Autocrine growth induced by the insulin-related factor in the insulin-independent teratoma cell line 1246-3A.
An insulin-independent teratoma-derived cell line, called 1246-3A, has been isolated from the adipogenic cell line 1246, which stringently requires insulin for proliferation. The 1246-3A cell line, which can proliferate in the absence of exogenous insulin, produces in its conditioned medium a growth factor similar to pancreatic insulin by its biological and immunological properties. This factor, called "insulin-related factor" (IRF), was purified and iodinated to study its binding to cell surface receptors. 125I-labeled IRF binding to intact 1246-3A cells is lower than to 1246 cells. Cell surface binding can be restored by culturing the 1246-3A cells in the presence of an anti-porcine insulin monoclonal antibody or by acid prewash of the cells prior to performing the binding. Scatchard analysis of binding indicates that IRF secreted by the 1246-3A cells partially occupies high-affinity binding sites on the producer cells. Moreover, insulin monoclonal antibody inhibits the proliferation of the IRF-producing 1246-3A cells, suggesting that these cells are dependent on the secreted IRF for growth in culture. We conclude that the insulin-related factor secreted by the insulin-independent 1246-3A cells stimulates their proliferation in an autocrine fashion.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002455:Cell Division; D006133:Growth Substances / Q000502:physiology*; D007328:Insulin / Q000276:immunology / Q000502:physiology*; D013724:Teratoma / Q000378:metabolism / Q000473:pathology; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D006133:Growth Substances; D007328:Insulin