PT  - JOURNAL ARTICLE
AU  - Irene M. Sroka
AU  - Elke H. Heiss
AU  - Libor Havlicek
AU  - Frank Totzke
AU  - Yasmin Aristei
AU  - Paul Pechan
AU  - Michael H. G. Kubbutat
AU  - Miroslav Strnad
AU  - Verena M. Dirsch
TI  - A Novel Roscovitine Derivative Potently Induces G<sub>1</sub>-Phase Arrest in Platelet-Derived Growth Factor-BB-Activated Vascular Smooth Muscle Cells
AID  - 10.1124/mol.109.060327
DP  - 2010 Feb 01
TA  - Molecular Pharmacology
PG  - 255--261
VI  - 77
IP  - 2
4099  - http://molpharm.aspetjournals.org/content/77/2/255.short
4100  - http://molpharm.aspetjournals.org/content/77/2/255.full
SO  - Mol Pharmacol2010 Feb 01; 77
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.