Abstract
EGF, a polypeptide hormone isolated from male mouse submaxillary glands, is a potent stimulator of cell division and may largely replace serum for the induction of cell division. Since different serum fractions stimulate growth of normal Swiss 3T3 and transformed SV403T3 fibroblasts and suggest that each cell type may have its own peculiar responsiveness to specific growth promoting factors, we studied the response of 3T3 and SV403T3 to EGF. Normal 3T3 required permissive amounts of serum (0.25%) for maximal response to EGF (initiation of DNA synthesis, clonal/mass culture growth). Half-maximal DNA stimulation occurred at 0.20 nM with 3T3. EGF did not significantly enhance the growth of the SV403T3. Comparative binding studies of 3T3 and SV403T3 using 123I-EGF at 24 and 37°C showed half-maximal saturation of receptor sites at 0.36 nM EGF; average dissociation rate was 0.44 × 10−4 sec−1. Maximal binding occurred between pH 6.8-7.6. Unla-beled EGF competed with 125I-EGF for receptor sites while fibroblastic growth factor and insulin did not. Scatchard analysis of the binding data revealed single high affinity binding sites with an observed Kd of 10−9 for both cell types. 3T3 and SV403T3 have essentially the same number of receptors on a per cell basis, but SV403T3 were smaller and had more receptor sites per μ2 of cell surface. Transformation of Swiss 3T3 is accompanied by an altered responsiveness to EGF and a change in surface density of EGF receptors.
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Brutico, C., Ladda, R. EPIDERMAL GROWTH FACTOR (EGF): BINDING CHARACTERISTICS AND GROWTH RESPONSE OF NORMAL AND VIRALLY TRANSFORMED MOUSE FIBROBLASTS. Pediatr Res 11, 404 (1977). https://doi.org/10.1203/00006450-197704000-00207
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DOI: https://doi.org/10.1203/00006450-197704000-00207