Department of Medical Sciences, University of Turin, Via Genova 3, I-10126 Turin, Italy.
Department of Medical Sciences, University of Turin, Via Genova 3, I-10126 Turin, Italy; Division of Oncological Endocrinology, Città della Salute e della Scienza University Hospital, Corso Bramante 88, I-10126 Turin, Italy.
Life Sci. 2018 Aug 15;207:372-380. doi: 10.1016/j.lfs.2018.06.024. Epub 2018 Jun 22.
Interaction of Sex Hormone-Binding Globulin (SHBG) with estrogen-sensitive breast cancer cells has a protective role against estrogen exposure. No specific membrane receptor for SHBG had been identified by now, but a putative interaction of SHBG with extracellular matrix associated-proteins (e.g. fibulins) was suggested. In this study we investigated the expression of fibulins, their functional relationship with SHBG and involvement in behavior of estrogen-sensitive breast cancer.
Gene expression of fibulins was performed by Real time-PCR on two estrogen-sensitive breast cancer cell lines, MCF-7 and T47D. Fibulin-1 protein expression and localization were determined by Western blot and immunofluorescence. SHBG interaction with-fibulin-1 was assessed by GST-pull down assay. MCF-7 cell growth and gene expression, after fibulin-1 silencing by siRNA, were evaluated. Finally, the expression of fibulin-1 was correlated to clinical and pathological data of 21 breast cancer tissue samples.
Fibulin-1 was expressed in both cell lines and it was increased by estradiol. SHBG interacted with fibulin-1C; proteins co-localized at MCF-7 cell membranes and SHBG localization at membranes disappeared after silencing fibulin-1. Fibulin-1 silencing, moreover, generated MCF-7 cells unresponsive to estradiol and SHBG and characterized by increased proliferation. Finally, in breast cancer tissue samples expressing fibulin-1 the proliferation index was significantly lower than in fibulin-1 negative samples.
Fibulin-1 interacts with SHBG, it is associated with a less aggressive behavior of breast cancer cells and correlates to a better prognosis of the tumor.
性激素结合球蛋白（SHBG）与雌激素敏感乳腺癌细胞的相互作用对雌激素暴露具有保护作用。目前尚未发现 SHBG 的特定膜受体，但有人提出 SHBG 与细胞外基质相关蛋白（如纤维蛋白）之间可能存在相互作用。在这项研究中，我们研究了纤维蛋白的表达、它们与 SHBG 的功能关系以及它们在雌激素敏感乳腺癌行为中的参与。
在两种雌激素敏感乳腺癌细胞系 MCF-7 和 T47D 上通过实时 PCR 进行纤维蛋白的基因表达。通过 Western blot 和免疫荧光测定纤维蛋白-1 蛋白的表达和定位。通过 GST 下拉测定评估 SHBG 与纤维蛋白-1 的相互作用。用 siRNA 沉默纤维蛋白-1 后，评估 MCF-7 细胞的生长和基因表达。最后，将纤维蛋白-1 的表达与 21 个乳腺癌组织样本的临床和病理数据相关联。
纤维蛋白-1 在两种细胞系中均有表达，并且在雌二醇作用下表达增加。SHBG 与纤维蛋白-1C 相互作用；蛋白质在 MCF-7 细胞膜上共定位，并且在用 siRNA 沉默纤维蛋白-1 后 SHBG 在细胞膜上的定位消失。此外，纤维蛋白-1 的沉默使 MCF-7 细胞对雌二醇和 SHBG 无反应，并表现出增殖增加。最后，在表达纤维蛋白-1 的乳腺癌组织样本中，增殖指数明显低于纤维蛋白-1 阴性样本。
纤维蛋白-1 与 SHBG 相互作用，与乳腺癌细胞侵袭性较弱的行为相关，并与肿瘤的更好预后相关。
