Abstract
Insulin stimulates intracellular carbohydrate protein and lipid metabolism, whereas insulin-like growth factor I (IGF I) promotes cell division. We recently demonstrated that human Burkitt type ALL cells in longterm culture displayed high affinity binding for insulin and IGF I. This rapidly proliferating cell line expresses large numbers of receptor binding sites both for insulin and IGF I.
Cell cycle specific separation was performed by counterflow centrifugation. Cells were analyzed by flowcytometry. Receptor binding was determined by Scatchard analysis. Cells could be enriched to 60-80% purity for G1-S-G2 phase. The insulin receptor displayed 10-15000 receptor sites/cell in G1-, 1000-5000 in S-and 40-50000 in G2-phase. The affinity of insulin binding decreased continously during cell cycle. The IGF I receptor displayed 2000 receptor sites/cell in G1-, 5000 in S- and 15000 in G2-phase The affinity of the IGF I receptor was high in G1-phase showing a sharp decrease towards S-phase followed by a slight increase towards G2-phase.
IGF I shows high affinity binding during G1 in Burkitt type ALL cells. This suggests that IGF I is important for initiation of proliferation. The outstanding reduction in insulin receptor binding sites during S-phase indicates refractoriness of the cell to the metabolic action of insulin during DNA replication.
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Vetter, U., Hartmann, W., Schlickenriedex, J. et al. CELL CYCLE DEPENDENT MODULATION OF INSULIN AND IGF I RECEPTOR BINDING TO HUMAN BURKITT TYPE ALL CELLS. Pediatr Res 20, 1185 (1986). https://doi.org/10.1203/00006450-198611000-00069
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DOI: https://doi.org/10.1203/00006450-198611000-00069