Small and Large Extracellular Vesicles Derived from Pleural Mesothelioma Cell Lines Offer Biomarker Potential

Our plain-English summary of Small and Large Extracellular Vesicles Derived from Pleural Mesothelioma Cell Lines Offer Biomarker Potential, by T. Ahmadzada, A. Vijayan, F. Vafaee, et al (Cancers, 2023).

The study

• Authors: T. Ahmadzada, A. Vijayan, F. Vafaee, A. Azimi, G. Reid, S. Clarke, S. Kao, G.E. Grau, E. Hosseini-Beheshti
• Journal: Cancers
• Published: 2023;15(8)
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pleural mesothelioma, previously known as malignant pleural mesothelioma, is an aggressive and fatal cancer of the pleura, with one of the poorest survival rates. Pleural mesothelioma is in urgent clinical need for biomarkers to aid early diagnosis, improve prognostication, and stratify patients for treatment. Extracellular vesicles (EVs) have great potential as biomarkers; however, there are limited studies to date on their role in pleural mesothelioma. We conducted a comprehensive proteomic analysis on different EV populations derived from five pleural mesothelioma cell lines and an immortalized control cell line. We characterized three subtypes of EVs (10 K, 18 K, and 100 K), and identified a total of 4054 unique proteins. Major differences were found in the cargo between the three EV subtypes. We show that 10 K EVs were enriched in mitochondrial components and metabolic processes, while 18 K and 100 K EVs were enriched in endoplasmic reticulum stress. We found 46 new cancer-associated proteins for pleural mesothelioma, and the presence of mesothelin and PD-L1/PD-L2 enriched in 100 K and 10 K EV, respectively. We demonstrate that different EV populations derived from pleural mesothelioma cells have unique cancer-specific proteomes and carry oncogenic cargo, which could offer a novel means to extract biomarkers of interest for pleural mesothelioma from liquid biopsies.

In plain English

This was a laboratory study of cells grown in culture. It did not study patients or asbestos exposure. The authors grew five pleural mesothelioma cell lines and one immortalized human mesothelial cell line, used as a control. They collected the tiny particles these cells release, called extracellular vesicles. They separated three vesicle groups by spinning samples at 10,000, 18,000 and 100,000 times gravity (called 10 K, 18 K and 100 K) and analyzed the proteins in each. They identified 4054 proteins in total. Forty-six proteins, including mesothelin, were present in every vesicle group from all five mesothelioma cell lines and absent from all control vesicles. The 10 K vesicles were mostly enriched with mitochondrial components, while 18 K and 100 K vesicles were mostly associated with the endoplasmic reticulum. PD-L1 was detected in 10 K vesicles of every mesothelioma cell line except H28, and in no 18 K vesicles. The authors concluded that each vesicle type carried cancer-related cargo with biomarker potential for pleural mesothelioma. They noted that their control cell line may not have been a robust control and that follow-up studies are needed to validate the candidate markers.

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 (cell culture) proteomic study of extracellular vesicles released by cell lines; no patients involved
• Who was studied: Five pleural mesothelioma cell lines (H28, VMC23 and H226, listed as epithelioid; MM05 and MSTO-211H, listed as biphasic) and one immortalized human mesothelial control cell line (MeT-5A). Four rounds of vesicle isolation were done per cell line, each with two technical replicates.
• Exposure: No asbestos or fiber exposure was studied. The comparison was between three vesicle subtypes isolated by centrifugation at 10,000, 18,000 and 100,000 times gravity, from mesothelioma cell lines versus the control cell line.
• Main results:
  • 4054 proteins were identified in total across all vesicle samples.
  • 935 proteins were found only in 10 K pellets, 134 only in 18 K pellets, and 224 only in 100 K pellets.
  • 46 cancer-associated proteins, including mesothelin and EGFR, were present in all vesicle pellets from all mesothelioma cell lines and absent from all vesicle pellets of the control cell line MeT-5A.
  • Overall, the mesothelioma cell lines produced more vesicles than the control cell line.
  • 10 K vesicles were mostly enriched with mitochondrial components; 18 K and 100 K vesicles were mostly associated with the endoplasmic reticulum.
  • On western blotting, PD-L1 was not detected in any 18 K pellet and was detected in 10 K vesicles of all mesothelioma cell lines except H28.
  • Mesothelin was detected in 10 K, 18 K and 100 K pellets from four of the mesothelioma cell lines, but not in vesicles from H28.
  • PD-L2 was significantly overexpressed only in the 10 K vesicles of the VMC23 and MM05 cell lines.
• The authors' conclusion: The authors concluded that three vesicle subtypes (10 K, 18 K and 100 K) can be isolated from pleural mesothelioma cell lines, each carrying cancer-related cargo with biomarker potential for pleural mesothelioma.
• Limitations the authors state:
  • The 10 K and 18 K vesicles were isolated without density gradient separation, which favored yield but may have compromised the purity of the pellets.
  • The particle-tracking technology limited size measurement to particles up to 1 micrometer.
  • The control cell line MeT-5A was transfected with simian virus 40 (SV40), proposed as a risk factor for mesothelioma, so it may not have been a robust control.
  • Cells in culture did not reflect tumor histology, so the authors could not establish clear distinctions between epithelioid and non-epithelioid subtypes.
  • The candidate markers still need validation in a follow-up study.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Biomarker, Pleura, Mesothelin, PD-L1.

Related studies

• Small Extracellular Vesicle-Derived Circular RNA hsa_circ_0007386 as a Biomarker for the Diagnosis of Pleural Mesothelioma — S. Zhand, J. Liao, et al. (2024)
• Serum Extracellular Vesicle-Derived microRNAs as Potential Biomarkers for Pleural Mesothelioma in a European Prospective Study — E. Casalone, G. Birolo, et al. (2022)
• Extracellular vesicles as biomarkers in malignant pleural mesothelioma: A review — T. Ahmadzada, S. Kao, et al. (2020)
• Plasmatic extracellular vesicle microRNAs in malignant pleural mesothelioma and asbestos-exposed subjects suggest a 2-miRNA signature as potential biomarker of disease — T. Cavalleri, L. Angelici, et al. (2017)
• 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)

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