Microrna-Based Markers In Cerebrospinal Fluid As Potential Diagnostic Tools For Leptomeningeal Metastasis In Lung Adenocarcinoma Patients

We hope to identify leptomeningeal metastasis (LM)-related cerebrospinal fluid (CSF) miroRNAs as potential molecular markers contributing to diagnosis of LM patients with lung adenocarcinoma. MATERIAL AND CSF samples were collected from lung adenocarcinoma patients with LM (positive group) and non-LM patients (negative group). Meanwhile, matching CSF samples from other lung adenocarcinoma LM patients were collected before and after effective LM-related treatment. Samples were screening using Agilent Human microRNA arrays. Differentially expressed microRNAs in both of two sets as well as significantly expressed microRNAs in either one set were selected as targets. Whereafter, expression of target CSF miRNAs was determined using quantitative real-time PCR (qRT-PCR). Differential microRNAs expression was analyzed by Mann-Whitney Test. Receiver Operating Characteristic (ROC) curve analysis was used to determine sensitivity and specificity. Twenty samples obtained from 10 LM patients and 10 non-LM controls (5 brain metastasis from lung adenocarcinoma and 5 nonneoplastic disease) were subjected to microRNA arrays. Meanwhile, 6 couples of matching samples were subjected to microRNA arrays.The intersection of significantly differential expression, miR-7977, miR-7975 and miR-4800-5p, were significantly up-regulated in positive group, and down-regulated after effective LM-related treatment. These three microRNAs were selected as targets and subjected to qRT-PCR. Significant increase was noticed in expression of miR-7977 (P=0.001), miR-7975 (P=0.001) and miR-4800-5p (P=0.024) in newly collected samples of 17 LM cases compared with 14 non-LM controls (9 brain metastasis from lung adenocarcinoma and 5 benign brain tumor). ROC analysis indicated that area under curve for miR-7977, miR-7975 and miR-4800-5p was 0.849(P=0.001, 95%CI 0.694–1.0), 0.840(P=0.001, 95%CI 0.688–0.992), and 0.739(P=0.024, 95%CI 0.564–0.915), respectively. The cutoff value, sensitivity and specificity were 48.3, 0.824 and 0.857 for miR-7977, 29.4, 0.824 and 0.929 for miR-7975, and 44.9, 0.765 and 0.643 for miR-4800-5p, respectively. MiR-7977, miR-7975 and miR-4800-5p may serve as molecular markers for diagnosis of LM from lung adenocarcinoma.