title: SELECTIVE INHIBITORS AND TARGETED DEGRADERS OF HISTONE DEACETYLASE 10
creator: Steimbach, Raphael René
subject: ddc-540
subject: 540 Chemistry and allied sciences
subject: ddc-570
subject: 570 Life sciences
description: Histone deacetylase 10 (HDAC10) stands out among the eleven zinc-dependent hydrolases of the histone deacetylase family as the only polyamine deacetylase. It exhibits remarkable substrate specificity for N-acetylputrescine and N8 acetylspermidine over N1 acetylspermidine and shows no activity on acetyllysine residues. Although the role of selective polyamine deacetylation in health and disease is enigmatic, HDAC10 received little attention from medicinal chemists and no selective inhibitors suitable as chemical probes were available prior to this study.  To address this deficiency, I developed the first well-characterized selective chemical probes for HDAC10 with unprecedented selectivity over other HDAC isozymes. The inhibitors were designed to imitate HDAC10’s polyamine substrates without also binding HDAC6, its closest relative. Insertion of an amino group into the hexyl linker moiety of the approved drug Vorinostat (SAHA) at the γ-position to the hydroxamic acid transformed SAHA from an unselective pan-inhibitor into a selective HDAC10 inhibitor. I further optimized the aza-SAHA scaffold in a medicinal chemistry campaign, which yielded DKFZ-748, a chemical probe for HDAC10 with a 22 nM IC50 against HDAC10 in cells and >500-fold selectivity over HDAC6, as well as Class I enzymes (HDAC1, 2, 3, 8). Selectivity and potency were validated by biochemical and cellular target engagement assays. Furthermore, cells treated with DKFZ-748 showed only accumulation of the polyamine substrates, but not hyperacetylation of HDAC6 or Class I substrates. Potency of the aza-SAHA derivatives could be rationalized with HDAC10 co-crystal structures and selectivity within the entire target landscape of HDAC drugs was demonstrated. Moreover, DKFZ-748 was successfully applied in a polyamine-limited in vitro tumor model, where it enabled HeLa cell growth inhibition, but showed no toxicity under other circumstances.   With potent and selective HDAC10 binders at hand, I transitioned from occupancy-driven pharmacology of inhibitors to the event-driven pharmacology of targeted degraders that can remove HDAC10 in cells via induced proteasomal degradation, including potential scaffolding functions of the HDAC10 protein. I demonstrated targeted degradation of HDAC10 using pan-inhibitor-based compounds as a proof of principle, and established a solid-phase synthesis of aza-SAHA-based degraders. These are promising candidates for the selective degradation of HDAC10, based on the excellent selectivity profile of the aza-SAHA derivatives.   Furthermore, in a separate approach, I investigated new scaffolds for selective HDAC10 inhibition based on a compound library screen. This part of the project aimed to develop selective HDAC10 inhibitors without the use of amino hydroxamic acids, which opens new therapeutic applications for HDAC10 inhibition beyond cancer therapy.
date: 2024
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/33158/1/Dissertation_Raphael_Steimbach.pdf
identifier: DOI:10.11588/heidok.00033158
identifier: urn:nbn:de:bsz:16-heidok-331582
identifier:   Steimbach, Raphael René  (2024) SELECTIVE INHIBITORS AND TARGETED DEGRADERS OF HISTONE DEACETYLASE 10.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/33158/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng