Background: Exosomal microRNAs (miRNAs) are potential biomarkers for a variety of tumors but have not yet been tested in diffuse large B-cell lymphoma (DLBCL). Here we sought to determine whether circulating exosomal miRNAs are differentially expressed in the blood of DLBCL patients compared with those in the blood of non-DLBCL patients with lymphoma and healthy subjects. In addition, we sought to explore whether circulating exosomal miRNAs could be used as prognostic predictors for DLBCL patients.
Methods: Circulating exosomal miRNAs were isolated and used to perform miRNA expression profiling using quantitative reverse transcription polymerase chain reaction (qRT-PCR) based on Exiqon microarray from 10 DLBCL patients and 5 healthy subjects. Using qRT-PCR, miRNA candidates were first evaluated in the testing stage (24 DLBCL patients vs. 24 healthy subjects) and further confirmed in validation stage(99 DLBCL patients vs. 65 healthy subjects). Meanwhile, we also explored miRNAs concentrations in 29 non-DLBCL lymphoma cases, which were enrolled as concurrent control in this study. And lastly, relationships between miRNA level and patient outcomes including overall survival (OS) and progression-free survival (PFS) were studied.
Results: Five circulating exosomal miRNAs (miR-379-5p, miR-135a-3p, miR-4476, miR-483-3p and miR-451a) were differently expressed in DLBCL patients compared with healthy controls. The 5-miRNA panel enabled us to predicted the probability of a diagnosis of DLBCL with an area under curve(AUC) of 0.863. Four circulating exosomal miRNAs (miR-379-5p, miR-135a-3p, miR-155-5p and miR-451a) were differently expressed between DLBCL patients and concurrent controls, the AUC of this 4-miRNA panel in distinguishing DLBCL patients from concurrent controls was 0.775. One miRNA, namely miR-451a, was significantly associated with both PFS and OS of DLBCL patients in the univariate analysis, and still statistically significant after adjusting for the International Prognostic Index(IPI) in the multivariate analysis. The combination of circulating miR-451a with IPI had a better predication for PFS and OS.
Conclusions: Our study suggested subsets of circulating exosomal miRNAs could be useful noninvasive biomarkers for the diagnosis of DLBCL and the use of circulating exosomal miRNA improves the identification of patients with newly diagnosed DLBCL with poor outcomes.