Circulating long non-coding RNA GAS5 (growth arrest-specific transcript 5) as a complement marker for the detection of malignant mesothelioma using liquid biopsies

Our plain-English summary of Circulating long non-coding RNA GAS5 (growth arrest-specific transcript 5) as a complement marker for the detection of malignant mesothelioma using liquid biopsies, by D.G. Weber, S. Casjens, A. Brik, et al (Biomarker Research, 2020).

The study

• Authors: D.G. Weber, S. Casjens, A. Brik, I. Raiko, M. Lehnert, D. Taeger, J. Gleichenhagen, J. Kollmeier, T.T. Bauer, T. Brüning, G. Johnen, MoMar study group
• Journal: Biomarker Research
• Published: 2020;8:15
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: For the detection of malignant mesothelioma additional markers are needed besides the established panel consisting of calretinin and mesothelin. The aim of this study was the identification and verification of long non-coding RNAs (lncRNAs) as complementing circulating markers.

Methods: Candidate lncRNAs were identified in silico using previously published RNA expression profiles and verified using quantitative PCR (qPCR) in mesothelioma cell lines as well as human plasma samples from mesothelioma patients and asbestos-exposed controls.

Results: GAS5 (growth arrest-specific transcript 5) as a single marker is marked by a low sensitivity of 14%, but the combination of GAS5 with calretinin and mesothelin increased the panel's sensitivity from 64 to 73% at a predefined specificity of 97%. Circulating GAS5 is not affected by pleurectomy before blood collection, age, or smoking status.

Conclusions: GAS5 is verified as an appropriate circulating marker for the supplement of calretinin and mesothelin to detect malignant mesothelioma. Although the sensitivity of GAS5 is too low for the use as a single marker, the addition of GAS5 as a third marker improves the performance of the established marker panel. The benefit of GAS5 for the detection of malignant mesothelioma at early stages needs to be validated in a prospective study.

© The Author(s) 2020.

In plain English

This study looked for blood-borne long non-coding RNAs that might help detect malignant mesothelioma alongside the established markers calretinin and mesothelin. The authors screened published pleural mesothelioma tissue data, then tested candidates in cell lines and plasma. In an initial check of nine plasma samples, only GAS5 was detectable in almost all, so it was carried forward. The main comparison used plasma from 22 male mesothelioma patients and 31 cancer-free asbestos-exposed men from a German cohort. The article reports excluding 11 of 44 matched controls because GAS5 or its reference RNA was undetectable, which would leave 33; it does not explain the difference. Median normalized plasma GAS5 was 4.05 in patients and 0.62 in controls. At a specificity of 97%, GAS5 alone detected 14% of patients. Calretinin and mesothelin together detected 64%. Adding GAS5 in a linear combination raised this to 73%. Pleurectomy, age and smoking did not influence GAS5 levels, the authors reported. They concluded GAS5 is too insensitive alone but improves the established panel. They noted small numbers, mostly late-stage cases, and the need for a prospective study.

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: Biomarker study: computer (in silico) analysis of published tissue expression data, followed by laboratory testing in mesothelioma cell lines and a comparison of plasma from mesothelioma patients with matched asbestos-exposed controls
• Who was studied: 22 male mesothelioma patients (14 epithelioid, 2 biphasic, 2 sarcomatoid, 4 unknown) and 44 matched men formerly exposed to asbestos, all cancer-free, from the German MoMar cohort. The article reports that 11 controls were excluded because GAS5 or its reference RNA RPLP0 was at or above the detection limit, and that 22 patients and 31 controls were analyzed. 44 minus 11 would be 33, and the article does not explain the difference.
• Exposure: Controls were German workers formerly exposed to asbestos with a confirmed asbestos-related disease (asbestosis and/or other non-malignant pleural disease). No fiber types or doses are given. The study measured the blood markers GAS5, calretinin and mesothelin.
• Main results:
  • In an initial detectability check of nine plasma samples (four mesothelioma patients, five asbestos-exposed subjects), GAS5 was detectable in almost all samples, unlike the other lncRNAs tested.
  • Eleven asbestos-exposed controls were excluded because GAS5 or RPLP0 values were at or above the detection limit. The article reports 22 patients and 31 controls analyzed.
  • Median normalized plasma GAS5 was 4.05 (IQR 2.94 to 8.38) in mesothelioma patients and 0.62 (IQR 0.28 to 0.96) in asbestos-exposed controls. The difference was statistically significant (p less than 0.0001).
  • For GAS5 alone, the AUC was 0.86 (95% CI 0.75 to 0.98).
  • At a predefined specificity of 97% (one false-positive test allowed), GAS5 alone had a sensitivity of 14% (3 true-positive tests).
  • At 97% specificity, calretinin alone had 55% sensitivity, mesothelin alone 41%, and the sequential combination of calretinin and mesothelin 64%.
  • At 97% specificity, combining GAS5 with calretinin and mesothelin gave 73% sensitivity in a linear combination and 68% in a sequential combination.
  • The linear three-marker combination produced two additional true-positive tests compared with calretinin and mesothelin alone.
  • Pleurectomy before blood collection, age, and smoking status did not influence plasma GAS5 levels. Having mesothelioma was associated with higher values.
• The authors' conclusion: The authors concluded that GAS5's sensitivity is too low for use as a single marker, but that adding it as a third marker improves the performance of the established calretinin and mesothelin panel. They stated that its benefit for early detection still needs to be validated in a prospective study.
• Limitations the authors state:
  • The results are based on small numbers.
  • Because of the small number of subjects, only one false-positive test could be allowed when setting specificity.
  • The patients had been diagnosed, mostly at late stages of tumor development.
  • The apparent robustness of GAS5 to influencing factors needs to be verified in larger study groups.
  • The effect of hemolysis on lncRNA levels needs further study.
  • The benefit for early detection using samples taken before diagnosis still needs to be validated in a prospective study.

Topics

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Calretinin, Mesothelin, Mesothelioma.

Related studies

• Tasks and Experiences of the Prospective, Longitudinal, Multicenter MoMar (Molecular Markers) Study for the Early Detection of Mesothelioma in Individuals Formerly Exposed to Asbestos Using Liquid Biopsies — D.G. Weber, S. Casjens, et al. (2023)
• Prediagnostic detection of mesothelioma by circulating calretinin and mesothelin - a case-control comparison nested into a prospective cohort of asbestos-exposed workers — G. Johnen, K. Burek, et al. (2018)
• 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)
• Sensitive Blood-Based Detection of Asbestos-Associated Diseases Using Cysteine-Rich Angiogenic Inducer 61 as Circulating Protein Biomarker — K. Bartkowiak, S. Casjens, et al. (2021)
• Non-Coding Transcript Heterogeneity in Mesothelioma: Insights from Asbestos-Exposed Mice — E. Felley-Bosco, H. Rehrauer (2018)
• A recombinant polypeptide of the megakaryocyte potentiating factor is a potential biomarker in plasma for the detection of mesothelioma — I. Raiko, H.P. Rihs, et al. (2017)

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