Background & Aims

Methylation of specific microRNAs (miRNAs) often occurs in an age-dependent manner, as a field defect in some instances, and may be an early event in colitis-associated carcinogenesis. We aimed to determine whether specific mRNA signature patterns (MIR1, MIR9, MIR124, MIR137, MIR34B/C) could be used to identify patients with ulcerative colitis (UC) who are at increased risk for colorectal neoplasia.

Methods

We obtained 387 colorectal tissue specimens collected from 238 patients with UC (152 without neoplasia, 17 with dysplasia, and 69 with UC-associated colorectal cancer [UC-CRC]), from 2 independent cohorts in Japan between 2005 and 2015. We quantified methylation of miRNAs by bisulfite pyrosequencing analysis. We analyzed clinical data to determine whether miRNA methylation patterns were associated with age, location, or segment of the colorectum (cecum, transverse colon, and rectum). Differences in tissue miRNA methylation and expression levels were compared among samples and associated with cancer risk using the Wilcoxon, Mann-Whitney, and Kruskal–Wallis tests as appropriate. We performed a validation study of samples from 90 patients without UC and 61 patients with UC-associated dysplasia or cancer to confirm the association between specific methylation patterns of miRNAs in non-tumor rectal mucosa from patients with UC at risk of UC-CRC.

Results

Among patients with UC without neoplasia, rectal tissues had significantly higher levels of methylation levels of MIR1, MIR9, MIR124, and MIR137 than in proximal mucosa; levels of methylation were associated with age and duration of UC in rectal mucosa. Methylation of all miRNAs was significantly higher in samples from patients with dysplasia or CRC compared with samples from patients without neoplasia. Receiver operating characteristic analysis revealed that methylation levels of miRNAs in rectal mucosa accurately differentiated patients with CRC from those without. Methylation of MIR137 in rectal mucosa was an independent risk factor for UC-CRC. Methylation patterns of a set of miRNAs (panel) could discriminate discriminate UC patients with or without dysplasia or CRC in the evaluation cohort (area under the curve, 0.81) and the validation cohort (area under the curve, 0.78).

Conclusions

In evaluation and validation cohorts, we found specific miRNAs to be methylated in rectal mucosal samples from patients with UC with dysplasia or CRC compared with patients without neoplasms. This pattern also associated with patient age and might be used to identify patients with UC at greatest risk for developing UC-CRC. Our findings provide evidence for a field defect in rectal mucosa from patients with UC-CRC.

中文翻译：

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一组甲基化MicroRNA生物标志物，用于鉴定溃疡性结肠炎相关大肠癌高危患者

背景与目标

特定microRNA（miRNA）的甲基化通常以年龄依赖的方式发生，在某些情况下是田间缺陷，并且可能是与结肠炎相关的致癌作用的早期事件。我们旨在确定是否可以使用特定的mRNA签名模式（MIR1，MIR9，MIR124，MIR137，MIR34B / C）来鉴定溃疡性结肠炎（UC）患者，这些患者的大肠癌形成风险增加。

方法

我们从2005年至2015年间，从日本的2个独立队列中，从238例UC患者中收集了387例大肠组织标本（152例无瘤形成，17例不典型增生，69例与UC相关的结直肠癌[UC-CRC]）。我们对甲基化进行了定量分析亚硫酸氢盐焦磷酸测序分析制备miRNA。我们分析了临床数据，以确定miRNA甲基化模式是否与年龄，结肠直肠部位或部位（盲肠，横结肠和直肠）有关。在适当的情况下，使用Wilcoxon，Mann-Whitney和Kruskal-Wallis检验比较了样本中组织miRNA甲基化和表达水平的差异，并将其与癌症风险相关。

结果

在没有肿瘤的UC患者中，直肠组织的MIR1，MIR9，MIR124和MIR137的甲基化水平明显高于近端粘膜。甲基化水平与直肠黏膜的年龄和UC持续时间有关。与发育不良或结直肠癌患者相比，患有发育不良或CRC的患者样本中所有miRNA的甲基化程度均显着更高。接受者操作特征分析显示，直肠粘膜中miRNA的甲基化水平可准确区分患有CRC和未患有CRC的患者。直肠粘膜中MIR137的甲基化是UC-CRC的独立危险因素。一组miRNA（面板）的甲基化模式可以区分评估队列中有或没有发育异常或CRC的UC患者（曲线下面积为0。

结论

在评估和验证队列中，与没有肿瘤的患者相比，我们发现患有异型增生或CRC的UC患者直肠黏膜样本中的特定miRNA被甲基化。这种模式也与患者年龄有关，可用于识别罹患UC-CRC的最大风险的UC患者。我们的发现提供了UC-CRC患者直肠黏膜视野缺损的证据。