Serum miR-342-3p is a novel diagnostic and prognostic biomarker for non-small cell lung cancer.

: Lung cancer is the leading cause of cancer-related mortality and non-small cell lung carcinoma (NSCLC) is the most common type. MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. Aberrant expression of miRNAs has been demonstrated to be a prominent feature in NSCLC. The aim of this study was to determine the potential clinical value of serum miR-342-3p in NSCLC. We first evaluated the miR-342-3p levels in NSCLC cell lines, culture media of NSCLC cell lines, and serum samples from NSCLC patients as well as in their respective controls. The associations between serum miR-342-3p levels and clinicopathological parameters as well as clinical outcome were then determined. miR-342-3p expression was significantly downregulated in NSCLC cell lines, culture media of NSCLC cell lines, and the serum samples from NSCLC patients compared to their controls. Serum miR-342-3p discriminated NSCLC patients from healthy individuals. Low expression of serum miR-342-3p was significantly associated with advanced TNM stage and positive lymph node metastasis. In addition, NSCLC patients in the low serum miR-342-3p expression group had remarkably shorter overall survival than those in the high serum miR-342-3p expression group. Serum miR-342-3p was shown to be an independent prognosis factor. In conclusion, serum miR-342-3p might be a promising biomarker for NSCLC that can be used to improve diagnosis and prognosis.