中文摘要：

LRP16是一个雌激素（E2）通过受体α（ERα）诱导表达的靶基因,LRP16不仅促进人乳腺癌MCF-7细胞的增殖,而且促进细胞的侵袭生长,但对LRP16作用的分子机制尚不清楚.首先,检测到LRP16表达缺陷明显削弱了MCF-7细胞对E2的反应性增殖能力;采用Northern印迹与Western印迹法,进一步检测到抑制LRP16表达,明显损害了ERα靶基因对E2诱导上调的反应性,这些基因包括了cyclin D1,c-myc,c-fos,MTS3,pS2和维甲酸受体α基因（RARα）等;以上结果提示,LRP16参与了ERα介导的信号途径.将ERα模式启动子报告基因3×ERE-TATA-Luc,ERα以及LRP16表达载体共转染MCF-7与HeLa细胞.结果发现,LRP16增强了ERα对报告基因的转录激活,并呈现对LRP16的剂量依赖性;进而采用GST-pull down以及免疫共沉淀方法证实了LRP16与ERα之间的直接相互作用,该作用不依赖于E2的存在,但可被E2增强;采用哺乳动物双杂交方法进一步证实了ERα与LRP16相互作用位点存在于A/B区的激活功能域-1（AF-1）.以上结果表明,LRP16是ERα的一个共激活因子,通过相互作用,LRP16增强了ERα介导转录活性.该研究为LRP16促进ERα阳性乳腺癌细胞增殖与侵袭生长提供了合理的分子解释.

英文摘要：

LRP16 is a target gene induced by estrogen receptor a （ERa）. Although there are evidences demonstrating the promotion roles of LRP16 on the proliferation and invasiveness of MCF-7 human breast cancer cells, the molecular mechanism underlying which is still unclear. It was found that the defect of LRP16 expression obviously reduced the response of MCF-7 cells to E2. Furthermore, Northern blotting and Western blotting analyses showed that the suppression of LRP16 expression obviously impaired E2-induced up-regulation of ERa target gene, such as cyclin D1, c-myc, c-fos, MTA3, pS2 and RARa. These results implied the involvement of LRP16 in the signal pathway of ERa. Results from cotransfection assays further demonstrated that the transcriptional activities of the classical ERa targeting promoter reporter 3 × ERE-TATA-Luc were enhanced by LRP16 in a dose-dependent manner in both MCF-7 and HeLa cells in the presence of estrogen. The physical interaction of LRP16 with ERa was confirmed by GST-pull down in vitro and co- immunoprecipitation （ColP） in vivo assays. Subsequently, the mammalian two-hybrid assays showed that the interaction domain of ERa with LRP16 was located at the site of AF-1 functional domain. These results demonstrate that the LRP16 is a novel ERa coactivator, which increased the ERa-mediated transcriptional activity by the interaction with each other. The finding of the study explained reasonably the molecular mechanism of the promotion roles of LRP16 on the proliferation and invasion in ERa-positive breast cancer cells.