Tet2 regulation and function in glioma cell phenotype reprogramming

胶质母细胞瘤（GBM）是原发性脑癌中最具侵袭性和致命性的形式。我们现在知道 GBM包含显示肿瘤增殖干细胞样表型（GBM干细胞）的细胞的小亚群， 细胞，GSC），其充当GBM对当前治疗和肿瘤复发的抗性的关键决定因素。 了解并最终靶向诱导和维持这些肿瘤的表观遗传机制- 增殖细胞亚群对于改善GBM治疗和患者结果至关重要。DNA模式改变 甲基化在人类GBM中被广泛报道。然而，在我们的国家， 了解负责这种表观遗传失调的分子机制，其下游 结果和作用的肿瘤传播GSC表型。这一建议建立在我们公布的和 致癌重编程转录因子诱导肿瘤增殖GBM干细胞的初步发现 细胞通过调节靶向DNA甲基化决定簇的miRNA网络。我们新的初步数据 涉及一种以前未被认识Sox 2：miR-10 b-5 p：Tet 2轴，Sox 2通过该轴诱导癌-miR-10 b-5 p， 抑制GBM细胞中的Tet 2脱甲基酶。该轴降低了5-甲基胞嘧啶向5-甲基胞嘧啶的转化。 羟甲基胞嘧啶（5 hmC），由泰特（10 - 11易位）蛋白催化的反应和一个关键的 DNA去甲基化中间步骤。该轴对致癌转录组的潜在意义 临床数据显示miR-10 b-5 p表达在GBM中显著升高， 低Tet 2和低5-hmc表达与GBM患者的不良预后相关，Tet 2敲除- 向下加速GBM异种移植物的侵入性生长。这项提议将检验Sox 2 通过激活抑制Tet 2的致癌miR-10 b-5 p来驱动肿瘤增殖GSC，从而导致肿瘤细胞增殖。 DNA甲基化组和转录组。这些目标将通过以下具体目标实现： 确定Sox 2：miR-10 b：Tet 2轴如何改变GSC的DNA甲基化景观;（ii）确定 Tet 2的酶促和非酶促功能如何调节GSC;（iii）确定治疗GBM的潜力 通过抑制miR-10 b-5 p下调Tet 2，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理解的关键空白， 因子通过转录沉默诱导GBM中的肿瘤增殖细胞，并建立了 通过靶向这种新的轴来治疗GBM，该轴通过Tet 2抑制来改变肿瘤转录组。

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.