Transforming events in thyroid tumorigenesis and their association with follicular lesions.
Thyroid tumors comprise a broad spectrum of neoplastic phenotypes, and distinct molecular events have been implicated in their pathogenesis. Pituitary tumor transforming gene, originally isolated from GH(4) pituitary cells, is tumorigenic in vivo, regulates basic fibroblast growth factor secretion, and is homologous to a securin inhibitor of chromatid separation. Pituitary tumor transforming gene 1 is expressed at low levels in several normal human tissues and is abundantly expressed in neoplasms, including colorectal carcinoma, where pituitary tumor transforming gene expression correlated highly with tumor invasiveness. As pituitary tumor transforming gene is regulated by E and as thyroid cancer shows a strong female preponderance, we examined pituitary tumor transforming gene 1 expression and action in human thyroid tumors and in normal human and rat thyroid cells. Increased pituitary tumor transforming gene 1 expression was evident early in thyroid tumors and was most abundantly expressed in a subset of thyroid hyperplasia, follicular adenomas, and follicular carcinomas (1.8-fold; P < 0.0001). Pituitary tumor transforming gene 1 overexpression in rat FRTL5 thyroid cells and in primary human thyroid cell cultures causes in vitro transformation and produces a dedifferentiated neoplastic phenotype. As pituitary tumor transforming gene 1 was abundantly overexpressed in follicular adenoma and follicular carcinoma, we propose that pituitary tumor transforming gene overexpression may play a role in the early molecular events leading to divergent development of follicular and papillary carcinoma.
Heaney
A P
AP
Department of Medicine, Cedars-Sinai Research Institute, University of California School of Medicine, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA. heaneya@csmc.edu
Nelson
V
V
Fernando
M
M
Horwitz
G
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic; D005260:Female; D006801:Humans; D007454:Iodides / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D064249:Securin; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000209:etiology* / Q000473:pathology; D013972:Thyrotropin / Q000494:pharmacology
D007454:Iodides; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D064249:Securin; C578002:pituitary tumor-transforming protein 1, human; D013972:Thyrotropin