Molecular Pharmacology, Vol 4, 147-154, Copyright © 1968 by the American Society for Pharmacology and Experimental Therapeutics

Reactions in Vitro of Some Tissue Nucleophiles with the Glucuronide of the Carcinogen N-Hydroxy-2-acetylaminofluorene

¹ McArdle Laboratory for Cancer Research, University of Wisconsin Medical Center, Madison, wisconsin 53706
² Veterans Administration Hospital and Department of Biochemistry, University of Tennessee, Memphis, Tennessee 38104

The metabolically formed glucuronide of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) is cleaved at the N—O bond in reactions in vitro at pH 7 with methionine, tryptophan, and guanosine. These reactions of the glucuronide (N-GlO-AAF) are similar to, but considerably slower than, those with esters of N-hydroxy-AAF such as N-acetoxy-AAF.

At pH 7 the major product of either N-acetoxy-AAF or N-GlO-AAF with methionine is 3-CH₃S-AAF. At pH levels greater than 7, N-GlO-AAF also yields considerable amounts of 3-CH₃S-2-aminofluorene (3-CH₃S-AF). Neither N-hydroxy-AAF nor the triacetyl methyl ester of N-GlO-AAF gives significant reaction with methionine at pH 5-9; with N-hydroxy-2-aminofluorene the reaction with methionine to yield 3-CH₃S-AF increases markedly below pH 5.5.

The reaction of N-GlO-AAF with guanosine appears to yield a mixture of N-(guanosin-8-yl)-2-acetylaminofluorene (the predominant product with N-acetoxy-AAF) and N-(guanosin-8-yl)-2-aminofluorene. The uncharacterized products formed by reaction of N-GlO-AAF or N-acetoxy-AAF with tryptophan appear to be similar.

Tumor development did not occur within 12 months after repeated subcutaneous injections of either the sodium or cupric salt or of the triacetyl methyl ester of N-GlO-AAF into female rats. Under the same conditions N-hydroxy-AAF induced high incidences of tumors in the subcutaneous tissue, mammary glands, and ear duct glands.

Whether or not metabolically formed N-GlO-AAF is involved in the formation of protein- and nucleic acid-bound fluorene derivatives in vivo and in tumor induction by AAF and N-hydroxy-AAF requires further investigation.

Note:
ACKNOWLEDGMENTS This research was supported at the University of Wisconsin by Grants CA-07175 and CRTY-5002 of the National Cancer Institute, U.S. Public Health Service, by a grant from the Jane Coffin Childs Memorial Fund for Medical Research, and by the Alexander and Margaret Stewart Trust Fund. It was supported in Memphis by the Veterans Administration Hospital and in part, by USPHS Research Grant CA-05490 from the National Cancer Institute.

This article has been cited by other articles:

				J. R. DeBaun, J. Y. R. Smith, E. C. Miller, and J. A. Miller Reactivity in vivo of the Carcinogen N-Hydroxy-2-acetylaminofluorene: Increase by Sulfate Ion Science, January 9, 1970; 167(3915): 184 - 186. [Abstract] [PDF]