title: The effects of the CDK inhibitor seliciclib alone or in combination with cisplatin in human uterine sarcoma cell lines.
abstract: OBJECTIVE
  Inhibition of cyclin-dependent-kinases (CDKs) represents an interesting approach in cancer therapy. We have explored this in cell lines of human uterine sarcoma-tumours associated with poor survival, chemo-unresponsiveness and deregulation of cell cycle components. We studied the effects of the CDK inhibitor seliciclib (CYC202, R-roscovitine) when used alone or in combination with cisplatin.
  
  
  METHODS
  Cell lines used: SK-UT-1, SK-UT-1b and SK-LMS-1, the cytotoxicity of seliciclib and cisplatin was measured by the MTT assay. In combination with cisplatin the effects of seliciclib were examined by isobologram analysis. CDK2 levels were examined at mRNA and protein level by immunoblotting and PCR. We also looked at the effects of seliciclib on p53-dependent response of cells to seliciclib using immunoblotting. The effects of combination treatment were analysed using annexin V and PI staining by flow cytometric analysis.
  
  
  RESULTS
  IC50 values for seliciclib were 10.5, 7.1 and 25.7 microM, for SK-UT-1, SK-UT-1b and SK-LMS-1 respectively, P53 in the SK-UT-1b (wild-type) and SK-LMS-1 lines (mutant) showed a wild-type response with induction seen with seliciclib treatment for 24 and 48 h. Seliciclib caused a decrease in CDK2 mRNA and protein over 72 h. A combination of cisplatin and seliciclib was synergistic in all three cell lines. Effects of combination treatment were an enhancement in apoptosis as judged by the emergence of a sub-G1 population in cell cycle analysis and a sub-G1 population with PI staining.
  
  
  CONCLUSIONS
  Our data demonstrate the effectiveness of seliciclib as a single agent and when used in combination with cisplatin where the effects are synergistic.
authors.affiliation: Postgraduate Medical School, Room 26PGM02, Daphne Jackson Road, Manor Park, University of Surrey, Guildford, Surrey GU2 7WG, UK. h.coley@surrey.ac.uk
authors.forename: Helen M
authors.initials: HM
authors.lastname: Coley
authors.forename: Christine F
authors.initials: CF
authors.lastname: Shotton
authors.forename: Maria I
authors.initials: MI
authors.lastname: Kokkinos
authors.forename: Hilary
authors.initials: H
authors.lastname: Thomas
mesh_terms: D017304:Annexin A5; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002945:Cisplatin / Q000008:administration & dosage; D051357:Cyclin-Dependent Kinase 2 / Q000096:biosynthesis / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D011687:Purines / Q000008:administration & dosage / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D000077546:Roscovitine; D012509:Sarcoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015533:Transcriptional Activation; D014594:Uterine Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D017304:Annexin A5; C493956:CDKN1A protein, human; C436291:CDKN1B protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D011687:Purines; D012333:RNA, Messenger; D000077546:Roscovitine; D050760:Cyclin-Dependent Kinase Inhibitor p27; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D002945:Cisplatin