Journal
ONCOGENE
Volume 24, Issue 55, Pages 8105-8113Publisher
NATURE PUBLISHING GROUP
DOI: 10.1038/sj.onc.1208958
Keywords
retinoblastoma tumor suppressor gene; topoisomerase II; etoposide; DNA damage; DNA repair
Funding
- NCI NIH HHS [CA70292, R01 CA070292-07, R01 CA070292] Funding Source: Medline
Ask authors/readers for more resources
Type II topoisomerases (TOP2) introduce transient double-stranded DNA breaks through a covalent TOP2 DNA intermediate. Anticancer agents like etoposide kill cells by trapping covalent TOP2-DNA cleavable complexes. Pathways influencing the repair of cleavable complexes are expected to be major determinants of therapeutic response to etoposide. Rb1 is required to enforce cell cycle checkpoints in response to DNA damage, but evidence for a direct role in the processing and repair of DNA lesions is lacking. We observe that degradation of trapped TOP2-cleavable complexes, liberation of DNA strand breaks, and repair of those breaks occurs more efficiently in cells expressing Rb1 protein (pRb). Cells lacking pRb are more sensitive to etoposide-induced cytotoxicity. Rb1-mediated processing and repair of TOP2-cleavable complexes is genetically separable from its ability to bind E2F and enforce DNA damage-induced cell cycle checkpoints. Rb1 protein binds both TOP2 and BRCA1 in intact cells, and pRb is required for association between TOP2 and BRCA1. These results suggest that pRb facilitates processing and repair of TOP2-cleavable complexes by recruiting proteins like BRCA1 to the damaged site. The functional status of pRb, therefore, may influence sensitivity to etoposide by facilitating the repair of trapped TOP2-DNA complexes as well as by enforcing cell cycle checkpoints.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available