cells Article ROS Overproduction Sensitises Myeloma Cells to Bortezomib-Induced Apoptosis and Alleviates Tumour Microenvironment-Mediated Cell Resistance Mélody Caillot 1 , Florence Zylbersztejn 1, Elsa Maitre 1,2 ,Jérôme Bourgeais 3, Olivier Hérault 3,4 and Brigitte Sola 1,* 1 INSERM, UNICAEN, Normandie Université, F-14000 Caen, France;
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[email protected] (E.M.) 2 Laboratoire d’Hématologie, CHU Côte de Nacre, F-14000 Caen, France 3 Service d’Hématologie Biologique, CHRU de Tours, F-37000 Tours, France;
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[email protected] (O.H.) 4 LNox, CNRS, Université de Tours, F-37000 Tours, France * Correspondence:
[email protected]; Tel.: +33-2-3156-8210 Received: 15 September 2020; Accepted: 25 October 2020; Published: 26 October 2020 Abstract: Multiple myeloma (MM) is a plasma cell neoplasm that remains incurable due to innate or acquired resistance. Although MM cells produce high intracellular levels of reactive oxygen species (ROS), we hypothesised that they could remain sensitive to ROS unbalance. We tested if the inhibition of ROS, on one hand, or the overproduction of ROS, on the other, could (re)sensitise cells to bortezomib (BTZ). Two drugs were used in a panel of MM cell lines with various responses to BTZ: VAS3947 (VAS), an inhibitor of NADPH oxidase and auranofin (AUR), an inhibitor of thioredoxin reductase (TXNRD1), an antioxidant enzyme overexpressed in MM cells. We used several culture models: in suspension, on a fibronectin layer, in coculture with HS-5 mesenchymal cells, and/or in 3-D culture (or spheroids) to study the response of MM primary cells and cell lines.