Nethrapalli Imam S, Tinnikov Alexander A, Krishnan Vaishnav, Lei Charles D, Toran-Allerand C Dominique
Departments of Anatomy & Cell Biology, Columbia University College of Physicians & Surgeons, New York, New York 10032, USA.
Endocrinology. 2005 Jan;146(1):56-63. doi: 10.1210/en.2004-1106. Epub 2004 Oct 28.
CHO-K1, COS-7, and Rat2 fibroblast cell lines are generally believed to be devoid of estrogen receptors (ERs) and have been widely used to study the functions of ER-alpha and ER-beta after transfection of their cDNAs. Numerous studies have demonstrated that transfected ER-alpha or ER-beta mediates estradiol-induced activation of multiple signaling pathways, including the MAPK/ERK pathways. We report here for the first time that both 17alpha-estradiol and 17beta-estradiol elicit activation of MAPK/ERK in native, nontransfected CHO-K1, COS-7, and Rat2 fibroblast cell lines. We further report that, contrary to the generally held belief, these cell lines are not unresponsive to estradiol in their native, nontransfected state, and that this estrogen responsiveness is associated with estrogen binding. Using multiple ER antibodies, we failed to find ER-alpha or ER-beta isoforms or even ER-X. In view of these findings, researchers, using such cells as models to investigate mechanisms of estrogen action, must always take into account the existence of endogenous estrogen binding proteins other than ER-alpha, ER-beta, or ER-X.
一般认为，CHO-K1、COS-7和Rat2成纤维细胞系缺乏雌激素受体（ERs），并且在转染其cDNA后已被广泛用于研究ER-α和ER-β的功能。大量研究表明，转染的ER-α或ER-β介导雌二醇诱导的多种信号通路的激活，包括MAPK/ERK通路。我们在此首次报道，17α-雌二醇和17β-雌二醇均可在天然的、未转染的CHO-K1、COS-7和Rat2成纤维细胞系中引发MAPK/ERK的激活。我们进一步报道，与普遍看法相反，这些细胞系在其天然的、未转染状态下并非对雌二醇无反应，并且这种雌激素反应性与雌激素结合相关。使用多种ER抗体，我们未能找到ER-α或ER-β亚型，甚至未找到ER-X。鉴于这些发现，将此类细胞用作模型来研究雌激素作用机制的研究人员必须始终考虑除ER-α、ER-β或ER-X之外的内源性雌激素结合蛋白的存在。
