DNA polymerase beta inhibitor pamoic acid : toxicity to metakaryotic human cancer stem cells (HT-29)

Amitotic cells with large, hollow bell-shaped nuclei, or metakaryotic stem cells, are the post-embryonic stem cells of the fetal organs from about the fourth week post conception through physical maturity. These metakaryotic stem cells, after acquiring necessary genetic, and possibly other events, are also the stem cells of precancerous, cancerous and metastatic lesions of carcinogenesis. Furthermore, our lab has discovered that metakaryotic stem cells, both in fetal development and tumor growth, use a peculiar mode of DNA synthesis and segregation that involves inter alia expression of large amounts of RNA polymerase beta during DNA synthesis. It was hypothesized that an inhibitor of DNA polymerase beta would be toxic to metakaryotic stem cells at concentrations lower than necessary to kill eukaryotic non stem cells. The polymerase beta small-molecule inhibitor chosen for this study was pamoic acid, a napthoic acid derivative. With it we determined the relative sensitivity of metakaryotes and eukaryotic cells in the human colorectal cancer cell culture, HT- 29mes, that expresses characteristics expected of colorectal cancer metastases. We conclude that, at 300 [mu]M and above pamoic acid does not selectively kill metakaryotes in cell culture below that concentration which kills eukaryotes. Rather, pamoic acid acts in a similar fashion as X-rays: eukaryotic non-stem cells are killed at lower doses than those that kill metakaryotic stem cells. Treatment of pamoic acid with these concentrations causes concomitant declines in colony-formation potential for both metakaryotes and eukaryotes alike. At lower overall survival levels, surviving colonies appear to have arisen from metakaryotic cells, not eukaryotic cells as evidenced by the presence of visible metakaryotic cells in most colonies and the ability of such colonies to support continuous growth upon passaging. We conclude with the possibility that this specific polymerase beta inhibitor is not an effective metakaryocide in culture, insofar as they are not selectively toxic for these stem cells in the HT-29mes colorectal cancer cell line.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Biological Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2016

Author dc:creator

• Kamath, Tushar Vinod

Advisor dc:contributor.advisor

• William G. Thilly.

• Biological Engineering.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/104219

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/104219