BAG2, MAD2L1, and MDK are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma

Our plain-English summary of BAG2, MAD2L1, and MDK are cancer-driver genes and candidate targets for novel therapies in malignant pleural mesothelioma, by L. Bisceglia, F. Morani, L. Guerrieri, et al (Cancer Gene Therapy, 2024).

The study

• Authors: L. Bisceglia, F. Morani, L. Guerrieri, E. Santoni-Rugiu, P. Çakılkaya, C. Scatena, R. Scarpitta, L.H. Engelholm, N. Behrendt, F. Gemignani, S. Landi
• Journal: Cancer Gene Therapy
• Published: 2024;31(11):1708-1720
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is an aggressive cancer with a poor prognosis and the identification of novel druggable targets is urgently needed. In previous work, we identified 15 deregulated genes highly expressed in MPM tissues and correlated with a poor prognosis. Here, we validated these findings on an independent dataset of 211 MPM patients (EGA, EGAD00001001915) and on a panel of MPM cell lines. Furthermore, we carried out in vitro gene silencing followed by proliferation, cytotoxicity, caspase, and migration assays to define whether these targets could be cancer-driver genes. We ended up with three novel candidates (i.e., BAG2, MAD2L1, and MDK), whose encoded proteins could be exploited as druggable targets. Moreover, of novelty, immunohistochemistry analysis on tissues revealed that the overexpression of BAG2 and MAD2L1 could differentiate MPM from RMP patients. Furthermore, when we tested Neratinib (an inhibitor of MAD2L1) and iMDK (an inhibitor of MDK) we found that they are effective on MPM cells, in part phenocopying the effects of MAD2L1 and MDK gene silencing. In summary, in the present work, we report that BAG2, MAD2L1, and MDK are bona fide cancer-driver genes for MPM worth of further studies.

© 2024. The Author(s).

In plain English

This laboratory study sought genes that may drive malignant pleural mesothelioma (MPM). The authors rechecked 15 genes they had earlier found overexpressed in MPM, using public RNA data from 211 patients. Fourteen were confirmed as overexpressed. In epithelioid cases, higher expression of nine was linked to shorter survival. Of six genes the authors tried to silence in cell lines, only BAG2, MAD2L1 and MDK were successfully silenced. Silencing them reduced the viability of MSTO cells, not MeT-5A cells, and raised caspase 3/7 activity, a sign of apoptotic cell death, in MSTO cells. Neratinib, a breast cancer drug reported to inhibit MAD2L1, reduced cell growth in both cell lines. iMDK, an experimental MDK inhibitor, did so only at its highest dose. Both drugs increased cell death. In tissue from 28 MPM patients, BAG2 and MAD2L1 levels were higher than in tissue from 12 patients with non-cancerous reactive mesothelial proliferation. MDK levels did not differ significantly between the groups. The authors concluded that BAG2 and MAD2L1 are strong candidates as cancer drivers. As a limitation, they noted that the cell experiments relied on one mesothelioma cell line, MSTO. Asbestos exposure was not studied.

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 combining analysis of a public gene-expression dataset, cell-line experiments (gene silencing and drug treatment), and immunohistochemistry on patient tissue samples
• Who was studied: RNA-seq data from 211 MPM patients in the European Genome-phenome Archive (141 epithelioid, 62 biphasic, 7 sarcomatoid, 1 desmoplastic), compared with 3 normal lung samples; cell lines MeT-5A and MSTO-211H; 40 tissue specimens from 28 MPM patients collected 2017 to 2020 at Rigshospitalet, Copenhagen, Denmark; 13 tissue samples from 12 patients with reactive mesothelial proliferation (RMP) as non-neoplastic controls
• Exposure: No asbestos or other environmental exposure was studied. The experimental treatments were silencing of genes with siRNA, and the drugs iMDK (7.5, 15 and 50 µM) and Neratinib (10, 20 and 40 µM) applied to cell lines
• Main results:
  • In the independent dataset of 211 MPM patients, 14 of the 15 previously identified genes were confirmed as overexpressed. TRAF2 was the exception.
  • Among epithelioid MPM cases, higher expression of nine genes (BAG2, CIT, KIF23, MAD2L1, MDK, PODXL, SPARC, TNNT1, UHRF1) was statistically significantly associated with shorter overall survival. PRSS23 was not.
  • Six candidate genes were selected for silencing: BAG2, CIT, MAD2L1, MDK, PODXL and TNNT1. Only BAG2, MAD2L1 and MDK were successfully silenced. The other three were not taken further.
  • Silencing BAG2, MAD2L1 or MDK statistically significantly reduced viability in MSTO cells but not in MeT-5A cells. It also increased caspase 3/7 activation in MSTO cells. Cell migration did not change significantly.
  • Neratinib (10 up to 40 µM) produced a dose-dependent reduction in proliferation of both cell lines. iMDK was effective on both lines only at 50 µM. Both drugs increased the rate of dead cells. The increase in caspase 3/7 activation was not statistically significant.
  • The effect of Neratinib was similar whether or not EGFR was silenced. HER2 was reported as not expressed in MSTO cells.
  • In patient tissues, BAG2 was statistically significantly higher in all MPM subtypes than in RMP. MAD2L1 was significantly higher only in epithelioid MPM. MDK showed no statistically significant difference between groups.
  • For distinguishing MPM from RMP, BAG2 had an AUC of 0.883 (sensitivity 0.77, specificity 1, threshold score 60).
  • For distinguishing MPM from RMP, MAD2L1 had an AUC of 0.797 (sensitivity 0.69, specificity 0.77, threshold score 90).
• The authors' conclusion: The authors concluded that BAG2 and MAD2L1 are strong candidates as drivers of pleural tumorigenesis. They also concluded that Neratinib, an already approved drug, conceivably has a rationale for being repurposed for MPM and warrants further investigation.
• Limitations the authors state:
  • The authors described as a limitation that the in vitro experiments relied on MSTO cells as the single malignant model. MSTO was the only screened line in which all three target genes were overexpressed. MeT-5A cells were also used as a comparison line.
  • No specific drugs were available to inhibit BAG2 or MAD2L1. iMDK is experimental and not approved, and Neratinib was approved for inhibiting HER1 and HER2.
  • Normal pleural tissue was not available as a reference in the databases used to identify the genes, which may have introduced selection bias.

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, Prognosis, Immunohistochemistry.

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