let-7a/STAT3/lin28正反馈环路对尤文肉瘤干细胞恶性表型的影响及其机制

Ewing's sarcoma (ES) is a highly malignant primary bone tumor. The existence of cancer stem cells (CSCs) of ES is the major factor that causes the metastasis and recurrence. So, the keypoint is to eliminate the CSCs throughout ES therapy. We previously found that the expression of let-7a is suppressed in either ES tissues or ES stem cells; Moreover, we also found that STAT3 is a putative target gene of let-7a. Combining with the facts that STAT3 can induce the expression of lin28, and lin28 can block the degradation of pri-let-7a/pre-let-7a into let-7a, we speculate there exists a positive feedback loop comprised of let-7a, STAT3 and lin28 in regulating the biological behavior of ES stem cells. In this study, using side group cells separation method and flow cytometry technique, we will identify the CSCs from ES cell lines in vitro, then explore the effect of let-7a on inhibiting the malignant phenotypes of Ewing's sarcoma CSCs. Finally, we will investigate the mechanism of let-7a/STAT3/lin28 loop in the tumorogenesis of ES in vitro and in vivo. This study aims at exploring the inhibitive effect of let-7a on the genesis, development and prognosis of Ewing's sarcoma CSCs and its mechanism, which will lay an experimental foundation and theoretical basis for the ES biological therapy in the future.

尤文肉瘤（ES）是高度恶性的原发骨肿瘤,尤文肉瘤干细胞(CSCs)是引起肿瘤复发和转移的主因,因此治愈ES的关键是消除尤文肉瘤CSCs.我们前期发现let-7a在ES组织和CSCs中均降低,STAT3是let-7a的直接靶基因;另有研究证实STAT3可诱导lin28表达,而后者能与let-7a前体结合抑制其裂解,导致let-7a成熟体表达下降.因此我们推测let-7a/STAT3/lin28通路在尤文肉瘤CSCs中形成正反馈环路,扮演关键的调控作用.本研究拟通过侧群细胞分选法及流式细胞技术从体外培养的ES细胞中分离出CSCs,然后检测let-7a对尤文肉瘤CSCs恶性表型的影响,并进一步在体内、外实验中验证let-7a/STAT3/lin28环路在尤文肉瘤CSCs中的调控作用.研究旨在深入探讨let-7a调控尤文肉瘤CSCs发生、发展及转归的机制,为ES的生物治疗奠定实验基础和理论依据.

尤文肉瘤（ES）是高度恶性的原发骨肿瘤,尤文肉瘤干细胞(CSCs)是引起肿瘤复发和转移的主因,因此治愈ES 的关键是消除尤文肉瘤CSCs.我们前期发现let-7a 在ES 组织和CSCs 中均降低,STAT3 是let-7a 的直接靶基因;另有研究证实STAT3 可诱导lin28 表达,而后者能与let-7a 前体结合抑制其裂解,导致let-7a 成熟体表达下降.因此我们推测let-7a/STAT3/lin28 通路在尤文肉瘤CSCs 中形成正反馈环路,扮演关键的调控作用.本项目在以上研究基础上，得出以下结果：let-7a能够抑制尤文肉瘤SP侧群细胞(CSCs)的恶性生物学表型，而STAT3/lin28通路可能参与其中的作用调控；以上的实验结果将为尤文肉瘤肿瘤的发生、发展体重新的理论基础，同时为尤文肉瘤的肿瘤生物治疗提供新的思路。