The effects of the CDK inhibitor seliciclib alone or in combination with cisplatin in human uterine sarcoma cell lines.
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.
Coley
Helen M
HM
Postgraduate Medical School, Room 26PGM02, Daphne Jackson Road, Manor Park, University of Surrey, Guildford, Surrey GU2 7WG, UK. h.coley@surrey.ac.uk
Shotton
Christine F
CF
Kokkinos
Maria I
MI
Thomas
Hilary
H
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
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