title: Anti-angiogenic effects of novel cyclin-dependent kinase inhibitors with a pyrazolo[4,3-d]pyrimidine scaffold.
abstract: Cyclin-dependent kinase 5 (CDK5) has recently emerged as an attractive target in several tumour entities. Inhibition of CDK5 has been shown to have anti-angiogenic effects in vitro and in vivo. However, potent inhibitors of CDK5, which can be applied in vivo, are still scarce. We have recently developed a new series of 5-substituted 3-isopropyl-7-[4-(2-pyridyl)benzyl]amino-1(2)H-pyrazolo[4,3-d]pyrimidines that show a preference for inhibiting CDK5 and tested them in vitro and in vivo in a murine model of hepatocellular carcinoma.
  
  
  
  All compounds were initially examined for effects on proliferation of HUVECs. The most potent compounds were then tested on migration, and one of them, LGR2674, was selected for assessing effects on nuclear fragmentation, cell cycle, cell viability and metabolic activity. Furthermore, LGR2674 was tested in a tube formation assay and in vivo in a murine model of hepatocellular carcinoma, induced by s.c. injection of HUH7 cells (measurement of in vivo toxicity, tumour vascularization, tumour cell proliferation and tumour size).
  
  
  
  LGR2674 showed an EC50 in the low nanomolar range in the proliferation and migration assays. Cytotoxic effects started at 50 nM, a concentration that did not influence the cell cycle. In vivo, LGR2674 was well tolerated and caused a clear reduction in vessel density in the tumours; also tumour cell proliferation was inhibited and tumour growth retarded.
  
  
  
  Pyrazolo[4,3-d]pyrimidine is a novel scaffold for the development of potent CDK inhibitors with in vivo potential. Such structures are good candidates for broadening our pharmacological arsenal against various tumours.
authors.affiliation: Chair of Pharmaceutical Biology, Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Chair of Pharmaceutical Biology, Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ulrich
authors.affiliation: Chair of Pharmaceutical Biology, Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Gromnicka
authors.affiliation: Isotope laboratory, Institute of Experimental Botany ASCR, Prague, Czech Republic.
authors.forename: L
authors.initials: L
authors.lastname: Havlíček
authors.affiliation: Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany AS CR, Olomouc, Czech Republic.
authors.forename: V
authors.initials: V
authors.lastname: Kryštof
authors.affiliation: Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany AS CR, Olomouc, Czech Republic.
authors.forename: R
authors.initials: R
authors.lastname: Jorda
authors.affiliation: Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany AS CR, Olomouc, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Strnad
authors.affiliation: Chair of Pharmaceutical Biology, Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: A M
authors.initials: AM
authors.lastname: Vollmar
authors.affiliation: Chair of Pharmaceutical Biology, Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Zahler
mesh_terms: D020533:Angiogenesis Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy / Q000473:pathology; D051379:Mice; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011743:Pyrimidines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D011720:Pyrazoles; D011743:Pyrimidines; C014175:pyrazolo(3,4-d)pyrimidine; D051360:Cyclin-Dependent Kinase 5; C495905:CDK5 protein, human