Micro-RNA-215 and -375 regulate thymidylate synthase protein expression in pleural mesothelioma and mediate epithelial to mesenchymal transition

Our plain-English summary of Micro-RNA-215 and -375 regulate thymidylate synthase protein expression in pleural mesothelioma and mediate epithelial to mesenchymal transition, by F. Napoli, I. Rapa, S. Izzo, et al (Virchows Archiv, 2022).

The study

• Authors: F. Napoli, I. Rapa, S. Izzo, A. Rigutto, R. Libener, C. Riganti, P. Bironzo, R. Taulli, M. Papotti, M. Volante, G. Scagliotti, L. Righi
• Journal: Virchows Archiv
• Published: 2022;481(2):233-244
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The standard front-line treatment for pleural mesothelioma (PM) is pemetrexed-based chemotherapy, whose major target is thymidylate synthase (TS). In several cancer models, miR-215 and miR-375 have been shown to target TS, while information on these miRNAs in PM are still limited although suggest their role in epithelial to mesenchymal transition. Seventy-one consecutive PM tissues (4 biphasic, 7 sarcomatoid, and 60 epithelioid types) and 16 commercial and patient-derived PM cell lines were screened for TS, miR-215, and miR-375 expression. REN and 570B cells were selected for miR-215 and miR-375 transient transfections to test TS modulation. ZEB1 protein expression in tumor samples was also tested. Moreover, genetic profile was investigated by means of BAP1 and p53 immunohistochemistry. Expression of both miR-215 and miR-375 was significantly higher in epithelioid histotype. Furthermore, inverse correlation between TS protein and both miR-215 and miR-375 expression was found. Efficiently transfected REN and 570B cell lines overexpressing miR-215 and miR-375 showed decreased TS protein levels. Epithelioid PM with a mesenchymal component highlighted by reticulin stain showed significantly higher TS and ZEB1 protein and lower miRNA expression. A better survival was recorded for BAP1 lost/TS low cases. Our data indicate that miR-215 and miR-375 are involved in TS regulation as well as in epithelial-to-mesenchymal transition in PM.

© 2022. The Author(s).

In plain English

This was a laboratory and tumor-tissue study of pleural mesothelioma. It did not look at asbestos exposure. The authors examined biopsies from 71 consecutive patients at San Luigi Hospital, Orbassano, Turin, Italy, collected from 2013 to 2016 (60 epithelioid, 7 sarcomatoid and 4 biphasic tumors), and 16 mesothelioma cell lines. They measured two micro-RNAs (small molecules that regulate genes), miR-215 and miR-375, and thymidylate synthase (TS), the main target of the chemotherapy drug pemetrexed. Both micro-RNAs were higher in epithelioid tumors. TS protein was higher in sarcomatoid and biphasic tumors (mean score 100.83 versus 45.9 in epithelioid). Tumors with more micro-RNA tended to have less TS protein. Adding the micro-RNAs to two cell lines lowered TS protein but did not significantly change the cells' response to pemetrexed. Among patients whose tumors had lost the protein BAP1, those with low TS survived longer (median 17 versus 10 months). The authors concluded that this pathway might drive a shift toward mesenchymal features in epithelioid tumors. They cautioned that differences in patients' disease stage and treatment could have influenced the survival results.

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: Retrospective study of consecutive patient tumor biopsies combined with laboratory experiments on mesothelioma cell lines
• Who was studied: 71 consecutive pleural mesothelioma biopsies (60 epithelioid, 7 sarcomatoid, 4 biphasic) from San Luigi Hospital, Orbassano, Turin, Italy, 2013 to 2016; plus 9 commercial and 7 patient-derived mesothelioma cell lines
• Exposure: Asbestos exposure was not assessed. The study measured miR-215, miR-375, TS protein and mRNA, ZEB1, BAP1 and p53 in tumor tissue. In the cell-line experiments, the micro-RNAs were introduced into the cells, which were then treated with pemetrexed.
• Main results:
  • Both miR-215 and miR-375 were significantly higher in epithelioid tumors than in sarcomatoid and biphasic tumors (p = 0.0002 for miR-215, p = 0.0005 for miR-375)
  • TS protein was higher in sarcomatoid and biphasic tumors (H-score mean 100.83, median 92.5) than in epithelioid tumors (mean 45.9, median 30); p = 0.0013
  • In all 71 tissues, TS protein was inversely correlated with miR-215 (r = -0.43, p = 0.009) and miR-375 (r = -0.31, p less than 0.0001). TS mRNA was not correlated with either micro-RNA.
  • In the REN (epithelioid-derived) and 570B (sarcomatoid-derived) cell lines, overexpression of miR-215 and miR-375 strongly reduced TS protein
  • In the transfected cell lines treated with pemetrexed, cell viability did not change significantly compared with control-transfected cells
  • ZEB1 protein was significantly higher in sarcomatoid tumors (mean H-score 246) than in epithelioid tumors (mean 138); p = 0.0012
  • Of 51 epithelioid tumors stained for reticulin, 29/51 had a fine/tight component. These tumors had significantly higher TS protein than tumors with a pure loose pattern (p = 0.01) and higher ZEB1 (p = 0.002). Their lower micro-RNA levels were not statistically significant (p = 0.25 and p = 0.08).
  • BAP1 loss was found in 32/51 epithelioid, 1/4 biphasic and 1/7 sarcomatoid tumors. BAP1 status was not correlated with micro-RNA levels, TS levels or epithelioid morphology.
  • Median overall survival was 10 months. Patients with low TS protein had median survival of 12 months versus 8.5 months with high TS (log-rank p = 0.05).
  • Survival did not differ significantly by miR-215 or miR-375 level
  • Among cases with BAP1 loss, those with low TS protein had significantly better survival (17 vs. 10 months; log-rank p = 0.04 in the text, p = 0.03 in the Fig. 6 legend)
• The authors' conclusion: The authors concluded that TS could be a target of both micro-RNAs, and that TS modulation by them was not associated with response to pemetrexed or with ZEB1. They concluded that the link of both micro-RNAs and TS with tumor type, and with a mesenchymal-like component in epithelioid tumors, suggests this pathway might drive epithelial-to-mesenchymal transition in epithelioid tumors.
• Limitations the authors state:
  • Because the series was consecutive and retrospective, patients differed in disease stage at diagnosis and in treatments received, which could have influenced survival
  • The data do not demonstrate a direct effect of the micro-RNAs on patient survival

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Pemetrexed (Alimta), Chemotherapy, Biphasic Mesothelioma, Sarcomatoid, Epithelioid, BAP1, Immunohistochemistry.

Related studies

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• Blockage of epithelial to mesenchymal transition and upregulation of let 7b are critically involved in ursolic acid induced apoptosis in malignant mesothelioma cell — E.J. Sohn, G. Won, et al. (2016)
• Periostin expression and epithelial-mesenchymal transition in cancer: a review and an update — L. Morra, H. Moch (2011)
• ¹⁸F-FDG uptake on PET is a predictive marker of thymidylate synthase expression in patients with thoracic neoplasms — K. Kaira, N. Yamamoto, et al. (2014)
• The Epithelial-to-Mesenchymal Transition (EMT) in the Development and Metastasis of Malignant Pleural Mesothelioma — V. Ramundo, G. Zanirato, et al. (2021)
• Epithelial-mesenchymal transition involved in pulmonary fibrosis induced by multi-walled carbon nanotubes via TGF-beta/Smad signaling pathway — T. Chen, H. Nie, et al. (2014)

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