Removal of Bound Carcinogen during DNA Repair in Nondividing Human Lymphocytes

Anthony Dipple, Michael W. Lieberman

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Removal of alkylation products from the DNA of mammalian cells was studied in nondividing human lymphocytes damaged with 7-bromomethylbenz(fl)anthracene, a carcinogenic alkylating agent that produces chemically stable products upon reaction with DNA. The reaction of 7-bromomethylbenz(fl)anthracene-3H with cells in lymphocyte culture was complete in about 20 min. The unlabeled compound induced unscheduled (repair) DNA synthesis in lymphocytes maintained in hydroxyurea, and this process was complete in about 12 hr. The DNA of cells treated with the radioactive bromo- compound (1 μM) exhibited a 15 to 17% loss of radioactivity in 12 hr, while exposure to a higher concentration of the agent (20 μM) resulted in an 8 to 9% loss of radioactivity. Salmon sperm DNA alkylated by this agent exhibited no detectable loss of radioactivity after heating for 22 hr at 50°. The major sites of attack of 7-bromomethylbenz(fl)anthracene on lymphocyte DNA were the amino groups of guanine and adenine. Analysis of DNA isolated from treated lymphocytes at zero time and 12 hr later suggested that the damaged adenine nucleotides were removed more extensively than were the damaged guanine nucleotides and that participation in the cell cycle is not a precondition for removal of bound carcinogen.

Original languageEnglish (US)
Pages (from-to)1855-1860
Number of pages6
JournalCancer research
Issue number9
StatePublished - Sep 1972

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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