title: Molecular expression analysis of beta-naphthoflavone-induced hepatocellular tumors in rats.
abstract: The present study was performed to characterize molecular expression levels of preneoplastic and neoplastic lesions induced by beta-naphthoflavone (BNF), an aryl hydrocarbon receptor (AhR) agonist in rat hepatocarcinogenesis. Male F344 rats were initiated with an intraperitoneal injection of 200 mg/kg N-diethylnitrosamine, and two weeks later, they were fed a diet containing 0% or 1% BNF for twenty-eight weeks. All animals were subjected to a two-thirds partial hepatectomy at week 3 and sacrificed at week 30. Histopathologically, BNF increased the incidence and multiplicity of altered foci (1.7-fold and 3.3-fold) and hepatocellular adenomas (HCAs) (4.0-fold and 4.7-fold). Immunohistochemically, BNF increased the number of proliferating cell nuclear antigen (PCNA)-positive cells in altered foci (2.3-fold) and HCAs (6.7-fold) compared with the surrounding tissue and decreased the staining of cell cycle regulators (P21, C/EBPalpha). In addition, loss of reactivity for AhR-regulated (CYP1A1, CYP1B1) molecules and increased reactivity of Nrf-2-regulated (AKR7, GPX2) molecules were also observed in proliferative lesions. Furthermore, increased staining of histone deacetylase (HDAC1) in the nucleus was prominent in HCAs. The differential expression patterns were confirmed at mRNA levels by real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. These results suggest that enhanced cell proliferation and protection against oxidative stress play an important role in BNF-induced hepatocarcinogenesis in rats.
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Dewa
authors.forename: Jihei
authors.initials: J
authors.lastname: Nishimura
authors.forename: Meilan
authors.initials: M
authors.lastname: Jin
authors.forename: Masaomi
authors.initials: M
authors.lastname: Kawai
authors.forename: Yukie
authors.initials: Y
authors.lastname: Saegusa
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Harada
authors.forename: Makoto
authors.initials: M
authors.lastname: Shibutani
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Mitsumori
mesh_terms: D018248:Adenoma, Liver Cell / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D003627:Data Interpretation, Statistical; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000633:toxicity*; D020869:Gene Expression Profiling; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019324:beta-Naphthoflavone / Q000633:toxicity*
chemical_list: D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D018336:Receptors, Aryl Hydrocarbon; D019324:beta-Naphthoflavone; C515890:Hdac1 protein, rat; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases