Ligand depletion negatively controls the mitogenic activity of epidermal growth factor.
EGF activates the ErbB1 receptor, but there appears only a limited correlation between its receptor binding affinity and mitogenic activity. This is indicated by our present observation that in cells with high ErbB1 expression, including SUM102 breast tumor cells, low affinity EGF/Notch chimeras have similarly high mitogenic activity as EGF, in spite of the fact that EGF is superior in inducing receptor tyrosine phosphorylation and p42/p44 MAP-kinase activity. However, as a result of receptor-mediated internalisation high-affinity ligands such as EGF are depleted much more rapidly from the extracellular medium than low-affinity EGF/Notch chimeras. As a consequence, the mitogenic activity of EGF on ErbB1 overexpressing cells is limited by substantial degradation of internalised ligand in the period before cells enter S-phase, a phenomenon that is not observed for low affinity mutant ligands. The mitogenic activity of EGF on ErbB1 overexpressing cells does therefore not only depend on the applied concentration but also on the total amount of ligand added, and is strongly underestimated when tested in a limited assay volume. No such dependence on the incubation volume was observed for EGF activity on cells with low ErbB1 expression levels and on cells for which EGF is growth inhibitory.
van de Poll
Monique L M
ML
Department of Cell Biology, Faculty of Science, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
van Rotterdam
Walter
W
Gadellaa
Mireille M
MM
Jacobs-Oomen
Saskia
S
van Zoelen
Everardus J J
EJ
D000818:Animals; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics; D004815:Epidermal Growth Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D025461:Feedback, Physiological / Q000502:physiology*; D005260:Female; D006133:Growth Substances / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D051379:Mice; D008938:Mitosis / Q000187:drug effects / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D041681:NIH 3T3 Cells; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D011940:Receptor Aggregation / Q000187:drug effects / Q000235:genetics*; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
D006133:Growth Substances; D008024:Ligands; C497761:NOTCH1 protein, human; C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D004815:Epidermal Growth Factor; D066246:ErbB Receptors