Downregulation of cell‐free miR‐198 as a diagnostic biomarker for lung adenocarcinoma‐associated malignant pleural effusion

Abstract

Circulating cell-free microRNAs (miRNAs) are potential cancer biomarkers. The aim of this study was to identify miRNAs that are differentially expressed between benign pleural effusion (BPE) and lung adenocarcinoma-associated malignant pleural effusion (LA-MPE). The expression level of cell-free miRNA was investigated in 107 patients with pleural effusion. Microarrays were used to screen 160 miRNAs in a discovery set comprising 20 effusion samples (ten BPEs and ten LA-MPEs). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate the profiling results obtained for the discovery set and those obtained for a validation set comprising 42 BPEs and 45 LA-MPEs. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic performance of the identified miRNAs and other common tumor markers, such as carcinoembryonic antigen (CEA) and cytokeratin fragment (CYFRA) 21-1. Microarray profiling showed that miR-198 was significantly downregulated in LA-MPE compared with BPE (p 5 0.002). The miRNA microarray analysis results were confirmed by qRT-PCR (p < 0.001) using the validation set. The AUCs for miR-198, CEA and CYFRA 21-1 in the validation set were 0.887, 0.898 and 0.836, respectively. The diagnostic performance of miR-198 was comparable with that of CEA, but better than that of CYFRA 21-1. The AUC for all three markers combined was 0.926 (95% confidence interval, 0.843-0.973) with a sensitivity of 89.2% and a specificity of 85.0%. The present study suggests that cell-free miR-198 from patients with pleural effusion might have diagnostic potential for differentiating LA-MPE from BPE.

Circulating microRNAs: potential biomarkers for common malignancies

“…Thirty-three miRNAs were found to be altered by twofold in malignant effusions between longersurvival and shorter-survival groups, and the levels of miR-93, miR-100, miR-134, miR-151 and miR-345 were significantly associated with overall survival. Further studies by Han et al [126] identified miRNAs differentially expressed between benign pleural effusion samples and adenocarcinoma-associated malignant pleural effusion (LA-MPE). Microarray profiling showed that miR-198 was significantly downregulated in LA-MPE compared with benign pleural effusion samples.…”

Pre-analytical issues in effusion cytology

“…miRNAs are short non-coding RNAs which negatively or positively regulate gene expression in physiological and pathological conditions by binding to the 3′-UTR of their target mRNA, thereby inhibiting target gene translation into proteins. Effusion supernatants from lung, gastric and ovarian carcinoma have been shown to differ from benign specimens [39][40][41]. The latter study, in which miRNA content was analyzed in exosomes, small secreted vesicles involved in tumor signaling, was performed on archived material frozen at -80°C, including specimens stored for over 10 years [40].…”

Diagnostic Value of Circulating Extracellular miR-134, miR-185, and miR-22 Levels in Lung Adenocarcinoma-Associated Malignant Pleural Effusion

“…In a previous study, we examined the differential expression of circulating miRNAs in BPE and LA-MPE samples using a peptide nucleic acid-based microarray [15]. The miRNA expression signatures were confirmed by RT-qPCR and cross-validated using an independent sample set.…”

“…The selection of suitable genes for the relative quantification of miRNA expression is essential to avoid inaccurate results and to improve the comparability of gene expression data. We previously examined the expression of the selected miRNAs, two small nuclear RNAs (RNU6B and U6 snRNA), and two small nucleolar RNAs (RNU44 and RNU48) to identify the most stably expressed genes for use as reference genes in pleural effusion samples [15]. U6 snRNA was identified as the most stable reference gene in the BPE and LA-MPE samples; thus, the expression levels of the three miRNAs were normalized to those of U6 snRNA.…”