Circulating miRNAs is a potential marker for gefitinib sensitivity and correlation with EGFR mutational status in human lung cancers.

miRNA expression is deregulated in non-small cell lung cancer (NSCLC), and some miRNAs are associated with gefitinib sensitivity. Here, we investigated if circulating miRNAs could be a useful biomarker for the prediction of EGFR mutation and the patient's prognosis. The differential miRNAs related to gefitinib sensitivity were screened and identified by microRNA array. Using Taqman-based real-time RT-PCR, we analyzed the expression of selected miRNAs in tumor tissues and plasma of 150 NSCLC patients. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to determine the association between miRNAs expression and survival. Receiver operating characteristic curve analysis was also performed. Compared with PC9 cell line, 41 microRNAs detected by microarray were significantly differentially expressed in A549 and H1299 cells. The 5 selected hsa-miRNAs were all found differently expressed between wild and mutant EGFR carriers (all P<0.01). Down-regulation of 5 selected miRNAs were independently associated with lymphatic invasion (all P<0.01) and clinical stage (all P<0.01), respectively. Both down-regulation of has-miR-195 (P=0.012) and has-miR-21 (P=0.004) were associated with poor differentiation. All up-regulation of 5 has-miRNAs were associated with smoking (All P<0.05). 5 hsa-miRNAs were up-regulated both in plasma and tissue samples. A model including 4 hsa-miRNAs may predict EGFR mutational status and gefitinib-sensitivity (both AUC: 0.869). Plasma levels of has-miR-125b expression were associated with disease-free survival (P=0.033) and overall survival in the patients (P=0.028). In a word, Circulating 5 selected miRNAs may especially be useful in predicting EGFR mutation, and circulating hsa-miR-125b may have prognostic values in NSCLC patients.