Background: MicroRNAs (miRNAs) in exosomes represent disease-specific profiles and are applied as biomarkers in oncology. However, in functional dyspepsia (FD), the role of exosomal miRNAs has not been fully elucidated.
Aims: To investigate exosomal miRNAs as potential biomarkers of FD using liquid biopsy.
Methods: This retrospective cohort study included 11 subjects with FD and 11 age- and sex-matched healthy controls (HCs). We collected gastric juice and isolated exosomal miRNAs. In a discovery cohort, expression levels of 2565 miRNAs were evaluated by 3D-Gene® microarray. miRNA expression profiles from exosomes of subjects with FD and HCs were compared by two normalization methods: (1) global normalization and (2) normalization by internal control. Subsequently, in a validation cohort, the expression levels of miRNAs were validated by quantitative reverse transcription PCR (RT-qPCR).
Results: Through microarray analysis using the two methods, we identified 39 miRNAs that were consistently and significantly downregulated in FD cases compared with those in HCs. Of these, 12 miRNAs (hsa-miR-933, hsa-miR-345-5p, hsa-miR-708-5p, hsa-miR-203a-3p, hsa-miR-619-5p, hsa-miR-4294, hsa-miR-4481, hsa-miR-196a-5p, hsa-miR-3918, hsa-miR-372-3p, hsa-miR-658, and hsa-miR-3654) were further validated by RT-qPCR. Our results indicated that hsa-miR-933 was significantly downregulated in FD compared with HCs (0.317 ± 0.205-fold, P = 0.0317). Furthermore, the expression level of hsa-miR-933 was negatively associated with dyspepsia score and the frequency of epigastric pain and/or burning (P < 0.01, r = - 0.835; P = 0.0280, r = - 0.688, respectively).
Conclusions: Exosomal hsa-miR-933 in gastric juice could be a candidate biomarker for FD.
Keywords: Biomarkers; Circulating microRNA; Dyspepsia; Gastric juice; MicroRNAs.