mRNA and miRNA analyses in cytologically positive endobronchial ultrasound‐guided transbronchial needle aspiration: Implications for molecular staging in lung cancer patients

Abstract

BACKGROUND: Lung cancer is highly aggressive and tends to metastasize early. Therefore, accurate mediastinal staging is important for therapeutic decision making. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has emerged as a minimally invasive procedure for mediastinal lymph node sampling and cancer staging. Classical EBUS-TBNA cytology has been combined with molecular staging techniques to improve sensitivity and specificity. This study aimed to assess mRNA integrity in samples acquired by EBUS-TBNA in the clinics. As proof-of-principle experiments, we also investigated whether stable miRNA could be detected in these samples. METHODS: Integrity of mRNA isolated from tumor-positive EBUS-TBNA samples was assessed by calculating the RNA integrity number (RIN). In addition, 4 microRNAs were investigated (miRNA 21, miRNA 155, miRNA 200c, and miRNA 34a) because their relation to lung cancer has been documented recently. A group of patients with benign mediastinal lymphadenopathy served as a control. RESULTS: mRNA isolated from EBUS-TBNA samples was nearly completely degraded if handled under clinical conditions(RIN <5). Intact miRNA was detected in all samples, with no nonspecific amplification in negative control samples. miRNA 21 and miRNA 200c levels were significantly higher in tumor-positive than in control samples (miRNA 21: median, 325,678 [range, 34,502] vs. 801,430 (range,17,362,145]; P <. 05; miRNA 200c: median,9,198 [range,121] vs. 42,870 [range,252]; P <.05). CONCLUSIONS: Under clinical conditions, mRNA detection is likely unsuitable for improving sensitivity of EBUS-TBNA-facilitated cancer staging. In contrast, detection of miRNA combined with EBUS-TBNA cytology may improve staging sensitivity. Cancer (Cancer Cytopathol) 2014;122:292-8.

Influence of microRNA-34a on proliferation, invasion and metastasis of HCT116 cells

“…miRNAs are single-stranded, endogenous, non-coding small molecule RNAs, the functions of which have become clearer in recent years. It is highly conserved in structure, and may alter this by specific binding to the target mRNA at the 3'-untranslated region, promoting the degradation of the target gene mRNA or inhibiting its translation and transcription, and therefore regulating target protein expression (15)(16)(17). Previous studies have demonstrated that numerous miRNAs are located in chromosomal regions of the tumor-associated genomes, which possess different functions and serve different regulatory roles in the malignant biological behaviors of tumor cells, particularly proliferation, invasion and metastasis (1).…”

Molecular Nodal Staging Using miRNA Expression in Lung Cancer Patients by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

“…Relative miR-200c expression showed similar tendencies for both types of sample and was ultimately deemed the best classifier in this study. The candidate miRNAs were selected based on the results of a previous study [15], but it has also been reported that miR-200c is highly expressed in metastatic lymph nodes [24]. However, the previous study did not examine the diagnostic yield of miR-200c as a classifying biomarker for detecting metastatic lymph nodes.…”

Current and future molecular diagnostics in non-small-cell lung cancer

“…Although mRNA has also been shown to be detectable in the plasma of cancer patients [98], the stability of miRNAs has been shown to be superior as compared to mRNAs, making laboratory diagnosis more feasible [99]. Circulating cellfree miRNAs may be derived from metastasizing cells originated from primary tumor mass or they are leaked from the tumor mass itself.…”