Transcription Inhibition by Platinum DNA Cross-links in Live Mammalian Cells
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ang et al JACS.pdf
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Author(s)
Ang, Wee Han
Myint, MyatNoeZin
Lippard, Stephen J.
Date Issued
May 2010
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society
Citation
Ang, Wee Han, MyatNoeZin Myint, and Stephen J. Lippard. “Transcription Inhibition by Platinum−DNA Cross-Links in Live Mammalian Cells.” Journal of the American Chemical Society 132.21 (2010) : 7429-7435.
Version
Author's final manuscript
Abstract
We have investigated the processing of site-specific Pt−DNA cross-links in live mammalian cells to enhance our understanding of the mechanism of action of platinum-based anticancer drugs. The activity of platinum drugs against cancer is mediated by a combination of processes including cell entry, drug activation, DNA-binding, and transcription inhibition. These drugs bind nuclear DNA to form Pt−DNA cross-links, which arrest key cellular functions, including transcription, and trigger a variety of responses, such as repair. Mechanistic investigations into the processing of specific Pt−DNA cross-links are critical for understanding the effects of platinum−DNA damage, but conventional in vitro techniques do not adequately account for the complex and intricate environment within a live cell. With this limitation in mind, we developed a strategy to study platinum cross-links on plasmid DNAs transfected into live mammalian cells based on luciferase reporter vectors containing defined platinum−DNA lesions that are either globally or site-specifically incorporated. Using cells with either competent or deficient nucleotide excision repair systems, we demonstrate that Pt−DNA cross-links impede transcription by blocking passage of the RNA polymerase complex and that nucleotide excision repair can remove the block and restore transcription. Results are presented for 3800-base pair plasmids that are either globally platinated or carry a single 1,2-d(GpG) or 1,3-d(GpTpG) intrastrand cross-link formed by either cis-{Pt(NH3)2}2+ or cis-{Pt(R,R-dach)}2+, where {Pt(NH3)2}2+ is the platinum unit conveyed by cisplatin and carboplatin and R,R-dach is the oxaliplatin ligand, R,R-1,2-diaminocyclohexane.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/ja101495v
