title: Pituitary changes in Prop1 transgenic mice: hormone producing tumors and signet-ring type gonadotropes.
abstract: Prophet of Pit-1 (Prop1) is an early transcription factor that delays the appearance of gonadotropin in the developing pituitaries. Prop1 transgenic (Tg) mice have been shown to generate pituitary tumors that either produce TSH or are non-hormone producing. In our series of Prop1 Tg mice, only 5 out of 9 female mice produced pituitary adenomas, and the adenomas were only GH, PRL, GH and PRL, PRL and gonadotropin or TSH producing. The pituitary cells that surrounded these adenomas showed hyperplasia of the corresponding hormone producing cells; i.e. the GH cells were increased in the pituitary that contained GH producing adenoma. In addition, although the adenomas lacked the expression of Prop1, the non-neoplastic pituitary cells showed expression of Prop1. The Prop1 Tg mice also showed vacuolated cells with eccentric nuclei, which are characteristic of "signet-ring hypertrophic cells". Using immunohistochemistry, these signet ring hypertrophic cells were found to be positive for gonadotropin.Taken together, our results suggest a (1) tumorigenic effect of Prop1 in the pituitaries, and (2) causative effects of signet ring-type gonadotropes.
authors.affiliation: Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Egashira
authors.forename: Takeo
authors.initials: T
authors.lastname: Minematsu
authors.forename: Syunsuke
authors.initials: S
authors.lastname: Miyai
authors.forename: Susumu
authors.initials: S
authors.lastname: Takekoshi
authors.forename: Sally A
authors.initials: SA
authors.lastname: Camper
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Osamura