Liao Yu-Ping, Chen Lin-Yu, Huang Rui-Lan, Su Po-Hsuan, Chan Michael W Y, Chang Cheng-Chang, Yu Mu-Hsien, Wang Peng-Hui, Yen Ming-Shyen, Nephew Kenneth P, Lai Hung-Cheng
Graduate Institute of Life Sciences and.
Hum Mol Genet. 2014 Apr 1;23(7):1894-906. doi: 10.1093/hmg/ddt583. Epub 2013 Nov 20.
DNA methylation contributes to tumor formation, development and metastasis. Epigenetic dysregulation of stem cells is thought to predispose to malignant development. The clinical significance of DNA methylation in ovarian tumor-initiating cells (OTICs) remains unexplored. We analyzed the methylomic profiles of OTICs (CP70sps) and their derived progeny using a human methylation array. qRT-PCR, quantitative methylation-specific PCR (qMSP) and pyrosequencing were used to verify gene expression and DNA methylation in cancer cell lines. The methylation status of genes was validated quantitatively in cancer tissues and correlated with clinicopathological factors. ATG4A and HIST1H2BN were hypomethylated in OTICs. Methylation analysis of ATG4A and HIST1H2BN by qMSP in 168 tissue samples from patients with ovarian cancer showed that HIST1H2BN methylation was a significant and independent predictor of progression-free survival (PFS) and overall survival (OS). Multivariate Cox regression analysis showed that patients with a low level of HIST1H2BN methylation had poor PFS (hazard ratio (HR), 4.5; 95% confidence interval (CI), 1.4-14.8) and OS (HR, 4.3; 95% CI, 1.3-14.0). Hypomethylation of both ATG4A and HIST1H2BN predicted a poor PFS (HR, 1.8; 95% CI, 1.0-3.6; median, 21 months) and OS (HR, 1.7; 95% CI, 1.0-3.0; median, 40 months). In an independent cohort of ovarian tumors, hypomethylation predicted early disease recurrence (HR, 1.7; 95% CI, 1.1-2.5) and death (HR, 1.4; 95% CI, 1.0-1.9). The demonstration that expression of ATG4A in cells increased their stem properties provided an indication of its biological function. Hypomethylation of ATG4A and HIST1H2BN in OTICs predicts a poor prognosis for ovarian cancer patients.
DNA甲基化促进肿瘤的形成、发展和转移。干细胞的表观遗传失调被认为易引发恶性肿瘤发展。卵巢肿瘤起始细胞（OTICs）中DNA甲基化的临床意义仍未得到探索。我们使用人类甲基化芯片分析了OTICs（CP70sps）及其衍生子代的甲基化组图谱。采用qRT-PCR、定量甲基化特异性PCR（qMSP）和焦磷酸测序来验证癌细胞系中的基因表达和DNA甲基化。对癌症组织中基因的甲基化状态进行定量验证，并与临床病理因素相关联。OTICs中ATG4A和HIST1H2BN发生低甲基化。通过qMSP对168例卵巢癌患者组织样本中的ATG4A和HIST1H2BN进行甲基化分析，结果显示HIST1H2BN甲基化是无进展生存期（PFS）和总生存期（OS）的显著且独立预测指标。多变量Cox回归分析表明，HIST1H2BN甲基化水平低的患者PFS较差（风险比（HR），4.5；95%置信区间（CI），1.4 - 14.8），OS也较差（HR，4.3；95% CI，1.3 - 14.0）。ATG4A和HIST1H2BN均低甲基化预示着PFS较差（HR，1.8；95% CI，1.0 - 3.6；中位数，21个月）和OS较差（HR，1.7；95% CI，1.0 - 3.0；中位数，40个月）。在一个独立的卵巢肿瘤队列中，低甲基化预示着疾病早期复发（HR，1.7；95% CI，1.1 - 2.5）和死亡（HR，1.4；95% CI，1.0 - 1.9）。细胞中ATG4A表达增加其干细胞特性的证明揭示了其生物学功能。OTICs中ATG4A和HIST1H2BN的低甲基化预示着卵巢癌患者预后不良。
