Clinical significance of serum miR-31 as a predictive biomarker for lung adenocarcinoma

Emerging studies have demonstrated that microRNA-31 (miR-31) play a critical role in the tumorigenesis of lung adenocarcinoma (LUAD). Nonetheless, the diagnostic and prognostic value of serum miR-31 in LUAD was largely unknown. The purpose of this study was to investigate the association between serum miR-31 levels and prognosis of LUAD. We first analyzed miR-31 as a predictor of overall survival in the LUAD patients from The Cancer Genome Atlas (TCGA). Then miR-31 expression was measured in the serum samples from LUAD patients and healthy controls using qRT-PCR. LUAD patients with higher tissue miR-31 expression suffered a significantly shorter overall survival than those with lower tissue miR-31 expression. Serum miR-31 levels were upregulated in patients with LUAD and could distinguished LUAD patients from healthy control subjects. Increased serum miR-31 expression was significantly associated with lymph node metastasis, high pathological grade and advanced clinical stage. In addition, patients assigned to the high serum miR-31 group exhibited poorer overall survival and recurrence free survival compared with patients in the low serum miR-31 group. Furthermore, high serum miR-31 expression was an independent unfavorable prognostic factor. Our study suggests that serum miR-31 may have clinical value in the early detection and outcome prediction of LUAD.