Insulin-like growth factor II increases cytoplasmic free calcium in competent Balb/c 3T3 cells treated with epidermal growth factor.
To determine the role of calcium in the action of insulin-like growth factor II (IGF-II), we have examined the effect of multiplication stimulating activity, the rat IGF-II, on cytoplasmic-free calcium concentration, [Ca2+]c, in aequorin-loaded Balb/c 3T3 cells. IGF-II does not cause any change in [Ca2+]c in quiescent cells. By contrast, IGF-II induces changes in [Ca2+]c in platelet-derived growth factor(PDGF) - pretreated competent cells: when competent cells are incubated with epidermal growth factor (EGF) for 10 min, subsequent IGF-II induces an immediate increase in [Ca2+]c. Without EGF treatment, IGF-II does not cause any increase in [Ca2+]c. The priming action of EGF is time dependent, requiring approximately 10 min for the maximum effect. The IGF-II-mediated increase in [Ca2+]c is totally dependent on extracellular calcium and is blocked by lanthanum. When DNA synthesis in PDGF-treated competent cells is assessed by measuring [3H]thymidine incorporation, IGF-II by itself has only a small effect. Likewise, a brief treatment with EGF results in only a small increase in [3H]thymidine incorporation. By contrast, in competent cells briefly treated with EGF, IGF-II causes a marked stimulation of [3H]thymidine incorporation. These results indicate that IGF-II increases [Ca2+]c in competent Balb/c 3T3 cells treated with EGF by stimulating calcium influx and that IGF-II-stimulated calcium influx may be related causally to its action on cell proliferation.
D000331:Aequorin; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D051379:Mice; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D013002:Somatomedins / Q000494:pharmacology*
D007328:Insulin; D010982:Platelet-Derived Growth Factor; D013002:Somatomedins; D000331:Aequorin; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D002118:Calcium