在對(duì)雌激素有反應(yīng)的MCF-7細(xì)胞中，雌二醇（E2）結(jié)合雌激素受體α參與調(diào)控細(xì)胞增殖和生存基因的轉(zhuǎn)錄,。微小RNA（miRNA的）已經(jīng)成為重要的轉(zhuǎn)錄后基因表達(dá)調(diào)控因子。

近日,，BMC Cancer雜志上的一項(xiàng)研究探討了miRNA是否參與激素調(diào)節(jié)雌激素受體基因的表達(dá),。研究人員采用Western blot和定量PCR分別來(lái)確定雌激素應(yīng)答基因和miRNA的表達(dá)。熒光素酶報(bào)告基因檢測(cè)和轉(zhuǎn)染miRNA的模仿或抑制miRNA來(lái)確定miRNA所調(diào)控的靶基因表達(dá),。常規(guī)MTS檢測(cè)細(xì)胞增殖活性,。

結(jié)果發(fā)現(xiàn)E2通過(guò)抑制MCF-7細(xì)胞中一系列miRNA（miR-16, miR-143和miR-203）水平，進(jìn)而顯著誘導(dǎo)Bcl-2,，cyclin D1和Survivin的表達(dá),。miRNA轉(zhuǎn)染技術(shù)和熒光素酶檢測(cè)證實(shí)Bcl-2由miR-16和miR-143調(diào)節(jié)，cyclinD1由miR-16的調(diào)控,。

重要的是,，miR-16, miR-143, miR-203都靶向調(diào)控蛋白survivin。E2的調(diào)節(jié)作用可被抗雌激素制劑,，雷洛昔芬或雌激素受體alpha轉(zhuǎn)染siRNA后所消除,，這說(shuō)明調(diào)控依賴于雌激素受體alpha。

為了研究這些miRNAs在雌激素受體細(xì)胞中的功能意義,，用miRNA轉(zhuǎn)染MCF-7細(xì)胞,。這些miRNA表達(dá)過(guò)高抑制E2誘導(dǎo)細(xì)胞增殖。進(jìn)一步研究表明,，miR-16,，miR-143和miR-203高表達(dá)于三重陽(yáng)性乳腺癌組織中（乳腺癌的亞型分為HER2陽(yáng)性、雌激素受體陽(yáng)性,、以及三種受體均為陰性等）,，這表明這些miRNA在ER陽(yáng)性乳腺癌中是一個(gè)潛在的腫瘤抑制因子?？傊Y(jié)果表明,，E2通過(guò)調(diào)控miRNA誘導(dǎo)Bcl-2，cyclin D1和survivin表達(dá)下調(diào),。（生物谷：Bioon.com）

doi:10.1186/1471-2407-12-29
PMC:
PMID:
Induction of cell proliferation and survival genes by estradiol-repressed microRNAs in breast cancer cells

Xinfeng Yu1*, Xuemei Zhang2, Ishwori B Dhakal3, Marjorie Beggs3, Susan Kadlubar3 and Dali Luo1

Background
In estrogen responsive MCF-7 cells, estradiol (E2) binding to ERα leads to transcriptional regulation of genes involved in the control of cell proliferation and survival. MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of gene expression. The aim of this study was to explore whether miRNAs were involved in hormonally regulated expression of estrogen responsive genes.

Methods
Western blot and QPCR were used to determine the expression of estrogen responsive genes and miRNAs respectively. Target gene expression regulated by miRNAs was validated by luciferase reporter assays and transfection of miRNA mimics or inhibitors. Cell proliferation was evaluated by MTS assay.

Results
E2 significantly induced bcl-2, cyclin D1 and survivin expression by suppressing the levels of a panel of miRNAs (miR-16, miR-143, miR-203) in MCF-7 cells. MiRNA transfection and luciferase assay confirmed that bcl-2 was regulated by miR-16 and miR-143, cyclinD1 was modulated by miR-16. Importantly, survivin was found to be targeted by miR-16, miR-143, miR-203. The regulatory effect of E2 can be either abrogated by anti-estrogen ICI 182, 780 and raloxifene pretreatment, or impaired by ERα siRNA, indicating the regulation is dependent on ERα. In order to investigate the functional significance of these miRNAs in estrogen responsive cells, miRNAs mimics were transfected into MCF-7 cells. It revealed that overexpression of these miRNAs significantly inhibited E2-induced cell proliferation. Further study of the expression of the miRNAs indicated that miR-16, miR-143 and miR-203 were highly expressed in triple positive breast cancer tissues, suggesting a potential tumor suppressing effect of these miRNAs in ER positive breast cancer.

Conclusions
These results demonstrate that E2 induces bcl-2, cyclin D1 and survivin by orchestrating the coordinate downregulation of a panel of miRNAs. In turn, the miRNAs manifest growth suppressive effects and control cell proliferation in response to E2. This sheds a new insight into the integral post-transcriptional regulation of cell proliferation and survival genes by miRNAs, a potential therapeutic option for breast cancer.