原癌基因ETS-1参与卵巢癌恶性外泌体调控肿瘤相关巨噬细胞诱导分化的机制研究

Numerouse studies have indicated that tumor microenvironment plays an important role in progression and metastasis of epithelial ovarian cancer (EOC), one of the most malignant gynecological tumors. More than 75% of the mononuclear immune cells in the EOC microenvironment are tumor-associated macrophages (TAMs), which are involved in chronic inflammation, tumor progression, and angiogenesis.TAMs are not simply a cell subset responsible for tumor progression, but rather a macrophage-like cell population under dynamic polarization. A number of components in the tumor microenvironment have been reported to be involved in the regulation of the polarization of TAMs, including miRNAs (miR-21, miR-222, and more), hypoxic stress, cancer-derived exosomes. However, it is unclear whether there could be interactions between these components and how to interact with one another. Our recent work reported that the levels of miR-21/222 in ascites were higher than in peripheral blood in ovarian cancer patients, and were correlated with their clinical pathological grading of cancer．Moreover, compared with benign exosomes, ovarian cancer-derived exosomes promote not only the secretion of chemokines such as CCL2 in lymphocytes, but also the transcriptional activity of HIF-2α and ETS-1 in macrophages stressed by hypoxia. Our pilot studies found that the proto-oncogene ETS-1 increased the exosomal secretion and the miR-21/222 levels of exosomes in ovarian cancer cell, suggesting that ETS-1 may play an important role in the secretion of malignant exosomes. Additionally, our proteomic data showed that malignant exosomes can lead to different expression of many cytokines, chemokines, and inflammatory factors, all of which were in relation to TAM polarization and tumor progression. In this project, we plan to determine whether: (1) proto-oncogene ETS-1 affects the exosomal secretion and CCL2 levels to increase recruitment of macrophages in the microenvironment, (2) miR-21/222 in exosome and HIF-2α / ETS-1 enhancer together induces TAM polarization under hypoxic conditions, and (3) combination effects of these factors of interest promote the development of ovarian cancer.

卵巢癌微环境中，肿瘤细胞与肿瘤相关巨噬细胞（TAMs）等协调促进肿瘤恶化。零散报道，miRNAs（如miR-21/222）参与TAMs促瘤、低氧诱导因子1/2（HIF-1/2）促进TAMs极化和外泌体影响TAMs活性等，但TAMs系统性分化机制不明。我们曾报道，卵巢癌腹水外泌体miR-21/222比其血浆水平高，还能促进CCL2等TAMs相关因子分泌。预试验发现，原癌基因ETS-1增加外泌体分泌及其内容物miR-21/222含量，但具体机制不明。另外，HIF-2α/ETS-1可一起结合增强子促进许多基因转录。我们在ETS-1基因敲除小鼠中，缺氧条件下IL-6把巨噬细胞诱导成TAMs效率显著下降。综上所述，ETS-1可能通过外泌体分泌和CCL2促进巨噬细胞募集，同时缺氧条件下miR-21/222、HIF-2α、ETS-1等共同促进其向TAMs诱导分化，促进卵巢癌发生发展。

背景：肿瘤源性外泌体通过诱导肿瘤微环境中的适应性反应参与卵巢癌网膜转移定植。然而原发肿瘤细胞与远端大网膜微环境之间通过外泌体进行细胞间通讯以及转移前微环境形成的机制尚不清楚。.方法：在这里，我们利用过表达EST-1卵巢癌细胞，结合体内、外实验研究其具体作用。.结果：ETS1过表达促进肿瘤细胞分泌的外泌体更大，laminin水平更高。此外，卵巢癌外泌体可通过integrin和laminin相互作用被网膜巨噬细胞吸收。与对照外泌体相比，来自过表达ETS1的卵巢癌细胞（LV-ETS1 Exos）的外泌体通过整合素αvβ5/AKT/Sp1信号通路，刺激更多巨噬细胞向M2表型（CD163标记）极化，并在巨噬细胞中产生更多CXCL5和CCL2。体内实验表明，LV-ETS1 Exos通过介导巨噬细胞的促瘤作用促进卵巢癌网膜转移，而整合素ανβ5抑制剂西连肽可对其产生抑制作用。.结论：ETS1可促使卵巢癌细胞释放具有较高laminin水平的外泌体，从而通过整合素αvβ5/AKT/Sp1信号通路加速外泌体介导的网膜巨噬细胞促转移作用，而整合素ανβ5抑制剂西连肽可抑制肿瘤源性外泌体驱动的卵巢癌网膜转移。