title: Role of non-TSH factors in thyroid cell growth.
abstract: The effects of insulin, the tumour promotor tetradecanoyl phorbol acetate (TPA), TSH and combinations of these factors on growth and DNA synthesis have been examined in the FRTL-5 cell strain and in sheep thyroid cells. In addition the regulation of the production by sheep thyroid cells of the insulin-like growth factors (IGF) by TSH and their possible autocrine roles have been investigated. We found that insulin and the IGF's stimulated DNA synthesis in both rat FRTL-5 cells and sheep cells. TPA also stimulated growth in both cell types, and its effects were additive to those of insulin. In the FRTL-5 cells, TPA was a less potent stimulator of growth than TSH, but the effects of TPA and TSH were not additive which may imply growth stimulation through a common pathway. In sheep cells TSH was not mitogenic and did not appear to activate protein kinase C, the receptor for TPA. Sheep cells, unlike FRTL-5 cells, were found to produce IGF-I and IGF-II, and their syntheses were regulated by TSH. Sheep cells were also found to produce IGF-binding proteins which may modulate the biologic effects of the IGF's. Sheep thyroid IGF binding proteins were found to copurify with urokinase-like plasminogen activator on immunoaffinity chromatography. The production of this serine protease has also been shown to be regulated by TSH.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology; D006728:Hormones / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D012756:Sheep; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013961:Thyroid Gland / Q000166:cytology* / Q000187:drug effects; D013972:Thyrotropin / Q000494:pharmacology*
chemical_list: D006728:Hormones; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013972:Thyrotropin; D013006:Growth Hormone; D013755:Tetradecanoylphorbol Acetate