The degree of microRNA-34b/c methylation in serum-circulating DNA is associated with malignant pleural mesothelioma

Our plain-English summary of The degree of microRNA-34b/c methylation in serum-circulating DNA is associated with malignant pleural mesothelioma, by T. Muraoka, J. Soh, S. Toyooka, et al (Lung Cancer, 2013).

The study

• Authors: T. Muraoka, J. Soh, S. Toyooka, K. Aoe, N. Fujimoto, S. Hashida, Y. Maki, N. Tanaka, K. Shien, M. Furukawa, H. Yamamoto, H. Asano, K. Tsukuda, T. Kishimoto, T. Otsuki, S. Miyoshi
• Journal: Lung Cancer
• Published: 2013;82(3):485-90
• Cited by: 41 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Malignant pleural mesothelioma (MPM) is an aggressive tumor with a poor prognosis. microRNA-34b/c (miR-34b/c), which plays an important role in the pathogenesis of MPM, is frequently downregulated by DNA methylation in approximately 90% of MPM cases. In this study, we estimated the degree of miR-34b/c methylation in serum-circulating DNA using a digital methylation specific PCR assay (MSP).

Materials And Methods: A real-time MSP assay was performed using the SYBR Green method. The melting temperature (Tm) of each PCR product was examined using a melting curve analysis. For a digital MSP assay, 40 wells were analyzed per sample. A total of 110 serum samples from 48 MPM cases, 21 benign asbestos pleurisy (BAP) cases, and 41 healthy volunteers (HVs) were examined.

Results: Positive range of Tm value for miR-34b/c methylation was defined as 77.71-78.79 °C which was the mean ± 3 standard deviations of 40 wells of a positive control. The number of miR-34b/c methylated wells was counted per sample according to this criterion. The number of miR-34b/c methylated wells in MPM cases was significantly higher than that in BAP cases (P=0.03) or HVs (P<0.001). Advanced MPM cases tended to have higher number of miR-34b/c methylated wells than early MPM cases. Receiver-operating characteristic (ROC) curve analysis revealed that three number of miR-34b/c methylated wells per sample was the best cut-off of positivity of MPM with a 67% of sensitivity and a 77% specificity for prediction. The area under the ROC curve was 0.77.

Conclusions: Our digital MSP assay can quantify miR-34b/c methylation in serum-circulating DNA. The degree of miR-34b/c methylation in serum-circulating DNA is associated with MPM, suggesting that this approach might be useful for the establishment of a new detection system for MPM.

Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

In plain English

This laboratory study tested whether a blood test could detect a chemical change (methylation) in a gene region called microRNA-34b/c in DNA circulating in serum. Between August 2006 and August 2011, three Japanese hospitals collected blood from 48 people with malignant pleural mesothelioma, 21 with benign asbestos pleurisy and 41 healthy volunteers. The article did not describe the participants' asbestos exposure. Each sample was split into 40 test wells, and the wells showing methylation were counted. Mesothelioma cases had significantly more methylated wells than benign asbestos pleurisy cases (P = 0.03) or healthy volunteers (P less than 0.001). Benign asbestos pleurisy cases also had more than healthy volunteers (P = 0.01). More advanced mesothelioma tended to show more methylated wells, except for two stage I cases. With three methylated wells as the cut-off, the test picked up 67% of mesothelioma cases with 77% specificity (area under the curve 0.77). It gave false positives in 43% of benign asbestos pleurisy cases and 12% of healthy volunteers. The authors called the accuracy moderate and concluded the approach might be useful for building a new detection system.

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 (biomarker) study comparing serum samples from mesothelioma patients, benign asbestos pleurisy patients and healthy volunteers
• Who was studied: 110 people: 48 malignant pleural mesothelioma cases, 21 benign asbestos pleurisy cases and 41 healthy volunteers, at Okayama University Hospital, Okayama Rosai Hospital and the National Hospital Organization Yamaguchi Ube Medical Center, Japan, August 2006 to August 2011
• Exposure: The article does not report fiber types, jobs or doses for the participants. The factor measured was methylation of microRNA-34b/c in serum-circulating DNA, counted as the number of positive wells out of 40 per sample.
• Main results:
  • Mesothelioma cases had significantly more methylated wells than benign asbestos pleurisy cases (P = 0.03) and healthy volunteers (P less than 0.001).
  • Benign asbestos pleurisy cases had significantly more methylated wells than healthy volunteers (P = 0.01).
  • No significant differences in methylated wells were seen by age, sex, smoking status or histological subtype.
  • Mesothelioma cases with advanced clinical stage tended to have more methylated wells than early-stage cases, except for two stage I cases, which had 34 and 22 methylated wells.
  • Comparing mesothelioma with the non-malignant cases, a cut-off of three methylated wells gave 67% sensitivity and 77% specificity. The area under the ROC curve was 0.77.
  • At a cut-off of three methylated wells, false positives occurred in 43% of benign asbestos pleurisy cases and 12% of healthy volunteers.
  • At 95% specificity the test's sensitivity was 38%. At 95% sensitivity its specificity was 24%.
• The authors' conclusion: The authors concluded that their assay can quantify miR-34b/c methylation in serum DNA, that it had moderate diagnostic accuracy, and that the approach might be useful for establishing a new detection system for mesothelioma.
• Limitations the authors state:
  • The authors said sensitivity and specificity need improving, for example by combining the test with other biomarkers.
  • The authors noted that clinical staging based on conventional radiology is limited, and that larger studies are needed.
  • The authors noted that miR-34b/c methylation also occurs in other cancers such as lung, colorectal and gastric cancer. They said these cancers were not obviously present in any case in this study.

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: Pleural Mesothelioma, Prognosis, Pleurisy.

Related studies

• Droplet digital PCR as a novel system for the detection of microRNA‑34b/c methylation in circulating DNA in malignant pleural mesothelioma — H. Sato, J. Soh, et al. (2019)
• Downregulation of microRNA-34 induces cell proliferation and invasion of human mesothelial cells — N. Tanaka, S. Toyooka, et al. (2013)
• miR-1254 and miR-574-5p: serum-based microRNA biomarkers for early-stage non-small cell lung cancer — K.M. Foss, C. Sima, et al. (2011)
• Are circulating microRNAs suitable for the early detection of malignant mesothelioma? Results from a nested case-control study — D.G. Weber, A. Brik, et al. (2019)
• Increased circulating miR-625-3p: a potential biomarker for patients with malignant pleural mesothelioma — M.B. Kirschner, Y.Y. Cheng, et al. (2012)
• Downregulated microRNAs in the differential diagnosis of malignant pleural mesothelioma — G.V. Gee, D.C. Koestler, et al. (2010)

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