Interleukin 32 Expression in Mesothelioma

Our plain-English summary of Interleukin 32 Expression in Mesothelioma, by T. Mikamo, R. Niwa, Y. Hanamatsu, et al (Thoracic Cancer, 2026).

The study

• Authors: T. Mikamo, R. Niwa, Y. Hanamatsu, T. Takeuchi
• Journal: Thoracic Cancer
• Published: 2026;17(14):e70353
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Interleukin 32 (IL32) has context-dependent roles in carcinogenesis across cancer types. In this study, we examined IL32 in mesotheliomas.

Methods: IL32 protein expression was evaluated by immunohistochemistry in 56 mesothelioma tissue microarray specimens and by immunoblot analysis in cultured mesothelioma cell lines. The functional roles of IL32 were examined through ectopic expression of IL32β and IL32θ isoforms in D-Meso-Sonobe cells with epithelial-mesenchymal plasticity and through siRNA-mediated IL32 downregulation followed by cell-detachment-induced apoptosis assays in epithelioid mesothelioma cells.

Results: IL32 immunoreactivity was detected in 20 of 56 mesothelioma tissue specimens, including cytoplasmic staining in 20 of 39 epithelioid cases, whereas little or no immunoreactivity was found in 17 sarcomatoid cases. In immunoblot analysis, an IL32 protein band was detected in two cultured epithelioid mesothelioma cell lines (MPM-2 and TCC-Meso-1), but not in sarcomatoid MPM-1 cells. Two IL32 isoforms, IL32β and IL32θ cDNAs, were isolated from MPM-2 cells. Ectopic expression of IL32θ, but not IL32β, inhibited the morphological transition from epithelioid to sarcomatoid features in D-Meso-Sonobe mesothelioma cells with mesothelial-mesenchymal transition plasticity. Conversely, siRNA-mediated downregulation of IL32 increased cell detachment-induced apoptosis in MPM-2 and TCC-Meso-1 epithelioid mesothelioma cells. Moreover, IL32 suppressed expression of secreted protein acidic and rich in cysteine, which is an epithelial-mesenchymal transition-related protein in mesothelioma cells.

Conclusions: These findings indicate that IL32 is expressed in epithelioid mesothelioma and may contribute to mesotheliomagenesis.

© 2026 The Author(s). Thoracic Cancer published by John Wiley & Sons Australia, Ltd.

In plain English

This laboratory study, by researchers in Gifu, Japan, looked at a protein called interleukin 32 (IL32) in mesothelioma. The authors stained 56 mesothelioma tissue samples from a commercially bought tissue microarray and tested mesothelioma cell lines grown in the laboratory. IL32 was detected in 20 of the 56 tissue samples. These were 20 of 39 epithelioid cases. The 17 sarcomatoid cases showed little or no staining. In cultured cells, IL32 was found in two epithelioid cell lines (MPM-2 and TCC-Meso-1) but not in the sarcomatoid line MPM-1. When cells of the D-Meso-Sonobe line were made to produce one form of IL32 (IL32θ), their change from epithelioid to sarcomatoid features was inhibited. Another form (IL32β) did not have this effect. Lowering IL32 increased cell death after detachment in the two epithelioid lines, and raised levels of a protein called SPARC in MPM-2 cells. The authors concluded that IL32 is expressed in epithelioid mesothelioma and may contribute to its development. The study did not look at asbestos exposure or patient outcomes.

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 study: immunohistochemical staining of a commercial mesothelioma tissue microarray, plus experiments on cultured mesothelioma cell lines (gene transfer and siRNA silencing)
• Who was studied: 56 mesothelioma tissue specimens on a tissue microarray purchased from US Biomax (USA): 39 epithelioid and 17 sarcomatoid. Also mesothelioma cell lines, several established in the authors' laboratory in Japan. No patient details, dates or tumor sites (pleural or peritoneal) are given for the tissue specimens.
• Exposure: No asbestos or other exposure was studied. The study examined IL32 protein in mesothelioma tissue and cells.
• Main results:
  • IL32 staining was detected in 20 of 56 mesothelioma tissue specimens
  • Cytoplasmic IL32 staining was found in 20 of 39 epithelioid cases
  • Little or no IL32 staining was found in the 17 sarcomatoid cases
  • IL32 protein was detected in two cultured epithelioid mesothelioma cell lines (MPM-2 and TCC-Meso-1) but not in sarcomatoid MPM-1 cells
  • Two IL32 forms (IL32β and IL32θ) were isolated from MPM-2 cells
  • In D-Meso-Sonobe cells, forced expression of IL32θ, but not IL32β, inhibited the change from epithelioid to sarcomatoid features
  • Lowering IL32 with siRNA increased detachment-induced cell death (apoptosis) in MPM-2 and TCC-Meso-1 epithelioid cells. No figures for the size of the increase are available in the text.
  • Lowering IL32 increased SPARC transcript and protein expression in MPM-2 epithelioid cells
• The authors' conclusion: The authors concluded that IL32 is expressed in epithelioid mesothelioma and may contribute to the development of mesothelioma.
• Limitations the authors state:
  • The authors examined IL32 mainly in relation to epithelial-mesenchymal transition. They state that further studies are needed on IL32 forms and the inflammatory tumor environment.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Carcinogenesis, Immunohistochemistry, Apoptosis, Epithelioid, Sarcomatoid.

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