Summary
Epidermal growth factor (EGF) has been shown to stimulate DNA synthesis in rat parenchymal hepatocytes both in vivo and in vitro (4,9). We report here that this response in vitro is dependent on the amino acids present in the media. Of all the amino acids, proline has the strongest effect. The response to EGF is absent without proline and none of the other amino acids can substitute for it. Added proline (1 mM) to the media caused the labeling index to increase from 11% to 55% in the presence of 50 ng/ml EGF and insulin. In the presence of proline, small additional increases of the EGF effect on DNA synthesis were stimulated by phenylalanine and tyrosine.
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This work was supported by NIH grants CA302241 and CA35373 and EPA CRA R811687010
EDITOR'S STATEMENT This paper describes an interesting, specific interaction between EGF and proline in stimulation of DNA synthesis in hepatocytes. This finding may shed light on the well-documented effect of amino acid load on hepatocyte proliferation in vivo and interactions of growth factors and nutrients in general. Wallace L. McKeehan
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Houck, K.A., Michalopoulos, G. Proline is required for the stimulation of DNA synthesis in hepatocyte cultures by EGF. In Vitro Cell Dev Biol 21, 121–124 (1985). https://doi.org/10.1007/BF02620953
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DOI: https://doi.org/10.1007/BF02620953