simultaneous-measurement-hdac1-hdac6-activity-hela-cells-using-uhplc

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since ...

Universités des Geneva–Lausanne (EPGL)

Histone deacetylase (HDAC) inhibitors have been demonstrated to be beneficial in animal models of neurodegenerative diseases. Such results were mainly associated with the epigenetic modulation caused by HDACs, especially those from class I, via chromatin deacetylation. However, other mechanisms may contribute to the neuroprotective effect of HDAC inhibitors, since each HDAC may present distinct specific functions within the neurodegenerative cascades. Such an example is HDAC6 for which the role in neurodegeneration has been partially elucidated so far. The strategy to be adopted in promising therapeutics targeting HDAC6 is still controversial. Specific inhibitors exert neuroprotection by increasing the acetylation levels of α-tubulin with subsequent improvement of the axonal transport, which is usually impaired in neurodegenerative disorders. On the other hand, an induction of HDAC6 would theoretically contribute to the degradation of protein aggregates which characterize various neurodegenerative disorders, including Alzheimer's, Parkinson's and Hutington's diseases. This review describes the specific role of HDAC6 compared to the other HDACs in the context of neurodegeneration, by collecting in silico, in vitro and in vivo results regarding the inhibition and/or knockdown of HDAC6 and other HDACs. Moreover, structure, function, subcellular localization, as well as the level of HDAC6 expression within brain regions are reviewed and compared to the other HDAC isoforms. In various neurodegenerative diseases, the mechanisms underlying HDAC6 interaction with other proteins seem to be a promising approach in understanding the modulation of HDAC6 activity.

HDAC6 as a target for neurodegenerative diseases: what makes it different from the other HDACs?

NMR and NP-HPLC-UV profiling of the exudate of Salvia corrugata revealed that its secondary metabolite composition was largely dominated by α-hydroxy-β-isopropyl-benzoquinone diterpenoids. Among them, four diterpenes not described previously were isolated and identified as fruticulin C (3), 7α-methoxy-19-acetoxy-royleanone (4), 7α,19-diacetoxy-royleanone (5), and 7-dehydroxy-conacytone (7). In addition, the known diterpenes fruticulin A (1), demethyl-fruticulin A (2) and 7α-O-methyl-conacytone (6) were also obtained. The isolated compounds were evaluated for their cancer chemopreventive activity by measuring quinone reductase induction activity and histone deacetylase inhibition. Three compounds (1, 2 and 5) showed promising activity.

Cancer chemopreventive diterpenes from Salvia corrugata.

In this study, a total of 22 flavonoids were tested for their HDAC inhibitory activity using fluorimetric and BRET-based assays. Four aurones were found to be active in both assays and showed IC50 values below 20 μM in the enzymatic assay. Molecular modelling revealed that the presence of hydroxyl groups was responsible for good compound orientation within the isoenzyme catalytic site and zinc chelation.

Aurones as histone deacetylase inhibitors: identification of key features.

Conditions for the metathesis of alkenes in the convergent synthesis of HDAC inhibitors have been improved by continuous catalyst flow injection in the reaction media. Intermediate and target compounds obtained were tested for their ability to induce HDAC inhibition and tubulin acetylation, revealing the key role of the tert-butyloxycarbonyl (BOC) group for more HDAC6 selectivity. Molecular modelling added rationale for this BOC effect.

Cross metathesis with hydroxamate and benzamide BOC-protected alkenes to access HDAC inhibitors and their biological evaluation highlighted intrinsic activity of BOC-protected dihydroxamates.

Modification of the cap group of biphenylacrylohydroxamic acid-based HDAC inhibitors led to the identification of a new derivative (3) characterized by an indolyl-substituted 4-phenylcinnamic skeleton. Molecular docking was used to predict the optimal conformation in the class I HDACs active site. Compound 3 showed HDAC inhibitory activity and antiproliferative activity against a panel of tumor cell lines, in the low μM range. The compound was further tested in vitro for acetylation of histone H4 and other non-histone proteins, and in vivo in a colon carcinoma model, showing significant proapoptotic and antitumor activities.

Biphenyl-4-yl-acrylohydroxamic acids: Identification of a novel indolyl-substituted HDAC inhibitor with antitumor activity.

