Asbestos increases mammalian AP-endonuclease gene expression, protein levels, and enzyme activity in mesothelial cells.
Only two DNA repair enzymes, DNA polymerase beta and O6-methylguanine-DNA methyltransferase, have been shown to be inducible in mammalian cells by genotoxic agents. We show here that crocidolite asbestos induces the DNA repair enzyme, apurinic/apyrimidinic (AP)-endonuclease, in isolated mesothelial cells, the progenitor cells of malignant mesothelioma. Asbestos at nontoxic concentrations of 1.25 and 2.5 microg/cm2 significantly increased AP-endonuclease mRNA and protein levels as well as enzyme activity (P < 0.05) in a dose-dependent manner in rat pleural mesothelial cells. These increases were persistent from 24 to 72 h after initial exposure to fibers. Changes were not observed with glass beads, a noncarcinogenic particle. Confocal scanning laser microscopy showed that AP-endonuclease was primarily localized in the nucleus but also in mitochondria. Our data are the first to demonstrate the inducibility of AP-endonuclease by a human class I carcinogen associated with oxidant stress in normal cells of the lung.
Fung
H
H
Department of Pathology, University of Vermont, Burlington 05405, USA.
Kow
Y W
YW
Van Houten
B
B
Taatjes
D J
DJ
Hatahet
Z
Z
Janssen
Y M
YM
Vacek
P
P
Faux
S P
SP
Mossman
B T
BT
D000818:Animals; D017638:Asbestos, Crocidolite / Q000494:pharmacology*; D015152:Blotting, Northern; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D002273:Carcinogens / Q000494:pharmacology*; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D019084:Fluorescent Antibody Technique, Indirect; D015971:Gene Expression Regulation, Enzymologic; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000201:enzymology; D009687:Nuclear Proteins / Q000378:metabolism*; D010994:Pleura / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D002273:Carcinogens; D017931:DNA Primers; D009687:Nuclear Proteins; D012333:RNA, Messenger; D017638:Asbestos, Crocidolite; D043223:Deoxyribonuclease IV (Phage T4-Induced); D019757:Carbon-Oxygen Lyases; C470319:Apex1 protein, rat; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase