A Unique Class of Topoisomerase Mutants that are Hypersensitive to Multiple Antitumor Angents
Abstract
The overall goal of this research is to understand the detailed mechanism of action of antitumor drugs that target type II topoisomerases. Bacteriophage T4 topoisomerase provides a useful model system for the study of these antitumor agents. Previous analysis of drug resistant mutations in the T4 topoisomerase has fortuitously led to the discovery of a hypersensitive mutant (Cancer Res. 58:1260-1267). 1 have purified this mutant enzyme and analyzed its drug sensitivity with DNA cleavage assays. As was expected from the previous in vivo data, the mutant enzyme was hypersensitive to m-AMSA and oxolinic acid. Additionally, the mutant was hypersensitive to a number of other cleavage-inducing inhibitors that cannot be tested in vivo such as VP-16, ellipticine, and mitoxantrone. I am currently using a modified filtration method to quantitate the levels of drug hypersensitivity. Surprisingly, in the absence of any inhibitors, the mutant enzyme appears to remain in the cleavage complex for a longer period of time compared to the wild type enzyme. Further, this mutation does not appear to alter the cleavage site specificity of the enzyme. Thus, this mutant seems to cause hypersensitivity in a unique manner by increasing the frequency of cleavage complexes available to inhibitors.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2001
- Accession Number
- ADA393396
Entities
People
- Erin K. O'reilly
- Kenneth Kreuzer
Organizations
- Duke University Hospital