Down-regulation of miR-92 in human plasma is a novel marker for acute leukemia patients

MicroRNAs are a family of 19- to 25-nucleotides noncoding small RNAs that primarily function as gene regulators. Aberrant microRNA expression has been described for several human malignancies, and this new class of small regulatory RNAs has both oncogenic and tumor suppressor functions. Despite this knowledge, there is little information regarding microRNAs in blood especially because microRNAs in blood, if exist, were thought to be digested by RNase. Recent studies, however, have revealed that microRNAs exist and escape digestion in serum and plasma. Thus, we performed microRNA microaray to obtain insight into microRNA deregulation in the plasma of a leukemia patient. Here, we have revealed that microRNA-638 (miR-638) is stably present in human plasmas, and miR-92a dramatically decreased in the plasmas of acute leukemia patients. Our data indicate that the ratio of miR-92a/miR-638 in plasma has strong potential for clinical application as a novel biomarker for detection of leukemia. Seven normal samples and two acute leukemia samples ware profiled and compared.

微小RNA（microRNA）是一类长度为19至25个核苷酸的非编码小RNA，主要作为基因调控因子发挥功能。多种人类恶性肿瘤中均已报道存在微小RNA表达异常，这类新型小调控RNA兼具致癌与抑癌双重功能。尽管已有上述认知，但关于血液中微小RNA的相关信息仍十分匮乏——这是因为此前人们认为血液中的微小RNA若存在，会被核糖核酸酶（RNase）降解。然而近期研究证实，微小RNA可稳定存在于血清与血浆中并免受核糖核酸酶降解。为此，我们通过微小RNA微阵列（microRNA microarray）分析，探究了急性白血病患者血浆中的微小RNA表达失调情况。本研究发现，微小RNA-638（miR-638）可稳定存在于人类血浆中，而急性白血病患者血浆中的miR-92a水平显著降低。本研究数据表明，血浆中miR-92a与miR-638的表达比值具备作为新型白血病检测生物标志物的巨大临床应用潜力。本研究共对7份正常对照样本与2份急性白血病样本进行了表达谱分析与比较。