卵巢癌外泌体向网膜递送miR-6780b-5p抑制FOXO3诱导微环境活化促进肿瘤转移的研究

The high mortality among women with ovarian cancer is tightly associated with omental metastasis. We have identified an pre-metastatic niche in omental tissues obtained from ovarian cancer patients without metastasis, which promoted omental metastasis. However, the mechanisms through which ovarian cancer regulates the function of mesenchymal cells in omentum in the absence of direct contact remain unclear. Exosomes play an essential role in cell-cell cross-talking. We have found ovarian cancer-derived exosomes (OCDEs) could induce activation of omental mesenchymal cells and promote metastasis, which implicated OCDEs in omental pre-metastatic niche formation. We analyzed miRNA microarray data and found miR-6780b-5p was significantly increased in OCDEs of high-metastatic cancer cells. Moreover, FOXO3, a transcription factor that can regulate mesenchymal cell functions, is a potential target of miR-6780b-5p. Based on these findings, we speculate that ovarian cancer cells mediate omental microenvironment activation through exosomal miR-6780b-5p that targets FOXO3, which in turn promotes metastasis of ovarian cancer. This hypothesis will be verified in the present project by using multiple models, gene editing, and bioinformatics analysis, and we will clarify for the first time the contribution of OCDE to omental pre-metastatic niche formation and the underlying mechanisms. In addition, we propose to explore the anti-metastatic effects of therapy targeting miR-6780b-5p and FOXO3 in ovarian cancer. Our findings will deepen our understanding of mechanisms underlying ovarian cancer metastasis and catalyze new therapeutic strategies.

卵巢癌的高死亡率与网膜转移密切相关。我们前期研究发现卵巢癌患者无转移网膜中多种细胞已发生活化，形成有利于肿瘤定植生长的转移前微环境并促进肿瘤转移，但具体机制尚不清楚。外泌体是细胞间信号传递的重要方式，我们发现卵巢癌来源的外泌体OCDE能在体内外活化网膜微环境并促进原位移植瘤转移，提示OCDE在网膜转移前微环境形成中起重要作用。我们分析miRNA芯片数据发现高转移卵巢癌OCDE中miR-6780b-5p显著增高，且已知的间质细胞功能调控因子FOXO3是其潜在靶基因，由此我们提出假设：卵巢癌细胞通过外泌体向网膜递送miR-6780b-5p抑制FOXO3使间质微环境活化，从而促进肿瘤转移。本项目将结合多层次模型、基因编辑技术和生物信息学，首次明确OCDE在网膜转移前微环境形成中的作用和机制，并探索miR-6780b-5p/FOXO3靶向治疗抑制网膜转移的作用，为改善卵巢癌治疗提供新思路。

外泌体能够介导肿瘤转移微环境形成，从而促进肿瘤发生发展。本研究探索卵巢癌细胞及腹水来源的外泌体介导肿瘤细胞转移以及网膜成纤维细胞和间充质干细胞的活化促进卵巢癌转移的作用及机制研究。本项目发现卵巢癌来源的外泌体可以使网膜间充质干细胞和成纤维细胞α-、FAP和炎性因子表达升高，同时其增殖、侵袭、迁移能力增强。通过高通量测序分析卵巢癌细胞株ES2和其网膜高转移株ES2-HM分泌的外泌体miRNA和piRNA表达谱，我们发现卵巢癌细胞分泌的外泌体miR-320a通过靶向抑制ITGA7诱导网膜间充质干细胞定向分化为癌相关成纤维细胞促进卵巢癌转移；此外，卵巢癌细胞分泌的外泌体piR-25783通过诱导成纤维细胞向肌成纤维细胞转化促进网膜转移前微环境的形成促进网膜转移。我们进一步探究了成纤维细胞对肿瘤转移的作用，发现低表达miR-29c-3p的成纤维细胞分泌的外泌体可以促进肿瘤细胞中MMP2的表达从而促进肿瘤生长转移。此外，通过生物信息学分析及体内体外实验，我们发现卵巢癌病人腹水来源的外泌体miR-6780b-5p高表达，并可以通过促进卵巢癌细胞发生上皮间质转化，促进卵巢癌转移。本课题的研究成果阐明了卵巢癌细胞/外泌体/间质细胞的相互作用对肿瘤转移的影响，揭示了miR-320a, piR-25783, miR-6780b-5p和miR-29c-3p等非编码RNA可能成为治疗卵巢癌转移的潜在靶点。