Bisecting-GlcNAc on Asn388 is characteristic to ERC/mesothelin expressed on epithelioid mesothelioma cells

Our plain-English summary of Bisecting-GlcNAc on Asn388 is characteristic to ERC/mesothelin expressed on epithelioid mesothelioma cells, by H. Fujihira, D. Takakura, A. Matsuda, et al (Journal of Biochemistry, 2021).

The study

• Authors: H. Fujihira, D. Takakura, A. Matsuda, M. Abe, M. Miyazaki, T. Nakagawa, K. Kajino, K. Denda-Nagai, M. Noji, O. Hino, T. Irimura
• Journal: Journal of Biochemistry
• Published: 2021;170(3):317-326
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Mesothelioma is a highly aggressive tumour associated with asbestos exposure and is histologically classified into three types: epithelioid-type, sarcomatoid-type and biphasic-type. The prognosis of mesothelioma patients is poor and there is no effective molecular-targeting therapy as yet. ERC/mesothelin is a glycoprotein that is highly expressed on several types of cancers including epithelioid mesothelioma, but also expressed on normal mesothelial cells. This is a predicted reason why there is no clinically approved therapeutic antibody targeting ERC/mesothelin. In the present study, we focussed on the differential glycosylation between ERC/mesothelin present on epithelioid mesothelioma and that on normal mesothelial cells and aimed to reveal a distinct feature of epithelioid mesothelioma cells. Lectin microarray analysis of ERC/mesothelin using cells and patient specimens showed significantly stronger binding of PHA-E4 lectin, which recognizes complex-type N-glycans having a so-called bisecting-GlcNAc structure, to ERC/mesothelin from epithelioid mesothelioma cells than that from normal mesothelial cells. Further, liquid chromatography/mass spectrometry analysis on ERC/mesothelin from epithelioid mesothelioma cells confirmed the presence of a bisecting-GlcNAc attached to Asn388 of ERC/mesothelin. These results suggest that this glycoproteome could serve as a potential target for the generation of a highly selective and safe therapeutic antibody for epithelioid mesothelioma.

© The Author(s) 2021. Published by Oxford University Press on behalf of the Japanese Biochemical Society.

In plain English

This laboratory study examined sugar chains (glycans) attached to ERC/mesothelin, a protein found on epithelioid mesothelioma cells and also on normal mesothelial cells. It did not study asbestos exposure. The authors compared ERC/mesothelin from two epithelioid mesothelioma cell lines (H226 and MESO-4) with that from an immortalized non-tumorous mesothelial cell line (MeT-5A) and primary normal mesothelial cells (MES-F). They also tested tissue from 4 epithelioid mesothelioma patients. A lectin called PHA-E4, which recognizes a sugar structure called bisecting-GlcNAc, bound significantly more strongly to ERC/mesothelin from the mesothelioma cells than to that from normal mesothelial cells. Its binding was also high in the patient samples. In H226 cells, mass spectrometry found bisecting-GlcNAc mostly at position Asn388, making up 11% of the glycans there. It made up 2.7% at Asn496 and was absent at Asn523. The authors concluded that this feature could serve as a potential target for a highly selective and safe therapeutic antibody for epithelioid mesothelioma. They said further studies are needed to explain the mechanism.

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 of cultured cells and archived patient tissue, using lectin microarray, lectin precipitation and liquid chromatography/mass spectrometry
• Who was studied: Two epithelioid mesothelioma cell lines (H226, MESO-4), an immortalized non-tumorous mesothelial cell line (MeT-5A) and primary normal mesothelial cells (MES-F). The study also used archived paraffin-embedded tissue sections from 4 epithelioid mesothelioma patients, under approval from Juntendo University, Japan.
• Exposure: Asbestos exposure was not studied. The study compared the glycans on the protein ERC/mesothelin from epithelioid mesothelioma cells with those from normal mesothelial cells.
• Main results:
  • In the lectin microarray, PHA-E4 lectin showed higher reactivity with ERC/mesothelin from the epithelioid mesothelioma cell lines than with ERC/mesothelin from normal mesothelial cells.
  • RCA120 lectin showed lower reactivity with ERC/mesothelin from the epithelioid mesothelioma cell lines than with ERC/mesothelin from normal mesothelial primary culture cells.
  • PHA-E4 lectin pulled down a greater portion of ERC/mesothelin from H226 and MESO-4 mesothelioma cells than from MES-F normal mesothelial cells.
  • After N-glycans were removed from H226 ERC/mesothelin with the enzyme PNGase F, almost all lectin signals, including PHA-E4, disappeared.
  • PHA-E4 binding was also high for ERC/mesothelin taken from the epithelioid mesothelioma patient specimens.
  • The authors measured PHA-E4 binding relative to ACG lectin. On this measure, binding was significantly stronger for ERC/mesothelin from epithelioid mesothelioma cells than for ERC/mesothelin from normal mesothelial cells.
  • In ERC/mesothelin from H226 cells, glycans estimated to contain bisecting-GlcNAc were most abundant at Asn388, making up 11% of the N-glycans at that site.
  • At Asn496 of ERC/mesothelin from H226 cells, glycans with bisecting-GlcNAc made up 2.7% of the N-glycans at that site.
  • None of the glycans attached at Asn523 of ERC/mesothelin from H226 cells contained bisecting-GlcNAc.
  • Expression of the enzyme GnT-III (MGAT3) was significantly higher in the epithelioid mesothelioma cells (H226, MESO-4) than in the normal mesothelial cells (MeT-5A). These results are reported in supplementary data.
  • In what the authors called preliminary results, MESO-4 cells with MGAT3 knocked out showed a reduced rate of cell proliferation.
• The authors' conclusion: The authors concluded that ERC/mesothelin carrying bisecting-GlcNAc at Asn388 could serve as a potential target for developing a highly selective and safe therapeutic antibody for epithelioid mesothelioma.
• Limitations the authors state:
  • The authors stated that further studies are needed to explain why bisecting-GlcNAc forms mainly at Asn388 of ERC/mesothelin.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelin, Epithelioid, Mesothelioma, Asbestos Exposure, Sarcomatoid, Biphasic Mesothelioma, Prognosis, Glycoprotein.

Related studies

• ERC/mesothelin is expressed in human gastric cancer tissues and cell lines — T. Ito, K. Kajino, et al. (2014)
• A novel PET imaging using ⁶⁴Cu-labeled monoclonal antibody against mesothelin commonly expressed on cancer cells — K. Kobayashi, T. Sasaki, et al. (2015)
• Identification of DAB2 and Intelectin-1 as Novel Positive Immunohistochemical Markers of Epithelioid Mesothelioma by Transcriptome Microarray Analysis for Its Differentiation From Pulmonary Adenocarcinoma — M. Kuraoka, V.J. Amatya, et al. (2017)
• V-domain Ig-containing suppressor of T-cell activation (VISTA), a potentially targetable immune checkpoint molecule, is highly expressed in epithelioid malignant pleural mesothelioma — S. Muller, W. Victoria Lai, et al. (2020)
• Mesothelin expression is a prognostic factor in cholangiocellular carcinoma — R. Nomura, H. Fujii, et al. (2013)
• Suppression of cell death by the secretory form of N-terminal ERC/mesothelin — T. Wang, K. Kajino, et al. (2010)

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