肝星状细胞通过NNMT调控CD44mRNA-m6A甲基化促进肝癌转移机制研究

The interactive crosstalk between hepatic stellate cells (HSCs) and hepatic carcinoma cells contributes to hepatocellular carcinoma (HCC), occurrence and procession, but the mechanism remains largely unexplored. Our preliminary experiments revealed that NNMT expression and metastasis level of HCC are positively correlated in human liver cancer tissues. Accordingly,activated HSCs upregulated expression of NNMT,resulting in an alteration of histone 3 modification，reduced CD44 mRNA-m6A methylation and increased CD44v3 protein level in hepatic carcinoma cells, which promoted invasion and metastasis of hepatic carcinoma cells. Hence, our results strongly suggested that activated HSCs-promotes invasion and metastasis of hepatic carcinoma cells via NNMT-regulated CD44 mRNA-m6A methylation and CD44v3 protein aggregation. In this study, we will further elaborate the mechanism of HSC promoted HCC metastasis by investigating how activated HSCs in tumor microenvironment regulate NNMT expression and the regulation mechanism of NNMT on histone 3 modification, CD44 mRNA-m6A methylation and CD44v3 protein stability in hepatic carcinoma cells and animal model. Our project will be the first mechanism study of activated HSCs on promoting invasion and metastasis of HCC via NNMT, which may provide a new target and promising strategy in therapy of HCC.

肝星状细胞（HSCs）与肝癌细胞交互作用促进肝癌侵袭转移，但其具体机制仍不明确。我们前期病理标本检测表明尼克酰胺N-甲基转移酶（NNMT）的表达与肝癌转移、CD44v3表达正相关。同时，我们发现活化的HSC能上调肝癌细胞中NNMT的表达，导致H3组蛋白修饰改变、CD44mRNA-m6A甲基化减少、CD44v3蛋白增加，进而促进肝癌细胞迁移与侵袭。这些结果表明活化的HSCs很可能通过NNMT调控CD44mRNA-m6A甲基化与CD44v3促进肝癌侵袭转移。为阐明其分子机理，我们将进一步在细胞分子水平、动物模型中明确肿瘤微环境中活化的HSCs如何调控肝癌细胞NNMT表达，以及NNMT对H3组蛋白修饰、CD44mRNA-m6A甲基化、CD44v3蛋白稳定性的调控机制。本项目将首次阐述HSC通过NNMT调控CD44mRNA-m6A甲基化促进肝癌侵袭转移的机制，为肝癌治疗提供新靶点、新思路。

肝星状细胞（HSC）与肝癌细胞之间的交互作用有助于肝细胞癌（HCC）的进展，但其潜在机制在很大程度上尚不清楚。我们研究发现激活的HSCs诱导烟酰胺N-甲基转移酶（NNMT）的上调，它可以调节肝脏肝癌细胞中的多种代谢途径。 HCC组织中高水平的NNMT与血管浸润，血清HBV-DNA水平升高和远处转移呈正相关。此外，功能分析表明，NNMT通过改变组蛋白H3促进了HCC细胞的侵袭和转移。NNMT介导的CD44 mRNA的N6-甲基腺苷修饰导致CD44v3剪接变体的形成，而其产物1-甲基-烟酰胺则通过防止泛素介导的降解来稳定CD44蛋白。最后，NNMT还被证明是抑制肝癌细胞转移的他汀类药物的靶标。综上所述，我们的研究首次表明NNMT/CD44v3轴调节HCC转移，并提出NNMT作为HCC有希望的预后生物标志物和治疗靶标。