title: Effects of ultraviolet radiation on FRTL-5 cell growth and thyroid-specific gene expression.
abstract: During space missions, radiation represents a major hazard for human health and involves all body organs and tissues. Regarding thyroid function, it has been shown that ultraviolet radiation (UVC) has dose-dependent apoptotic effects on FRTL-5 cells, a normal strain of rat thyrocytes. We examined the effects of a sublethal dose of UVC on FRTL-5 cell growth and gene expression. Cells exposed to 10 J/m(2) UVC showed no differences in viability compared to control cells after 24 h, but the BrdU incorporation was reduced, indicating a cytostatic effect. Quantitative RT-PCR carried out at 24 and 48 h after irradiation demonstrated that the mRNA levels of thyroglobulin (Tg), thyroperoxidase (Tpo), and sodium/iodide symporter (Nis) were transiently decreased at 24 h in treated cells, while the mRNAs of the thyroid transcription factors TTF1, Foxe1, and Pax8 were not affected. In cells cultured with TSH-free medium, the basal transcription of Tg, Tpo, and Nis genes was equally impaired by radiation and no longer stimulated by TSH. Overall, the results demonstrate that a sub-apoptotic dose of UVC compromises not only thyrocyte proliferation but also the expression of genes involved in thyroid hormone production. These findings might contribute to explaining the histological, biochemical, and clinical features of hypothyroidism observed in both animals and humans during spaceflight, and suggest that free thyroxine levels of astronauts during prolonged space missions should be monitored.
authors.affiliation: Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Enke
authors.initials: E
authors.lastname: Baldini
authors.forename: Massimino
authors.initials: M
authors.lastname: D'Armiento
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sorrenti
authors.forename: Marianna
authors.initials: M
authors.lastname: Del Sordo
authors.forename: Renzo
authors.initials: R
authors.lastname: Mocini
authors.forename: Stefania
authors.initials: S
authors.lastname: Morrone
authors.forename: Lucio
authors.initials: L
authors.lastname: Gnessi
authors.forename: Francesco
authors.initials: F
authors.lastname: Curcio
authors.forename: Salvatore
authors.initials: S
authors.lastname: Ulisse
mesh_terms: D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000528:radiation effects*; D002460:Cell Line; D017931:DNA Primers; D015870:Gene Expression / Q000528:radiation effects*; D016133:Polymerase Chain Reaction; D051381:Rats; D013961:Thyroid Gland / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D017931:DNA Primers