Insulin-like growth factor I stimulates inositol phosphate accumulation, a rise in cytoplasmic free calcium, and proliferation in cultured porcine thyroid cells

• Published in: The Journal of biological chemistry 1989-11, Vol.264 (31), p.18485-18488
• Main Authors: Takasu, N, Takasu, M, Komiya, I, Nagasawa, Y, Asawa, T, Shimizu, Y, Yamada, T
• Format: Article
• Language: English
• Subjects: Animals; Benzofurans; Biological and medical sciences; Calcium - metabolism; Cell Division - drug effects; Cell physiology; Cells, Cultured; Cytoplasm - metabolism; Dose-Response Relationship, Drug; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; Fura-2; Inositol Phosphates - metabolism; Insulin-Like Growth Factor I - administration & dosage; Insulin-Like Growth Factor I - pharmacology; Kinetics; Molecular and cellular biology; Responses to growth factors, tumor promotors, other factors; Somatomedins - pharmacology; Spectrometry, Fluorescence; Swine; Thyroid Gland - cytology; Thyroid Gland - drug effects; Thyroid Gland - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)51492-7

Insulin-like growth factor (IGF-I) stimulates thyroid cell proliferation. Using primary cultured porcine thyroid cells, we studied the intracellular pathways that mediate the action of IGF-I on thyroid cell proliferation. IGF-I stimulates inositol phosphate accumulation, a rise in cytoplasmic free calcium [(Ca2+]i), and cell proliferation. Exposure to IGF-I results in a time- and dose-dependent accumulation of inositol monophosphate, inositol bisphosphate, and inositol trisphosphate. IGF-I also increases [Ca2+]i, measured using fura-2, a fluorescent Ca2+ indicator; the IGF-I-induced [Ca2+]i response occurs immediately, reaches a maximum within 1 min, and then slowly declines. IGF-I stimulates thyroid cell proliferation, stimulates thymidine incorporation, and increases cell numbers. The IGF-I-induced inositol phosphate accumulation and [Ca2+]i response parallel thyroid cell proliferation in a dose-dependent manner; the maximal response is observed at a concentration of 100 ng/ml IGF-I, with half-maximal stimulation at approximately 10 ng/ml. Inositol phosphate accumulation and [Ca2+]i response after IGF-I stimulation may function as intracellular messengers for thyroid cell proliferation. This report may constitute the first demonstration of IGF-I-stimulated inositol phosphate accumulation and [Ca2+]i response in the cells.