title: Histone deacetylase inhibition-mediated post-translational elevation of p27KIP1 protein levels is required for G1 arrest in fibroblasts.
abstract: Butyrate, a non-toxic short-chain fatty acid (SCFA) and inhibitor of histone deacetylase (HDAC), has potential as an anti-tumor agent because it imposes a reversible G1 block in normal cells yet induces apoptosis in tumor lines. As a potent reactivator of fetal globin transcription, butyrate is used clinically in the treatment of hemoglobinopathies. The anti-proliferative effect of butyrate and its derivatives on in vivo erythroid cell maturation, however, has limited their utility. The molecular mechanisms underlying the G1 arrest induced by butyrate and related SCFAs remain unclear. One model, drawing on tumor cell data, proposes that HDAC inhibition and subsequent transcriptional induction of cyclin-dependent kinase inhibitor (CKI) p21CIP are required. However, because of potentially confounding genetic mutations present in tumor models, we examined SCFA effects on CKIs in a non-transformed growth control model. Using murine 3T3 fibroblasts, we find p27KIP1 is also strongly induced. Unlike previously described effects of butyrate and HDAC inhibition on p21CIP, p27KIP1 induction did not occur at the transcriptional level; instead, the stability of the p27KIP1 protein increased. Other structurally unrelated HDAC inhibitors, including trichostatin A (TSA), induced p27KIP1 similarly. p27KIP1 was found in cyclin E/Cdk2 complexes, concomitant with suppression of cdk2 activity. Elevation of p27KIP1 is required for the observed G1 blockade, as p27KIP1-deficient fibroblasts were resistant to HDAC inhibition-induced arrest. These data suggest a novel activity for HDAC inhibitors and demonstrate a critical role for p27KIP1 in mediating G1 arrest in response to these drugs.
authors.affiliation: Cancer Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Chen
authors.forename: Douglas V
authors.initials: DV
authors.lastname: Faller
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D002087:Butyrates / Q000494:pharmacology; D042846:CDC2-CDC28 Kinases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004791:Enzyme Inhibitors / Q000494:pharmacology; D025461:Feedback, Physiological / Q000187:drug effects / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D016193:G1 Phase / Q000235:genetics*; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000494:pharmacology; D051379:Mice; D041681:NIH 3T3 Cells; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D002087:Butyrates; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D019927:Cyclin E; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; C012589:trichostatin A; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D006655:Histone Deacetylases