MSLN gene silencing has an anti-malignant effect on cell lines overexpressing mesothelin deriving from malignant pleural mesothelioma

Our plain-English summary of MSLN gene silencing has an anti-malignant effect on cell lines overexpressing mesothelin deriving from malignant pleural mesothelioma, by O. Melaiu, J. Stebbing, Y. Lombardo, et al (PloS One, 2014).

The study

• Authors: O. Melaiu, J. Stebbing, Y. Lombardo, E. Bracci, N. Uehara, A. Bonotti, A. Cristaudo, R. Foddis, L. Mutti, R. Barale, F. Gemignani, G. Giamas, S. Landi
• Journal: PloS One
• Published: 2014;9(1):e85935
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Genes involved in the carcinogenetic mechanisms underlying malignant pleural mesothelioma (MPM) are still poorly characterized. So far, mesothelin (MSLN) has aroused the most interest. It encodes for a membrane glycoprotein, frequently over-expressed in various malignancies such as MPM, and ovarian and pancreatic cancers. It has been proposed as a diagnostic and immunotherapeutic target with promising results. However, an alternative therapeutic approach seems to rise, whereby synthetic molecules, such as antisense oligonucleotides, could be used to inhibit MSLN activity. To date, such a gene-level inhibition has been attempted in two studies only, both on pancreatic and ovarian carcinoma cell lines, with the use of silencing RNA approaches. With regard to MPM, only one cell line (H2373) has been employed to study the effects of MSLN depletion. Indeed, the knowledge on the role of MSLN in MPM needs expanding. Accordingly, we investigated the expression of MSLN in a panel of three MPM cell lines, i.e., NCI-H28, Mero-14, and IstMes2; one non-MPM cell line was used as reference (Met5A). MSLN knock-down experiments on MSLN-overexpressing cells were also performed through silencing RNA (siRNA) to verify whether previous findings could be generalized to a different set of cell cultures. In agreement with previous studies, transient MSLN-silencing caused decreased proliferation rate and reduced invasive capacity and sphere formation in MSLN-overexpressing Mero-14 cells. Moreover, MSLN-siRNA combined with cisplatin, triggered a marked increase in apoptosis and a decrease in proliferation as compared to cells treated with each agent alone, thereby suggesting a sensitizing effect of siRNA towards cisplatin. In summary, our findings confirm that MSLN should be considered a key molecular target for novel gene-based targeted therapies of cancer.

In plain English

This laboratory study used cancer cells grown in dishes; it did not study people or asbestos exposure. The authors measured the protein mesothelin (MSLN) in three malignant pleural mesothelioma cell lines (Mero-14, IstMes2, NCI-H28) and a non-malignant mesothelial line, Met5A. Mero-14 had the highest levels; NCI-H28 showed none. The authors then lowered MSLN in Mero-14 cells with silencing RNA, a temporary method; the version they used reduced MSLN by more than 95%. Compared with control-treated cells, silenced cells grew more slowly (an 86% decrease by day 6), formed smaller spheres, had fewer dividing cells and invaded less through a membrane; migration did not differ significantly. Silencing alone did not raise cell-death markers. Combined with the drug cisplatin, silencing completely stopped growth and increased cell-death activity compared with cisplatin plus control treatment, although the statistical test for a combined effect on growth was not significant. Adding silencing to imatinib or gemcitabine gave no significant further growth reduction. The authors concluded that MSLN should be considered a key target for new gene-based cancer therapies.

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 (in vitro) cell-line experiment using transient gene silencing (silencing RNA, siRNA)
• Who was studied: Three human malignant pleural mesothelioma (MPM) cell lines (NCI-H28, Mero-14, IstMes2) and one non-MPM immortalized mesothelial cell line (Met5A) used as reference; silencing experiments were done in Mero-14 cells. No human subjects.
• Exposure: No asbestos exposure was studied. Mero-14 cells were treated with silencing RNA against MSLN (siMSLN-1, 40 nM) or a non-targeting control (siCtrl), alone or combined with cisplatin, imatinib or gemcitabine.
• Main results:
  • Among the cell lines, Mero-14 showed the highest MSLN expression (P = 0.02); no MSLN was observed in NCI-H28.
  • The silencing RNA chosen for further experiments (siMSLN-1) reduced MSLN by more than 95% in Mero-14 cells; the silencing was transient.
  • In Mero-14 cells, MSLN silencing significantly reduced proliferation (p less than 0.05) from the third day compared with control siRNA, reaching an 86% decrease at day 6.
  • In 3D culture, about 72.5% of control-treated Mero-14 spheres and only 22.5% of MSLN-silenced spheres were in the larger size class.
  • The share of Mero-14 cells in the S+G2+M phases of the cell cycle was slightly reduced after MSLN silencing (P = 0.033).
  • MSLN silencing alone did not change the activity of apoptosis markers caspase-3 and -7 in Mero-14 cells at 48 h.
  • Migration of Mero-14 cells did not differ significantly after silencing.
  • Invasion of Mero-14 cells was significantly reduced 48 h after MSLN silencing (P = 0.0044).
  • In Mero-14 cells, cisplatin alone reduced proliferation by 26% (not statistically significant); combined with MSLN silencing, growth was completely inhibited.
  • In the statistical model for proliferation at day 6, the interaction term for the combined effect of cisplatin and MSLN silencing was not statistically significant (P = 0.145).
  • In Mero-14 cells, MSLN silencing plus cisplatin markedly increased apoptosis (caspase activity) compared with cisplatin plus control siRNA (P = 0.018).
  • In Mero-14 cultures treated with imatinib, gemcitabine, or both, adding MSLN silencing gave further reductions in proliferation that were not statistically significant (p = 0.21, p = 0.38, p = 0.17).
• The authors' conclusion: The authors concluded that MSLN should be considered a key molecular target for novel gene-based targeted cancer therapies, not only a diagnostic marker or immunotherapy target.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelin, Pleural Mesothelioma, Glycoprotein, Carcinoma, Cisplatin, Apoptosis.

Related studies

• A common polymorphism within MSLN affects miR-611 binding site and soluble mesothelin levels in healthy people — S. Garritano, C. De Santi, et al. (2014)
• Expression status of candidate genes in mesothelioma tissues and cell lines — O. Melaiu, E. Melissari, et al. (2015)
• Megakaryocytic potentiating factor and mature mesothelin stimulate the growth of a lung cancer cell line in the peritoneal cavity of mice — J. Zhang, T.K. Bera, et al. (2014)
• Comparison of the diagnostic accuracy of the MSLN gene products, mesothelin and megakaryocyte potentiating factor, as biomarkers for mesothelioma in pleural effusions and serum — J. Creaney, S. Sneddon, et al. (2013)
• Pan-cancer profiles of mesothelin (MSLN) unveil diagnostic potential and therapeutic targetability of pancreatic adenocarcinoma — M.R. Sheikh, B. Mistry, et al. (2026)
• Mesothelin promoter variants are associated with increased soluble mesothelin-related peptide levels in asbestos-exposed individuals — C. De Santi, P. Pucci, et al. (2017)

Browse more research in PloS One, or return to medical research.