Estradiol induction of cAMP in breast cancer cells is mediated by foetal calf serum (FCS) and sex hormone-binding globulin (SHBG)
Estradiol induction of cAMP in breast cancer cells is mediated by foetal calf serum (FCS) and sex hormone-binding globulin (SHBG)
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DOI：
10.1016/s0960-0760(99)00092-8
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发表时间：
1999-07-01
影响因子：
4.1
通讯作者：
Frairia, R
中科院分区：
文献类型：
--
作者：
Fortunati, N;Fissore, F;Frairia, R
血浆性激素结合球蛋白（SHBG或SEP）是雌二醇和雄激素的特异性载体，在与其膜受体（SHBG- r）结合后，在无血清培养基中维持的乳腺癌（MCF-7）和前列腺癌（LNCaP）细胞中，在雌二醇存在的情况下，cAMP显著增加。另一方面，有人提出，除了众所周知的核受体途径外，雌激素在乳腺癌和子宫细胞中通过直接的膜作用，发挥其诱导cAMP的生物学效应。本研究的目的是通过验证MCF-7细胞中的cAMP增加是雌二醇的直接作用，还是由FCS蛋白（如牛性激素结合球蛋白）介导，来澄清这一有争议的问题；并重新评估人SHBG在FCS存在下对cAMP诱导的影响。MCF-7细胞分别保存在DCC- fcs（用DCC处理以去除类固醇）、SHBG-FREE/DCC- fcs（用DCC和特定亲和层析处理以去除牛性激素结合球蛋白）或无血清培养基（SFM）中。观察到雌二醇仅在维持在10% DCC-FCS中的MCF-7细胞中决定了cAMP的显着时间依赖性增加。当细胞维持在10% SHBG-FREE/DCC-FCS中时，雌二醇没有可检测到的影响。然而，在添加人SHBG后，再次观察到其增加cAMP的能力，剂量范围为5至50 nM。此外，在10% SHBG- free /DCC-FCS存在的情况下，即使没有雌二醇，SHBG也会引起cAMP的显著增加。综上所述，本研究报道的数据表明，雌二醇诱导MCF-7细胞cAMP的能力不是由于激素的直接膜效应，而是由FCS介导的。SHBG是介导雌二醇作用的血清因子之一。最后，证明SHBG在生理培养条件和生理浓度下触发MCF-7细胞的cAMP通路。1999爱思唯尔科学有限公司版权所有。
Plasma sex hormone-binding globulin (SHBG or SEP), the specific carrier for estradiol and androgens, after binding to its membrane receptor (SHBG-R), causes a significant increase of cAMP in the presence of estradiol, in both breast (MCF-7) and prostate (LNCaP) cancer cells maintained in serum-free medium. On the other hand, it has been proposed that estrogens, in addition to the well-known nuclear receptor pathway, exert their biological effect inducing cAMP, as a consequence of a direct membrane action, in breast cancer and uterine cells. The aim of the present study was to clarify this controversial issue by verifying if the cAMP increase in MCF-7 cells was a direct effect of estradiol, or if it was mediated by FCS proteins, such as bovine sex hormone-binding globulin; and to reevaluate the effect of human SHBG on cAMP induction in the presence of FCS. MCF-7 cells were maintained in DCC-FCS (treated with DCC to remove steroids), in SHBG-FREE/DCC-FCS (treated with DCC and with a specific affinity chromatography to remove bovine sex hormone-binding globulin), or in serum-free medium (SFM). It was observed that estradiol determined a significant time-dependent increase of cAMP only in MCF-7 cells maintained in 10% DCC-FCS. When cells were maintained in 10% SHBG-FREE/DCC-FCS, estradiol had no detectable effect. However, its ability to increase cAMP was observed again after the addition of human SHBG, in doses ranging from 5 to 50 nM. Moreover, in the presence of 10% SHBG-FREE/DCC-FCS, SHBG, even in the absence of estradiol, caused a significant increase of cAMP. In conclusion, the data reported in the present study suggest that the ability of estradiol to induce cAMP in MCF-7 cells is not due to a direct membrane effect of the hormone, but rather it is mediated by FCS. SHBG is one of the serum factors mediating estradiol action. Lastly, it was proven that SHBG triggers the cAMP pathway in MCF-7 cells in a physiologic culture condition and at physiologic concentrations. (C) 1999 Elsevier Science Ltd. All rights reserved.