Notch信号介导的骨肉瘤干细胞与内皮细胞的相互作用及分子机制研究

Osteosarcoma stem cells (OSCs) not only participates the initiation of osteosarcoma but also the process of invassion, metastasis and chemotherapy resistance. Targeting OSCs holds enormous therapeutic implications. The microinviroment of OSCs play an important role in maintaining the stemness of OSCs. But the mechanisms is still unclear. Previously, we found increased Notch activities in OSCs. Because of the ligand-dependence of Notch signal, we examined the high level expression of Notch ligands in the lung metastastic osteosarcoma tissues and co-culture system of Huvec and OSCs. Therefore, we hypothesized that the Dll4/Notch signal may play an important role in the interaction of OSCs and endothelial cells, and lung metastasis of OSCs. To conform this hypothesis, we will first investigat the expression and location of Notch receptors and ligands. Next, by differenciated expressed Notch recedptors and ligands, the expression of Notch ，the remolding of the osteosarcoma vascular and the stemness of OSCs will be investigated. Thus, we may found the possible mechanisms underlying regulation of OSCs by endothelial cells , and this study will provide a biological basis for exploring the therapeutic significance of targeting OSC and microinviroment.

骨肉瘤干细胞（OSCs）不仅参与骨肉瘤的始动，也参与其转移。靶向OSCs是治疗的关键。肿瘤微环境在维持OSCs干性中发挥重要作用，但对OSCs与微环境间的相互作用机制尚不明确。前期研究发现OSCs中Notch活性升高，而Notch的激活依赖于邻近细胞配体的表达，检测到富于血管的骨肉瘤组织及OSCs球与内皮细胞（ECs）共培养体系中高表达Dll4，因此我们提出Dll4/Notch信号介导了OSCs与ECs的相互作用，通过影响骨肉瘤的血管重塑和OSCs的干性而在肺转移中发挥重要作用。为此，拟利用人骨肉瘤组织、骨肉瘤原位移植模型及肺转移模型及OSCs共培养系统验证Notch相关信号分子的分布及表达变化；并通过差异表达Notch受体和配体来探讨Notch介导的OSCs与ECs的相互作用及Dll4/Notch的下游分子机制。为深入阐明骨肉瘤的演进机制及以OSC和ECs为靶点的治疗提供理论和实验依据。

骨肉瘤干细胞（OSCs）不仅参与骨肉瘤的始动，也参与其转移。靶向OSCs是治疗的关键。肿瘤微环境在维持OSCs干性中发挥重要作用，但对OSCs与微环境间的相互作用机制尚不明确。我们研究发现Dll4/Notch3信号介导了OSCs与ECs的相互作用，通过影响骨肉瘤的血管重塑和OSCs的干性而在肺转移中发挥重要作用；Notch3表达是骨肉瘤的独立预后因素，其高表达与患者不良预后显著相关；Notch3通过其下游分子Hes1和MMP7显著增强骨肉瘤的侵袭及远处转移，敲低Notch3可显著抑制骨肉瘤细胞的增殖、侵袭和转移，促进凋亡。我们的上述研究为为深入阐明骨肉瘤的演进机制及以OSC和ECs为靶点的治疗提供理论和实验依据。