Epithelioid Mesothelioma Cells Exhibit Increased Ferroptosis Sensitivity Compared to Non-Epithelioid Mesothelioma Cells

Our plain-English summary of Epithelioid Mesothelioma Cells Exhibit Increased Ferroptosis Sensitivity Compared to Non-Epithelioid Mesothelioma Cells, by T. Sato, I. Hasegawa, H. Ikeda, et al (Cancers, 2025).

The study

• Authors: T. Sato, I. Hasegawa, H. Ikeda, T. Ohshiro, L. Kondo-Ida, S. Mukai, S. Ohte, T. Maeda, Y. Sekido
• Journal: Cancers
• Published: 2025;17(24)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background/Objectives: Mesothelioma is a highly aggressive tumor with a poor prognosis that typically develops after a long latency period following asbestos exposure. Although immunotherapy combined with chemotherapy is increasingly used, the efficacy of standard treatments remains limited. This study aimed to explore ferroptosis induction as a potential therapeutic strategy for mesothelioma. Methods: We first screened microbial culture extracts collected from soil and marine environments to identify compounds with selective cytotoxicity against mesothelioma cells. Gene expression profiling was performed to investigate the mechanism of cell death induced by the identified compound. To assess intrinsic ferroptosis susceptibility, patient-derived mesothelioma cell lines and immortalized mesothelial cell lines were treated with RSL3, a GPX4 inhibitor. Results: Screening identified brefeldin A as a compound that selectively induces cell death in mesothelioma cells. Gene expression profiling revealed transcriptional changes consistent with ferroptosis induction. Treatment with RSL3 demonstrated marked variability in ferroptosis sensitivity across cell lines; the subgroup showing high sensitivity to RSL3 did not exhibit significant genetic alterations in NF2 or BAP1, but contained a significantly higher proportion of epithelioid tumors in histological classification. Conclusions: Our findings highlight ferroptosis induction as a promising antitumor mechanism in mesothelioma, particularly in the epithelioid subtype. While GPX4 inhibitors such as RSL3 are effective in vitro, further studies are needed to overcome pharmacological limitations and define molecular determinants of ferroptosis susceptibility, which may inform future personalized therapeutic strategies.

In plain English

This was a laboratory study of cells grown in dishes. It did not study asbestos exposure or patients. The authors tested 1,188 ethanol extracts from soil and marine microorganisms on three mesothelioma cell lines and one immortalized mesothelial cell line, MeT-5A. An extract from a soil fungus collected in Hokkaido, Japan, slowed the growth of all three mesothelioma lines more than MeT-5A cells. Its active compound was identified as brefeldin A, an already known compound. At 10 ng/mL, brefeldin A caused cell death in the mesothelioma lines but not in MeT-5A cells. The authors reported changes in gene expression and a buildup of damaged fats (lipid peroxides) consistent with ferroptosis, a type of cell death driven by such fats. A ferroptosis blocker reduced the cell death. They then tested RSL3, an experimental compound that triggers ferroptosis, on a larger panel of cell lines. Sensitivity did not differ significantly by NF2 alteration, by NF2 and/or LATS2 alteration, or by BAP1 alteration. Lines from epithelioid tumors needed consistently less RSL3 than non-epithelioid lines. The authors noted that all of the work was done in cell culture.

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 human cell lines: a screening of microbial extracts followed by cell growth, gene expression and drug-sensitivity experiments
• Who was studied: Microbial extracts: 1,188 ethanol extracts (450 from marine and 738 from soil microorganisms). These were screened on three mesothelioma cell lines (Y-MESO-27, NCI-H2052, NCI-H2452) and one immortalized mesothelial cell line (MeT-5A). RSL3 testing used what the text describes as 18 patient-derived mesothelioma cell lines and 4 immortalized mesothelial cell lines.
• Exposure: No asbestos exposure was studied. Cells were treated with brefeldin A, which was identified from fungal strain BF-0398 and then obtained commercially, mainly at 10 ng/mL. They were also treated with RSL3 (a GPX4 inhibitor) at various concentrations and with the ferroptosis inhibitor Ferrostatin-1.
• Main results:
  • In the first screening, 144 extracts caused at least 90% growth inhibition in at least one mesothelioma cell line. These went on to a second round of screening.
  • At 10 ng/mL, brefeldin A reduced the growth of Y-MESO-27 mesothelioma cells to about 40% by 96 hours. It almost completely inhibited the growth of NCI-H2052 and NCI-H2452 cells. It showed no effect on MeT-5A mesothelial cell growth for up to 120 hours.
  • Brefeldin A at 10 ng/mL caused cell death in the three mesothelioma cell lines but not in MeT-5A cells.
  • In the three mesothelioma cell lines, 557 genes were commonly increased in expression and 479 decreased after brefeldin A treatment. MeT-5A cells showed minimal changes.
  • Changes in the expression of the ferroptosis-related genes GPX4, SLC7A11 and ACSL4 were consistently seen in two of the three mesothelioma cell lines.
  • All three mesothelioma cell lines showed strong lipid peroxide staining after brefeldin A. MeT-5A cells showed no increase.
  • Adding Ferrostatin-1 together with brefeldin A significantly reduced cell death in all three mesothelioma cell lines.
  • With RSL3, the three mesothelioma cell lines used in the earlier experiments all had lower IC50 values than any of the four mesothelial cell lines. A lower IC50 means less RSL3 was needed to cut survival by half.
  • RSL3 IC50 values were compared between intact and altered groups for NF2 alone, for NF2 and/or LATS2, and for BAP1. None of these comparisons showed a significant difference.
  • Mesothelioma cell lines of epithelioid origin had consistently lower RSL3 IC50 values than those of non-epithelioid origin. The comparison used a Mann-Whitney U-test, and one line of unknown histology was excluded.
• The authors' conclusion: The authors concluded that epithelioid mesothelioma cell lines showed greater intrinsic vulnerability to ferroptosis than non-epithelioid lines. They also concluded that ferroptosis is a promising therapeutic target in mesothelioma.
• Limitations the authors state:
  • The study was done entirely in cell culture and does not capture the complex tumor environment found in the body.
  • Non-epithelioid mesotheliomas might be vulnerable to ferroptosis in the body even though they were less sensitive in cell culture.
  • The study did not directly measure lipid metabolism, reactive oxygen species or iron balance, which regulate ferroptosis.
  • GPX4 inhibitors such as RSL3 face safety, off-target and pharmacokinetic barriers to use in patients.
  • One cell line (Y-MESO-48) was excluded from the histology comparison because its histological origin was unknown.

Topics

Medical terms in this study, explained in our Lexicon: Epithelioid, Mesothelioma, Non-epithelioid, Prognosis, Latency, Asbestos Exposure, Immunotherapy, Chemotherapy.

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