title: Histone deacetylase inhibitors enhance the anticancer activity of nutlin-3 and induce p53 hyperacetylation and downregulation of MDM2 and MDM4 gene expression.
abstract: Nutlin-3, a small-molecule MDM2 inhibitor, restores p53 function and is, thus, an appealing candidate for the treatment of cancers retaining wild-type p53. However, nutlin-3 applied as single agent may be insufficient for cancer therapy. Therefore, we explored whether the anticancer activity of nutlin-3 could be enhanced by combination with histone deacetylase inhibitors (HDACi), i.e. vorinostat, sodium butyrate, MS-275 and apicidin. We found that nutlin-3 and HDACi cooperated to induce cell death in the p53 wild-type cell lines A549 and A2780, but not in the p53 null cell line PC-3, as assessed by Alamar Blue assay and flow cytometric analyses of propidium iodide uptake and mitochondrial depolarization. Combination index analysis showed that the effect was synergistic. For comparison, we tested nutlin-3 in combination with paclitaxel, revealing that nutlin-3 antagonized the cytotoxic activity of paclitaxel. To shed light on the underlying mechanism of the synergistic action of nutlin-3 and HDACi, we determined the acetylation status of p53 by immunoblotting and the mRNA levels of MDM2 and MDM4 by real-time RT-PCR. We observed vorinostat to induce p53 hyperacetylation, to reduce the constitutive gene expression of MDM2 and MDM4, and to counteract the nutlin-3-induced upregulation of MDM2 gene expression. In conclusion, our study shows that HDACi amplify the antitumor activity of nutlin-3-possibly by inducing p53 hyperacetylation and/or MDM2 and/or MDM4 downregulation-suggesting that treatment with a combination of nutlin-3 and HDACi may be an effective strategy for treating tumors with wild-type p53.
authors.affiliation: Department of Pediatric Hematology and Oncology, University Children's Hospital Jena, Jena, Germany.
authors.forename: Chithra D
authors.initials: CD
authors.lastname: Palani
authors.forename: James F
authors.initials: JF
authors.lastname: Beck
authors.forename: Jürgen
authors.initials: J
authors.lastname: Sonnemann
mesh_terms: D000107:Acetylation; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001549:Benzamides / Q000494:pharmacology; D015153:Blotting, Western; D002087:Butyrates / Q000494:pharmacology; D018797:Cell Cycle Proteins; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004357:Drug Synergism; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D009369:Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D000077337:Vorinostat
chemical_list: D001549:Benzamides; D002087:Butyrates; D018797:Cell Cycle Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007093:Imidazoles; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D010456:Peptides, Cyclic; D010879:Piperazines; D011518:Proto-Oncogene Proteins; D011725:Pyridines; D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C102351:apicidin; C118739:entinostat; C482205:nutlin 3; D000077337:Vorinostat; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D017239:Paclitaxel