The role of the insulin receptor in mediating the insulin-stimulated growth response in Reuber H-35 cells

Insulin is able to stimulate a growth response in a variety of different cell types. However, the role of the insulin receptor in mediating this response is not clear. Indeed, it has been reported that the ability of insulin to stimulate a growth response is a result of its interaction with other growth factor receptors rather than the insulin receptor. We have previously reported that the H-35 hepatoma cell line responded to physiological concentrations of insulin as a growth factor and that the relative potency of proinsulin suggested that this response was mediated by the insulin receptor. In this report, two experimental approaches are used to demonstrate the involvement of the insulin receptor in mediating the growth response. Two different preparations of antibody to the insulin receptor are found to be capable of stimulating this response. In addition, the human insulin-like growth factors (IGF-I and II) show very low cross-reactivity with the insulin receptor and are significantly less potent than insulin in stimulating the growth response.