Sodium phenylbutyrate induces apoptosis in human retinoblastoma Y79 cells: the effect of combined treatment with the topoisomerase I-inhibitor topotecan.
Our results demonstrate that sodium phenylbutyrate, a compound with a low degree of toxicity, exerted a cytotoxic effect on human retinoblastoma Y79 cells in a time- and dose-dependent manner. Treatment of Y79 cells for 72 h with phenylbutyrate reduced cell viability by 63% at 2 mM and 90% at 4 mM. Cell death caused by phenylbutyrate exhibited the typical features of apoptosis, as shown by light and fluorescent microscopy. Western blot analysis demonstrated that exposure of Y79 cells to phenylbutyrate decreased the level of the antiapoptotic factor Bcl-2 and induced the activation of caspase-3, a key enzyme in the execution phase of apoptosis. Moreover, treatment with phenylbutyrate markedly increased the level of acetylated histone-H3. Combined treatment with phenylbutyrate and topotecan, a topoisomerase I-inhibitor, resulted in a clear synergistic effect. We suggest that the effects exerted by phenylbutyrate on Y79 cells essentially depend on modifications of gene expression consequent to histone hyperacetylation.
Calvaruso
G
G
Department of Cell and Developmental Biology, Section of Biochemistry, University of Palermo, Policlinico, Palermo, Italy.
Carabillò
M
M
Giuliano
M
M
Lauricella
M
M
D'Anneo
A
A
Vento
R
R
Tesoriere
G
G
D000107:Acetylation; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006657:Histones / Q000378:metabolism; D006801:Humans; D010654:Phenylbutyrates / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012175:Retinoblastoma / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D059004:Topoisomerase I Inhibitors; D019772:Topotecan / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D004791:Enzyme Inhibitors; D006657:Histones; D010654:Phenylbutyrates; D019253:Proto-Oncogene Proteins c-bcl-2; D059004:Topoisomerase I Inhibitors; D016159:Tumor Suppressor Protein p53; D019772:Topotecan; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases