Characterization of mesothelin gene expression in dogs and overexpression in canine mesotheliomas

Our plain-English summary of Characterization of mesothelin gene expression in dogs and overexpression in canine mesotheliomas, by R. Nabeta, A. Kanaya, K. Shimada, et al (Frontiers in Veterinary Science, 2024).

The study

• Authors: R. Nabeta, A. Kanaya, K. Shimada, K. Matsuura, A. Yoshimura, T. Oyamada, D. Azakami, T. Furuya, T. Uchide
• Journal: Frontiers in Veterinary Science
• Published: 2024;11:1436621
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Canine mesotheliomas are uncommon malignant tumors typically detected late. Minimally invasive diagnostic biomarkers would facilitate diagnosis at earlier stages, thereby improving clinical outcomes. We hypothesized that mesothelin could be used as a reliable diagnostic biomarker for canine mesotheliomas since it has been used as a cancer biomarker for human mesothelioma. We aimed to explore and characterize mesothelin gene expression in dogs and assess its use as a diagnostic biomarker for canine mesotheliomas.

Materials And Methods: We quantified expressed canine mesothelin transcripts via reverse transcription polymerase chain reaction (RT-PCR) and sequenced them using ribonucleic acid (RNA) extracted from a canine mesothelioma cell line. After confirming mesothelin expression, we assessed its levels in major organ tissues and compared them with those in the mesothelioma tissues using quantitative PCR (qPCR). Mesothelin overexpression in mesotheliomas was detected, and we further compared its levels using qPCR between mesotheliomas and non-mesotheliomas using tumor tissues and clinical sample effusions, confirming its significance as a diagnostic biomarker for canine mesothelioma.

Results: Mesothelin complementary deoxyribonucleic acid (cDNA) was amplified via RT-PCR, yielding a single band of expected upon DNA electrophoresis. Sequence analyses confirmed it as a predicted canine mesothelin transcript from the genome sequence database. Comparative sequence analysis of the deduced amino acid sequence of the expressed canine mesothelin demonstrated molecular signature similarities with the human mesothelin. However, the pre-sequence of canine mesothelin lacks the mature megakaryocyte potentiating factor (MPF) portion, which is typically cleaved post-translationally with furin. Mesothelin expression was quantified via qPCR revealing low levels in the mesothelial and lung tissues, with negligible expression in the other major organs. Canine mesothelin exhibited significantly higher expression in the canine mesotheliomas than in the noncancerous tissues. Moreover, analysis of clinical samples using qPCR demonstrated markedly elevated mesothelin expression in canine mesotheliomas compared to non-mesothelioma cases.

Discussion And Conclusion: Canine mesothelin exhibits molecular and biological characteristics akin to human mesothelin. It could serve as a vital biomarker for diagnosing canine mesotheliomas, applicable to both tissue- and effusion-based samples.

Copyright © 2024 Nabeta, Kanaya, Shimada, Matsuura, Yoshimura, Oyamada, Azakami, Furuya and Uchide.

In plain English

This laboratory study measured activity of the gene for mesothelin, a protein used as a mesothelioma marker in people, to see whether it could help diagnose mesothelioma in dogs. It did not study asbestos or any other exposure. The authors detected mesothelin RNA in cultured canine mesothelioma cells and sequenced a 534-base-pair fragment copied from it. The predicted protein resembled human mesothelin but lacked the part corresponding to human megakaryocyte potentiating factor (MPF). In organs from four tumor-free beagles, expression was low in pleura, lung and pericardium and negligible elsewhere. Four mesothelioma tissue samples showed a mean relative level of 9.40 (95% confidence interval 7.73 to 11.43), compared with 0.016 (0.012 to 0.021) in 24 other tumor samples. Nine effusions from dogs with mesothelioma averaged 6.99 (5.82 to 8.40), against 0.65 (0.55 to 0.77) in 10 effusions from dogs with other conditions. The authors called this a preliminary study. They concluded that mesothelin could serve as a diagnostic biomarker for canine mesothelioma in tissue and effusion samples, noting the small number of mesothelioma cases.

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 (detection of mesothelin RNA and sequencing of an RT-PCR product from cultured canine mesothelioma cells, and quantitative PCR comparison of mesothelin gene expression in tissue and effusion samples from dogs); the authors call it a preliminary study
• Who was studied: Organ tissues (n = 24) from four beagle dogs without tumors. Clinical tumor tissues and effusions from 40 dogs (various breeds, 2 to 18 years old) collected between 2018 and 2023 in Japan: 28 tumor tissue specimens (4 mesotheliomas, 24 other tumors), and 19 effusion samples (pleural, pericardial and peritoneal), of which 9 were from dogs with mesothelioma and 10 from dogs with other conditions. Also cultured cells from canine pericardial mesothelioma.
• Exposure: Not applicable: no asbestos or other exposure was studied. The study measured mesothelin gene expression, relative to the reference gene HPRT1.
• Main results:
  • A 534-base-pair RT-PCR product from cultured canine mesothelioma cells was sequenced and matched canine mesothelin
  • The predicted canine mesothelin protein lacked the region corresponding to human megakaryocyte potentiating factor (MPF)
  • In dogs without tumors, mesothelin expression was detected in pleura (mean 1.78; 95% CI 1.60 to 1.98), lung (mean 1.70; 95% CI 1.59 to 1.84) and pericardium (mean 1.02; 95% CI 0.98 to 1.06), and was negligible (mean less than 0.1) in other major organs
  • The 4 mesothelioma tumor tissues showed significantly higher mesothelin expression (mean 9.40; 95% CI 7.73 to 11.43) than the 24 non-mesothelioma tumors (mean 0.016; 95% CI 0.012 to 0.021), p less than 0.001
  • Among non-mesothelioma tumors, epithelial tumors (mean 0.037; 95% CI 0.025 to 0.054) had significantly higher mesothelin levels than mesenchymal tumors (mean 0.006; 95% CI 0.004 to 0.008), p = 0.045
  • Malignant and benign non-mesothelioma tumors had similar mesothelin levels (p = 0.656)
  • The 9 effusions from dogs with mesothelioma had significantly higher mesothelin expression (mean 6.99; 95% CI 5.82 to 8.40) than the 10 effusions from dogs without mesothelioma (mean 0.65; 95% CI 0.55 to 0.77), p less than 0.001
  • Among non-mesothelioma effusions, the lymphoma effusion showed the highest mesothelin expression (2.63)
• The authors' conclusion: The authors concluded that canine and human mesothelin share molecular and biological similarities. They concluded that mesothelin could serve as a diagnostic biomarker of canine mesotheliomas in tissue and effusion samples, and that further studies are warranted to confirm the findings.
• Limitations the authors state:
  • Only a limited number of mesothelioma cases were included, so further studies are needed to confirm the findings
  • There were few cases in each non-mesothelioma malignancy group, which the authors say likely contributed to the lack of significant differences among them

Topics

Medical terms in this study, explained in our Lexicon: Mesothelin, Mesothelioma, Biomarker.

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