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Increased cytosine DNA-methyltransferase activity in A/J mouse lung cells following carcinogen exposure and during tumor progression

Technical Report ·
OSTI ID:54824
; ;  [1]
  1. Johns Hopkins Univ., Baltimore, MD (United States)
Considerable evidence has accumulated that 5-methylcytosine modification of mammalian DNA, both in exons and CpG rich islands located in promoter regions, is important in gene regulation. For example, a decrease of 5-methylcytosine in 5{prime} flanking regions or exons of genes has been associated with increased gene transcription. In addition, hypermethylation at specific regions of chromosomes 17p and 3p have also been observed in lung and colon cancer. During colon cancer development, these hypermethylation changes precede allelic loss. In addition, the activity of the enzyme which maintains the methylation status at CpG dinucleotides, DNA methyltransferase (MT), has been shown to increase during colon cancer progression. These observations suggest changes in methylation patterns within specific genes could result in either inappropriate gene expression or gene deletion, both of which would contribute to the establishment of the malignant phenotype. The purpose of this investigation was to determine if DNA MT activity is elevated in target (alveolar type II), but not in nontarget (Clara, endothelial, macrophage) lung cells isolated from the A/J mouse following exposure to nitrosamine 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK). In addition, the activity of this enzyme during tumor progression was examined.
Research Organization:
Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States). Inhalation Toxicology Research Inst.
DOE Contract Number:
AC04-76EV01013
OSTI ID:
54824
Report Number(s):
ITRI--144; ON: DE95007526; CNN: Contract 1-P50-CA58184
Country of Publication:
United States
Language:
English