新型血清标志物d-GM3糖脂抗原在恶性黑色素瘤转移中的作用及Rg3的干预机制研究

Malignant melanoma is an incurable tumor with poor prognosis.The recurrence and distant metastasis of it is the leading cause of high mortality in malignant melanoma patients; whereas the mechanism is still not clear and lack of the efficient prevention and interfering methodology.The glycomics has become an new hot spot in tumor study in recent years. Our previous study confirmed that the specific tumor glycolid antigen d-GM3 was a novel molecule which caused invasion and metasis of malignant melanoma (Cancer Res, 2009). The aims of the project are: further exploring the roles of d-GM3 in the growth and metastasis in maligant melanoma by in vivo, animal and clinic study, and proposing that d-GM3 is a new target of cancer treatment; suggesting and supporting the new theory that histone deacetylase HDAC3 is the key enzyme controlling d-GM3 biosynthesis; screening the downstream signalling pathway network mediated by HDAC3/d-GM3 by microfluid chip assay; searching for the the new epigenetics and glycobiology mechanism in tumorigenesis; identifying the inhibitory activities of ginsenoside Rg3 as one of the HDAC inhibitors in regulating d-GM3 synthesis and the possibilities applied in the prevention and treatment of malignant melanoma; setting up new, sensitive and specific serum d-GM3 assay for screening, diagnosing and monitoring disease progression. The project will supply the new idea and strategy for the diagnosis and treatment for malignant melanoma.

恶性黑色素瘤（简称“恶黑”）是预后极差的难治性肿瘤。复发和转移为患者死亡的首要原因，但确切机制仍不清楚，尚缺乏有效的预防及干预手段。糖组学是近年来肿瘤研究领域的新热点。前期工作已证实肿瘤特异性糖脂抗原d-GM3是导致恶黑侵袭和转移的新分子（Cancer Res, 2009）。本课题拟通过体外-动物-临床研究进行以下研究：深入探讨d-GM3在恶黑生长和转移中的作用，提出d-GM3可作为恶黑治疗的新靶点；提出并验证调控d-GM3合成的关键酶是去乙酰化酶HDAC3的新学说；利用微流控芯片筛选HDAC3/d-GM3的下游信号网络；探讨人参皂苷Rg3的表观遗传学及糖生物学抗肿瘤新机制，证明Rg3具有HDAC3抑制剂活性并能抑制d-GM3合成，可用于恶黑转移的预防及治疗；建立灵敏特异的d-GM3血清检测新方法，用于恶黑转移的筛查、诊断及监测。本课题将为恶黑的诊断及治疗提供新思路与新方法。

人参皂苷Rg3是人参中提取的一种二醇类四环三萜皂苷，为国家第一个中药一类单体抗肿瘤新药。目前已证实Rg3对多种实体瘤中具有良好的抗肿瘤活性，主要通过抑制肿瘤细胞生长转移、促进细胞凋亡及减少肿瘤新生血管形成等机制。表观遗传学是涉及DNA及蛋白质分子甲基化及乙酰化修饰的基因表达调控过程，参与了肿瘤的发生发展的各个环节。组蛋白去乙酰化和去乙酰化是蛋白质翻译后修饰的关键过程，肿瘤的发生与乙酰化及去乙酰化过程的动态失衡密切相关。其中乙酰化酶(histone deacetylases，HDACs)是调控组蛋白去乙酰化作用的关键酶。HDAC3是去乙酰化酶的一种。本研究利用生物信息学、分子生物学及肿瘤生物学等研究方法揭示Rg3通过抑制HDAC3、EMT及FUT7介导的肿瘤发生、发展、侵袭转移，与顺铂联用可增加非小细胞肺癌细胞的化疗敏感性。重要结论如下：（1）Rg3能够下调HDAC3表达抑制皮肤鳞状细胞癌EMT通过调控c-Jun的乙酰化；（2）HDAC3通过调控GATA3的乙酰化来调节FUT7的基因及蛋白水平的表达，从而促进黑色素瘤细胞上皮-间质转化（EMT）。从而影响黑色素瘤细胞的EMT能力，为HDAC3能成为黑色素瘤治疗靶点及为HDAC抑制剂与糖基转移酶抑制剂联合用药提供理论依据。（3）Rg3增加肺癌缺氧细胞对顺铂的敏感性通过抑制NF-κB信号介导的EMT和干性，为逆转化疗耐药提供新思路。综上所述，本研究阐明Rg3通过调控HDAC3和EMT，在抑制肿瘤发生发展、肿瘤侵袭转移，增加化疗药物敏感性等方面，具有重要的理论价值与临床应用意义。