Tet2 regulation and function in glioma cell phenotype reprogramming

胶质母细胞瘤(GBM)是最具侵袭性和致命性的原发性脑癌。我们现在知道 该GBM包含显示肿瘤传播性干细胞样表型(GBM干细胞)的细胞的小亚群 细胞、GSCs)，这些细胞是GBM对当前治疗的耐药性和肿瘤复发的关键决定因素。 了解并最终针对诱发和维持这些肿瘤的表观遗传机制- 细胞亚群的增殖对于改善GBM治疗和患者预后至关重要。DNA模式的改变 甲基化在人类GBM中被广泛报道。然而，我们的知识差距仍然很大。 理解这种表观遗传失调的分子机制，其下游 在肿瘤增殖性GSC表型中的作用和后果。这项建议建立在我们发布的和 癌基因重编程转录因子诱导肿瘤增殖的初步研究 通过调节针对DNA甲基化决定因素的miRNA网络。我们新的初步数据 暗示了一个以前未被识别的Sox2：miR-10b-5p：TET2轴，SOX2通过该轴诱导onco-miR10b-5p 抑制GBM细胞中的TET2去甲基酶。这个轴减少了5-甲基胞嘧啶到5-甲基胞嘧啶的转化。 羟甲基胞嘧啶(5hmC)--TET(Ten Eleven TransLocation)蛋白催化的反应及其关键 DNA去甲基化的中间步骤。该轴在癌基因转录组中的潜在意义 临床数据支持miR-10b-5p在GBM中的表达显著升高， TET2的低表达和5-HMC的低表达与GBM患者的预后不良相关，而TET2的低表达与GBM的预后相关。 向下加速基底膜异种移植的侵袭性生长。这一提议将检验Sox2的假设 通过激活抑制TET2的onco-miR-10b-5p来驱动肿瘤增殖的GSCs DNA甲基组和转录组。这些目标将通过以下具体目标实现：(一) 确定Sox2：MIR-10b：TET2轴如何修改GSC的DNA甲基化格局；(Ii)确定 TET2的酶和非酶功能如何调控GSCs；(Iii)确定治疗GBM的潜力 在体内，通过抑制miR-10b-5p下调TET2来实现。成功执行拟议的研究计划 将填补我们对表观遗传分子事件的理解的关键空白，通过重新编程转录 因子通过转录沉默诱导GBM中的肿瘤增殖细胞，并建立了潜在的 通过靶向通过抑制TET2改变肿瘤转录组的这种新的轴来治疗GBM。

Glioblastoma (GBM) represents the most aggressive and lethal form of primary brain cancer. We now know that GBM contains small subsets of cells that display tumor-propagating stem-like phenotypes (GBM stem cells, GSCs) that act as critical determinants of GBM resistance to current treatments and tumor recurrence. Understanding and ultimately targeting the epigenetic mechanisms that induce and maintain these tumor- propagating cell subsets is critical to improving GBM therapy and patient outcomes. Altered patterns of DNA methylation are widely reported in human GBM. However, substantial knowledge gaps remain in our understanding of the molecular mechanisms responsible for this epigenetic dysregulation, its downstream consequences and role in the tumor propagating GSC phenotype. This proposal builds on our published and preliminary findings that oncogenic reprogramming transcription factors induce tumor propagating GBM stem cells by regulating miRNA networks that target determinants of DNA methylation. Our new preliminary data implicate a previously unrecognized Sox2:miR-10b-5p:Tet2 axis by which Sox2 induces onco-miR10b-5p that represses the Tet2 demethylase in GBM cells. This axis decreases the conversion of 5-methylcytosine to 5- hydroxymethylcytosine (5hmC), the reaction catalyzed by TET (Ten Eleven Translocation) proteins and a key intermediate step in DNA de-methylation. The potential significance of this axis on oncogenic transcriptome generation is supported by clinical data showing that miR-10b-5p expression is substantially elevated in GBM, that low Tet2 and low 5-hmc expression correlate with poor prognosis in GBM patients, and that Tet2 knock- down accelerates the invasive growth of GBM xenografts. This proposal will test the hypothesis that Sox2 drives tumor-propagating GSCs by activating onco-miR-10b-5p that represses Tet2 resulting in an oncogenic DNA methylome and transcriptome. These goals will be achieved through the following specific aims: (i) Determine how the Sox2:miR-10b:Tet2 axis modifies the DNA methylation landscape of GSCs; (ii) Determine how enzymatic and non-enzymatic functions of Tet2 regulate GSCs; (iii) Determine the potential to treat GBM in vivo by inhibiting Tet2 down-regulation by miR-10b-5p. Successful execution of the proposed research plan will fill critical gaps in our understanding of epigenetic molecular events by which reprogramming transcription factors induce tumor propagating cells in GBM through transcriptional silencing, and establish the potential to treat GBM by targeting this novel axis that alters the tumor transcriptome via Tet2 inhibition.