Recent data suggest that rhabdomyosarcoma (RMS) cells might be vulnerable to oxidative stress‐induced cell death. Here, we show that RMS are susceptible to cell death induced by Erastin, an inhibitor of the glutamate/cystine antiporter xc− that can increase reactive oxygen species (ROS) production via glutathione (GSH) depletion. Prior to cell death, Erastin caused GSH depletion, ROS production and lipid peroxidation. Importantly, pharmacological inhibitors of lipid peroxidation (i.e., Ferrostatin‐1, Liproxstatin‐1), ROS scavengers (i.e., α‐Tocopherol, GSH) and the iron chelator Deferoxamine inhibited ROS accumulation, lipid peroxidation and cell death, consistent with ferroptosis. Interestingly, the broad‐spectrum protein kinase C (PKC) inhibitor Bisindolylmaleimide I as well as the PKCα‐ and β‐selective inhibitor Gö6976 significantly reduced Erastin‐induced cell death. Similarly, genetic knockdown of PKCα significantly protected RMS cells from Erastin‐induced cell death. Furthermore, the broad‐spectrum nicotinamide adenine dinucleotide phosphate‐oxidase (NOX) inhibitor Diphenyleneiodonium and the selective NOX1/4 isoform inhibitor GKT137831 significantly decreased Erastin‐stimulated ROS, lipid ROS and cell death. These data provide new insights into the molecular mechanisms of ferroptosis in RMS, contributing to the development of new redox‐based treatment strategies.

Rhabdomyosarcoma (RMS) cells have recently been reported to be sensitive to oxidative stress. Therefore, we investigated whether concomitant inhibition of the two main antioxidant defense pathways, that is, the thioredoxin (TRX) and the glutathione (GSH) systems, presents a new strategy to trigger cell death in RMS. In this study, we discover that GSH-depleting agents, i.e. γ-glutamylcysteine synthetase inhibitor, buthionine sulfoximine (BSO) or the cystine/glutamate antiporter inhibitor erastin (ERA), synergize with thioredoxin reductase (TrxR) inhibitor auranofin (AUR) to induce cell death in RMS cells. Interestingly, AUR causes accumulation of ubiquitinated proteins when combined with BSO or ERA, in line with recent reports showing that AUR inhibits the proteasome besides TrxR. Consistently, AUR/BSO or AUR/ERA cotreatment increases ubiquitination and expression of the short-lived proteins NOXA and MCL-1, accompanied by increased binding of NOXA to MCL-1. Notably, NOXA knockdown significantly rescues RMS cells from AUR/BSO- or AUR/ERA-induced cell death. In addition, AUR acts together with BSO or ERA to stimulate BAX/BAK and caspase activation. Of note, BSO or ERA abolish the AUR-stimulated increase in GSH levels, leading to reduced GSH levels upon cotreatment. Although AUR/BSO or AUR/ERA cotreatment enhances reactive oxygen species (ROS) production, only thiol-containing antioxidants (i.e., N-acetylcysteine (NAC), GSH), but not the non-thiol-containing ROS scavenger α-Tocopherol consistently suppress AUR/BSO- and AUR/ERA-stimulated cell death in both cell lines. Importantly, re-supply of GSH or its precursor NAC completely prevents AUR/ERA- and AUR/BSO-induced accumulation of ubiquitinated proteins, NOXA upregulation and cell death, indicating that GSH depletion rather than ROS production is critical for AUR/BSO- or AUR/ERA-mediated cell death. Thus, by demonstrating that GSH-depleting agents enhance the antitumor activity of AUR, we highlight new treatment options for RMS by targeting the redox homeostasis.

Zusammenfassung. Kinder psychisch belasteter Eltern bilden eine Hochrisikogruppe für die Entwicklung psychischer Auffälligkeiten und weisen im Vergleich zur Gesamtbevölkerung eine geringere gesundheitsbezogene Lebensqualität auf. Für die Entwicklung spezifischer präventiver und therapeutischer Unterstützungsprogramme wurden veränderungssensitive Faktoren der psychischen Gesunderhaltung in einer Stichprobe von psychisch belasteten Eltern und ihren 13- bis 17-jährigen Kindern untersucht. Es wurden signifikante Prädiktoren aus den drei Bereichen personale, familiäre und soziale Ressourcen sowohl für die psychische Gesundheit als auch für die gesundheitsbezogene Lebensqualität identifiziert. Für psychische Gesundheit waren dies soziale Kompetenz, familiäre Unterstützung und Schulklima, für Lebensqualität Selbstwirksamkeitserwartung, Optimismus, Familienklima und Schulklima. Die Ergebnisse machen deutlich, dass personale, familiäre und soziale Ressourcen für Kinder psychisch belasteter Eltern von großer Bedeutung sind für die psychische Gesunderhaltung. Sie profitieren insbesondere von Ressourcen, die außerhalb der Familie angesiedelt sind, wie einer guten schulischen Integration. Spezifische Interventionsprogramme für Kinder psychisch belasteter Eltern sollten neben der persönlichen und familiären deshalb unbedingt auch die schulische Situation berücksichtigen.