Young investigator challenge: MicroRNA-21/MicroRNA-126 profiling as a novel tool for the diagnosis of malignant mesothelioma in pleural effusion cytology

Our plain-English summary of Young investigator challenge: MicroRNA-21/MicroRNA-126 profiling as a novel tool for the diagnosis of malignant mesothelioma in pleural effusion cytology, by R. Cappellesso, L. Nicolè, B. Caroccia, et al (Cancer Cytopathology, 2016).

The study

• Authors: R. Cappellesso, L. Nicolè, B. Caroccia, V. Guzzardo, L. Ventura, M. Fassan, A. Fassina
• Journal: Cancer Cytopathology
• Published: 2016;124(1):28-37
• Cited by: 38 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: In pleural effusion cytology, the distinction of malignant mesothelioma (MM) from reactive mesothelial cells (RMCs) may be challenging, even with the aid of immunocytochemistry or fluorescence in situ hybridization. It has been demonstrated that several microRNAs (miRNAs) are useful for this purpose in cell lines and histologic samples. In the current study, the authors evaluated the utility of an miRNA-based classifier as a complement to cytology.

Methods: Quantitative reverse transcriptase-polymerase chain reaction analysis of 15 miRNAs was performed in mesothelial (MET-5A) and MM (H28 and H2052) cell lines. Significant miRNAs were validated in 51 MM and 40 nonneoplastic pleural histologic samples and then were tested in 29 MM and 24 RMC cytologic specimens. The performance of individual and combined miRNAs was assessed for their ability to differentiate between MM and RMCs.

Results: MiRNA-19a (MiR-19a), miR-19b, miR-21, miR-25, and miR-126 were differentially expressed in cell lines and histologic samples. MiR-126 was down-regulated in MM surgical specimens compared with nonneoplastic specimens, whereas all of the other miRNAs were overexpressed. In cytologic specimens, all miRNAs except miR-25 were confirmed, exhibiting a sensitivity or a specificity higher than the threshold of 0.80, as recommended by the International Mesothelioma Interest Group. The best classifier resulted from the combination of miR-21 and miR-126, which achieved 0.86 sensitivity and 0.87 specificity.

Conclusions: Subject to validation of the current results in further larger studies, miR-21 and miR-126 profiling could be an effective and reliable tool for the diagnosis of MM in pleural effusions complementary to cytology evaluation.

© 2016 American Cancer Society.

In plain English

This laboratory study from Padua, Italy, tested whether measuring microRNAs (small RNA molecules) could help tell malignant mesothelioma from reactive (non-cancerous) mesothelial cells in pleural effusion fluid. The authors first measured 15 microRNAs, chosen from published studies, in one non-cancerous and two mesothelioma cell lines. Five (miR-19a, miR-19b, miR-21, miR-25 and miR-126) met their selection criteria. All five showed the same pattern in archived tissue from 51 mesotheliomas and 40 benign or reactive pleurae. In archived smears from 29 epithelioid mesothelioma and 24 reactive cases, four of the five differed significantly between groups; miR-25 did not. A combined miR-21 and miR-126 test correctly classified 46 of 53 smears (accuracy 0.87, 95% confidence interval 0.75 to 0.94). It flagged 25 of 29 mesotheliomas and cleared 21 of 24 reactive cases (sensitivity 0.86, 95% CI 0.69 to 0.95; specificity 0.87, 95% CI 0.68 to 0.96). The authors concluded that, subject to larger studies, this profiling could aid cytology diagnosis. They noted limitations: a small, retrospective sample, candidate microRNAs taken from the literature, and a virus-immortalized control cell line. The study did not examine asbestos exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory diagnostic accuracy study using cell lines and retrospectively retrieved archival tissue and cytology samples
• Who was studied: One mesothelial cell line (MET-5A) and two malignant mesothelioma cell lines (H28, H2052). Archival tissue from 40 benign/reactive pleurae and 51 malignant mesotheliomas (34 epithelioid, 7 sarcomatoid, 10 biphasic). Cytology smears from 24 reactive mesothelial cell pleural effusions and 29 epithelioid mesothelioma pleural effusions, collected 2008 to 2014, from the archives of the University of Padua, Italy
• Exposure: Not studied. This was a diagnostic test study; patients' asbestos exposure was not reported. The test measured levels of 15 microRNAs selected from earlier literature.
• Main results:
  • In the cell lines, only miR-19a, miR-19b, miR-21, miR-25 and miR-126 met the selection criteria. MiR-126 was lower and the others higher in the mesothelioma cell lines than in the mesothelial cell line.
  • In tissue samples (51 mesotheliomas vs 40 benign/reactive pleurae), all five microRNAs kept the same upward or downward pattern, with a fold change greater than 1.5.
  • In cytology smears (29 mesothelioma vs 24 reactive), miR-19a, miR-19b and miR-21 were significantly higher and miR-126 significantly lower in mesothelioma. MiR-25 levels were comparable between the groups (P = .267).
  • Ability of single microRNAs to distinguish mesothelioma from reactive cells in cytology (area under the curve): miR-21 0.79 (95% CI 0.66-0.91); miR-126 0.71 (95% CI 0.57-0.85); miR-19a 0.69; miR-19b 0.68; miR-25 0.59 (95% CI 0.43-0.75). The authors judged miR-25 nondiscriminant.
  • The combined miR-21 and miR-126 classifier had an area under the curve of 0.92 (95% CI 0.84-0.99) in the cytology samples.
  • Using the combined classifier, 46 of 53 cytology specimens (87%) were correctly classified: sensitivity 0.86 (95% CI 0.69-0.95), specificity 0.87 (95% CI 0.68-0.96), accuracy 0.87 (95% CI 0.75-0.94). By the authors' table, 25 of 29 mesothelioma and 3 of 24 reactive specimens tested positive.
• The authors' conclusion: The authors concluded that, subject to validation in further larger studies, miR-21 and miR-126 profiling could be an effective and reliable tool, complementary to cytology, for diagnosing malignant mesothelioma in pleural effusions. They described it as a promising aid for cytopathologists.
• Limitations the authors state:
  • Because of budget and time constraints, candidate microRNAs were selected from the literature rather than by comprehensive array analysis, so several potentially diagnostic markers were not tested.
  • The control mesothelial cell line was immortalized by simian virus 40 infection, which may have altered its microRNA expression, and only 2 mesothelioma cell cultures were used.
  • The number of cytologic cases was relatively limited, which did not allow analysis by mesothelioma subtype, and the study was retrospective.
  • Cytologic mesothelioma samples were all epithelioid, while the tissue samples also included sarcomatoid and biphasic subtypes.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Pleural Effusion, Cytology, Reactive Mesothelial Cells, Fluorescence In Situ Hybridization (FISH), Mesothelioma.

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• The diagnosis of malignant mesothelioma in effusion cytology: a reappraisal and results of a multi-institution survey — A. Paintal, K. Raparia, et al. (2013)
• Genome-wide profiling reveals novel microRNAs in hand-spinning-specific chrysotile exposure — J. Jia, X. Guo, et al. (2019)
• A diagnosis of malignant pleural mesothelioma can be made by effusion cytology: results of a 20 year audit — A. Segal, G.F. Sterrett, et al. (2013)
• Small orangiophilic squamous-like cells: an underrecognized and useful morphological feature for the diagnosis of malignant mesothelioma in pleural effusion cytology — L. Chen, S.G. Caldero, et al. (2014)
• The analysis of novel microRNA mimic sequences in cancer cells reveals lack of specificity in stem-loop RT-qPCR-based microRNA detection — P. Winata, M. Williams, et al. (2017)

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