PCL2调控表观遗传修饰相关的骨形成蛋白抑制胶质母细胞瘤干细胞的作用和机制研究

Glioblastoma (GB) is the most common primary brain tumor in adults. According to the cancer stem cell concept, resistance to conventional therapy may reside in the glioblastoma stem cells (GSCs). Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-β (TGF-β) superfamily serving multiple functions in many cell and tissue types. In recent years, BMP2-mediated growth regulation has been extensively studied in carcinogenesis. The findings are diverse. Our previous study has also found that, BMP2 (80 ng/ml) can induce the differentiation and reduce the growth of GSCs, but high concentration of BMP2 can result the diverse, and the molecular mechanism was still unclear. There were some research indicated that the epigenetic silence of BMP signaling pathway was leading to disorders of the GSCs differentiation, the PCL2 gene may play a key role. In this project, firstly, we would study the relationship between the gene of PCL2 gene and the biological characteristics of astrocytomas. Secondly, we would research the PCL2 gene over expression or knock down on GSCs differentiation. In the third place, we would apply high and low concentrations of BMP2 and Noggin protein to intervene the GSCs, and the GSCs had been treated by over expression or knock down of PCL2 gene, in this process, the result would descript the role of PCL2 gene in BMP2 regulating GSCs growth. Choose CDKN1C as a target and research the interaction between the PCL2 and CDKN1C, to clarify the molecular mechanisms of PCL2 regulating GSCs growth. The research would provide a direct evidence of PCL2 is a key gene that involved BMP2 regulating the growth of glioblastoma, the results will provide a new ideas for clinical development of cancer stem cell inhibitors.

胶质母细胞瘤干细胞（GSCs）是导致肿瘤发生和生长迅速的根源，针对GSCs治疗是目前研究的热点。文献和我们前期研究发现，BMP2能促进GSCs分化、抑制GSCs生长；BMP信号对于肿瘤是一把双刃剑，既是致癌基因又是肿瘤抑制剂，PCL2基因介导的表观遗传修饰可能在控制BMP作用的方向上发挥了关键作用。本项目首先研究PCL2的表达与星形细胞肿瘤生物学特性的关系；进行GSCs中PCL2基因过表达/干扰，研究PCL2对GSCs分化的影响；应用高、低浓度BMP2以及Noggin蛋白干预PCL2过表达/干扰的GSCs，研究PCL2在BMP2正负调控GSCs生长中的作用；选择CDKN1C作为靶点，研究PCL2与CDKN1C相互作用关系，进一步阐明PCL2调控GSCs生长的分子机制。这项研究将提供直接证据说明PCL2是否是参与BMP2调控GSCs生长的关键基因，结果将为临床研发肿瘤干细胞抑制剂提供新思路。

胶质母细胞瘤（GB）是大脑最好发的，恶性程度最高的星形细胞肿瘤，以肿瘤反复复发和患者快速死亡为特征。表观遗传修饰在控制GB生长过程中发挥重要作用，PRC2全酶复合物是控制生长发育及肿瘤发生的重要表观遗传因子，PCLs是PRC2最重要的多肽，能够与PRC2的全部靶基因相互作用，通过EZH2进行PRC2基因的募集和全酶活性的调节。PCL2基因介导的表观遗传修饰可能在GB生长及演进过程中发挥关键作用。本项目研究发现PCL2基因在星形细胞肿瘤组织呈高表达，在有厚壁血管形成的组织样本中表达水平较高，其机制可能是PCL2基因能促进NRF2信号轴关键基因NRF2和HO-1-1，从而影响肿瘤血管生成能力。本研究进一步发现，过表达PCL2基因能够促进胶质瘤U87和U251细胞增殖、增强细胞集落形成能力、促进细胞周期中S期增高；干扰PCL2基因能够促进肿瘤细胞凋亡、抑制细胞增殖和集落形成能力。相关机制研究表明，过表达\干扰PCL2基因，能够上调\下调PRC2关键基因（EZH2、SUZ12、EED），下调\上调PRC1关键基因（RING1A、RING1B、BMIL）的表达，以及改变组蛋白H3K27甲基化和组蛋白H2AK119泛素化，从而改变胶质瘤细胞的生物学行为。进一步探索机制发现，应用EZH2抑制剂DZNep干预BGC细胞，细胞增殖、集落形成、侵袭和迁移能力均明显下降，凋亡增加，其机制是通过抑制缺氧诱导因子Hif-1α ，进一步抑制 Wnt信号通路关键基因的表达，从而抑制肿瘤的恶性生物学行为。本研究发现，骨形成蛋白2（BMP2）能促进胶质母细胞瘤干细胞（GSCs）分化、抑制GSCs生长，并增强胶质瘤细胞对放疗敏感性。相关机制研究表明，PCL2基因可能在BMP2抑制肿瘤生长的过程中发挥了关键作用。这些研究揭示了PCL2基因在GB发生和演进过程中的重要作用，结果将为临床研发肿瘤抑制剂提供新思路。