三阴性乳腺癌具有恶性程度高、易复发转移、预后差等临床特征。临床上尚无有效治疗方案。三阴性乳腺癌的靶向治疗成为目前研究的热点、难点问题。本课题组拟在前期研究的PI3K/AKT/mTOR信号通路分子mTOR、S6K1及4EBP1在三阴性乳腺癌发生发展中的调控作用的基础上，利用Crisper/cas-9系统构建低表达c-Myc的三阴性乳腺癌细胞系，结合基础实验及临床标本资料，围绕PI3K/AKT/mTOR信号通路下游向核内转导信号的c-Myc基因，分析与其调控密切相关的Let-7a及传输Let-7a相关的外泌体对三阴性乳腺癌的调控机制。探索三阴性乳腺癌中外泌体的特征及特异性表达分子，以期阐明外泌体、Let-7a及c-Myc基因对三阴性乳腺癌细胞侵袭性、增殖能力及肿瘤微环境的调控作用。为进一步利用外泌体构建肿瘤杀伤载体、探索三阴性乳腺癌特异性靶点奠定理论基础。

Triple negative breast cancer got poor prognosis,and majority of patients came to be relapse and metastasis in three years. However the lack of a recognized target for molecular-oriented therapy, makes TNBC a new orphan disease. Our previous study showed that PI3K/AKT/Mtor signal pathway regulated the development of TNBC. In previously research, we analysed the regular function of mTOR、S6K1 and 4EBP1 of PI3K/AKT/mTOR signal pathway in TNBC. C-Myc is the end of multiple cell signal pathway, and it transferred cell signal to the nuclear, which made c-myc to be the key point in tumor development. In this study, we will establish a triple negative breast cancer cell line that low expression of c-Myc, using Crisper/cas-9 systerm. Then, combine experiment data with clinical specimens to analysis the relationship between exosome、Let-7a、c-Myc and development of TNBC. To explore the characteristic and special molecular of exosome in TNBC. And clarify that exosomes transfer Let-7a regulated c-Myc expression can affect the proliferation、invasion and tumor microenvironment of TNBC. In order to make a good foundation of using exosome to establish a vector carry special miRNA or protein to target tumor cells and kill tumor cells.