Induction of apoptosis in human leukemia cells by the CDK1 inhibitor CGP74514A.
We have examined the effects of the CDK1 inhibitor CGP74514A on cell cycle- and apoptosis-related events in human leukemia cells. An 18-hr exposure to 5 microM CGP74514A induced mitochondrial damage (i.e., loss of Delta psi(m)) and apoptosis in multiple human leukemia cell lines (e.g., U937, HL-60, KG-1, CCRF-CEM, Raji, and THP; range 30-95%). In U937 cells, CGP74514A- induced apoptosis (5 microM) became apparent within 4 hr and approached 100% by 24 hr. The pan- caspase inhibitor Boc-fmk and the caspase-8 inhibitor lETD-fmk opposed CGP74514A-induced caspase-9 activation and PARP degradation, but not cytochrome c or Smac/DIABLO release. CGP74514A-mediated apoptosis was substantially blocked by ectopic expression of full-length Bel- 2, a loop-deleted mutant Bcl-2, and Bcl-x(L). CGP74514A treatment (5 microM; 18 hr) resulted in increased p21(CIP1) expression, p27(KIP1) degradation, diminished E2F1 expression, and dephosphorylation of p34(CDC2). It also induced early (i.e., within 2 hr) inhibition of CDK1 activity and dephosphorylation of pRb, followed by pRb degradation, but did not block pRb phosphorylation at CDK2- and CDK4- specific sites. These findings indicate that the selective CDK1 inhibitor, CGP74514A, induces complex changes in cell cycle-related proteins in human leukemia cells accompanied by extensive mitochondrial damage, caspase activation, and apoptosis.
Dai
Yun
Y
Departments of Medicine, Medical College of Virginia; Virginia Commonwealth University; Richmond, Virginia 23298, USA.
Dent
Paul
P
Grant
Steven
S
D015075:2-Aminopurine / Q000031:analogs & derivatives / Q000494:pharmacology*; D017209:Apoptosis; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D051358:Cyclin-Dependent Kinase 4; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D015843:Serpins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D020298:U937 Cells; D014764:Viral Proteins; D048051:p38 Mitogen-Activated Protein Kinases
C493956:CDKN1A protein, human; D061945:Caspase Inhibitors; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C469937:N(2)-(2-aminocyclohexyl)-N(6)-(3-chlorophenyl)-9-ethyl-9H-purine-2,6-diamine; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016160:Retinoblastoma Protein; D015843:Serpins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014764:Viral Proteins; C425644:isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; D050760:Cyclin-Dependent Kinase Inhibitor p27; D015075:2-Aminopurine; C074641:interleukin-1beta-converting enzyme inhibitor; D016203:CDC2 Protein Kinase; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9