CaltechTHESIS
  A Caltech Library Service

Biological activity of a Py-Im polyamide androgen receptor antagonist

Citation

Phillips, John W. (2011) Biological activity of a Py-Im polyamide androgen receptor antagonist. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06022011-172257819

Abstract

Py-Im polyamides are cell-permeable, programmable, sequence-specific, DNA minor groove-binding small molecules. When designed to bind a DNA sequence that matches the consensus DNA-binding sequence of a transcription factor, they can be used to block the binding of that transcription factor to its response element in vitro and in cell culture. We have used this approach to inhibit the genotropic activity of the endogenous transcription factors HIF1α, glucocorticoid receptor (GR), and androgen receptor (AR). In this work, we report the completion of a library of hairpin Py-Im polyamides targeted to all possible 5’-WGNNNW-3’ (W = A or T) sequences. These compounds bind their target DNA sequences with high affinity. One compound from this set targets the sequence 5’-WGWWCW-3’, which matches the DNA binding consensus sequence of GR and AR and has been shown to inhibit the gene regulatory activity of these proteins in cell culture. Herein, we show that a cyclic derivative of this compound maintains its activity against AR-driven gene expression in hormone-sensitive LNCaP prostate cancer cells. As androgen receptor signaling is crucial to prostate cancer growth and metastasis even in its recurrent form, we next examine the activity of the AR/GR antagonist in a tissue culture model of castration-resistant prostate cancer. In this model, the polyamide retains its activity against AR-driven mRNA expression, but it fails to inhibit the binding of AR to its response element. The polyamide-mediated repression is also accompanied by significant cell stress and cytotoxicity, which are explored in the final two chapters of this thesis. The former investigates a role for polyamides as inhibitors of DNA Topoisomerase II. Despite in vitro evidence indicating polyamides prevent Topoisomerase II binding, no evidence for this is found in cell culture. The final chapter reveals that polyamide-mediated cytotoxicity is likely due to inhibition of DNA synthesis. This occurs at concentrations similar to those used for transcription factor inhibition, suggesting that S-phase disturbance accompanies efforts to regulate gene expression with polyamides.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:polyamide Py-Im androgen S-phase cytotoxicity hairpin DNA-binding
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Biochemistry and Molecular Biophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dervan, Peter B.
Thesis Committee:
  • Dougherty, Dennis A. (chair)
  • Campbell, Judith L.
  • Clemons, William M.
  • Dervan, Peter B.
Defense Date:31 May 2011
Author Email:jhnwphillips (AT) gmail.com
Record Number:CaltechTHESIS:06022011-172257819
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06022011-172257819
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6493
Collection:CaltechTHESIS
Deposited By: John Phillips
Deposited On:03 Jun 2011 18:41
Last Modified:16 Apr 2013 23:20

Thesis Files

[img]
Preview
PDF (Complete Thesis) - Final Version
See Usage Policy.

8Mb
[img]
Preview
PDF (Table of Contents) - Final Version
See Usage Policy.

131Kb
[img]
Preview
PDF (Chapter 1 Introduction) - Final Version
See Usage Policy.

4Mb
[img]
Preview
PDF (Chapter 2 Polyamide Library) - Final Version
See Usage Policy.

2013Kb
[img]
Preview
PDF (Chapter 3 AR-Targeted Cyclic Polyamides) - Final Version
See Usage Policy.

983Kb
[img]
Preview
PDF (Chapter 4 LN-AR) - Final Version
See Usage Policy.

917Kb
[img]
Preview
PDF (Chapter 5 TopII inhbition in vitro) - Final Version
See Usage Policy.

1228Kb
[img]
Preview
PDF (Chapter 6 Cytotoxicity) - Final Version
See Usage Policy.

767Kb

Repository Staff Only: item control page