PAI-1调控长链非编码RNA SOX2-OT促进TNBC侵袭和转移的机制研究

Triple negative breast cancer (TNBC) patients have a poor prognosis, and were easy to recurrence and metastasis. The role of PAI-1 in the recurrence and metastasis of TNBC is not clear. We previously found that TNBC patients with high PAI-1expression are prone to relapse and distant metastasis. Cytological experiments show that PAI-1 could activate PI3K/Akt/mTOR signaling pathway. LncRNA expression profiles indicated LncRNA SOX2-OT was induced by PAI-1. Further bioinformatics analysis and preliminary experiment showed that SOX2-OT could regulate the transcription of PIK3CA gene, suggesting that PAI-1-induced SOX2-OT promotes TNBC cells invasion and metastasis through the activation of PI3K/Akt/mTOR signaling pathway. This project intends to explore the regulation role of PAI-1 on the expression and biological functions of SOX2-OT in TNBC cells by TNBC cell lines, PAI-1 knock down mice model and TNBC tissues. The present study will focuse on the regulation of SOX2-OT on PIK3CA transcription, and illuminate the molecular mechanism that PAI-1-SOX2-OT promoted TNBC cells invasion and metastasis through the activation of PI3K/Akt/mTOR signaling pathway, which may provide potential novel targets for treatment of clinical TNBC patients.

三阴性乳腺癌(TNBC)具有预后差、易发生复发和转移等特点。纤溶酶原激活物抑制因子PAI-1在TNBC复发转移过程中的作用及其机制尚不明确。课题组前期研究发现PAI-1可激活PI3K/Akt/mTOR信号通路促进TNBC细胞侵袭和转移；高通量表达谱筛选并实验证实PAI-1通过介导LncRNA SOX2-OT调控PIK3CA基因转录水平，由此推测PAI-1可通过介导SOX2-OT转录调控PIK3CA，从而激活PI3K/Akt/mTOR信号通路促进TNBC侵袭和转移。本项目拟从细胞模型、PAI-1基因敲除小鼠、临床标本三个层面明确PAI-1对TNBC侵袭和转移生物学特性的影响，揭示SOX2-OT对PIK3CA转录调控的具体机制；最终阐明PAI-1调控SOX2-OT激活PI3K/Akt/mTOR信号通路促进TNBC侵袭和转移的分子机制，为临床TNBC患者个体化诊疗提供提供新的作用靶点和理论依据。

三阴性乳腺癌(TNBC)具有预后差、易发生复发和转移等特点。我们之前的研究表明纤溶酶原激活物抑制因子PAI-1能够促进TNBC细胞的侵袭和转移，但是其中的分子机制并不清楚。而本项目则对PAI-1促进TNBC细胞侵袭和转移的机制进行了深入的研究。我们发现PAI-1在TNBC中呈现显著的高表达，进一步分析发现PAI-1与乳腺癌尤其是TNBC患者的不良预后相关，具有潜在的预后价值。细胞实验表明PAI-1可促进TNBC细胞的恶性表型。通过LncRNA表达谱，我们首次筛选并验证得到PAI-1调控的长链非编码RNA—LncRNA SOX2-OT；功能实验表明SOX2-OT促进TNBC的增殖、侵袭和转移。通过生物信息学分析、并运用双荧光素酶报告基因实验、RNA-pull-down和RIP实验验证得到SOX2-OT可作为miR-942-5p的分子海绵体。进一步的实验得到miR-942-5p调控的下游靶基因PIK3CA，及发现下游的PI3K/Akt信号通路的激活，最终导致TNBC细胞的侵袭和转移。小鼠皮下移植瘤和转移瘤模型均证实了SOX2-OT对TNBC侵袭和转移的调控作用。据此，我们得出结论：PAI-1可诱导SOX2-OT通过miR-942-5p/PI3K/Akt信号通路促进三阴性乳腺癌转移。本研究的发现对我们理解TNBC转移的发病机制具有重要意义，并为未来开发新的靶向SOX2-OT治疗临床TNBC患者的提供理论基础。