TGF-β1/miR-411/MAPK信号通路参与调控横纹肌肉瘤肌分化调节因子MyoD功能的分子机制研究

Different levels of MyoD family are expressed by various RMSs, however, the mechanism of the lack of differentiation commitment by RMS remains unclear. We have reported a correlation between the high expression of TGF-β1 and the dysfunction of MyoD in RMS. Recently, miRNA screening revealed that TGF-β1-associated miR-411 can promote RMS differentiation. We further found that silencing SPRY4, the target gene of miR-411, significantly increased p38 phosphorylation. These suggest that TGF-β1 regulation of MAPK signaling pathways through miR-411 is the likely mechanism regulating MyoD function. In this proposal, target genes of miR-411 that are tightly associated with key factors in MAPK signaling pathway, including ERK, JNK and p38, will be predicted by bioinformatics and further analyzed at molecular and tissue levels in combination with in vivo animal experimentations and clinical data analysis. These studies will yield further insight into the relationships among TGF-β1-associated miR-411, MAPK signaling pathway, and MyoD functional regulation, leading to new therapeutic targets that can commit RMS to differentiation.

尽管各型横纹肌肉瘤（RMS）都不同程度地表达肌分化调节因子MyoD家族，却不能完成终末分化，机制至今不详。本课题组前期研究发现RMS中MyoD的功能障碍与高分泌TGF-β1密切相关，近期通过miRNA芯片筛选发现TGF-β1相关miR-411具有促进RMS分化的作用，更重要的是发现沉默miR-411的靶基因SPRY4能明显提高p38的磷酸化水平，TGF-β1通过miR-411调控MAPK信号通路是MyoD功能调控的可能参与机制。本研究拟通过生物信息学预测与MAPK信号通路ERK、JNK及p38等关键蛋白密切相关的miR-411靶基因，并通过分子水平、组织水平、动物体内实验和临床资料分析，探讨TGF-β1相关miR411与MAPK信号通路的关系，旨在阐明TGF-β1调控的miR411 如何通过靶基因调控MAPK信号通路影响MyoD功能状态的分子机制，有望为RMS的分化治疗筛选出新的治疗靶点。

尽管各型横纹肌肉瘤（RMS）都不同程度地表达肌分化调节因子MyoD家族，却不能完成终末分化，机制至今不详。本研究主要研究结果：（1）在RMS中 TGF-β1负调控miR-411-5p表达；（2）miR-411-5p在体内和体外抑制RMS的增殖；（3）SPRY4是miR-411-5p的直接靶基因；（4）SPRY4抑制PKCα介导MAPK活化；（5）SPRY4抑制p38活性有助于RMS的分化阻滞；（6）TGF-β1、SPRY4 和P-p38的表达在RMS组织和临床病理中的关系；（7）TGF-β1沉默RD细胞凋亡现象明显增加，TGF-β1沉默RD细胞在分化培养过程中肌丝结构逐渐形成；（8）外源性TGF-β1促进RD细胞核内p65、p50的表达；（9）RMS石蜡组织中p65、p50、RelB和p52的蛋白表达。旨在阐明TGF-β1调控的miR411 如何通过靶基因调控MAPK信号通路影响MyoD功能状态的分子机制，有望为RMS的分化治疗筛选出新的治疗靶点。