BACKGROUND 5-Hydroxymethylcytosine (5hmC) is a novel epigenetic mark and may be involved in the mechanisms of tumorigenesis and malignant transformation. However, the role of 5hmC in ependymoma, the third most common brain tumor in children, remains unclear. The aim of this study sought to identify the characterization of 5hmC levels in pediatric posterior fossa ependymoma and to evaluate whether 5hmC levels could be a potential factor to predict clinical outcomes. RESULTS Our results showed that 5hmC levels were globally decreased in posterior fossa ependymoma compared with normal cerebellum tissues (P < 0.001). Group A posterior fossa ependymomas had higher 5hmC levels than group B tumors (P = 0.007). Moreover, 5hmC levels positively correlated with Ki-67 index in posterior fossa ependymoma (r = 0.428, P = 0.003). Multivariate Cox hazards model revealed that patients with high 5hmC levels (> 0.102%) had worse PFS and OS than patients with lower 5hmC levels (< 0.102%) (PFS: HR = 3.014; 95% CI, 1.040-8.738; P = 0.042; OS: HR = 2.788; 95% CI, 0.974-7.982; P = 0.047). CONCLUSIONS Our findings suggest that loss of 5hmC is an epigenetic hallmark for pediatric posterior fossa ependymoma. 5hmC levels may represent a potential biomarker to predict prognosis in children with posterior fossa ependymoma.

中文翻译：

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小儿后颅窝室管膜瘤中整体5-羟甲基胞嘧啶的特征。

背景技术5-羟甲基胞嘧啶（5hmC）是一种新型的表观遗传标记，可能参与了肿瘤发生和恶性转化的机制。然而，尚不清楚5hmC在儿童第三大常见脑肿瘤室间隔膜瘤中的作用。这项研究的目的是确定小儿后颅窝室间隔瘤中5hmC水平的特征，并评估5hmC水平是否可能是预测临床结果的潜在因素。结果我们的结果显示，与正常的小脑组织相比，后颅窝室间隔膜瘤的5hmC水平总体降低（P <0.001）。A组后颅窝室间隔膜瘤比B组肿瘤具有更高的5hmC水平（P = 0.007）。此外，后颅窝室间隔瘤中5hmC水平与Ki-67指数呈正相关（r = 0.428，P = 0.003）。多元Cox危害模型显示，高5hmC水平（> 0.102％）的患者的PFS和OS比低5hmC水平（<0.102％）的患者差（PFS：HR = 3.014; 95％CI，1.040-8.738; P = 0.042 ； OS：HR ＝ 2.788； 95％CI，0.974-7.982； P ＝ 0.047）。结论我们的研究结果表明5hmC的丧失是小儿后颅窝室间隔膜瘤的表观遗传标志。5hmC水平可能代表潜在的生物标志物，以预测后颅窝室间隔膜瘤患儿的预后。