinase assays and in silico studies regarding the pharmacokinetic profile of both compounds were performed. LGR1406 shows a stronger (IC50 = 3.0 μM) antiproliferative activity than ROSC (IC50 = 16.9 μM), halting VSMCs in G0/G1 phase of the cell cycle, whereas ROSC does not arrest but rather delays cell cycle progression. Neither of the compounds interferes with early PDGF-BB-induced signaling pathways (p38, extracellular signal-regulated kinase 1/2, c-Jun NH2-terminal kinase, Akt, signal transducer and activator of transcription 3), and both inhibit CDKs, with LGR1406 exerting a slightly higher potency against CDK1/2 and 4 than ROSC. Expression of cyclins A and E as well as hyperphosphorylation of the pocket proteins retinoblastoma protein and p107 are negatively affected by both compounds, although to a different extent. In silico calculations predicted a much higher metabolic stability for LGR1406 compared with ROSC. Altogether, ROSC derivatives, such as LGR1406 seem to be promising compounds for further development in antirestenotic therapy.