The discovery of small molecule inhibitors of poly(ADP-ribose) mediated cell death

The emergence of resistance to cancer treatments through methods that generate cell death by inducing DNA damage, such as chemotherapeutics and radiation therapy, is a major obstacle to overcoming the disease. Resistance occurs through the repair of single strand DNA breaks by the poly(ADP-ribose) (PAR) cycle, which is an enzymatic cycle that promotes DNA repair after mild DNA damage. In contrast, upon severe DNA damage, the PAR cycle is known to promote acute cell death, which can result in ischemia or neurological diseases. Therefore, proteins in this pathway are being studied as potential pharmacological targets for cancer and ischemic events. Poly(ADP-ribose) polymerase-1 (PARP-1), the enzyme that synthesizes PAR, inhibitors are currently in clinical trials as chemopotentiators, and as personalized treatments for patients with the BRCA-1/-2 mutation. However, there is a lack of small molecule inhibitors of other important enzymes and proteins in this pathway. Therefore, described herein is the discovery and evaluation of small-molecule inhibitors of poly(ADP-ribose) glycohydrolase (PARG), the enzyme that degrades PAR, and apoptosis inducing factor (AIF), a protein that orchestrates stage I chromatin condensation. Recognizing that the phosphate moiety, which is cell impermeable, is necessary for PARG recognition and binding, Chapter 2 describes how small molecules containing the rhodanine motif, a known phosphate replacement, were screened for PARG inhibition in hopes of discovering a cell permeable inhibitor of PARG. A compound was identified as a PARG inhibitor, and upon derivative synthesis, its properties were optimized to improve potency (IC50 <10 uM) and solubility. After analyzing compound specificity, the rhodanine-containing PARG inhibitors were tested in both cell lysate and cell culture to assess their ability to inhibit PARG in complex environments. In Chapter 3, compounds that prevented the ability of AIF to bind DNA were identified and chemically optimized. Although, the inhibitors of AIF proceeded with less success, the identified compounds were used in a proof-of-concept analysis of photonic crystal biosensors to identify aggregating compounds, and as a novel and facile mechanism to label proteins.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Finch, Kristin E.

Contributors dc:contributor

• Hergenrother, Paul J.
• Burke, Martin D.
• Rienstra, Chad M.
• Oldfield, Eric

• poly(ADP-ribose) glycohydrolase (PARG)
• Poly(ADP-ribose) polymerase (PARP)
• poly(ADP-ribose) (PAR)
• Rhodanines
• small molecule inhibitors

Statement dc:rights

• Copyright 2011 Kristin E. Finch

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/24355

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/24355