DNA adducts of decarbamoyl mitomycin C efficiently kill cells without wild-type p53 resulting from proteasome-mediated degradation of checkpoint protein 1.

Abstract

The mitomycin derivative 10-decarbamoyl mitomycin C (DMC) more rapidly activates a p53-independent cell death pathway than mitomycin C (MC). We recently documented that an increased proportion of mitosene1-beta-adduct formation occurs in human cells treated with DMC in comparison to those treated with MC. Here, we compare the cellular and molecular response of human cancer cells treated with MC and DMC. We find the increase in mitosene 1-beta-adduct formation correlates with a condensed nuclear morphology and increased cytotoxicity in human cancer cells with or without p53. DMC caused more DNA damage than MC in the nuclear and mitochondrial genomes. Checkpoint 1 protein (Chk1) was depleted following DMC, and the depletion of Chk1 by DMC was achieved through the ubiquitin proteasome pathway since chemical inhibition of the proteasome protected against Chk1 depletion. Gene silencing of Chk1 by siRNA increased the cytotoxicity of MC. DMC treatment caused a decrease in the level of total ubiquitinated proteins without increasing proteasome activity, suggesting that DMC mediated DNA adducts facilitate signal transduction to a pathway targeting cellular proteins for proteolysis. Thus, the mitosene-1-beta stereoisomeric DNA adducts produced by the DMC signal for a p53-independent mode of cell death correlated with reduced nuclear size, persistent DNA damage, increased ubiquitin proteolysis and reduced Chk1 protein.

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Citation

Published Version (Please cite this version)

10.1021/tx900420k

Publication Info

Boamah, Ernest K, Angelika Brekman, Maria Tomasz, Natura Myeku, Maria Figueiredo-Pereira, Senyene Hunter, Joel Meyer, Rahul C Bhosle, et al. (2010). DNA adducts of decarbamoyl mitomycin C efficiently kill cells without wild-type p53 resulting from proteasome-mediated degradation of checkpoint protein 1. Chem Res Toxicol, 23(7). pp. 1151–1162. 10.1021/tx900420k Retrieved from https://hdl.handle.net/10161/4114.

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Meyer

Joel Meyer

Professor of Environmental Genomics in the Division of Environmental Sciences and Policy

Dr. Meyer studies the effects of toxic agents and stressors on human and wildlife health. He is particularly interested in understanding the mechanisms by which environmental agents cause DNA damage, the molecular processes that organisms employ to protect prevent and repair DNA damage, and genetic differences that may lead to increased or decreased sensitivity to DNA damage. Mitochondrial DNA damage and repair, as well as mitochondrial function in general, are a particular focus. He studies these effects in the nematode Caenorhabditis elegans, in cell culture, and collaboratively in other laboratory model organisms as well as in human populations in the USA and globally.


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