Mechanistic Basis of Sensitivity/Resistance Towards Anti-Cancer Drugs Targeting Topoisomerase II
Abstract
Human topoisomerase Ila (hstopo lia) is an essential enzyme that is the target of a number of anticancer drugs in clinical use. Clinically, resistance to anticancer drugs develops through various mechanisms, one of which can be found in a class of atypical multidrug resistant mutants (at-MDR) of hstopo Ia. Our goal is to clarify the biochemical basis of at-MDR among hstopo Ila mutants to shed more light on the topo II enzymatic mechanism. Additionally, we have identified sites of covalent thiol modification of hstopo lia by anticancer drugs and chemopreventive agents. To this end, we developed a cysteine footprinting technique using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESl-MS) to assess the differential reactivities of the cysteine residues of hstopo Ila and compared their relative solvent accessibilities to a solvent contact surface (SOS) analysis of a structural model of hstopo Ila. Experiments are in progress to evaluate the effects of DNA, nucleotide cofactors, and at-MDR mutants on the relative thiol reactivities of hstopo Ila. Additionally, using LC-ESl-MS, we have located sites of covalent cysteine modification of hstopo Ila by both anticancer drugs and chemopreventive agents, resulting in the first direct evidence of this novel poisoning mechanism by thiol alkylation of hstopo Ila.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2005
- Accession Number
- ADA437191
Entities
People
- Tammy R. Collins
- Tao-shih Hsieh
Organizations
- Duke University