title: Rapid rounding of human epidermoid carcinoma cells A-431 induced by epidermal growth factor.
abstract: Epidermal growth factor (EGF) induces rapid rounding of A-431 human epidermoid carcinoma cells in Ca(++)-free medium. Cell rounding is not induced by a variety of other polypeptide hormones, antiserum to cell membranes, local anesthetics, colchicine, cytochalasin B, or cyclic nucleotides. However, trypsin, like EGF, induces rounding of A- 431 cells in the absence of Ca(++). Both trypsin- and EGF-induced rounding are temperature dependent, appear to be energy dependent, and are inhibited by cytochalasins, suggesting that the active participation of microfilaments in cell rounding. However, a medium transfer experiment suggests that EGF-induced rounding is not attributable to secretion of a protease, and a number of serine protease inhibitors have no effect on the EGF-induced rounding process. Cell rounding is not attributable to the slight stimulation by EGF of the release of Ca(++) that is observed in the Ca(++)-free medium, as stimulation of such release by the ionophore A23187 neither induces cell rounding nor blocks EGF-induced rounding. Cells that have rounded up after treatment with EGF or trypsin spread out upon addition of Ca(++) to the medium, even in the continuing presence of EGF or typsin. Like the cell-rounding process, the cell-spreading process is temperature dependent, appears to be energy dependent, and is inhibited by cytochalasin B. Thus, EGF does not destroy the ability of the cell to spread; rather, in the presence of the EGF (or trypsin), cell spreading and the maintenance of the flattened state become dependent on external Ca(++). Because untreated cells remain flattened in the absence of Ca(++), the data suggest that EGF may disrupt Ca(++)-independent mechanisms of adhesion normally present in A-431 cells.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002294:Carcinoma, Squamous Cell; D002460:Cell Line; D002478:Cells, Cultured / Q000166:cytology*; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D003599:Cytoskeleton / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D008870:Microtubules / Q000502:physiology; D010455:Peptides / Q000494:pharmacology*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D010455:Peptides; D004815:Epidermal Growth Factor; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D014357:Trypsin; D006152:Cyclic GMP; D002118:Calcium