Identification of HDAC10 Inhibitors that Modulate Autophagy-Related Proteins in Transformed Cells

Abstract

Histone deacetylases (HDACs) are a family of 18 epigenetic modifiers that fall into 4 classes. Histone deacetylase inhibitors (HDACi) are valid tools to assess HDAC functions. HDAC6 and HDAC10 belong to the class IIb subgroup of the HDAC family. The targets and biological functions of HDAC10 are ill-defined. This lack of knowledge is due to a lack of specific and potent HDAC10 inhibitors with cellular activity. Here, we have synthesized and characterized piperidine-4-acrylhydroxamates as potent and highly selective inhibitors of HDAC10. This was achieved by addressing the acidic gatekeeper residue Glu274 of HDAC10 with a basic piperidine moiety that is mimicking the interaction of the oligoamine substrate of HDAC10. Promising candidates were selected based on their specificity by in vitro profiling using recombinant HDACs. The most promising HDAC10 inhibitors 13b and 10c were tested for specificity in acute myeloid leukemia (AML) cells with the FLT3-ITD oncogene. By immunoblot experiments we assessed the hyperacetylation of histones and tubulin-α, which are class I and HDAC6 substrates, respectively. As validated test for HDAC10 inhibition we used flow cytometry assessing autolysosome formation in neuroblastoma and AML cells. We demonstrate that this is not a consequence of apoptosis and 13b and 10c are not toxic for normal human kidney cells. These data unravel that 13b and 10c are micromolar inhibitors of HDAC10 with high specificity. Thus, our new HDAC10 inhibitors are tools to identify the downstream targets and functions of HDAC10 in cells.

Development of First-in-Class Dual Sirt2/HDAC6 Inhibitors as Molecular Tools for Dual Inhibition of Tubulin Deacetylation

“…The docking setup was previously used for Sirt2/HDAC inhibitor docking and could be validated by the structures of cocrystallized inhibitors. [19,85,86] Redocking procedure was also able to reproduce the binding mode of 5 in Sirt2 with RMSD value of 0.227 Å and that of 55/57 in HDAC6 with RMSD values of 0.548 and 1.448 Å, respectively (crystal structures of the present work, 8G1Z, 8G20 and 8OWZ). RMDS value of 57 was slightly higher due to the flexibility of the two n-butyl chains in the capping group.…”

First Fluorescent Acetylspermidine Deacetylation Assay for HDAC10 Identifies Selective Inhibitors with Cellular Target Engagement**

“…In recent years, HDAC10 has been linked to tumor development and proliferation [15] . The development of potential drugs that block HDAC10 has emerged as a potential new therapeutic strategy for the treatment of cancer, e. g. neuroblastoma, [13a,16] lung cancer, [17] ovarian cancer [18] and leukemia [19] …”

“…[15] The development of potential drugs that block HDAC10 has emerged as a potential new therapeutic strategy for the treatment of cancer, e. g. neuroblastoma, [13a,16] lung cancer, [17] ovarian cancer [18] and leukemia. [19] The first potent HDAC inhibitors (HDACis) trichostatin A (TSA, 5) (Figure 2) and trapoxin were reported many years ago. [20] Since vorinostat (6) was approved as the first HDACi for treatment of cutaneous T-cell lymphoma by the FDA three more HDAC inhibitors (romidepsin (7), belinostat (8), panobinostat ( 9)) received FDA approval for cancer treatment.…”