Nakae D, Kishida H, Enami T, Konishi Y, Hensley KL, Floyd RA, Kotake Y. Effects of phenyl N-tert-butyl nitrone and its derivatives on the early phase of hepatocarcinogenesis in rats fed a choline-deficient, L-amino acid-defined diet.
Cancer Sci 2003;
94:26-31. [PMID:
12708470 PMCID:
PMC11160203 DOI:
10.1111/j.1349-7006.2003.tb01347.x]
[Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2002] [Revised: 10/31/2002] [Accepted: 11/12/2002] [Indexed: 11/29/2022] Open
Abstract
The present study examined the effects of various derivatives of a radical trapping agent, phenyl N-tert-butyl nitrone, on the early phase of hepatocarcinogenesis in male Wistar rats fed a choline-deficient, L-amino acid-defined diet for 16 weeks. The derivatives used were 4-hydroxyphenyl (a physiologically major metabolite), 3-hydroxyphenyl, 2-hydroxyphenyl and 2-sulfoxyphenyl N-tert-butyl nitrone, and their effects were studied in a comparison with those of the parent compound, phenyl N-tert-butyl nitrone. The sizes of putatively preneoplastic, glutathione S-transferase placental form-positive lesions and the levels of extra-nuclear oxidative injury of hepatocytes, using the formation of 2-thiobarbituric acid-reacting substances as a parameter, were decreased by all doses (0.009%, 0.045% and 0.090% in diet) of 4-hydroxyphenyl N-tert-butyl nitrone and only by the highest dose of 3-hydroxyphenyl N-tert-butyl nitrone and phenyl N-tert-butyl nitrone. While 4-hydroxyphenyl N-tert-butyl nitrone, 3-hydroxyphenyl N-tert-butyl nitrone and phenyl N-tert-butyl nitrone all enhanced and inhibited hepatocellular apoptosis in preneoplastic lesions and their surrounding tissue, respectively, only 4-hydroxyphenyl N-tert-butyl nitrone additionally inhibited hepatocyte proliferation both in preneoplastic lesions and their surrounding tissue. 2-Hydroxyphenyl or 2-sulfoxyphenyl N-tert-butyl nitrone did not exert any of the above effects. These results suggest that the selective induction of apoptosis in preneoplastic hepatocyte populations plays a crucial role in the inhibition of hepatocarcinogenesis derived by phenyl N-tert-butyl nitrone and its effective derivatives. Further, the metabolic conversion to 4-hydroxyphenyl N-tert-butyl nitrone may also be important for the inhibitory effects of phenyl N-tert-butyl nitrone on hepatocarcinogenesis.
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