Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, 30322, USA.
Department of Biostatistics and Health Data Science, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
Genome Biol. 2021 Apr 29;22(1):125. doi: 10.1186/s13059-021-02352-9.
Medulloblastoma (MB) is the most common malignant pediatric brain tumor that originates in the cerebellum and brainstem. Frequent somatic mutations and deregulated expression of epigenetic regulators in MB highlight the substantial role of epigenetic alterations. 5-hydroxymethylcytosine (5hmC) is a highly abundant cytosine modification in the developing cerebellum and is regulated by ten-eleven translocation (TET) enzymes.
We investigate the alterations of 5hmC and TET enzymes in MB and their significance to cerebellar cancer formation. We show total abundance of 5hmC is reduced in MB, but identify significant enrichment of MB-specific 5hmC marks at regulatory regions of genes implicated in stem-like properties and Nanog-binding motifs. While TET1 and TET2 levels are high in MBs, only knockout of Tet1 in the smoothened (SmoA1) mouse model attenuates uncontrolled proliferation, leading to a favorable prognosis. The pharmacological Tet1 inhibition reduces cell viability and platelet-derived growth factor signaling pathway-associated genes.
These results together suggest a potential key role of 5hmC and indicate an oncogenic nature for TET1 in MB tumorigenesis, suggesting it as a potential therapeutic target for MBs.
髓母细胞瘤(MB)是起源于小脑和脑干的最常见的小儿脑恶性肿瘤。MB 中频繁的体细胞突变和表观遗传调控因子的失调表达突出了表观遗传改变的重要作用。5-羟甲基胞嘧啶(5hmC)是发育中小脑内高度丰富的胞嘧啶修饰物,由 ten-eleven translocation(TET)酶调控。
我们研究了 MB 中 5hmC 和 TET 酶的改变及其对小脑癌形成的意义。我们表明,MB 中的 5hmC 总丰度降低,但在与干细胞样特性和 Nanog 结合基序相关的基因的调控区域中,鉴定到 MB 特异性 5hmC 标记的显著富集。虽然 TET1 和 TET2 在 MB 中含量较高,但只有在 smoothened(SmoA1)小鼠模型中敲除 Tet1 才能减弱不受控制的增殖,从而导致有利的预后。TET1 的药理学抑制降低了细胞活力和血小板衍生生长因子信号通路相关基因的表达。
这些结果共同表明 5hmC 可能具有潜在的关键作用,并表明 TET1 在 MB 肿瘤发生中的致癌性质,提示其可能成为 MB 的潜在治疗靶点。