FOXO1直接拮抗MYH9诱导miR-200b抑制鼻咽癌转移和肿瘤干性研究

We preliminarily observed that FOXO1 suppressed cell metastasis, and cancer stemness maintenance in nasopharyngeal carcinoma(NPC). Further, CoIP combinded with mass spectrography and exogenous co-immunoprecipitation assays revealed that MYH9 is a potentially direct interaction protein of FOXO1 in NPC. Furthermore, FOXO1 was observed to induce the expression of miR-200b and MYH9 was found to suppress the miR-200b expression in NPC. We speculated that FOXO1 directly antagonized MYH9 and induced the miR-200b, a tumor suppressive-miRNA that could directly target EMT and cancer stemness-related genes including ZEB2, ZEB1, and Bmi-1, by modulating corresponding signals, which blocked cell metastasis and cancer stemness maintenance in NPC. The further works are as followed: 1) Identifying the respectively detailed roles of FOXO1 and MYH9 in modulating the metastasis and cancer stemness maintenance as well as their specific molecular mechanism in NPC. 2) Confirming that FOXO1 directly antagonized MYH9, which further induced the expression of miR-200 suppressing cell metastasis and cancer stemness maintenance and increasing the sensitization of radiotherapy and chemotherapy in NPC. 3) Confirming the expression correlation of FOXO1, MYH9, and miR-200b and their roles in clinical progression and prognosis in NPC. Our work will firstly report that tumor-suppressive nucleus transcription factor FOXO1 directly antagonized cytoplasmic expression protein MYH9 suppressing cell metastasis and cancer stemness maintenance in NPC.

我们初步发现FOXO1抑制鼻咽癌细胞转移和肿瘤干性维持。进一步，CoIP结合质谱分析以及外源性免疫共沉淀实验揭示MYH9为FOXO1在鼻咽癌中候选直接作用蛋白。除此之外，FOXO1还被发现诱导miR-200b表达，而MYH9则抑制其表达。我们推测，FOXO1在鼻咽癌中直接拮抗MYH9，通过相应信号通路诱导miR-200b表达，从靶击ZEB2、ZEB1和Bmi-1等EMT和干性相关基因，进而抑制鼻咽癌转移和肿瘤干性。进一步工作如下：明确FOXO1和MYH9分别抑制和诱导鼻咽癌转移和肿瘤干性以及它们具体分子机制；明确FOXO1直接拮抗MYH9，诱导miR-200b，抑制鼻咽癌转移和肿瘤干性以及放化疗增敏；明确FOXO1、MYH9和miR-200b在鼻咽癌中表达相关性以及临床进展和预后关系；我们的工作将首次报导抑癌核转录因子FOXO1通过直接拮抗胞浆蛋白MYH9，抑制鼻咽癌转移和肿瘤干性的维持。

在本研究中，我们阐明FOXO1抑制鼻咽癌（NPC）发生发展的发病机理及其分子机制。首先，我们发现FOXO1不仅在体外和体内控制了肿瘤的干性和转移，并诱导鼻咽癌细胞对顺铂（DDP）化疗敏感性。机理研究表明，FOXO1通过抑制GSK3β/β-catenin/ TCF4通路介导的ZEB1促进miR-200b表达，从而减少了肿瘤干性和上皮-间质转化（EMT）信号。此外，我们观察到FOXO1与MYH9相互作用，并通过调节PI3K / AKT / c-Myc / P53 / miR-133a-3p途径抑制MYH9表达。 MYH9表达的降低不仅降低了其与GSK3β的相互作用，而且减弱了TRAF6的表达，进而降低了泛素介导的GSK3β蛋白降解。 GSK3β表达的增加刺激了β-catenin/ TCF4 / ZEB1 / miR-200b网络，从而增加了下游肿瘤干性和EMT信号。在临床样品中，FOXO1低表达和MYH9高表达的患者总体生存率最差。我们的研究表明，FOXO1/MYH9复合物调节鼻咽癌的肿瘤干性、转移，从而有效诱导了FOXO1介导的DDP敏感性。