Changes in plasma miR-9, miR-16, miR-205 and miR-486 levels after non-small cell lung cancer resection

The majority of non-small cell lung cancer (NSCLC) patients presents with an advanced-stage disease and, consequently, exhibits a poor overall survival rate. We aimed to assess changes in plasma miR-9, miR-16, miR-205 and miR-486 levels and their potential as biomarkers for the diagnosis and monitoring of NSCLC patients. Plasma was collected from 50 healthy donors and from NSCLC patients before surgery (n = 61), 1 month after surgery (n = 37) and 1 year after surgery (n = 14). microRNA levels were quantified using qRT-PCR. We found in NSCLC patients before treatment, both with squamous cell carcinoma (SQCC) and adenocarcinoma (ADC), significantly higher plasma miR-16 and miR-486 levels than in healthy individuals. Pre-treatment miR-205 concentrations were found to be significantly higher in SQCC than in ADC patients, and only SQCC patients presented significantly higher circulating miR-205 levels than healthy donors. SQCC plasma miR-9 levels were not different from normal control levels, but in ADC they were found to be significantly decreased. A combination of plasma miR-16, miR-205 and miR-486 measurements was found to discriminate NSCLC patients from healthy persons, with a specificity of 95% and a sensitivity of 80%. Following tumor resection, we found that the miR-9 and miR-205 levels significantly decreased, even below the normal level, whereas the increased miR-486 level persisted up to one year after surgery, and the miR-16 level decreased to normal. After tumor resection, none of the miR levels tested was found to relate to recurrence. Our data indicate that miR-9, miR-16, miR-205 and miR-486 may serve as NSCLC biomarkers. The observed cancer-related pre- and post-operative changes in their plasma levels may not only reflect the presence of a primary cancer, but also of a systemic response to cancer.