Disulfiram suppresses growth of the malignant pleural mesothelioma cells in part by inducing apoptosis

Our plain-English summary of Disulfiram suppresses growth of the malignant pleural mesothelioma cells in part by inducing apoptosis, by V.T. Cheriyan, Y. Wang, M. Muthu, et al (PloS One, 2014).

The study

• Authors: V.T. Cheriyan, Y. Wang, M. Muthu, S. Jamal, D. Chen, H. Yang, L.A. Polin, A.L. Tarca, H.I. Pass, Q.P. Dou, S. Sharma, A. Wali, A.K. Rishi
• Journal: PloS One
• Published: 2014;9(4):e93711
• Cited by: 38 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Dithiocarbamate compound Disulfiram (DSF) that binds with copper and functions as an inhibitor of aldehyde dehydrogenase is a Food and Drug Administration approved agent for treatment of alcoholism. Copper complexed DSF (DSF-Cu) also possesses anti-tumor and chemosensitizing properties; however, its molecular mechanisms of action remain unclear. Here we investigated malignant pleural mesothelioma (MPM) suppressive effects of DSF-Cu and the molecular mechanisms involved. DSF-Cu inhibited growth of the murine as well as human MPM cells in part by increasing levels of ubiquitinated proteins. DSF-Cu exposure stimulated apoptosis in MPM cells that involved activation of stress-activated protein kinases (SAPKs) p38 and JNK1/2, caspase-3, and cleavage of poly-(ADP-ribose)-polymerase, as well as increased expression of sulfatase 1 and apoptosis transducing CARP-1/CCAR1 protein. Gene-array based analyses revealed that DSF-Cu suppressed cell growth and metastasis-promoting genes including matrix metallopeptidase 3 and 10. DSF inhibited MPM cell growth and survival by upregulating cell cycle inhibitor p27Kip1, IGFBP7, and inhibitors of NF-κB such as ABIN 1 and 2 and Inhibitory κB (IκB)α and β proteins. DSF-Cu promoted cleavage of vimentin, as well as serine-phosphorylation and lysine-63 linked ubiquitination of podoplanin. Administration of 50 mg/kg DSF-Cu by daily i.p injections inhibited growth of murine MPM cell-derived tumors in vivo. Although podoplanin expression often correlates with metastatic disease and poor prognosis, phosphorylation of serines in cytoplasmic domain of podoplanin has recently been shown to interfere with cellular motility and migration signaling. Post-translational modification of podoplanin and cleavage of vimentin by DSF-Cu underscore a metastasis inhibitory property of this agent and together with our in vivo studies underscore its potential as an anti-MPM agent.

In plain English

This was a laboratory study of cells and mice, not of people, and it did not study asbestos exposure. The authors tested disulfiram, a drug approved in the US for treating alcoholism, combined with copper (called DSF-Cu), on malignant pleural mesothelioma cells. In five human mesothelioma cell lines grown in the laboratory, DSF-Cu reduced the number of living cells. One line, H2595, was less sensitive than the others. Treated cells showed signs of apoptosis (programmed cell death), including activation of caspase-3 and caspase-9. They also showed a build-up of ubiquitin-tagged proteins, activation of the stress enzymes JNK and p38, and higher levels of proteins that hold back NF-kB signaling. In female BALB/c mice with tumors grown from mouse mesothelioma AB12 cells (5 mice per group), daily injections of 50 mg/kg DSF-Cu were followed by smaller tumors. Treated tumors averaged 509 mm3 and control tumors 1786 mm3, which the authors called a 71% inhibition. The authors concluded that these proof-of-concept studies underscore the compound's potential against mesothelioma. They noted that the roles of tumor cell type, drug formulation and route of administration remain to be clarified.

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: experiments on mesothelioma cell lines in culture, plus a mouse tumor (allograft) experiment
• Who was studied: Human malignant pleural mesothelioma cell lines (H2373, H2452, H2595, H2714 and H2461 for viability testing, plus H226 and H-Meso), the mouse mesothelioma cell line AB12, and female BALB/c mice implanted with AB12 cells (n = 5 per group)
• Exposure: Disulfiram complexed with copper (DSF-Cu) at a range of doses in cell culture. In mice: 50 mg/kg DSF-Cu by daily intraperitoneal injection, compared with vehicle alone. No asbestos exposure was studied.
• Main results:
  • In human mesothelioma cell lines, the dose printed as 1 mM caused a loss of viability printed as ',70%' (most likely about 70%) in all lines except H2595
  • H2595 cells were less sensitive, with a loss of viability printed as ',30%' at the doses printed as 1 and 5 mM
  • In H2373 cells, DSF-Cu activated caspases-3 and -9 but not caspases-2 or -8. The authors interpreted this as the intrinsic (mitochondria-mediated) apoptosis pathway.
  • DSF-Cu increased ubiquitinated proteins in mesothelioma cells in a dose-dependent manner
  • DSF-Cu activated the stress kinases JNK1/2 and p38 in both mouse and human mesothelioma cells
  • In a gene-array analysis of H2373 cells, DSF-Cu was reported to lower expression of growth- and metastasis-related genes, including MMP3 and MMP10. The article's table lists MMP10 as 3.29-fold down (adjusted p-value 0.055) and MMP3 as 3.5-fold down (adjusted p-value 0.999).
  • DSF-Cu increased levels of IkB alpha and beta, which are inhibitors of NF-kB, in both mouse and human mesothelioma cells
  • DSF-Cu caused cleavage of vimentin in mouse and human mesothelioma cells
  • In mice, control tumors averaged 1786 mm3 and DSF-Cu-treated tumors averaged 509 mm3, reported as a 71% inhibition
  • Average tumor weight was 1.35 g in vehicle-treated mice and 0.33 g in DSF-Cu-treated mice, a 75% reduction (the authors state the data are not shown)
  • TUNEL staining showed more apoptotic cells in a representative tumor from a DSF-Cu-treated mouse than in a control tumor
• The authors' conclusion: The authors concluded that their proof-of-concept studies add to the evidence of anti-cancer properties of DSF-Cu and underscore its potential to inhibit mesothelioma
• Limitations the authors state:
  • The authors state that it remains to be clarified whether the effect in mice depends on the tumor cell type used, and how much the formulation and route of administration contributed
  • The authors state it remains to be clarified whether DSF-Cu reduced activation of receptor tyrosine kinases in mesothelioma cells

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: Pleural Mesothelioma, Apoptosis, Metastasis, Podoplanin (D2-40), Prognosis.

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