Migliaccio A, Di Domenico M, Castoria G, de Falco A, Bontempo P, Nola E, Auricchio F
Istituto di Patologia Generale e Oncologia, Facoltà di Medicina e Chirurgia, Napoli, Italia.
EMBO J. 1996 Mar 15;15(6):1292-300.
The mechanism by which estradiol acts on cell multiplication is still unclear. Under conditions of estradiol-dependent growth, estradiol treatment of human mammary cancer MCF-7 cells triggers rapid and transient activation of the mitogen-activated (MAP) kinases, erk-1 and erk-2, increases the active form of p21ras, tyrosine phosphorylation of Shc and p190 protein and induces association of p190 to p21ras-GAP. Both Shc and p190 are substrates of activated src and once phosphorylated, they interact with other proteins and upregulate p21ras. Estradiol activates the tyrosine kinase/p21ras/MAP-kinase pathway in MCF-7 cells with kinetics which are similar to those of peptide mitogens. It is only after introduction of the human wild-type 67 kDa estradiol receptor cDNA that Cos cells become estradiol-responsive in terms of erk-2 activity. This finding, together with the inhibition by the pure anti-estrogen ICI 182 780 of the stimulatory effect of estradiol on each step of the pathway in MCF-7 cells proves that the classic estradiol receptor is responsible for the transduction pathway activation. Transfection experiments of Cos cells with the estradiol receptor cDNA and in vitro experiments with c-src show that the estradiol receptor activates c-src and this activation requires occupancy of the receptor by hormone. Our experiments suggest that c-src is an initial and integral part of the signaling events mediated by the estradiol receptor.
雌二醇作用于细胞增殖的机制仍不清楚。在依赖雌二醇生长的条件下，用雌二醇处理人乳腺癌MCF-7细胞会触发丝裂原活化（MAP）激酶erk-1和erk-2的快速短暂激活，增加p21ras的活性形式、Shc和p190蛋白的酪氨酸磷酸化，并诱导p190与p21ras-GAP结合。Shc和p190都是活化src的底物，一旦磷酸化，它们就会与其他蛋白质相互作用并上调p21ras。雌二醇以与肽类丝裂原相似的动力学激活MCF-7细胞中的酪氨酸激酶/p21ras/MAP激酶途径。只有在导入人野生型67 kDa雌二醇受体cDNA后，Cos细胞才在erk-2活性方面对雌二醇产生反应。这一发现，连同纯抗雌激素ICI 182 780对雌二醇在MCF-7细胞中对该途径各步骤刺激作用的抑制，证明经典雌二醇受体负责转导途径的激活。用雌二醇受体cDNA转染Cos细胞的实验以及用c-src进行的体外实验表明，雌二醇受体激活c-src，而这种激活需要激素占据受体。我们的实验表明，c-src是由雌二醇受体介导的信号事件的初始且不可或缺的一部分。
