title: Characterization of novel checkpoint kinase 1 inhibitors by in vitro assays and in human cancer cells treated with topoisomerase inhibitors.
abstract: OBJECTIVE
  We have developed biochemical and cell based assays to characterize small therapeutic molecules that inhibit the DNA damage checkpoint enzyme, Chk1 (Checkpoint kinase 1).
  
  
  METHODS
  To prepare a screen of large chemical libraries, we purified the full-length and the catalytic domain versions of human Chk1. We characterized their properties and then selected full-length Chk1 as the variant most suitable for screening. We then identified and characterized structurally different Chk1 inhibitors in cell based-assays by measuring cytotoxicity and checkpoint bypass activity.
  
  
  RESULTS
  We treated human cells with topoisomerase I inhibitors and demonstrated that at the time of Chk1 inhibitor addition, the cells have damaged DNA and activated Chk1. One Chk1 inhibitor, the indolocarbazole S27888, was active in the checkpoint bypass assay.
  
  
  CONCLUSIONS
  Knowing that the protein kinase inhibitory properties are different for each inhibitor, it seems that only a limited range of inhibitory activity is tolerated by cells. Chk1 has an essential role in determining how cancer cells respond to genotoxic treatments, therefore, inhibitors of this protein kinase are of great medical interest.
authors: Institut de Recherches Servier, Molecular and Cellular Pharmacology, 125 chemin de Ronde, 78290 Croissy-sur Seine, France.
authors: Gilles
authors: G
authors: Ferry
authors: Aurélie
authors: A
authors: Studeny
authors: Céline
authors: C
authors: Bossard
authors: Philip M
authors: PM
authors: Kubara
authors: Denis
authors: D
authors: Zeyer
authors: Jean-Paul
authors: JP
authors: Renaud
authors: Patrick
authors: P
authors: Casara
authors: Guillaume
authors: G
authors: de Nanteuil
authors: Michel
authors: M
authors: Wierzbicki
authors: Bruno
authors: B
authors: Pfeiffer
authors: Michelle
authors: M
authors: Prudhomme
authors: Stephane
authors: S
authors: Leonce
authors: Alain
authors: A
authors: Pierré
authors: Jean A
authors: JA
authors: Boutin
authors: Roy M
authors: RM
authors: Golsteyn
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera / Q000166:cytology; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology*
chemical_list: D002227:Carbazoles; D004273:DNA, Neoplasm; C561368:S 27888; D059004:Topoisomerase I Inhibitors; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1