Cell-Free RNA Content in Peripheral Blood as Potential Biomarkers for Detecting Circulating Tumor Cells in Non-Small Cell Lung Carcinoma.

Circulating tumor cells (CTCs) have been implicated in tumor progression and prognosis. Techniques detecting CTCs in the peripheral blood of patients with non-small cell lung carcinoma (NSCLC) may help to identify individuals likely to benefit from early systemic treatment. However, the detection of CTCs with a single marker is challenging, owing to low specificity and sensitivity and due to the heterogeneity and rareness of CTCs. Herein, the probability of cell-free RNA content in the peripheral blood as a potential biomarker for detecting CTCs in cancer patients was investigated. An immunomagnetic enrichment of real-time reverse-transcription PCR (RT-PCR) technology for analysis of CTCs in NSCLC patients was also developed. The mRNA levels of four candidate genes, cytokeratin 7 (CK7), E74-like factor 3 (ELF3), epidermal growth factor receptor (EGFR), and erythropoietin-producing hepatocellular carcinoma receptor B4 (EphB4) that were significantly elevated in tumor tissues and peripheral blood mononuclear cells (PBMCs) were determined. The expression of CK7 and ELF3 in tumor tissues and EGFR in PBMCs was associated with lymph node metastasis (all p < 0.05). The expression of CK7 in PBMCs was correlated with age and EphB4 in PBMCs correlated with histopathological type, respectively (all p < 0.05). The expression of all four genes in tumor tissues and PBMCs was significantly correlated with the clinical stage (all p < 0.01). Survival analysis showed that the patients with enhanced expression of CK7, ELF3, EGFR, and EphB4 mRNA in PBMCs had poorer disease-free survival (DFS) and overall survival (OS) than those without (all p < 0.0001). The present study showed that this alteration of cell-free RNA content in peripheral blood might have clinical ramifications in the diagnosis and treatment of NSCLC patients.

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.