低氧调控的SOX2去甲基化促进子宫内膜癌干细胞自我更新的分子机制研究

The ground state of cancer stem cells is closely related to the development of cancer. Tumor stem cell maintain its homeostasis by expressing stem-ness genes and inhibiting differentiation genes. Hypoxia-inducing factors have been reported to be involved in tumor stem-ness genes' regulation. The methylation modification and activity of core transcription factor Sox2 determine the initiation and function of tumor cells. The prophase research of this project has found that hypoxia promoted endometrial cancer stem cells self-renew, significantly increased the expression of tumor stem-ness factor Sox2 and demethylase ALKBH5. Therefore, we hypothesize that Hypoxia induces the endometrial cancer stem cell self-renew by HIF-dependent demethylation of Sox2. In this study we will discuss the relationship between HIFs, Sox2 and ALKBH5 in hypoxic culture, determine the effect of HIFs signal pathway on the tumor stem-ness factor methylation modification, discuss the molecular mechanism of tumor stem-ness factor Sox2 and demethylase ALKBH5 and self-renewal of human endometrial cancer stem cells, aim to provide basis for basic research and application for endometrial cancer stem cells.

肿瘤干细胞内稳态在肿瘤发生发展中发挥着重要作用，肿瘤干细胞通过表达肿瘤干性基因而抑制分化基因以实现体内平衡。已有研究证实，肿瘤微环境中缺氧诱导因子HIFs参与肿瘤干性基因调控，且肿瘤干性因子Sox2的表观修饰状态及活性决定了肿瘤细胞的起始和功能。我们前期研究发现低氧微环境维持子宫内膜癌干细胞自我更新状态，同时显著提高肿瘤干性因子Sox2活性，并促进去甲基化酶ALKBH5表达。据此，我们假设子宫内膜癌干细胞内稳态中存在HIFs调控肿瘤干性转录因子的甲基化修饰。我们拟通过探究低氧微环境中HIFs信号通路、肿瘤干性基因Sox2与表观遗传去甲基化酶ALKBH5的相互作用关系，解析低氧微环境中HIFs信号通路对Sox2和ALKBH5的作用和调控机理，由此阐明HIFs信号通路调控人子宫内膜癌干细胞多能性的作用机制。本研究将为子宫内膜癌干细胞自我更新的机制研究和临床应用提供新的参考和依据。

子宫内膜癌干细胞是具有自我更新和分化能力的干细胞样细胞，这些细胞在子宫内膜癌的癌症进展中至关重要。缺氧和缺氧诱导因子(HIF)是肿瘤微环境(TME)的标志，会导致肿瘤干细胞基因(如SOX2)的失调。在此背景下，我们研究了HIF和SOX2在ECSCs发育过程中的调控机制。本研究发现，从EC细胞系和组织中分离的ECSC在诱导其扩展后，表达了干性基因(CD133、ALDH1)。值得注意的是，RNA的m6A甲基化和依赖HIF-1α/2α的AlkB同源物5(ALKBH5)参与了EC中SOX2的调控，观察到ECSCs在低氧条件下m6A去甲基化酶ALKBH5的mRNA水平显著升高。此外，低氧和高水平的ALKBH5可恢复分化的ECSC状态，增加ECSC样表型，而敲低HIF或ALKBH5可显著降低其肿瘤启动能力。此外，我们的研究结果证实了ALKBH5通过mRNA去甲基化促进SOX2转录的作用，从而维持了ECSCs干性状态和致瘤潜能。总之，这些观察结果证明了m6A甲基化介导的HIF-ALKBH5-SOX2轴在低氧TMEs中ECSC调控程中的关键作用。