trichostatin-a and ciglitazone

We previously demonstrated that the PPARgamma agonist Troglitazone (TRG), a potent antiproliferative agent, in combination with the anthracycline antibiotic Doxorubicin (DOX), is an effective killer of multiple drug resistant (MDR) human cancer cells. Cell killing was accompanied by increased global histone H3 acetylation. Presently, we investigated the epigenetic and cell killing effects of TRG in estrogen receptor (ER) positive MCF7 breast cancer cells. MCF7 cells were treated with the Thiazolidinediones (TZDs) TRG and Ciglitazone (CIG), the non-TZD PPARgamma agonist 15PGJ2, and the histone deacetylase inhibitors (HDACi's) Trichostatin A (TSA), sodium butyrate and PXD101. Using MTT cell viability assays, Western analyzes and mass spectrometry, we showed a dose-dependent increase in cell killing in TRG and HDACi treated cells, that was associated with increased H3 lysine 9 (H3K9) and H3K23 acetylation, H2AX and H3S10 phosphorylation, and H3K79 mono- and di-methylation. These effects were mediated through an ER independent pathway. Using HDAC activity assays, TRG inhibited HDAC activity in cells and in cell lysates, similar to that observed with TSA. Furthermore, TRG and TSA induced a slower migrating HDAC1 species that was refractory to HDAC2 associations. Lastly, TRG and the HDACi's decreased total and phosphorylated AKT levels. These findings suggest that TRG's mode of killing may involve downregulation of PI3K signaling through HDAC inhibition, leading to increased global histone post-translational modifications.

Topics: Acetylation; Antineoplastic Agents; Blotting, Western; Breast Neoplasms; Butyrates; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chromans; Dose-Response Relationship, Drug; Epigenesis, Genetic; Female; Histone Deacetylase 1; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Histone Deacetylases; Histones; Humans; Hydroxamic Acids; Methylation; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Binding; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Receptors, Estrogen; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Sulfonamides; Thiazolidinediones; Troglitazone

Neuroblastoma is a childhood cancer, which spontaneously regresses. This has led to a search for agents that mimic this process. We show that both natural and synthetic ligands of PPARgamma (peroxisome-proliferator-activated receptor gamma) inhibit the growth of neuroblastoma cells in vitro. The degree of PPAR activation was attenuated however in the presence of the retinoblastoma protein. Addition of trichostatin A, a histone deacetylase inhibitor, abolished retinoblastoma protein repression of PPAR activity. Moreover, enhanced growth inhibition was observed when neuroblastoma cells were treated with a PPARgamma ligand and a histone deacetylase inhibitor, suggesting a combination therapy to treat neuroblastoma might prove more effective than using either agent alone.

Topics: Carboxy-Lyases; Cell Line, Tumor; Dose-Response Relationship, Drug; Enzyme Inhibitors; Genes, Reporter; Histones; Humans; Hydroxamic Acids; Ligands; Neuroblastoma; PPAR gamma; Prostaglandin D2; Retinoblastoma Protein; Thiazolidinediones; Time Factors; Transcription, Genetic; Transfection

Histone deacetylase (HDAC) inhibitors and ligands of the peroxisome proliferator-activated receptor gamma (PPARgamma) have been shown previously to induce growth arrest and differentiation in a variety of cancer cell lines. The purpose of this study was to determine whether HDAC inhibitors function similarly in non-small cell lung cancer (NSCLC) and whether combination treatment with HDAC inhibitors and PPARgamma ligands is more efficacious than either agent alone.. Nanomolar concentrations of trichostatin A induced growth arrest in five of seven NSCLC cell lines, whereas sodium phenylbutyrate (PB) was markedly less potent. In adenocarcinomas, trichostatin A up-regulated general differentiation markers (gelsolin, Mad, and p21/WAF1) and down-regulated markers of the type II pneumocyte progenitor cell lineage (MUC1 and SP-A), indicative of a more mature phenotype. PB had a similar effect. Simultaneous treatment with a PPARgamma ligand and PB enhanced the growth inhibition in adenocarcinomas but not in nonadenocarcinomas. Growth arrest was accompanied by markedly decreased cyclin D1 expression but not enhanced differentiation.. The present study demonstrates potent growth-inhibitory and differentiation-inducing activity of HDAC inhibitors in NSCLC and suggests that combination differentiation therapy should be explored further for the treatment of lung adenocarcinomas.

Topics: Adenocarcinoma; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Blotting, Western; Carcinoma, Non-Small-Cell Lung; Cell Differentiation; Cell Division; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Synergism; Gelsolin; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Ligands; Lung Neoplasms; Phenylbutyrates; Receptors, Cytoplasmic and Nuclear; Repressor Proteins; RNA; Thiazoles; Thiazolidinediones; Transcription Factors; Tumor Cells, Cultured