Simultaneous production of IGF-I and EGF competing growth factors by HT-29 human colon cancer line.
The conditioned medium from the HT-29 human colonic adenocarcinoma cell line contains a potent mitogenic activity that can markedly stimulate the proliferation of both rat and human fibroblasts in the absence of serum. Fractionation of conditioned medium on Bio-Gel P-100 shows that HT-29 cells simultaneously produce 2 different types of endogenous growth factors. The first one (molecular mass of 35, 8 and 5.5 kDa) exhibits an IGF-I competing activity which is positively correlated to mitogenic activity. This mitogen is recognized by anti-IGF-I antibodies but is resistant to reducing agents. It is distinct from IGF-II, insulin and PDGF. The second one (molecular mass of 40- and 20-kDa) is able to displace EGF binding to its receptor. This factor is immunologically recognized by anti-EGF antibodies but with a lower affinity as compared to EGF. This suggests that this endogenous HT-29-growth factor is related to but distinct from native EGF. Although more active in radioreceptor assay than in radioimmunoassay, the EGF-competing factor is distinct from TGF alpha or beta since it is unable to induce anchorage-independent growth of NRK or FR3T3 target cells in the presence or absence of exogenous EGF. Moreover, free functional EGF receptors are available at the HT-29 cell surface.
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000906:Antibodies / Q000494:pharmacology; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D003470:Culture Media / Q000032:analysis; D004815:Epidermal Growth Factor / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000276:immunology / Q000378:metabolism*; D011863:Radioimmunoassay; D013002:Somatomedins / Q000378:metabolism*
D000906:Antibodies; D003470:Culture Media; D013002:Somatomedins; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I