Circulating microRNA expression is associated with genetic subtype and survival of multiple myeloma.

Circulating microRNAs (miRNAs) have shown potential as non-invasive prognostic biomarkers in cancer. Here, we investigated whether miRNAs present in the plasma of multiple myeloma (MM) patients have prognostic utility. We evaluated global miRNA expression profiles in the plasma of 12 multiple myeloma patients and 8 healthy controls using TaqMan Low-Density Arrays. Six miRNAs (miR-148a, miR-181a, miR-20a, miR-221, miR-625, and miR-99b) that were significantly upregulated in MM were selected and further quantified independently by quantitative reverse transcription PCR in plasma from 28 MM patients and 12 healthy controls. Moreover, within the patient group, the expression levels of miR-99b and miR-221 were associated with chromosomal abnormalities t(4; 14) and del(13q), respectively. High levels of miR-20a and miR-148a were related to shorter relapse-free survival. In summary, we have identified aberrant expression of particular circulating miRNAs that are associated with the genetic subtype and survival of MM. These plasma miRNAs have potential as clinical biomarkers in MM.