Circulating miR-125b is a novel biomarker for screening non-small-cell lung cancer and predicts poor prognosis.

PURPOSE: MicroRNAs are small, non-coding RNAs that are critical regulators of various diseases including cancer, and may represent a novel class of cancer biomarkers. Recent reports have highlighted the oncogenic aspects of miR-125b. However, the level and clinical relevance of circulating miR-125b transcripts in human serum of non-small-cell lung cancer (NSCLC) patients are unclear. The purpose of this study was to identify circulating miR-125b transcripts in human serum for use as a biomarker for stratification and prediction of prognosis in NSCLC.

METHODS: We analyzed serum levels of miR-125b in 193 patients with different stages of NSCLC. Blood samples were collected before surgery and therapy. Quantitative reverse transcription-polymerase chain reaction of circulating miR-125b transcripts was performed directly in serum to improve the efficiency of miRNA assessment. Receiver operating characteristic analysis was used to evaluate the sensitivity and specificity of serum miR-125b.

RESULTS: We found that serum miR-125b was consistently expressed in the non-tumor group and was significantly associated with NSCLC stage. miR-125b expression was capable of separating NSCLC patients from control groups with an area under the curve of 0.786. Furthermore, patients with high miR-125b expression displayed a significantly poorer prognosis compared with patients with low expression (p < 0.0001). Multivariate analysis indicated that high miR-125b expression was an independent prognostic factor for survival.

CONCLUSIONS: We propose that serum miR-125b may represent a novel biomarker in NSCLC patients and that high miR-125b expression is an independent prognostic factor for survival.