Send to:

Choose Destination
See comment in PubMed Commons below
Carcinogenesis. 2007 Jul;28(7):1499-503. Epub 2007 Mar 14.

Modulation by budesonide of a CpG endonuclease in mouse lung tumors.

Author information

  • 1Department of Biochemistry and Cancer Biology, Medical University of Ohio, 3055 Arlington Avenue, Toledo, OH 43614-5806, USA.


CpG endonuclease activity was identified in nuclear extracts obtained from mouse lung tumors. Enzyme activity was determined using a 333 bp polymerase chain reaction product of the estrogen receptor-alpha gene that contained either radiolabeled cytosine or tritium-labeled methyl groups at CpG sites. Activity was measured as the release of radioactivity from the substrate. The product of the nuclease activity was identified by high pressure liquid chromatography (HPLC) as either 5-methyl-2'-deoxycytidine when the CpG sites in the substrate were methylated or 2'-deoxycytidine when the CpG sites were not methylated. The CpG endonuclease activity was dependent on nuclear protein and temperature, had a proclivity for double-stranded over single-stranded DNA and was inhibited by ethylenediaminetetraacetic acid or 2-mercaptoethanol. Strain A/J mouse lung tumors induced by vinyl carbamate had a greater level of CpG endonuclease activity than non-involved lung tissue. Budesonide, a potent chemopreventive agent in mouse lung, not only prevented an increase in CpG endonuclease activity in lung tumors but, when administered to mice with established tumors, also decreased the level of endonuclease activity in the tumors. The effect of budesonide on CpG endonuclease activity in lung tumors was inversely related to its published effect on DNA methylation in mouse lung tumors, i.e. the drug decreased CpG endonuclease activity and increased the methylation of DNA. The increased CpG endonuclease activity in mouse lung tumors and its inhibition by budesonide would suggest this endonuclease as a potential molecular target for chemoprevention.

[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk