Date of Award

Spring 2022

Document Type

Open Access Dissertation

Department

College of Pharmacy

First Advisor

Michael D. Wyatt

Second Advisor

Campbell McInnes

Abstract

Polo-like kinase 1 (PLK1) is a central player in regulating entry into and progression through mitosis. Inhibition of sub-cellular localization and kinase activity of PLK1 through the Polo-box domain (PBD) is emerging as a viable alternative to ATP binding site directed drugs for which the development of resistant mutants and inhibition of closely related members of the PLK family (tumor suppressor roles) are primary concerns. I describe related novel non-peptidic PBD binding inhibitors, termed abbapolins, identified through successful application of the REPLACE strategy and demonstrate their potent antiproliferative activity in prostate tumors and other cell lines. Furthermore, the abbapolins show PLK1-specific binding and inhibitory activity as measured by a cellular thermal denaturation assay and their ability to block phosphorylation of TCTP, a key marker of PLK1 mediated kinase activity. I also made a novel observation that abbapolins upon binding to PLK1 induced its intracellular loss in a mechanism at least partially dependent on the proteasome. The therapeutic potential of these compounds was further indicated through their antiproliferative activity on a cell line (C67V PLK1 mutation) which is dramatically resistant to ATP competitive PLK1 inhibitors. I report novel findings during mitosis inferred from our collective data, namely that catalytic site binding by BI2536 or volasertib unexpectedly decreased the stability of PLK1 as determined by thermal stability assay, suggesting an induction of a conformational change in intracellular PLK1.

Available for download on Wednesday, May 31, 2023

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