Oncostatin M and interleukin 6 inhibit cell cycle progression by prevention of p27kip1 degradation in HepG2 cells.
We analysed the regulation of G1-phase progression in relation to cytokine receptor signalling in HepG2 hepatoma cells, stably transduced with the IL-10 receptor after stimulation with Oncostatin M (OSM), IL-6, Leukaemia Inhibitory Factor (LIF) and IL-10. All cytokines induced STAT3 phosphorylation to approximately the same level, but only OSM, and to a lesser extent IL-6, induced STAT5 phosphorylation. The cytokines also stimulated phosphorylation of ERK in the order of decreasing effectiveness: OSM > IL-6 > LIF > IL-10. The same order of activity of the cytokines was observed on inhibition of DNA synthesis and accumulation of cells in the G1-phase of the cell cycle. These processes were accompanied by a decrease in cyclin A expression and CDK2 activity, and enhanced accumulation of p27kip1. The level of p27kip1 mRNA expression was unaffected by the cytokines, and maintenance of the elevated level of p27kip1 occurred independently of de novo protein synthesis. Furthermore, inhibition of proteasomal activity increased the level of p27kip1 in the unstimulated cells to the same level as in OSM-treated cells. Inhibition of MEK activation completely abrogated OSM and IL-6 induced p27kip1 accumulation, while expression of dominant negative STAT5 decreased the OSM and IL-6 mediated inhibition of DNA-synthesis and partially inhibited p27kip1 accumulation.
Klausen
P
P
Department of Haematology, The Finsen Centre, Rigshospitalet, Copenhagen, Denmark.
Pedersen
L
L
Jurlander
J
J
Baumann
H
H
D000818:Animals; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D051357:Cyclin-Dependent Kinase 2; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D016207:Cytokines / Q000378:metabolism* / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism; D006131:Growth Inhibitors / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism* / Q000494:pharmacology; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000378:metabolism / Q000494:pharmacology; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008894:Milk Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053683:Oncostatin M; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D051381:Rats; D018123:Receptors, Interleukin / Q000235:genetics / Q000378:metabolism; D053701:Receptors, Interleukin-10; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D015854:Up-Regulation
C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D016207:Cytokines; D004268:DNA-Binding Proteins; D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines; D008869:Microtubule-Associated Proteins; D008894:Milk Proteins; C508351:OSM protein, human; D010455:Peptides; D018123:Receptors, Interleukin; D053701:Receptors, Interleukin-10; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D053683:Oncostatin M; D016753:Interleukin-10; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004247:DNA; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D020928:Mitogen-Activated Protein Kinases