title: A novel animal model of thymic tumour: development of epithelial thymoma in transgenic rats carrying human T lymphocyte virus type I pX gene.
abstract: The pX region encodes a major product of human T lymphocyte virus type I (HTLV-I) that has been implicated previously in tumour formation. To investigate the pathogenesis of pX gene in lymphoid tissues, we established a series of novel transgenic rats carrying the pX gene under the control of a rat lymphocyte-specific protein tyrosine kinase (p56lck) proximal promoter. The transgene was constructed with the -269 to +26 region of a rat p56lck proximal promoter and the pX cDNA, and was microinjected into fertilized ova of Fischer 344/jcl female rats. Six transgenic lines from 114 pups were established. Integration and expression of the transgene were detected by polymerase chain reaction (PCR) and Southern hybridization or by reverse transcriptase-PCR, northern hybridization, and immunostaining. Thymic tumours with lethal expansion occurred in 4 of 6 transgenic lines. The tumour consisted of spindle shaped cells. Immunohistochemical and ultra-structural analysis characterized the tumour cells to as epithelial cell type, and in the tumour arose in the medulla. Therefore, the tumour is classified into predominantly epithelial and spindle cell of medullary thymoma (type A of the new World Health Organization classification), as based on the human classification. Tumor occurrence increased in proportion to levels of the pX transcription in the thymus, for each line, and sex distinction was evident regarding rates related to tumour expansion. The transgenic rat model described here is suitable as a model for analysing tumorigenesis in epithelial thymoma occurring in humans.
authors.affiliation: Department of Pathology/Pathophysiology, Division of Pathophysiological Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ikeda
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuchikawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuji
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fugo
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sugaya
authors.forename: Yuetsu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Tateno
authors.forename: Naoki
authors.initials: N
authors.lastname: Maruyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiki
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D005260:Female; D016355:Genes, pX; D008854:Microscopy, Electron; D023421:Models, Animal; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D013945:Thymoma / Q000473:pathology; D013953:Thymus Neoplasms / Q000473:pathology
chemical_list: D012333:RNA, Messenger