Role for DNA topoisomerase II in prostatic growth
In the studies presented the role of the mammalian type II topoisomerase in the proliferation of normal and neoplastic rat prostate cells in vitro and in vivo was evaluated. First, the utility of mammalian type II topoisomerase inhibitors for the study of the biologic functions of the enzyme was assessed. Novobiocin inhibited rat topoisomerase II, but also interacted directly with chromatin in rat ventral prostate nuclei as well. Teniposide and amsacrine both trapped topoisomerase II in a covalent enzyme-DNA reaction intermediate that could be recovered using a K-SDS precipitation assay. The specific trapping of covalent topoisomerase II-DNA complexes by teniposide was exploited to implicate topoisomerase II in DNA replication in cultured Dunning R3327-G rat prostatic adenocarcinoma cells. In /sup 3/H-thymidine pulse and pulse-chase labelling experiments, newly replicated DNA was found to be enriched among DNA linked topoisomerase II following teniposide treatment. Additional experiments demonstrated that topoisomerase II formed covalent complexes in the presence of teniposide directly with nascent DNA chains. On the basis of this data, a model for topoisomerase II function in untangling intertwined daughter DNA strands during replication by acting in the wake of the DNA replication fork near the site of DNA synthesis was proposed.
- Research Organization:
- Johns Hopkins Univ., Baltimore, MD (USA)
- OSTI ID:
- 7140868
- Country of Publication:
- United States
- Language:
- English
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550901 -- Pathology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
AZINES
BIOLOGICAL FUNCTIONS
BODY
CARCINOMAS
CELL PROLIFERATION
DISEASES
DNA
DNA REPLICATION
ENZYME INHIBITORS
ENZYMES
FUNCTIONS
GLANDS
HETEROCYCLIC COMPOUNDS
ISOMERASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MALE GENITALS
MATHEMATICAL MODELS
NEOPLASMS
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROSTATE
PYRIMIDINES
RIBOSIDES
THYMIDINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TUMOR CELLS