Human embryonal carcinoma cells express low levels of functional receptor for epidermal growth factor

Using immunological probes, we have detected expression of the receptor for epidermal growth factor (EGF) at the cell surface of the clonally-derived human embryonal carcinoma (EC) cell lines, 2102Ep cl. 4D3 and NTERA-2 cl. D1. By this method, the level of receptor expression by these cells is estimated to be 3- to 5-fold less than for the human diploid fibroblast cell line, WI38, and our results indicate that it is the EC stem cells that display this receptor and not a subpopulation of differentiated cells. The human EC cell receptor binds ligand and catalyses autophosphorylation at tyrosine in a normal fashion. Treatment of NTERA-2 cl. D1 cells with retinoic acid (RA) for 7 days to induce differentiation results in decreased levels of receptor expression, and a subpopulation of differentiated cells possessing a markedly higher level of the EGF receptor was not detected among the cultures exposed to RA for longer periods.