Upregulated Expression of Serum Exosomal microRNAs as Diagnostic Biomarkers of Lung Adenocarcinoma

Lung cancer is the leading cause of cancer-related death worldwide. Lung adenocarcinoma (AC) cases account for approximately 40% of lung cancers. Early diagnosis can reduce mortality, improve prognosis, prolong survival, and improve quality of life. Specific and stable biomarkers for early diagnosis of AC are still lacking. Exosomal miRNAs are enriched in the circulatory system and are remarkably stable compared to extracellular miRNAs because exosomes protect them from RNase degradation. In our study, we isolated serum exosomal miRNAs from AC patients and from healthy controls to find highly stable and sensitive biomarkers for early detection of AC. 23 AC patients and 16 healthy controls were included in this study. After microRNA (miR) extraction from serum exosomes (ex-miR), the expression of ex-miRs in cases and controls was quantified by quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). Overexpression of serum ex-miR-21-5p, -126-3p, and -140-5p was observed in AC patients. Area under the curve values for selected candidate ex-miRs were 0.97(95% confidence interval [CI], 0.846-0.99) for ex-miR-21-5p, 0.91(95% CI, 0.77-0.98) for ex-miR-126-3p, and 0.88 (95% CI, 0.73-0.97) for ex-miR-140-5p. Conclusion: Serums ex-miR-21-5p, -126-3p, and -140-5p have great potential to serve as highly sensitive, stable, and repeatable biomarkers for early diagnosis of AC. However, larger cohort studies are necessary to validate these results.