P53/miR-29a环路在调控胶质瘤发生发展及化疗耐药中的作用机制研究

Intensive studies have conveyed that the therapeutic effect of malignant glioma is closely associated with tumor development and chemotherapy resistance, but the underlying molecular mechanisms remain unclear. The latest literatures and our preliminary study demonstrate that the expressions of p53 and miR-29a are downregulated significantly in glioma and p53 is involved in the regulation of miR-29a.Through bioinformatics analysis and laboratory research, for the first time, we find that MDM2, MDM4 and BCL2L2 are the direct targets of miR-29a while MDM family is the most important negative regulator of p53.Therefore, it is the first time that we propose the hypothesis that a circuit regulatory pattern consisted by p53/miR-29a/MDM2/MDM4/BCL2L2/p53 may be present in glioma.This project gives a deep research on the regulatory role and molecular mechanism of p53/miR-29a/MDM2/MDM4/BCL2L2/p53 circuit in glioma development and chemoresistance by using new technologies such as orthotopic animal model of intracranial glioma, chimeric tumor model and molecular biology. It is confirmed that this circuit exists in glioma and the restoration of circuit activity can inhibit the development and increase the chemosensitivity of malignant glioma, which provides the theoretical basis for new treatment options of glioma in the future.

大量研究表明恶性胶质瘤的疗效与肿瘤的发生发展及化疗耐药密切相关，但其机制尚不明确。最新文献报道和我们前期研究发现在胶质瘤中p53和miR-29a表达显著下调，而p53参与调控miR-29a的表达，我们通过生物信息学分析和实验室研究首次发现MDM2、MDM4和BCL2L2是miR-29a的直接作用靶点，而MDM家族是p53最重要的负性调节因子，因此我们首次提出胶质瘤中可能存在p53/miR-29a/MDM2/MDM4/BCL2L2/p53形成的环路调控模式假说。本项目应用胶质瘤颅内原位动物模型、嵌合瘤模型和分子生物学等技术深入研究p53/miR-29a/MDM2/MDM4/BCL2L2/p53环路在胶质瘤发生发展及化疗耐药中的调控作用和分子机制，证实胶质瘤中存在该环路，且恢复该环路活性能抑制恶性胶质瘤发生发展和增加其化疗敏感性，为将来胶质瘤新的治疗方案提供理论依据。

目的：探讨P53/miR-29a/MDM2环路在调控胶质瘤发生发展及化疗耐药中的作用机制.方法：首先，我们收集了30例胶质瘤组织和10例对照组，qRT-PCR检测miR-29a的表达情况，探究其与胶质瘤组织临床分级以及恶性程度的相关性。同时在体外，我们利用CCK-8和Transwell等技术检测miR-29a表达改变对胶质瘤细胞增殖、凋亡、迁移、侵袭以及凋亡的影响。进一步探究其机制，我们利用双荧光素酶报告基因技术在转录水平上明确P53/miR-29a/MDM2这一环路。最后通过细胞及动物模型探讨P53/miR-29a/MDM2环路对胶质瘤化疗耐药的作用。.结果：1、miR-29a的表达与人胶质瘤的肿瘤级别呈负相关；2、miR-29a可在体外抑制胶质瘤细胞增殖、迁移、侵袭，促进胶质瘤细胞凋亡；3、p53可诱导miR-29a表达，导致miR-29a靶向的MDM2 异常表达，最终导致p53-miR-29a-MDM2环路的活性失调；4、miR-29a调节的p53/MDM2信号使胶质瘤细胞对替莫唑胺治疗的反应敏感。.结论：本研究展示了胶质瘤发生的潜在分子机制，并为未来胶质瘤的治疗提供了一个可能的靶点。