Analysis of the abnormalities of microRNA and epigenome and the clinical application in gastroenterological cancers

MicroRNAs(MiRNA)是一类具有转录后基因调控功能的非编码小RNA分子。MiRNAs可以作为癌基因或肿瘤抑制基因发挥作用。因此，它们被越来越多地认为是各种人类癌症的有用生物标志物。异时性胃癌(GC)可在胃镜下切除后发展，不能根据临床特征进行预测。我们发现非癌胃体粘膜中microRNA-34b/c(miR-34b/c)的DNA甲基化可能是预测异时性胃癌风险的有用生物标志物。关于结直肠癌，我们最近利用miRNA阵列分析发现，与野生型结直肠癌相比，BRAF突变结直肠癌中microRNA-31(miR-31)的表达显著上调。此外，miR-31的表达、近端肿瘤位置和预后不良之间也有关联。此外，功能分析结果表明miR-31可能调节BRAF的激活，miR-31的致癌作用及其作为治疗靶点的可能性。因此，我们目前的数据表明miR-31可能是结直肠癌的诊断生物标志物和治疗靶点。这些新的数据可能导致建立一个新的治疗靶点或胃肠肿瘤的治疗程序。

MicroRNAs (miRNA) constitute a class of small non-coding RNA molecules that function as post-transcriptional gene regulators. miRNAs can function as oncogenes or tumour suppressors. Therefore, they have been increasingly recognized as useful biomarkers for various human cancers. Metachronous gastric cancer (GC) can develop after endoscopic resection of GC and cannot be predicted based on clinical signature. We identified that DNA methylation of microRNA-34b/c (miR-34b/c) in the mucosa of the noncancerous gastric body may be a useful biomarker for predicting the risk of metachronous GC. With regard to colorectal cancers (CRCs), using miRNA array analysis, we recently discovered that microRNA-31 (miR-31) expression is significantly up-regulated in BRAF-mutated colorectal cancers (CRCs) compared with that in wild-type CRCs. Moreover, associations were identified between miR-31 expression, proximal tumor location and poor prognosis for CRCs. Moreover, the results of functional analysis showed that miR-31 may regulate BRAF activation and that the oncogenic role of miR-31 and its possibility of therapeutic target in CRCs. Thus, our current data suggest that miR-31 may be a diagnostic biomarker and therapeutic target in CRC. These novel data may lead to the establishment of a new therapeutic target or a theranostic procedure in gastroenterological cancers.