乳腺癌转移灶内CAF通过外泌体调控乳腺癌干细胞间质-上皮转化的机制研究

It is important and difficult to clarify the molecular mechanisms of mesenchymal-epithelial transition (MET) of breast cancer stem cell (BCSC) in metastatic organ. The cellular and molecular regulators that promote MET of BCSC remain unknown. Our previous study showed that metastatic cancer associated fibroblasts (MCAF) can promote MET of BCSC through releasing exosomes which can be intaked by cancer cells. Accordingly, we proposed that MCAF may regulate MET of BCSC by releasing exosome miR-449a, which can target to 3’-UTR of AXL. We will further discover the evidences that BCSC can intake the exosomes and illustrate the following molecular mechanisms using cell lines, the metastatic cancer tissue of patients and the mouse in vivo. ① MCAF can communicate with BCSC through miR-449a in exosomes. ② MiR-449a can decrease the expression of AXL protein by targeting to 3’-UTR of AXL. ③ The MCAF promote the MET of cancer cells by releasing exosoms. If this project can be carried out, inhibiting the releasing exosomes of MCAF, perhaps in combination with conventional chemotherapeutics, may represent a potential therapeutic strategy for combating metastatic disease.

阐明循环乳腺癌干细胞（BCSC）进入转移靶器官后产生间质-上皮转化（MET）并进一步增殖形成转移灶的分子机理是乳腺癌转移研究的重点和难点。我们研究发现：肺内的BCSC诱导成纤维细胞转变为转移灶内CAF（MCAF），MCAF源性外泌体促进BCSC产生MET。通过对MCAF与原发乳腺癌组织CAF源性外泌体内miRNA差异表达谱分析，我们提出“MCAF通过外泌体内miR-449a靶向降低BCSC的AXL蛋白表达并促进BCSC产生MET”的科学假说。我们将进一步确认BCSC摄取MCAF源性外泌体的证据，并拟在癌细胞、患者乳腺癌和小鼠转移癌模型体内阐明三个关键问题的机制：①miR-449a通过外泌体在BCSC和MCAF间进行跨细胞间“通讯”；② miR-449a进入BCSC后靶向性降低了AXL表达；③BCSC内AXL降低促进了BCSC的MET。本课题的实施，将为抑制乳腺癌转移提供新的理论依据。

本课题阐明了循环乳腺癌干细胞（BCSC）进入转移靶器官后产生间质-上皮转化（MET）并进一步增殖形成转移灶的分子机理。我们研究发现：肺内的BCSC诱导成纤维细胞转变为转移灶内CAF（MCAF），MCAF源性外泌体促进BCSC产生MET。通过对MCAF与原发乳腺癌组织CAF源性外泌体内miRNA差异表达谱分析，我们得到了“MCAF通过外泌体内miR-449a靶向降低BCSC的AXL蛋白表达并促进BCSC产生MET”的科学结论。我们进一步确认了BCSC摄取MCAF源性外泌体的证据，并在癌细胞、患者乳腺癌和小鼠转移癌模型体内阐明了三个关键问题的机制：①miR-449a通过外泌体在BCSC和MCAF间进行跨细胞间“通讯”；② miR-449a进入BCSC后靶向性抑制AXL表达；③BCSC内AXL降低促进了BCSC的MET。本课题的实施，为抑制乳腺癌转移提供新的理论依据。我们还证明了癌相关成纤维细胞来源的外泌体miR-18b通过与TCEAL7的3'UTR区结合调控TCEAL7，减少其对NF-κB通路的抑制作用，进而促进乳腺癌的侵袭和转移。我们还证明了miR-4319通过靶向调控USP2抑制乳腺癌细胞侵袭。同时我们还发现Linc00426促进MMP-2和MMP-9表达、F-肌动蛋白聚合、LIMK和cofilin磷酸化从而促进LUAD肿瘤发生和转移；并且Linc00426可作为内源性分子海绵发挥作用，竞争性结合miR-455-5p并上调UBE2V1表达，进而促进肺腺癌进展。我们证明了miR-193a-3p通过靶向BTRC调控胶质瘤细胞的侵袭、迁移和间充质转化，从而促进胶质瘤的侵袭、迁移和间质转化。

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