Small Extracellular Vesicle-Derived Circular RNA hsa\_circ\_0007386 as a Biomarker for the Diagnosis of Pleural Mesothelioma

Our plain-English summary of Small Extracellular Vesicle-Derived Circular RNA hsa_circ_0007386 as a Biomarker for the Diagnosis of Pleural Mesothelioma, by S. Zhand, J. Liao, A. Castorina, et al (Cells, 2024).

The study

• Authors: S. Zhand, J. Liao, A. Castorina, M.L. Yuen, M. Ebrahimi Warkiani, Y.Y. Cheng
• Journal: Cells
• Published: 2024;13(12)
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pleural mesothelioma (PM) is a highly aggressive tumor that is caused by asbestos exposure and lacks effective therapeutic regimens. Current procedures for PM diagnosis are invasive and can take a long time to reach a definitive result. Small extracellular vesicles (sEVs) have been identified as important communicators between tumor cells and their microenvironment via their cargo including circular RNAs (circRNAs). CircRNAs are thermodynamically stable, highly conserved, and have been found to be dysregulated in cancer. This study aimed to identify potential biomarkers for PM diagnosis by investigating the expression of specific circRNA gene pattern (hsa_circ_0007386) in cells and sEVs using digital polymerase chain reaction (dPCR). For this reason, 5 PM, 14 non-PM, and one normal mesothelial cell line were cultured. The sEV was isolated from the cells using the gold standard ultracentrifuge method. The RNA was extracted from both cells and sEVs, cDNA was synthesized, and dPCR was run. Results showed that hsa_circ_0007386 was significantly overexpressed in PM cell lines and sEVs compared to non-PM and normal mesothelial cell lines (p < 0.0001). The upregulation of hsa_circ_0007386 in PM highlights its potential as a diagnostic biomarker. This study underscores the importance and potential of circRNAs and sEVs as cancer diagnostic tools.

In plain English

This was a laboratory study of cultured cell lines. No patients were tested, and asbestos exposure was not studied. The authors grew five pleural mesothelioma (PM) cell lines, a normal mesothelial line (MeT5A), a microglial line (BV-2) and other cancer lines. They used digital PCR to measure a circular RNA, hsa_circ_0007386, in the cells and in small extracellular vesicles (tiny particles) the cells released. In the cells, the ratio to a reference RNA ranged from 0.0908 to 0.183 across the five PM lines and was reported as significantly lower in non-PM cancer lines (p less than 0.0001). In vesicles, PM ratios ranged from 0.087 to 0.187. The authors reported 90% sensitivity and 93.3% specificity for cell RNA, and 81.81% and 87.5% for the vesicles. The non-PM lung cancer line H1975 had ratios above some PM lines (0.12 in cells, 0.1630 in vesicles). The authors also called HepG2 (liver cancer) higher, but its vesicle ratio of 0.086 fell below every PM value. The authors concluded that the vesicle-derived RNA was an effective, novel biomarker for PM. They stated that validation in patient samples is imperative.

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 (in vitro) study of cultured human cell lines, measuring a circular RNA in cells and in the small extracellular vesicles they released, using digital PCR
• Who was studied: Cell lines, not people. Five commercially available human mesothelioma cell lines (NCI-H28, NCI-H226, H2052, MSTO-211H, H2452) came from ATCC. The comparison lines were MeT5A (the normal mesothelium line), BV-2 (a microglial line), and lung, gastric, colorectal, breast, melanoma, liver and prostate cancer lines from ATCC and Cell Bank Australia. The work was done at the University of Technology Sydney.
• Exposure: No asbestos exposure was studied. What was measured was the level of the circular RNA hsa_circ_0007386, normalized to the reference circular RNA hsa_circ_0000284, in cell RNA and in RNA from small extracellular vesicles.
• Main results:
  • Raw copy numbers in the PM cell lines were 1218.3 copies per microliter in NCI-H28, 696.7 in H2052, 555.6 in H226, 412.5 in H2452 and 187 in MSTO-211H.
  • The normal mesothelial cell line (MeT5A) showed 448 copies per microliter in raw copy number.
  • After normalization to the reference RNA, the ratios in the five PM cell lines were 0.183, 0.168, 0.098, 0.0943 and 0.0908.
  • In the non-PM cancer cell lines listed, the normalized ratio was reported as significantly lower (p less than 0.0001). Values ranged from 0.0042 (Colo679 melanoma) to 0.068 (HepG2 liver cancer).
  • In vesicles from the PM cell lines, raw copy numbers were 36.23 copies per microliter for H226, 23 for MSTO-211H, 11.71 for H2452, 9.54 for H2052 and 6.77 for NCI-H28.
  • Normalized ratios in the PM vesicles were 0.187 for H2452, 0.171 for NCI-H28, 0.121 for MSTO-211H, 0.1045 for H2052 and 0.087 for H226.
  • In vesicles from the non-PM cancer lines listed, the ratio was reported as significantly lower (p less than 0.0001). Values ranged from 0.0053 (Colo679) to 0.0580 (Colo 794).
  • Expression was reported as significantly higher in the PM cell lines and the PM vesicles than in the normal mesothelial line (MeT5A) and the microglial line (BV-2) (p less than 0.0001).
  • Reported diagnostic performance among cell lines was 90% sensitivity and 93.3% specificity using cell RNA, and 81.81% and 87.5% using vesicles.
  • The non-PM lung cancer line H1975 had a vesicle ratio of 0.1630, above some PM vesicle ratios. The authors also described the liver cancer line HepG2's vesicle ratio (0.086) as apparently higher than some PM lines, but that value is below the lowest reported PM vesicle ratio (0.087). The authors reported that absolute copy numbers showed a statistically significant difference (p less than 0.0001).
  • In cells, H1975 had a ratio of 0.12, higher than the PM cell lines MSTO-211H, H226 and H2452.
• The authors' conclusion: The authors concluded that vesicle-derived hsa_circ_0007386 was an effective and novel biomarker for pleural mesothelioma that may be involved in the disease's occurrence and development. They suggested it could be used in less-invasive liquid biopsy in the future.
• Limitations the authors state:
  • The findings come from cell lines only. The authors stated that validation using patient samples is needed.
  • The mesothelioma cell lines were commercially available in vitro models of PM.
  • The mechanism by which specific circular RNAs are packaged into vesicles is not yet clear.
  • Issues such as specimen preservation, the cell source of vesicles and vesicle isolation methods must be resolved before these markers can be used as reliable biomarkers.

Topics

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

Medical terms in this study, explained in our Lexicon: Biomarker, Pleural Mesothelioma, Asbestos Exposure, Mesothelial Cells.

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• Small and Large Extracellular Vesicles Derived from Pleural Mesothelioma Cell Lines Offer Biomarker Potential — T. Ahmadzada, A. Vijayan, et al. (2023)
• Extracellular Vesicles Isolated from Malignant Mesothelioma Cancer-Associated Fibroblasts Induce Pro-Oncogenic Changes in Healthy Mesothelial Cells — T. Chernova, S. Grosso, et al. (2022)
• Ferroptosis-dependent extracellular vesicles from macrophage contribute to asbestos-induced mesothelial carcinogenesis through loading ferritin — F. Ito, K. Kato, et al. (2021)
• Serum Extracellular Vesicle-Derived microRNAs as Potential Biomarkers for Pleural Mesothelioma in a European Prospective Study — E. Casalone, G. Birolo, et al. (2022)

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