Efficacy of cyclin-dependent-kinase 9 inhibitors in a murine model of mixed-lineage leukemia.
Mixed-lineage leukemia fusion proteins activate their target genes predominantly by stimulating transcriptional elongation. A core component necessary for this activity is cyclin-dependent kinase 9. Here we explored the effectiveness of small molecules targeting this enzyme as potential therapeutics. A screen of seven compounds with anti-CDK9 activity applied to a panel of leukemia cell lines identified flavopiridol and the experimental inhibitor PC585 as superior in efficacy with inhibitory concentrations in the submicromolar range. Both substances induced rapid dephosphorylation of the RNA polymerase II C-terminal domain, accompanied by downregulation of CDK9-dependent transcripts for MYC and HOXA9. Global gene expression analysis indicated the induction of a general stress response program, culminating in widespread apoptosis. Importantly, colony-forming activity in leukemia lines and primary patient samples could be completely inhibited under conditions that did not affect native precursors from bone marrow. In vivo application in a mouse transplant model significantly delayed disease with PC585 showing also oral activity. These results suggest CDK9 inhibition as novel treatment option for mixed-lineage leukemia.
Department of Genetics, University Erlangen, Erlangen, Germany.
M-P
MP
Garcia-Cuellar
Department of Genetics, University Erlangen, Erlangen, Germany.
E
E
Füller
Department of Genetics, University Erlangen, Erlangen, Germany.
E
E
Mäthner
Department of Genetics, University Erlangen, Erlangen, Germany.
C
C
Breitinger
Department of Genetics, University Erlangen, Erlangen, Germany.
K
K
Hetzner
Ingenium Pharmaceuticals AG, Munich, Germany.
L
L
Zeitlmann
Clinic of Paediatric Oncology, Haematology and Clinical Immunology, Centre for Child and Adolescent Health, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
A
A
Borkhardt
Department of Genetics, University Erlangen, Erlangen, Germany.
R K
0000000220289759
RK
Slany
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000235:genetics; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D015456:Leukemia, Biphenotypic, Acute / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012319:RNA Polymerase II / Q000378:metabolism; D014410:Tumor Stem Cell Assay; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II