Notes: Researchers were interested in screening compounds to inhibit endogenous class I and II histone deacetylases (HDACs). HCT116, HEK293, HepG2, and SU-DHL-6 cells were seeded at various cell densities (e.g., 1,500 or 4,000 cells/well) into 1,536-well white solid-bottom assay plates in a total volume of 5µl. Plates were treated with fibronectin prior to plating 5µl of human neural stem cells. Then 23nl of test compounds or DMSO were added to each well, and the plate incubated at 37°C for 1, 3, 6 or 18 hours. After incubation with the compounds, either the HDAC-Glo™ I/II Assay or CellTiter-Glo® Luminescent Cell Viability Assay were added to each well. Researchers confirmed 37 known HDAC inhibitors from two libraries of known epigenetics-active compounds and identified a group of potential HDAC inhibitors when screening the 2527 small-molecule compounds in the National Center for Advancing Translational Sciences (NCATS) Pharmaceutical Collection. (4697)

Notes: The HDAC-Glo™ I/II Assays were used to assess the specificity and inhibitory activity of three synthetic HDAC inhibitor analogs that had been shown to suppress growth, induced apoptosis, and reactivate expression of the sodium symporter gene in cell lines derived from aggressive thyroid cancers. (4574)

Notes: The potency of the phenylbutyrate (PBA) HDAC inhibitor was assayed on LN-229 and LN-18 human glioblastoma cells using the HDAC-Glo™ I/II Assay. LN-229 cells were treated for 24 or 48 hours with PBA and analyzed for changes in expression of seven targets via dye-based RT-qPCR. The total RNA for these studies was isolated with the ReliaPrep™ RNA Cell Miniprep System. The total RNA was analyzed with an Agilent Bioanalyzer and samples with RIN >9 were chosen for the RT-qPCR analysis. (4599)

Notes: A robust ELISA-based histone deacetylase (HDAC) activity assay was developed for use with mammalian cells. The assay was then shown effective in screening selective HDAC inhibitors. Mammalian cell-derived HDAC isoforms, instead of recombinant proteins, was a key feature of this ELISA, developed using the HDAC-Glo™ Class IIa Assay (Cat.# G9560) and HDAC-Glo™ 2 Assay (Cat.# G9590). (4634)

Notes: This paper describes the evaluation of the HDAC-Glo™ I/II and SIRT-Glo™ Assays. For all enzymes assayed (HDAC-I, HDAC-3, HDAC-6 and SIRT-1), the K_m values obtained using the luminogenic assays were comparable to those reported in the literature. Furthermore, the assays tolerated well the concentrations of DMSO used to deliver known HDAC inhibitors. The authors used the assays to generate dose-response curves and IC₅₀ values for standard inhibitors of several HDAC isoforms. They indicate that all data sets were of high quality and that the IC₅₀ values obtained were comparable to those reported in the literature. The authors screened four HDAC isoforms (HDAC-1, HDAC-3, HDAC-6 and SIRT-1) in duplicate against 640 FDA-approved drugs, and they screened HDAC-6 and SIRT-1 against the Hypha Discovery MycoDiverse natural products library. For both screens, “hits” were classified as compounds that showed >50% inhibition at their screening concentration. For the 640-drug screen, the confirmation of hits was >80%, and the false-positive hit rate was <20%. The Z´-factor values were 0.65 for the HDAC-6 screen and >0.85 for the SIRT-1 in the Hypha Discovery MycoDiverse natural products library screen. A Z´ factor of 0.5 or greater is indicative of an assay with low data variability but good dynamic range. The authors conclude that the HDAC-Glo™ I/II and SIRT-Glo™ Assays met the criteria of sensitivity, signal stability, low background, DMSO tolerance, data variability and dynamic range, and scalability required for a suitable drug-screening assay. (4137)