Pro-apoptotic activity of oncogenic H-Ras for histone deacetylase inhibitor to induce apoptosis of human cancer HT29 cells.
OBJECTIVE
To verify the pro-apoptotic activity of oncogenic H-Ras in the increased susceptibility of human cancer cells to histone deacetylase inhibitor (HDACI).


METHODS
The pro-apoptotic activity of oncogenic H-Ras(V12) was verified by its ability to increase susceptibility of human colorectal adenocarcinoma HT29 cells to HDACI for inducing apoptosis and growth inhibition, assayed by various methods. The mode of action of HDACI FR901228 was studied by its ability to modulate protein phosphorylation, acetylation, and expression levels in various signaling pathways, measured by Western blot analysis.


RESULTS
Activation of caspase-3, -7, and -8, and serine protease by FR901228 was facilitated by oncogenic H-Ras to induce apoptosis. Expression of H-Ras(V12) changed the intrinsic modulation of Raf in cells responding to FR901228 treatment. Both p21( Cip1 ) and p27( Kip1 ) were induced in FR901228-treated cells arrested in either the G0/G1 or G2/M phase of the cell cycle. Deacetylation of FR901228-induced acetylation of core histones was accelerated by H-Ras(V12) in cells undergoing apoptosis.


CONCLUSIONS
Expression of H-Ras(V12) increased susceptibility of HT29 cells to HDACI FR901228 and Trichostatin A for inducing apoptosis. The pro-apoptotic activity of H-Ras(V12) responding to HDACI indicates a potential value of this new class of anticancer agents in treating Ras-related human cancers.
Choudhary
Shambhunath
S
Department of Pathobiology, College of Veterinary Medicine, The University of Tennessee, 2407 River Drive, Knoxville, TN 37996, USA.
Wang
Hwa-Chain Robert
HC
D000107:Acetylation / Q000187:drug effects; D000230:Adenocarcinoma / Q000473:pathology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000473:pathology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000187:drug effects / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000187:drug effects / Q000378:metabolism; D047630:Depsipeptides / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D011905:Genes, ras / Q000502:physiology*; D019073:HT29 Cells; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000187:drug effects; D006801:Humans; D012697:Serine Endopeptidases / Q000187:drug effects / Q000378:metabolism; D014162:Transfection
D000903:Antibiotics, Antineoplastic; D050759:Cyclin-Dependent Kinase Inhibitor p21; D047630:Depsipeptides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D050760:Cyclin-Dependent Kinase Inhibitor p27; C087123:romidepsin; D012697:Serine Endopeptidases; D020169:Caspases