Insulin binding to the HL-60 human promyelocytic cell line

The HL-60 cell is a human leukemic promyelocyte that can be grown in liquid suspension culture. This cell line binds radiolabeled insulin in a rapid, reversible specific manner indicating that it contains cells surface insulin-binding sites. These sites show a pH optimum of 7.8–8.0.Maximal binding was achieved in approx. 60 min at 22°C and was linear with cell number between 5 × 10⁶ and 10⁸ cells per ml. Displacement of labeled insulin by unlabeled hormone was consistent with a ‘two site’ model with a high affinity site of 2.71 ± 0.55 × 10⁸ M^? and 8700 sites per cell. Release of labeled insulin from its binding site was accelerated by unlabeled insulin at temperatures above 22°C, but not at 4 or 15°C.We conclude that the HL-60 cell contains cell surface binding sites for insulin with properties similar to other well-described insulin receptors of other tissues.