Serum Exosomal miR-1290 is a Potential Biomarker for Lung Adenocarcinoma

Abstract

Purpose: Lung cancer is a leading cause of cancer-related death, with lung adenocarcinoma (LUAD) representing the most common subtype. Recently, exosome-based biomarkers have provided new diagnostic approaches for malignancies. We aimed to identify specific exosomal microRNAs (miRNAs) as noninvasive biomarkers for LUAD.

Patients and methods: A total of 110 participants were enrolled and randomly divided into two sets: the discovery set (n=20) and the validation set (n=90). Exosomes were isolated from serum, and miRNAs were subsequently extracted. Candidate miRNAs (miR-21, miR-221-3p, miR-222-3p, miR-223, miR-638 and miR-1290) were detected by quantitative real-time PCR (qRT-PCR) in the discovery set. The upregulated miR-1290 was then selected for further analysis in the validation set along with three tumor markers (CEA, CYFRA21-1 and NSE). The diagnostic and prognostic value of exosomal miR-1290 were estimated through receiver-operating characteristic (ROC) and survival analysis.

Results: Serum exosomal miR-1290 was significantly upregulated in LUAD patients compared to healthy controls (P<0.001) and decreased after resection (P=0.0029). Its expression level was associated with tumor stage, tumor size, lymph node and distant metastasis (all P <0.05). Exosomal miR-1290 had a higher diagnostic efficacy than CEA, CYFRA21-1 and NSE, with a sensitivity of 80.0% and specificity of 96.7% (AUC: 0.937, 95% CI: 0.890-0.985; P<0.001). Moreover, LUAD patients with a high level of exosomal miR-1290 had significantly poorer progression-free survival (PFS) than those with a low level of exosomal miR-1290 (mean PFS: 14 months vs 37 months, P<0.001). Cox proportional hazards model analysis demonstrated that exosomal miR-1290 could be an independent risk factor for the prognosis of LUAD (HR=7.80, P=0.017).

Conclusion: Serum exosomal miR-1290 could be a potential diagnostic and prognostic biomarker for LUAD.

Keywords: biomarker; circulating miRNA; exosome; lung adenocarcinoma.

Figure 1

Characterization of isolated exosomes. (A) Exosomes were visualized by TEM. Typical exosomes were indicated with the black arrows. (B) NTA analysis revealed that the size distribution of exosomes was 50–150 nm. (C) The exosomal protein marker CD9 was analyzed in exosomes (E) and exosome-depleted serum (EDS) by Western blotting.

Figure 2

Expression levels of the miRNA candidates in the discovery set was assessed by qRT-PCR. Relative expression levels of miR-1290 (A), miR-21 (B), miR-638 (C), miR-221-3p (D), miR-222-3p (E) and miR-223 (F) in the healthy controls and LUAD patients are shown. U6 snRNA served as the internal control. **P<0.01. Abbreviation: NS, non-significant.

Figure 3

Expression of serum exosomal miR-1290 in the validation set. The absolute concentrations of serum miR-1290 were measured in healthy controls (HCs), early LUAD and advanced LUAD patients (A) (all P<0.01, ANOVA). The levels of serum exosomal miR-1290 in LUAD patients significantly decreased after surgery (B). **P<0.01, ***P<0.001.

Figure 4

ROC analysis to discriminate LUAD patients from healthy controls according to serum exosomal miR-1290, CEA, CYFRA21-1 and NSE.

Figure 5

Kaplan–Meier survival analysis of patients with LUAD based on serum exosomal miR-1290 levels. The median serum exosomal miR-1290 level (2530.71 fmol/l) was set as the cut-off value. LUAD patients with high serum exosomal miR-1290 levels showed significantly lower progression-free survival (PFS) than those with low serum exosomal miR-1290 levels (P <0.001; Log rank test) (A). Analysis of PFS according to the expression levels of exosomal miR-1290 in early-stage LUAD patients (B) and advanced-stage LUAD patients (C). *P<0.05, ****P<0.0001.