Histone deacetylases (HDAC) are involved in several diseases including cancer, cardiovascular and neurodegenerative disorders, and the search for inhibitors is a current topic in drug discovery. Four HDAC inhibitors have already been approved by the FDA for cancer therapy and others are under clinical studies. However, the clinical utility of some of them is limited because of unfavorable toxicities associated with their broad range of HDAC inhibitory effects. Toxicity could be decreased by using HDAC inhibitors with improved specificity. To date, the most popular screening assays are based on fluorescence-labeled substrates incubated with an enzymatic source (cells extracts or recombinant isoforms). Here, we describe a high-throughput cell-based UHPLC-ESI-MS/MS assay able to rapidly predict activity against HDAC1 and HDAC6 in a cell environment. This method is predicted to be a useful tool to accelerate the search for class-selective HDAC inhibitors in drug discovery.

Cell-based multi-substrate assay coupled to UHPLC-ESI-MS/MS for a quick identification of class-specific HDAC inhibitors.

In recent years, the role of HDAC6 in neurodegeneration has been partially elucidated, which led some authors to propose HDAC6 inhibitors as a therapeutic strategy to treat neurodegenerative diseases. In an effort to develop a selective HDAC6 inhibitor which can cross the blood brain barrier (BBB), a modified hydroxamate derivative (compound 3) was designed and synthetized. This compound was predicted to have potential for BBB penetration based on in silico and in vitro evaluation of passive permeability. When tested for its HDAC inhibitory activity, the IC50 value of compound 3 towards HDAC6 was in the nM range in both enzymatic and cell-based assays. Compound 3 showed a cell-based selectivity profile close to that of tubastatin A in SH-SY5Y human neuroblastoma cells, and a good BBB permeability profile.

Synthesis of a selective HDAC6 inhibitor active in neuroblasts.

Histone deacetylases (HDAC) are considered as promising targets for cancer treatment. Today, four HDAC inhibitors, vorinostat, romidepsin, belinostat, and panobinostat, have been approved by the Food and Drug Administration (FDA) for cancer treatment, while others are in clinical trials. Among them, several are naturally occurring fungal metabolites.

UHPLC-MS-based HDAC Assay Applied to Bio-guided Microfractionation of Fungal Extracts.

A small uncharged cyclopeptide scaffold inspired by a natural product and designed to undergo postfunctionalizations was used as a new transmembrane vector. A bioactive and fluorescent triazole aminocoumarin was bound to this carrier to facilitate its moving across cell and subcellular membranes, and this led to an increase in its cell toxicity.

Article	Year
HDAC6 as a target for neurodegenerative diseases: what makes it different from the other HDACs? Molecular neurodegeneration\| PubMed ID: 23356410	2013
Cancer chemopreventive diterpenes from Salvia corrugata. Phytochemistry\| PubMed ID: 24120298	2013
Aurones as histone deacetylase inhibitors: identification of key features. Bioorganic & medicinal chemistry letters\| PubMed ID: 25455492	2014
Cross metathesis with hydroxamate and benzamide BOC-protected alkenes to access HDAC inhibitors and their biological evaluation highlighted intrinsic activity of BOC-protected dihydroxamates... Bioorganic & medicinal chemistry letters\| PubMed ID: 26611919	2016
Biphenyl-4-yl-acrylohydroxamic acids: Identification of a novel indolyl-substituted HDAC inhibitor with antitumor activity. European journal of medicinal chemistry\| PubMed ID: 26890116	2016
Cell-based multi-substrate assay coupled to UHPLC-ESI-MS/MS for a quick identification of class-specific HDAC inhibitors. Journal of enzyme inhibition and medicinal chemistry\| PubMed ID: 27149362	2016
Synthesis of a selective HDAC6 inhibitor active in neuroblasts. Bioorganic & medicinal chemistry letters\| PubMed ID: 27650925	2016
UHPLC-MS-based HDAC Assay Applied to Bio-guided Microfractionation of Fungal Extracts. Phytochemical analysis : PCA\| PubMed ID: 27921344	2017
Synthesis of an Uncharged Tetra-cyclopeptide Acting as a Transmembrane Carrier: Enhanced Cellular and Nuclear Uptake. Organic letters\| PubMed ID: 28107021	2017

Vincent Zwick

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