CaltechTHESIS
  A Caltech Library Service

Biological Activity of Rhodium Metalloinsertors and the Design of Bifunctional Conjugates

Citation

Weidmann, Alyson Gloria (2015) Biological Activity of Rhodium Metalloinsertors and the Design of Bifunctional Conjugates. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9RX991X. http://resolver.caltech.edu/CaltechTHESIS:06022015-104348919

Abstract

The Barton laboratory has established that octahedral rhodium complexes bearing the sterically expansive 5,6-chrysene diimine ligand can target thermodynamically destabilized sites, such as base pair mismatches, in DNA with high affinity and selectivity. These complexes approach DNA from the minor groove, ejecting the mismatched base pairs from the duplex in a binding mode termed metalloinsertion. In recent years, we have shown that these metalloinsertor complexes also exhibit cytotoxicity preferentially in cancer cells that are deficient in the mismatch repair (MMR) machinery.

Here, we establish that a sensitive structure-activity relationship exists for rhodium metalloinsertors. We studied the relationship between the chemical structures of metalloinsertors and their effect on biological activity for ten complexes with similar DNA binding affinities, but wide variation in their lipophilicity. Drastic differences were observed in the selectivities of the complexes for MMR-deficient cells. Compounds with hydrophilic ligands were highly selective, exhibiting preferential cytotoxicity in MMR-deficient cells at low concentrations and short incubation periods, whereas complexes with lipophilic ligands displayed poor cell-selectivity. It was discovered that all of the complexes localized to the nucleus in concentrations sufficient for mismatch binding; however, highly lipophilic complexes also exhibited high mitochondrial uptake. Significantly, these results support the notion that mitochondrial DNA is not the desired target for our metalloinsertor complexes; instead, selectivity stems from targeting mismatches in genomic DNA.

We have also explored the potential for metalloinsertors to be developed into more complex structures with multiple functionalities that could either enhance their overall potency or impart mismatch selectivity onto other therapeutic cargo. We have constructed a family of bifunctional metalloinsertor conjugates incorporating cis-platinum, each unique in its chemical structure, DNA binding interactions, and biological activity. The study of these complexes in MMR-deficient cells has established that the cell-selective biological activity of rhodium metalloinsertors proceeds through a critical cellular pathway leading to necrosis.

We further explored the underlying mechanisms surrounding the biological response to mismatch recognition by metalloinsertors in the genome. Immunofluorescence assays of MMR-deficient and MMR-proficient cells revealed that a critical biomarker for DNA damage, phosphorylation of histone H2AX (γH2AX) rapidly accumulates in response to metalloinsertor treatment, signifying the induction of double strand breaks in the genome. Significantly, we have discovered that our metalloinsertor complexes selectively inhibit transcription in MMR-deficient cells, which may be a crucial checkpoint in the eventual breakdown of the cell via necrosis. Additionally, preliminary in vivo studies have revealed the capability of these compounds to traverse the complex environments of multicellular organisms and accumulate in MMR-deficient tumors. Our ever-increasing understanding of metalloinsertors, as well as the development of new generations of complexes both monofunctional and bifunctional, enables their continued progress into the clinic as promising new chemotherapeutic agents.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:DNA, rhodium metalloinsertor, mismatch repair
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Barton, Jacqueline K.
Thesis Committee:
  • Gray, Harry B. (chair)
  • Stoltz, Brian M.
  • Peters, Jonas C.
  • Barton, Jacqueline K.
Defense Date:28 May 2015
Funders:
Funding AgencyGrant Number
National Institutes of HealthGM033309
NRSA Training Grant5T32GM7616-33
Record Number:CaltechTHESIS:06022015-104348919
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06022015-104348919
DOI:10.7907/Z9RX991X
Related URLs:
URLURL TypeDescription
http://www.tandfonline.com/doi/abs/10.1080/02603594.2014.890099?journalCode=gcic20DOITargeted Chemotherapy with Metal Complexes
http://rsta.royalsocietypublishing.org/content/371/1995/20120117DOIBiological effects of simple changes in functionality on rhodium metalloinsertors
http://pubs.acs.org/doi/abs/10.1021/ja3090687DOI Cell-Selective Biological Activity of Rhodium Metalloinsertors Correlates with Subcellular Localization
http://pubs.acs.org/doi/abs/10.1021/ic501509xDOIConstruction and Application of a Rh–Pt DNA Metalloinsertor Conjugate
ORCID:
AuthorORCID
Weidmann, Alyson Gloria0000-0003-3876-2847
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8968
Collection:CaltechTHESIS
Deposited By: Alyson Weidmann
Deposited On:02 Jun 2015 23:23
Last Modified:01 Jun 2016 20:39

Thesis Files

[img] PDF (AGW thesis final) - Final Version
Restricted to Caltech community only
See Usage Policy.

44Mb
[img]
Preview
PDF (Acknowledgments_Abstract_TOC) - Final Version
See Usage Policy.

241Kb
[img]
Preview
PDF (AGW Chapter 1) - Final Version
See Usage Policy.

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

4Mb
[img]
Preview
PDF (AGW Chapter 3) - Final Version
See Usage Policy.

6Mb
[img]
Preview
PDF (AGW Chapter 4) - Final Version
See Usage Policy.

7Mb
[img]
Preview
PDF (AGW Chapter 5) - Final Version
See Usage Policy.

9Mb
[img]
Preview
PDF (AGW Chapter 6) - Final Version
See Usage Policy.

12Mb
[img]
Preview
PDF (AGW Chapter 7) - Final Version
See Usage Policy.

74Kb

Repository Staff Only: item control page