title: Expression of beta-catenin in rat oral epithelial dysplasia induced by 4-nitroquinoline 1-oxide.
abstract: The aim of this study was to evaluate whether beta-catenin accumulation is useful for diagnosing the malignant potential of oral precancerous lesions. We investigated oral epithelial dysplasia adjacent to early cancer induced by 4-nitroquinoline 1-oxide in rats. Localization of beta-catenin and cell proliferation were detected immunohistochemically, and exon 3 of the beta-catenin gene was analyzed. Accumulation of beta-catenin in the cytoplasm and nucleus was evident in 10 of 16 dysplasia lesions. Since almost all of the dysplastic lesions in these rats transformed to invasive cancer, beta-catenin accumulation may contribute to the early stage of carcinogenesis. The Ki-67 labeling index was significantly higher in dysplasia and early cancer than in no change. However, there were no significant differences between the expression patterns of beta-catenin protein, suggesting that other proliferation pathways are involved in the early stage of tumor development in addition to beta-catenin accumulation. No mutations of exon 3 of the beta-catenin gene were detected in any of the dysplasia or early cancer lesions. These findings suggested that beta-catenin accumulation in the cytoplasm and nucleus without mutation of exon 3 is an early event during carcinogenesis in this tongue cancer model.
authors.affiliation: Department of Oral Medicine, Tokyo Dental College, 5-11-13 Sugano, Ichikawa City, Chiba 272-8513, Japan. ksatou@tdc.ac.jp
authors.forename: Kazumichi
authors.initials: K
authors.lastname: Sato
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Okazaki
authors.forename: Morio
authors.initials: M
authors.lastname: Tonogi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Gen-yuki
authors.initials: GY
authors.lastname: Yamane
mesh_terms: D015112:4-Nitroquinoline-1-oxide; D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002273:Carcinogens; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism*; D011230:Precancerous Conditions / Q000139:chemically induced* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014062:Tongue Neoplasms / Q000139:chemically induced* / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D051176:beta Catenin
chemical_list: D014408:Biomarkers, Tumor; D002273:Carcinogens; C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D015534:Trans-Activators; D051176:beta Catenin; D015112:4-Nitroquinoline-1-oxide