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

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. Overall design: Seven normal samples and two acute leukemia samples ware profiled and compared.