Comparative Tumor-initiating Activity of Methylated Benzo(a)pyrene Derivatives in Mouse Skin 1

R. P. Iyer, J. W. Lyga, J. A. Secrist, G. H. Daub, T. J. Slaga

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


The abilities of various mono and dimethyl derivatives of benzo(a)pyrene (BP) to initiate skin tumors in mice were determined by using a two-stage system of tumorigenesis. 11 -Methylbenzo(a)pyrene was found to be approximately 3 times more active as a tumor initiator than was the parent hydrocarbon; 1 - methyl benzo(a)pyrene was about twice as active as was BP. Substitution of a methyl group in positions 7, 8, 9, or 10 of BP, which would be involved in a bay-region diol-epoxide, completely counteracts the tumor-initiating ability of BP. 3-, 4-, and 12-methyl-benzo(a)pyrenes had activity equivalent to that of BP, whereas 2-, 5-, and 6-methylbenzo(a)pyrenes, as well as 1,2-, 4,5-, 1,6-, and 3,6-dimethylbenzo(a)pyrenes, were all less active than BP. The concepts of steric inhibition of metabolic activation and stereospecific activation are suggested to explain the tumor-initiating activities of various methylated derivatives.

Original languageEnglish (US)
Pages (from-to)1073-1076
Number of pages4
JournalCancer Research
Issue number4
StatePublished - Apr 1 1979
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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