title: Chinese hamster ovary cell variants resistant to monensin, an ionophoric antibiotic. II. Growth requirement for insulin and altered insulin-receptor activity.
abstract: From the Chinese hamster ovary (CHO) cell, genetic variants (MonR-31 and MonR-32) relatively resistant to monensin, an ionophoric antibiotic, have been isolated. Growth of both MonR-31 and MonR-32 clones required higher doses of serum than CHO. Addition of insulin to media containing a low dose of serum restored full colony formation, but growth of MonR-31 or MonR-32 cells required more insulin than CHO cells. Specific binding of [125I]insulin was observed in these cell lines. The two MonR clones bound about one-half or less the [125I]insulin bound by CHO cells. Scatchard analysis for [125I]insulin binding at 4 degrees C and 37 degrees C showed altered number of binding sites, but not insulin affinity: The number of binding sites in the MonR cell was about a half or less that of the parental CHO cell. Down-regulation of insulin receptor was assayed when both CHO and MonR cells were incubated with 1 microgram/ml insulin. A 50-60% decrease in levels of insulin surface binding capacities was observed in CHO after exposure to insulin, whereas there was no decrease in MonR cell. The cellular uptake of 2-[3H]deoxyglucose into CHO cells was significantly enhanced in the presence of insulin, but only slight, if any, increase was observed in MonR cells.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media; D003847:Deoxyglucose / Q000378:metabolism; D004351:Drug Resistance; D005260:Female; D005663:Furans / Q000633:toxicity*; D014644:Genetic Variation; D007328:Insulin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008985:Monensin / Q000633:toxicity*; D010053:Ovary; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003470:Culture Media; D005663:Furans; D007328:Insulin; C008147:insulin, iodo-; D008985:Monensin; D003847:Deoxyglucose; D011972:Receptor, Insulin