FEN1是参与DNA修复的特异性核酸酶，最近研究显示其在乳腺癌细胞中过表达。我们预实验和文献提示E2上调了其在乳腺癌细胞中的表达，但信号机制和生物学意义不清。由于FEN1启动子区没有ER结合位点，而存在4个潜在的Elk-1结合位点，且预实验结果显示其启动子活性依赖Elk-1，因此，E2可能通过ER非基因组活性即ER-MAPK-Elk-1途径上调FEN1的表达并发挥生物学效应。本项目拟采用Real-time PCR、Western blot、EMSA、ChIP 、CoIP等技术研究ER非基因组活性对乳腺癌细胞中FEN1表达上调的信号机制及其在乳腺癌进程和顺铂化疗耐药中的作用，项目的实施将率先阐明FEN1的表达受E2上调的信号机制，确定其在影响乳腺癌进程中的潜在标志物作用以及与E2、ER的关系，以加深对FEN1基因表达调控和乳腺癌发病机制的认识，并为临床寻找增强乳腺癌化疗敏感性的新措施奠定基础

Flap endonuclease 1 (FEN1) is a specific endonuclease invovled in DNA repair. Recent research data have demonstrated it is highly expresses in breast cancer cells and tissues. Our preliminary data and other references showed that estrogen(E2) increased FEN1 expression in breast cancer cells, but the signaling mechanism and biological significance of E2-induced FEN1 up-regulation are unclear. Because there are four potential Elk-1 binding sites but no ER-binding sites in FEN1 promoter region, and our data showed that the promoter activity of FEN1 is dependent on Elk-1 activation,E2 is likely to increase FEN1 expression through ER non-genomic activity,i.e.ER-MAPK- Elk-1 pathway by which FEN1 mediates biological effects in breast cancer cells . The project intends to study the mechanism of E2-induced FEN1 up-regulation through this ER non-genomic activity and its role of FEN1 overexpression resulted by this mechanism in tumorgenesis of breast cancer. The results from this project will first demonstrate the signaling mechanism of E2-induced FEN1 up-regulation and determine the role of FEN1 as a potential markers as well as the relation among E2, ER and FEN1 in tumorgenesis of breast cancer, which can deepen our understanding of FEN1 gene expression regulation and the pathogenesis of breast cancer, and lay the foundations for finding a new strategy to enhance chemotherapy sensitivity of breast cancer.