BACKGROUND Liver cancer stem cells (LCSCs) contribute to hepatocellular carcinoma (HCC) development, metastasis, and drug resistance. MSI2 and Notch1 signaling are involved in the maintenance of CSCs. However, it is unknown whether MSI2 and Notch1 are involved in the maintenance of CD44v6+ LCSCs. Therefore, we investigated the clinical significance and function of MSI2 and its relationship with Notch1 signaling in the maintenance of stemness properties in CD44v6+ LCSCs. METHODS The expression of MSI2 and CD44v6 were detected by fresh specimens and a HCC tissue microarray. The tissue microarray containing 82 HCC samples was used to analyze the correlation between CD44v6 and MSI2. CD44v6+/- cells were isolated using microbeads sorting. We explored the roles of MSI2 and Notch1 signaling in CD44v6+ LCSCs by sphere formation assay, transwell assay, clone formation assay in vitro, and xenograft tumor models in vivo. A Notch RT2 PCR Array, Co-immunoprecipitation, and RNA-immunoprecipitation were used to further investigate the molecular mechanism of MSI2 in activating Notch1 signaling. RESULTS Here, we found MSI2 expression was positively correlated with high CD44v6 expression in HCC tissues, and further correlated with tumor differentiation. CD44v6+ cells isolated from HCC cell lines exhibited increased self-renewal, proliferation, migration and invasion, resistance to Sorafenib and tumorigenic capacity. Both MSI2 and Notch1 signaling were elevated in sorted CD44v6+ cells than CD44v6- cells and played essential roles in the maintenance of stemness of CD44v6+ LCSCs. Mechanically, MSI2 directly bound to Lunatic fringe (LFNG) mRNA and protein, resulting in Notch1 activation. CONCLUSIONS Our results demonstrated that MSI2 maintained the stemness of CD44v6+ LCSCs by activating Notch1 signaling through the interaction with LFNG, which could be a potential molecular target for stem cell-targeted therapy for liver cancer.

中文翻译：

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Musashi2通过notch1信号通路有助于维持CD44v6 +肝癌干细胞。

背景技术肝癌干细胞（LCSC）有助于肝细胞癌（HCC）的发展，转移和耐药性。MSI2和Notch1信令与CSC的维护有关。但是，未知MSI2和Notch1是否参与CD44v6 + LCSC的维护。因此，我们研究了MSI2的临床意义和功能及其与Notch1信号传导在维持CD44v6 + LCSCs干性中的关系。方法用新鲜标本和肝癌组织芯片检测MSI2和CD44v6的表达。使用包含82个HCC样本的组织微阵列分析CD44v6与MSI2之间的相关性。使用微珠分选分离CD44v6 +/-细胞。我们通过球形成实验，transwell实验，CD44v6 + LCSC探索了MSI2和Notch1信号转导的作用，在体外进行克隆形成测定，在体内进行异种移植肿瘤模型。Notch RT2 PCR阵列，共免疫沉淀和RNA免疫沉淀被用于进一步研究MSI2激活Notch1信号传导的分子机制。结果在这里，我们发现MSI2表达与HCC组织中高CD44v6表达正相关，并进一步与肿瘤分化相关。从HCC细胞系分离的CD44v6 +细胞表现出增强的自我更新，增殖，迁移和侵袭，对索拉非尼的抗性和致瘤能力。在排序的CD44v6 +细胞中，MSI2和Notch1信号均比CD44v6-细胞升高，并且在维持CD44v6 + LCSC的干性中起重要作用。机械上，MSI2直接绑定到Lunatic条纹（LFNG）mRNA和蛋白质，导致Notch1激活。