Transient vs. prolonged histone hyperacetylation: effects on colon cancer cell growth, differentiation, and apoptosis.
The role of histone hyperacetylation in regard to growth, differentiation, and apoptosis in colon cancer cells was assessed in an in vitro model system. HT-29 cells were grown in +/-10% fetal bovine serum with either 5 mM sodium butyrate or 0.3 microM trichostatin A [single dose (T) or 3 doses 8 h apart (TR)] for 24 h. Serum-starved HT-29 cells were further treated with epidermal growth factor or insulin-like growth factor I for an additional 24 h. Apoptosis was quantified with propidium iodide and characterized by electron microscopy. Northern blot analyses were performed with cDNA probes specific for intestinal alkaline phosphatase, Na-K-2Cl cotransporter, the cell cycle inhibitor p21, and the actin control. Flow cytometric analysis revealed a time-dependent growth suppression along with early induction of p21 mRNA in the butyrate, T, and TR groups. Histone hyperacetylation, assessed by acid-urea-triton gel electrophoresis, was transient in the T group but persisted for up to 24 h in the butyrate and TR groups. Induction of apoptosis, growth factor unresponsiveness, and differentiation occurred in the butyrate- and TR-treated cells but not those treated with a single dose of trichostatin A. Thus transient hyperacetylation of histones is sufficient to induce p21 expression and produce cellular growth arrest, but prolonged histone hyperacetylation is required for induction of the programs of differentiation, apoptosis, and growth factor unresponsiveness.
Wu
J T
JT
Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
Archer
S Y
SY
Hinnebusch
B
B
Meng
S
S
Hodin
R A
RA
D000107:Acetylation / Q000187:drug effects; D000199:Actins / Q000235:genetics / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D015152:Blotting, Northern; D002087:Butyrates / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005434:Flow Cytometry; D019073:HT29 Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters; D014407:Tumor Cells, Cultured
D000199:Actins; D002087:Butyrates; C493956:CDKN1A protein, human; D002352:Carrier Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D006657:Histones; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D028021:Sodium-Potassium-Chloride Symporters; C012589:trichostatin A; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D000469:Alkaline Phosphatase