Date of Award

January 2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Medicinal Chemistry and Molecular Pharmacology

First Advisor

Vincent J Davisson

Committee Member 1

Robert L Geahlen

Committee Member 2

Markus A Lill

Committee Member 3

Mark A Lipton

Abstract

Integral to cell viability is the homotrimeric protein complex Proliferating Cell Nuclear Antigen (PCNA) that encircles chromatin-bound DNA and functionally acts as a DNA clamp that provides topological sites for recruitment of proteins necessary for DNA replication and damage repair. PCNA has critical roles in the survival and proliferation of cells, as disease-associated dysregulation of associated functions can have dire effects on genome stability, leading to the formation of various malignancies ranging from non-Hodgkin’s lymphoma to skin, laryngeal, ocular, prostate and breast cancers. Here, a strategy was explored with PCNA as a drug target that may have wider implications for targeting protein-protein interactions (PPIs) as well as for fragment-based drug design. A design platform using peptidomimetic small molecules was developed that maps ideal surface binding interaction sites at a PPI interface before considering detailed conformations of an optimal ligand. A novel in silico multi-fragment, combinatorial screening approach was used to guide the selection and subsequent synthesis of tripeptoid ligands, which were evaluated in a PCNA-based competitive displacement assay. From the results, some of the peptoid-based compounds that were synthesized displayed the ability to disrupt the interaction between PCNA and a PIP box-containing peptide. The IC50 values of these compounds had similar or improved affinity to that of T2AA, an established inhibitor of PCNA-PIP box interactions. The information gained here could be useful for subsequent drug lead candidate identification.

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