title: LONG R3IGF-I as a more potent alternative to insulin in serum-free culture of HEK293 cells.
abstract: LONG R3IGF-I, an analogue of insulin-like growth factor (IGF)-I, was specifically engineered for use in biopharmaceutical protein production in mammalian cells. LONG R3IGF-I is capable of supporting the growth and survival of Chinese hamster ovary cells in serum-free media at concentrations at least 200-fold lower than required for insulin. LONG R3IGF-I also acts as a more potent growth and survival factor than either insulin or native IGF-I in SF culture of human embryonic kidney (HEK293) cells. To investigate the basis of the enhanced potency of LONG R3IGF-I we have examined the mechanism of action of these mitogens in HEK293 cells. All mitogens tested were found to activate the Type I IGF receptor (IGF-IR) and insulin receptor (IR) in a dose-responsive manner. However, the level of activation of both receptors after stimulation with LONG R3IGF-I, at lower concentrations, was greater than with either insulin or IGF-I. The greater potency of LONG R3IGF-I in activating the IR, despite having a low affinity for IRs, suggests the presence of heterotetrameric IGF-IR/IR dimers. Interestingly, the decrease in IGF-IR activation at higher concentrations of LONG R3IGF-I suggests that the dose-response curve may be bell-shaped.
authors.affiliation: Animal Cell Technology, GroPep Ltd., 28 Dalgleish St., Thebarton 5031, SA, Australia.
authors.forename: Danny
authors.initials: D
authors.lastname: Voorhamme
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Yandell
mesh_terms: D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000031:analogs & derivatives* / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology*; D017526:Receptor, IGF Type 1 / Q000819:agonists*; D011972:Receptor, Insulin / Q000819:agonists*
chemical_list: D016895:Culture Media, Serum-Free; D007328:Insulin; D008934:Mitogens; C085700:long R(3)-insulin-like growth factor-I; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin