[Expression of the gene for transforming growth factor type alpha, transferred into A431 cells by a recombinant retroviral vector].

Cells of human epidermoid carcinoma A431 were used for obtaining of the cell line constantly expressing TGF-alpha. Recombinant virions were obtained by introducing the proviral DNA into PA317 cells by means of electrotransfection. A protein with the EGF-competing activity was found in a conditioned media of the chosen clone A431/1522-4. The concentration of this protein was several times higher than in a conditioned media of wild type A431 cells. By means of electrophoresis, isoelectric focusing, and immunochemical analysis it was shown that the protein is TGF-alpha. Similarly to EGF, the extracted TGF-alpha entirely displaced 125I-EGF specifically bound to receptor. TGF-alpha produced by the A431/1522 cells also stimulated autophosphorylation of the EGF receptor.