PERSISTENCE OF ALKYLATED DNA IN CARCINOGENESIS

  • Pegg, Anthony (PI)
  • Pegg, Anthony (PI)
  • Kanugula, Sreenivas (PI)
  • Kanugula, Sreenivas (PI)
  • Pegg, Anthony E. (PI)
  • PEGG, ANTHONY (PI)
  • PEGG, ANTHONY (PI)

Project: Research project

Project Details

Description

The research is aimed at understanding basic mechanisms by which
alkylating carcinogens, such as dimethylnitrosamine, lead to initiation
of tumors, and the physiological processes by virtue of which cells are
resistant to this initiation. More specifically, the studies cover two
separate factors which play key roles in tumor initiation; the
interaction of alkylating agents with DNA and the subsequent repair of
these alkylation lesions. Experiments will be carried out to investigate
the sequence specificity and mechanism of DNA alkylation with particular
reference to the formation of O6-alkylguanine, O4-methylthymine, 7-
methylguanine and the ring opened form of 7-methylguanine. Preliminary
studies with oligodeoxynucleotides of defined sequence suggest that there
may be a major effect of DNA sequence on the extent of methylation of
guanines which has so far been overlooked. More detailed investigation
of the extent of specificity and the reasons for it will be carried out.
DNA repair systems for the alkylation products described above will be
characterized and the factors regulating their activity will be studied
in detail. It is intended to obtain specific antibodies to these
proteins and to obtain cDNA and genomic clones for them in order to
facilitate this work. Continued investigations of the mammalian alkyltransferase protein
responsible for the repair of O6-alkylguanine in DNA will be a major
portion of the proposed studies. These will include: (a) investigation
of its sequence specificity by synthesizing oligodeoxynucleotides of
defined sequence containing O6-alkylguanine and measuring their rate of
repair; (b) studying the mechanism of the reaction and designing
inhibitors of it; (c) purifying the protein from human liver and raising
antibodies to it; (d) isolating the gene and cDNA clones for the protein
by transfection procedures and by screening of human cDNA libraries in
lambda gt 11; and e) using these tools to study the regulation of the
protein in normal and neoplastic cells. The studies of the regulation of
the alkyltransferase will be combined with studies of the concomitant
changes in the amounts of proteins responsible for the repair of other
alkylation products. Dimethylnitrosamine and related compounds containing the N-nitroso-group
form a large class of chemical carcinogens which have considerable
potential environmental significance since they are so widespread that it
may not be possible to avoid exposure completely. The processes
underlying DNA alkylation and repair which will be studied in this work
may greatly influence the sensitivity of response to nitrosamines. The
understanding of these factors at the molecular level will permit more
detailed response to nitrosamines. The understanding of these factors at
the molecular level will permit more detailed analysis of the risks
associated with exposure to N-nitroso compounds and may enable strategies
to be designed to increase resistance to the hazards associated with
exposure to them.
StatusFinished
Effective start/end date12/31/891/31/13

Funding

  • National Cancer Institute: $306,534.00
  • National Cancer Institute
  • National Cancer Institute: $323,847.00
  • National Cancer Institute: $258,788.00
  • National Cancer Institute
  • National Cancer Institute
  • National Cancer Institute
  • National Cancer Institute: $332,567.00
  • National Cancer Institute
  • National Cancer Institute: $323,847.00
  • National Cancer Institute: $323,847.00
  • National Cancer Institute: $340,677.00
  • National Cancer Institute
  • National Cancer Institute: $340,625.00
  • National Cancer Institute: $306,485.00
  • National Cancer Institute

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