Human growth hormone stimulates somatomedin C/insulin-like growth factor I production by the human lymphoid cell line, IM-9.
The human lymphoid cell line, IM-9, is known to possess receptors for human growth hormone (hGH), but the only biological response that has been shown to follow binding of this hormone to the cells is receptor down-regulation. We have studied the actions of hGH on production of insulin-like growth factor I (IGF-I) by IM-9 cells. In order to demonstrate effects cells had to be transferred to a serum-free medium in which cell multiplication almost ceased, and cell viability fell to 50-60%. hGH stimulated IGF-I production by up to 400%. The effect was dose-related, but the dose-response curve was bimodal, with peaks of activity at approximately 15 ng/ml and 1000 ng/ml hGH. The effect of hGH was of slow onset, becoming significant only after about 24 h, and approaching a maximum after 2-5 days of treatment. hGH had a much greater stimulatory effect than non-primate growth hormones. The physiological significance of the effect observed is not yet clear, but it is apparent that the IM-9 line is a potentially useful model for study of the actions of growth hormone.
Palmer
J M
JM
Biochemistry Laboratory, School of Biological Sciences, University of Sussex, Brighton, U.K.
Wallis
M
M
D002460:Cell Line; D013006:Growth Hormone / Q000494:pharmacology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D008221:Lymphoid Tissue / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D011986:Receptors, Somatotropin / Q000032:analysis; D013002:Somatomedins / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
D011986:Receptors, Somatotropin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone