Endonuclease cleavage of blocked replication forks: An indirect pathway of DNA damage from antitumor drug-topoisomerase complexes.

Journal Article (Journal Article)

The cytotoxicity of several important antitumor drugs depends on formation of the covalent topoisomerase-DNA cleavage complex. However, cellular processes such as DNA replication are necessary to convert the cleavage complex into a cytotoxic lesion, but the molecular mechanism of this conversion and the precise nature of the cytotoxic lesion are unknown. Using a bacteriophage T4 model system, we have previously shown that antitumor drug-induced cleavage complexes block replication forks in vivo. In this report, we show that these blocked forks can be cleaved by T4 endonuclease VII to create overt DNA breaks. The accumulation of blocked forks increased in endonuclease VII-deficient infections, suggesting that endonuclease cleavage contributes to fork processing in vivo. Furthermore, purified endonuclease VII cleaved the blocked forks in vitro close to the branch points. These results suggest that an indirect pathway of branched-DNA cleavage contributes to the cytotoxicity of antitumor drugs that target DNA topoisomerases.

Full Text

Duke Authors

Cited Authors

  • Hong, G; Kreuzer, KN

Published Date

  • April 29, 2003

Published In

Volume / Issue

  • 100 / 9

Start / End Page

  • 5046 - 5051

PubMed ID

  • 12704241

Pubmed Central ID

  • PMC154295

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.0835166100


  • eng

Conference Location

  • United States