Malignant mesothelioma (MM) is an aggressive type of tumour causing high mortality. One reason for this paradigm may be the existence of a subpopulation of tumour-initiating cells (TICs) that endow MM with drug resistance and recurrence. The objective of this study was to identify and characterise a TIC subpopulation in MM cells, using spheroid cultures, mesospheres, as a model of MM TICs. Mesospheres, typified by the stemness markers CD24, ABCG2 and OCT4, initiated tumours in immunodeficient mice more efficiently than adherent cells. CD24 knock-down cells lost the sphere-forming capacity and featured lower tumorigenicity. Upon serial transplantation, mesospheres were gradually more efficiently tumrigenic with increased level of stem cell markers. We also show that mesospheres feature mitochondrial and metabolic properties similar to those of normal and cancer stem cells. Finally, we show that mesothelioma-initiating cells are highly susceptible to mitochondrially targeted vitamin E succinate. This study documents that mesospheres can be used as a plausible model of mesothelioma-initiating cells and that they can be utilised in the search for efficient agents against MM.

Biomedical Research Center University Hospital Hradec Kralove Hradec Kralove Czech Republic

Department of Molecular and Clinical Sciences Polytechnic University of Marche Ancona Italy

Institute of Biotechnology Academy of Sciences of the Czech Republic Prague Czech Republic

Institute of Molecular Genetics Academy of Sciences of the Czech Republic Prague Czech Republic

School of Medical Science Griffith University Southport Queensland Australia

School of Medical Science Griffith University Southport Queensland Australia; Institute of Biotechnology Academy of Sciences of the Czech Republic Prague Czech Republic

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PLoS One. 2016 May 17;11(5):e0156012. doi: 10.1371/journal.pone.0156012. PubMed

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Alternative assembly of respiratory complex II connects energy stress to metabolic checkpoints