MEIS2通过AuroraA-Plk1信号通路调控神经母细胞瘤有丝分裂的机制研究

Neuroblastoma is a common childhood malignant tumor of the nervous system. Treatment approaches consist of different combinations of chemotherapy, surgery and other comprehensive therapy. But the long-time survival for high-risk neuroblastoma still remains low because of drug resistance, distant metastasis and recurrence. Our previous study revealed that MEIS2 gene had an important role in regulating neuroblastoma cell division and proliferation. Depletion of MEIS2 in neuroblastoma cells leaded to M-phase arrest and mitotic catastrophe. Gene expression profiling revealed an essential role of MEIS2 in maintaining the expression of a large number of late cell-cycle genes. In addition to that, the key genes of AuroraA-Plk1 pathway was found downregulated by depletion of MEIS2, which just be identified in our latest study. However, the role of MEIS2 and AuroraA-Plk1 pathway in neuroblastoma cell division were not fully explored. So we hypothesis that the regulating effect of MEIS2 in neuroblastoma cell division was mediated by AuroraA-Plk1 pathway. The mRNA and protein expression level of AURKA can be downregulated by MEIS2 depletion, and then the phosphorylation of Plk1 decreased, which leads to M-phase arrest and mitotic catastrophe of tumor cells. Next, the essential role of MEIS2 and AuroraA-Plk1 pathway in regulating neuroblastoma cell division and proliferation will be studied；The interacted regulation mechanism between MEIS2 and the gene of AuroraA-Plk1 pathway will be identified; The other target genes and signal pathway regulated by MEIS2 in neuroblastoma cell division will also be explored. The study will help us understanding the mechanism of neuroblastoma initiation and progression. It can also provide us a promising approach for the therapeutic treatment of neuroblastoma.

神经母细胞瘤是儿童常见神经系统恶性肿瘤，多采用手术、化疗等综合治疗，但存在药物抵抗、远处转移和复发等问题，远期预后差。我们研究发现MEIS2在神经母细胞瘤有丝分裂过程中有重要作用，基因沉默MEIS2可下调有丝分裂相关信号通路基因致细胞死亡，进一步研究发现MEIS2沉默可下调AuroraA-Plk1信号通路关键基因表达，但机制尚不清楚，由此我们提出:“MEIS2通过AuroraA-Plk1信号通路调控神经母细胞瘤有丝分裂，基因沉默MEIS2可下调AURKA表达、抑制PLK1的磷酸化导致细胞有丝分裂灾变死亡”。拟从:MEIS2与AuroraA-Plk1信号通路在有丝分裂中的调控作用；MEIS2调控AuroraA-Plk1信号通路机制；MEIS2调控神经母细胞瘤细胞有丝分裂的其他可能机制三个方面开展研究以验证我们的假说，深入研究该机制为明确神经母细胞瘤的发生发展及抗肿瘤药物开发提供新思路。

神经母细胞瘤是儿童常见神经系统恶性肿瘤，目前尚无特异性治疗方案，远期预后差，而MYCN基因扩增神经母细胞瘤具有更高的恶性程度，且对化疗药物抵抗。我们研究发现MEIS2基因和MYCN基因在神经母细胞瘤发生、发展过程中有重要作用，一方面利用生物信息学分析发现MEIS2基因在神经系统中表达增高且与神经母细胞瘤预后呈负相关，在神经母细胞瘤细胞系中利用shRNA技术基因沉默MEIS2可导致细胞发生有丝分裂灾变死亡，并伴随有丝分裂通路 AuroraA-Plk1关键基因表达下调，而外源性高表达MEIS2基因可促进神经母细胞瘤细胞增殖并激活AuroraA-Plk1通路基因表达，提示MEIS2与AuroraA-Plk1存在相互作用，后续研究将进一步阐述MEIS2与Aurora-Plk1信号通路相互作用方式；另一方面，在上述研究中我们发现MYCN基因扩增可激活肿瘤细胞丝氨酸-甘氨酸-一碳单位代谢通路而促进肿瘤细胞增殖，进一步机制研究发现MYCN蛋白通过结合于ATF4基因启动子上调控其表达，而ATF4表达增高可作用于肿瘤细胞丝氨酸-甘氨酸-一碳单位代谢通路关键基因启动子上激活该信号通路，最终调控肿瘤细胞增殖及化疗药物抵抗，而使用丝氨酸-甘氨酸代谢通路特异性抑制剂NCT-503可选择性抑制MYCN扩增神经母细胞瘤细胞增殖，但对非MYCN扩增细胞无明显作用，体外实验进一步证明NCT-503可延长MYCN扩增细胞成瘤小鼠生存时间。通过上述研究，我们阐述了MEIS2基因及MYCN基因调控神经母细胞瘤增殖及代谢的机制，为神经母细胞瘤的发生发展研究及抗肿瘤药物开发提供了新思路。