title: AT7519, a cyclin-dependent kinase inhibitor, exerts its effects by transcriptional inhibition in leukemia cell lines and patient samples.
abstract: AT7519 is a potent inhibitor of several cyclin-dependent kinases and is currently in early phase clinical development. Recently, cyclin-dependent kinases 7, 8, and 9 have been shown to regulate transcription through phosphorylation of RNA polymerase II. B-cell lymphoproliferative disorders, including chronic lymphocytic leukemia, rely on the expression of transcripts with a short half-life, such as Mcl-1, Bcl-2, and XIAP, for survival. Here, we describe the characterization of AT7519 in leukemia cell lines, and compare and contrast the response in cell lines derived from solid tumors. Finally, we use these mechanistic insights to show activity in peripheral blood mononuclear cells isolated from 16 chronic lymphocytic leukemia patients. AT7519 induced apoptosis at concentrations of 100 to 700 nmol/L and was equally effective regardless of Rai stage or known prognostic markers. Short-term treatments (4-6 hours) resulted in inhibition of phosphorylation of the transcriptional marker RNA polymerase II and downregulation of the antiapoptotic protein Mcl-1, with no effect on either XIAP or Bcl-2 levels. The reduction in Mcl-1 protein level was associated with an increase in cleaved poly(ADP-ribose) polymerase. Together the data suggest AT7519 offers a promising treatment for patients with advanced B-cell leukemia. Mol Cancer Ther; 9(4); 920-8. (c)2010 AACR.
authors.affiliation: Astex Therapeutics Ltd, 436 Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom. m.squires@astex-therapeutics.com
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Squires
authors.forename: Laurence
authors.initials: L
authors.lastname: Cooke
authors.forename: Victoria
authors.initials: V
authors.lastname: Lock
authors.forename: Wenqing
authors.initials: W
authors.lastname: Qi
authors.forename: E Jonathan
authors.initials: EJ
authors.lastname: Lewis
authors.forename: Neil T
authors.initials: NT
authors.lastname: Thompson
authors.forename: John F
authors.initials: JF
authors.lastname: Lyons
authors.forename: Daruka
authors.initials: D
authors.lastname: Mahadevan
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007938:Leukemia / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D010880:Piperidines / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays
chemical_list: C531230:4-(2,6-dichlorobenzoylamino)-1H-pyrazole-3-carboxylic acid piperidin-4-ylamide; D051017:Apoptosis Regulatory Proteins; D010880:Piperidines; D011720:Pyrazoles; D018844:Cyclin-Dependent Kinases; D012319:RNA Polymerase II