Access Type

Open Access Dissertation

Date of Award

January 2024

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Mary Kay H. Pflum

Abstract

Histone deacetylase (HDAC) proteins are linked to disease states, including cancer, and have become important targets for therapeutic development. Many inhibitors have been developed to target HDAC proteins, including FDA-approved inhibitors Vorinostat (SAHA), Belinostat, Romidepsin, and Panobinostat. These inhibitors non-specifically influence most of the 11 metal-dependent HDAC isoforms, which might contribute to the side effects that patients experience during treatment. The lack of selectivity also diminishes the use of HDAC inhibitors as biomedical research tools. To address these drawbacks, the development of selective inhibitors has been heavily studied. Yet, reported inhibitors are predominantly selective for class I HDAC isoforms (HDACs 1, 2, 3 and 8) or the entirety of class I. There is a lack of selective inhibitors for class IIa HDAC isoforms (HDACs 4, 5, 7 and 9), which have been linked to disease states, including cancer and neurodegenerative disorders. With class IIa HDAC proteins as necessary targets for selective HDAC inhibitor development, one long-term goal of this project is to develop and synthesize potent class IIa isoform selective HDAC inhibitors based on previous work and docking studies.HDAC inhibitors are generally tested for potency and selectivity using a deacetylation activity assay. However, a challenge with testing HDAC4, HDAC5, HDAC7, and HDAC9 is their low enzymatic activity. To overcome the low enzymatic activity of class IIa HDAC proteins in this activity assay, an unnatural trifluoro acetyl substrate is used to encourage deacetylation. Additionally, the activity assay uses recombinant protein rather than cellular proteins. These limitations of low enzymatic activity and use of purified protein suggest a need for a physiologically relevant binding assay to compliment the necessary activity assay. A second long term goal of this project is development of a simple, accessible, and cell-based activity assay for inhibitor screening. The significant outcomes of this project are isoform selective class IIa HDAC inhibitors and a cellular binding assay.

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