Fig. 2

Identification of exosomal microRNA (miRNA) expression profiles in patients with SCLC. The miRNA array was performed using serum-derived exosomes from non-cancerous lung nodules (control) and patients with SCLC (n = 5 per group). (A) Principal component analysis (PCA) plot of merged miRNA array data sets. (B) Venn diagrams show the number of all miRNAs differentially expressed between groups. (C) The average or total number of miRNAs identified through the miRNA array. (D) Volcano plots showing the distribution of 2-fold up- and down-regulated miRNAs. The seven exosomal miRNAs validated in the large cohort are shown as colored dots (blue: FC < 2.0, orange: FC > 2.0). (E) Heatmap analysis showing 31 exosomal miRNAs reveals significantly more than 2-fold up- and down-regulation (p < 0.05). (F) Ten exosomal miRNAs with the highest or lowest expression, respectively in patients with SCLC and non-cancerous lung nodules (controls). The 25 miRNAs validated in the “Analytic set” are shown in red and blue (red: upregulated, blue: downregulated), and the seven miRNAs validated in the “Test set” are indicated by orange arrows