Geistlich A, Gehring H
Biochemisches Institut der Universität Zürich, Switzerland.
Exp Cell Res. 1993 Feb;204(2):329-35. doi: 10.1006/excr.1993.1040.
Chicken embryo fibroblast (CEF)-derived growth factor (CDGF), which was recently isolated from serum-free conditioned medium (SFCM) of confluent primary cultures of CEF (A. Geistlich and H. Gehring, Eur. J. Biochem. 207, 147-153, 1992), exhibited a strong mitogenic activity on sparse cultures of NIH/3T3 cells. The activity of CDGF was different from that of SFCM; i.e., the onset of DNA synthesis was delayed for about 7 h. CDGF induced maximally 25% of the activity of serum or SFCM if the activity was measured with a 2-h[3H]thymidine pulse starting 15 h after stimulation of the cells, indicating loss of a protein which modulated the mitogenic activity of CDGF. However, [3H]-thymidine incorporation of cells stimulated with approximately 50 pM CDGF reached serum values after prolongation of the thymidine pulse to 24 h. PDGF, at a concentration of approximately 300 pM, and bFGF (approximately 10 pM) exhibited strong activities in the 2-h pulse, whereas TGF-beta behaved like CDGF. IGF-I induced [3H]thymidine incorporation only weakly and only in the 2-h pulse. EGF did not induce any [3H]thymidine incorporation at all. CDGF together with small concentrations of bFGF (3.5 pM), higher concentrations of PDGF (300 pM), or IGF-I (1 nM) increased synergistically thymidine incorporation in the 2-h pulse, exceeding in the case of PDGF and bFGF the values obtained with 10% serum. Such a synergism could not be demonstrated with alpha-fetoprotein or fetuin, two serum proteins which have been reported to cooperate with growth factors. Regarding induction of cellular growth, only PDGF proved similar to serum, whereas cells stimulated with CDGF or TGF-beta showed a decreased rate of multiplication during the first day after stimulation. After this lag, however, CDGF- and TGF-beta-stimulated cells grew also with a rate similar to that obtained with serum, indicating the induction of an autocrine mitogen by CDGF or TGF-beta. FGF, IGF-I, and PDGF all enhanced CDGF-induced cell growth during the first day, whereas an additive stimulation over at least 2 days was observed with PDGF. CDGF behaved similar to TGF-beta in the synergism with IGF-I.
鸡胚成纤维细胞（CEF）衍生生长因子（CDGF），最近从CEF汇合原代培养物的无血清条件培养基（SFCM）中分离得到（A. Geistlich和H. Gehring，《欧洲生物化学杂志》207，147 - 153，1992），对NIH/3T3细胞稀疏培养物表现出强烈的促有丝分裂活性。CDGF的活性与SFCM不同；即DNA合成的起始延迟约7小时。如果在细胞刺激后15小时开始用2小时的[³H]胸腺嘧啶脉冲测量活性，CDGF诱导的活性最大为血清或SFCM活性的25%，这表明一种调节CDGF促有丝分裂活性的蛋白质丢失了。然而，用约50 pM CDGF刺激的细胞，将胸腺嘧啶脉冲延长至24小时后，[³H]胸腺嘧啶掺入量达到血清水平。浓度约为300 pM的血小板衍生生长因子（PDGF）和（约10 pM）碱性成纤维细胞生长因子（bFGF）在2小时脉冲中表现出强烈活性，而转化生长因子 - β（TGF - β）的表现与CDGF相似。胰岛素样生长因子 - I（IGF - I）仅在2小时脉冲中微弱地诱导[³H]胸腺嘧啶掺入。表皮生长因子（EGF）根本不诱导任何[³H]胸腺嘧啶掺入。CDGF与低浓度的bFGF（3.5 pM）、高浓度的PDGF（300 pM）或IGF - I（1 nM）一起在2小时脉冲中协同增加胸腺嘧啶掺入，在PDGF和bFGF的情况下超过了用10%血清获得的值。甲胎蛋白或胎球蛋白这两种已报道与生长因子协同作用的血清蛋白，未表现出这种协同作用。关于细胞生长的诱导，只有PDGF被证明与血清相似，而用CDGF或TGF - β刺激的细胞在刺激后的第一天增殖速率降低。然而，在这个延迟期之后，CDGF和TGF - β刺激的细胞也以与血清相似的速率生长，表明CDGF或TGF - β诱导了一种自分泌有丝分裂原。在第一天，FGF、IGF - I和PDGF都增强了CDGF诱导的细胞生长，而PDGF在至少2天内观察到相加刺激作用。在与IGF - I的协同作用中，CDGF的表现与TGF - β相似。
