Involvement of Wnt pathway in thyroid cancer around Semipalatinsk Nuclear Test Site Serik K. Meirmanov a, * , Masahiro Nakashima b , Noboru Takamura c , Masahiro Ito d , Yuri V. Prouglo e , Shunichi Yamashita f,g , Ichiro Sekine a,b a Department of Molecular Pathology, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan b Tissue and Histopathology Section, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan c Department of Public Health, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan d Department of Pathology, National Nagasaki Medical Center, Nagasaki, Japan e Department of Pathology, Semipalatinsk Medical Academy, Semipalatinsk, Kazakhstan f Department of Nature Medicine, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan g Department of International Health and Radiation Research, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan Abstract. A total of 459 nuclear tests were officially conducted at the Semipalatinsk Nuclear Test Site of Kazakhstan during the period from 1949 to 1989. The exposure to radioactive fallout could affect the population health. The aberrant activation of Wnt pathway elements is linked to thyroid tumorigenesis. The activated Wnt signaling stabilizes h-catenin and results in transactivation of target genes including cyclin D1. To investigate the involvement of the Wnt/h-catenin pathway in thyroid carcinomas around the Semipalatinsk Nuclear Test Site, we compared immunohistochemical results for h-catenin and cyclin D1 expression in chronic thyroiditis, follicular adenoma and papillary carcinoma. This study revealed a higher prevalence of both aberrant h-catenin expression and cyclin D1 overexpression in papillary thyroid cancers around the Semipalatinsk Nuclear Test Site than sporadic cases. The analysis of the alteration of the Wnt signaling-related molecules in thyroid cancer around the Semipalatinsk Nuclear Test Site may be important to gain an insight into radiation-induced thyroid tumorigenesis. D 2003 Elsevier B.V. All rights reserved. Keywords: Wnt pathway; h-catenin; Thyroid tumors; Semipalatinsk Nuclear Test Site; Radiation 0531-5131/ D 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0531-5131(03)01198-1 * Corresponding author. Tel.: +81-95-849-7107; fax: +81-95-849-7108. E-mail address: f1304@cc.nagasaki-u.ac.jp (S.K. Meirmanov). www.ics-elsevier.com International Congress Series 1258 (2003) 177 – 183