Resistance of A-431 epidermoid carcinoma cells to early membrane changes induced by tumour promoters

Abstract
The A-431 human epidermoid carcinoma cell line was resistant to 12-O-tetradecanoylphorbol-13-acetate (TPA) inhibition of epidermal growth factor binding, enhanced incorporation of [ 3 H]choline into phospholipids and uptake of 86 Rb and [ 3 H]2-deoxyglucose. The cells were also resistant to TPA-stimulated release of radioactive choline derivatives and aracholdonic acid from cells prelabelled with [ 3 H]choline or [ 14 C]arachidonic acid, respectively. The A-431 cells did not metabolise [ 3 H]TPA. Despite their TPA-unresponsiveness, A-431 cells contained specific, high affinity binding sites for [ 3 H]phorbol-12,13-dibutyrate with characteristics similar to other cultured cell lines.