Tri-iodothyronine and cycloheximide enhance insulin-like growth factor-binding protein-1 gene expression in human hepatoma cells.

摘要: The growth-regulating actions of IGFs are modulated by their binding proteins (IGFBPs). serum concentration IGFBP-1 is down-regulated insulin, and in-vitro studies have demonstrated that secretion from various tissues cells can be stimulated theophylline, forskolin, oestrogen progesterone. We studied the effects mechanisms thyroid hormone action on gene expression human hepatoma in vitro. Tri-iodothyronine dose-dependently enhanced serum-free HepG2 cell cultures after 24-48 h exposure, as measured a specific immunofluorometric assay. This was accompanied an increase (+ 50%) amount mRNA, which could prevented cycloheximide, protein synthesis inhibitor. Cycloheximide transiently 200%) accumulation mRNA at 3-12 incubation, when no effect tri-iodothyronine observed. It concluded stimulates slowly enhancing mediator. acute stimulation transcription cycloheximide associates this with number growth-related genes encoding growth- tumour-associated peptides.