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Oxidative Medicine and Cellular Longevity
Volume 2017, Article ID 8541064, 16 pages
https://doi.org/10.1155/2017/8541064
Research Article

Progression of Hepatic Adenoma to Carcinoma in Ogg1 Mutant Mice Induced by Phenobarbital

Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-Ku, Asahi-Machi 1-4-3, Osaka 545-8585, Japan

Correspondence should be addressed to Anna Kakehashi; pj.ca.uc-akaso.dem@anna

Received 22 March 2017; Revised 19 May 2017; Accepted 14 June 2017; Published 13 July 2017

Academic Editor: Laura Giusti

Copyright © 2017 Anna Kakehashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The carcinogenic potential of phenobarbital (PB) was assessed in a mouse line carrying a mutant Mmh allele of the Mmh/Ogg1 gene encoding the enzyme oxoguanine DNA glycosylase (Ogg1) responsible for the repair of 8-hydroxy-2′-deoxyguanosine (8-OHdG). Mmh homozygous mutant (Ogg1−/−) and wild-type (Ogg1+/+) male and female, 10-week-old, mice were treated with 500 ppm PB in diet for 78 weeks. Hepatocellular carcinomas (HCCs) were found in PB-treated Ogg1−/− mice, while Ogg1+/+ animals developed only hepatocellular adenomas (HCAs) at the same rate. This was coordinated with PB-induced significant elevation of 8-OHdG formation in DNA and cell proliferation in adjacent liver of Ogg1−/− mice. Proteome analysis predicted activation of transcriptional factor Nrf2 in the livers and HCAs of PB-administered Ogg1+/+ mice; however, its activation was insufficient or absent in the livers and HCCs of Ogg1−/− mice, respectively. Significant elevation of phase I and II metabolizing enzymes was demonstrated in both Ogg1−/− and Ogg1+/+ animals. Treatment of Ogg1−/− mice with PB resulted in significant elevation of cell proliferation in the liver. These results indicate that PB induced progression from HCA to HCC in Ogg1−/− mice, due to persistent accumulation of DNA oxidative base modifications and suppression of Nrf2-mediated oxidative stress response, resulting in significant elevation of cell proliferation.