Effects of insulin and insulin-like growth factor I on growth of human leukemia cells in serum-free and protein-free medium.
Human myeloid leukemia cells (HL60) and malignant lymphocytes (Namalwa) were grown in protein-free, Fe-supplemented media and used to study growth responses to insulin and insulin-like growth factor 1 (IGF-I). HL60 cells previously grown in serum-free medium containing microgram quantities of insulin showed an 18-fold reduction in cumulative cell production when grown without insulin. However, the same cells showed reduced or absent growth stimulation with 1 to 100 ng/mL insulin or IGF-I for at least four days following insulin deprivation, indicating that culture conditions modified insulin and IGF-I responses. When the same cells were grown in Fe-supplemented, protein-free medium (RPMI-Fe), insulin and IGF-I caused dose-dependent stimulation of HL60 cell growth with half-maximal stimulation at nanogram concentrations. Namalwa cells grown in protein-free medium showed no response to either hormone. Radioligand binding showed the presence of insulin and IGF-I receptors on both HL60 and Namalwa cells grown in RPMI-Fe. HL60 cells grown in fetal bovine serum had higher, and cells grown with microgram quantities of insulin dramatically reduced, insulin binding. Competitive binding studies and cultures with anti-IGF-I receptor antibody showed insulin and IGF-I stimulated growth through their respective specific receptors. Both insulin and IGF-I stimulate growth of some cultured human leukemia cells, but the presence of insulin or IGF-I receptors alone does not predict growth responses. Culture conditions affect both cellular responses and ligand binding by these hormones and must be closely controlled to study growth responses.
Sinclair
J
J
Department of Medicine, University of California, San Diego 92103.
McClain
D
D
Taetle
R
R
D000911:Antibodies, Monoclonal / Q000502:physiology; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D003470:Culture Media / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D007938:Leukemia / Q000378:metabolism / Q000473:pathology*; D011506:Proteins; D011972:Receptor, Insulin / Q000032:analysis / Q000187:drug effects / Q000276:immunology; D013002:Somatomedins / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology*
D000911:Antibodies, Monoclonal; D003470:Culture Media; D007328:Insulin; D011506:Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin