Characteristics of insulin receptors and insulin action in human myelogenous leukemia cell line K-562.
Specific binding sites for insulin have been identified and characterized for the human erythroleukemia cell line K-562. The binding of [125I]-insulin to the cells increased as a function of time, reaching a maximum at 20 min when incubation was performed at 37 degrees C. The binding of [125I]-insulin was dose-dependently inhibited by insulin or proinsulin. Scatchard plot of the binding data was curvilinear, and the number of insulin receptors was approximately 39,000. Insulin at concentrations of 0.05-10.0 ng/ml stimulated CO2 production and DNA and protein synthesis in K-562 cells in a dose-dependent manner, indicating that the insulin binding sites are functionally important in mediating these biochemical events induced by insulin. Maximal insulin responses were elicited at concentrations of less than 5 ng/ml, when (at most) 10% of the insulin receptors were occupied. After binding to the cells, [125I]-insulin was degraded in a time- and temperature-dependent manner. As reported for other types of cells, unlabeled insulin also downregulated insulin receptors in K-562 cells. When the cells were incubated with 1 X 10(-7) M unlabeled insulin for 24 h, the number of insulin receptors decreased by 50% without a change of affinity. K-562 cells may be useful in studying the role of insulin receptors in cell functions induced by insulin.
D002245:Carbon Dioxide / Q000378:metabolism; D002460:Cell Line; D004273:DNA, Neoplasm / Q000096:biosynthesis; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D011972:Receptor, Insulin / Q000378:metabolism*; D013696:Temperature
D004273:DNA, Neoplasm; D007328:Insulin; D009363:Neoplasm Proteins; D002245:Carbon Dioxide; D011972:Receptor, Insulin