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Updated: Jul 8, 2026
Generation and Expansion of Primary, Malignant Pleural Mesothelioma Tumor Lines
Published on: April 21, 2022
Aberrant splicing and protease involvement in mesothelin release from epithelioid mesothelioma cells
Carole Sapede1, Anne Gauvrit, Isabelle Barbieux
1INSERM U601, Département de Recherche en Cancérologie, Institut de Biologie/CHU, 44093 Nantes, France.
Abstract:
Elevated amounts of soluble mesothelin-related proteins (SMRP) have already been reported in sera and pleural effusions from mesothelioma patients, providing a useful diagnostic marker for malignant pleural mesothelioma (MPM). However, the origin of SMRP is not yet understood. Production of SMRP could be related to abnormal splicing events leading to synthesis of a secreted protein (release) or to an enzymatic cleavage from membrane-bound mesothelin (ectodomain shedding). To test these hypotheses, we used a panel of mesothelioma cells established in culture from pleural effusions of MPM patients. Our in vitro results confirmed specific mesothelin expression and SMRP production in supernatants from epithelioid MPM cell lines, thus providing a relevant cellular model to study soluble mesothelin production mechanisms. The expression of mesothelin-encoding RNA variants was screened by reverse transcription-polymerase chain reaction experiments. Protease involvement in mesothelin cleavage from the cellular surface was investigated by treatment of MPM cells with GM6001, a broad-spectrum MMP- and ADAM-family inhibitor. GM6001 treatment significantly impaired SMRP production by MPM cell lines, in favor of an enzymatic-mediated shedding process. In addition, a splice variant transcript of mesothelin (variant 3) was detected in these MPM cell lines, in accordance with the release of a secreted part of the protein. Our results indicate that both mechanisms could be implicated in soluble mesothelin production by epithelioid mesothelioma cells.
Insights
Soluble mesothelin-related proteins (SMRP) in mesothelioma patients may originate from abnormal splicing or enzymatic shedding. This study used mesothelioma cell lines to investigate these production mechanisms.
Area of Science:
- Oncology
- Biochemistry
- Molecular Biology
Background:
- Soluble mesothelin-related proteins (SMRP) are elevated in mesothelioma patients, serving as a diagnostic marker.
- The precise mechanisms of SMRP production remain unclear.
- Potential mechanisms include alternative splicing or ectodomain shedding of membrane-bound mesothelin.
Purpose of the Study:
- To investigate the cellular origins and production mechanisms of SMRP in malignant pleural mesothelioma (MPM).
- To determine whether SMRP is produced via protein release through splicing or enzymatic cleavage from the cell surface.
- To establish a relevant in vitro model for studying SMRP production.
Main Methods:
- Utilized a panel of mesothelioma cell lines derived from patient pleural effusions.
- Analyzed SMRP production in cell culture supernatants.
- Screened for mesothelin-encoding RNA variants using reverse transcription-polymerase chain reaction (RT-PCR).
- Investigated protease involvement by treating cells with GM6001, an MMP and ADAM inhibitor.
Main Results:
- Confirmed mesothelin expression and SMRP production in epithelioid MPM cell line supernatants.
- GM6001 treatment significantly reduced SMRP production, supporting an enzymatic shedding process.
- Detected a mesothelin splice variant transcript (variant 3) in MPM cell lines.
- Both ectodomain shedding and potential release via splicing appear implicated in SMRP production.
Conclusions:
- Epithelioid mesothelioma cells produce SMRP through a combination of enzymatic shedding and possibly alternative splicing.
- These findings provide insights into the molecular basis of SMRP production in MPM.
- The established cell culture model is valuable for further research into SMRP regulation.
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