Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner
Madlen Meinert,
Christina Jessen,
Anita Hufnagel,
Julia Katharina Charlotte Kreß,
Mychal Burnworth,
Theo Däubler,
Till Gallasch,
Thamara Nishida Xavier da Silva,
Ancély Ferreira dos Santos,
Carsten Patrick Ade,
Werner Schmitz,
Susanne Kneitz,
José Pedro Friedmann Angeli,
Svenja Meierjohann
Affiliations
Madlen Meinert
Department of Physiological Chemistry, University of Würzburg, Würzburg, Germany
Christina Jessen
Institute of Pathology, University of Würzburg, Würzburg, Germany
Anita Hufnagel
Institute of Pathology, University of Würzburg, Würzburg, Germany
Julia Katharina Charlotte Kreß
Institute of Pathology, University of Würzburg, Würzburg, Germany
Mychal Burnworth
Institute of Pathology, University of Würzburg, Würzburg, Germany
Theo Däubler
Institute of Pathology, University of Würzburg, Würzburg, Germany
Till Gallasch
Institute of Pathology, University of Würzburg, Würzburg, Germany
Thamara Nishida Xavier da Silva
Rudolf-Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
Ancély Ferreira dos Santos
Rudolf-Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
Carsten Patrick Ade
Department of Biochemistry and Molecular Biology, University of Würzburg, Würzburg, Germany
Werner Schmitz
Department of Biochemistry and Molecular Biology, University of Würzburg, Würzburg, Germany
Susanne Kneitz
Department of Biochemistry and Cell Biology, University of Würzburg, Würzburg, Germany
José Pedro Friedmann Angeli
Rudolf-Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
Svenja Meierjohann
Department of Physiological Chemistry, University of Würzburg, Würzburg, Germany; Institute of Pathology, University of Würzburg, Würzburg, Germany; Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, Würzburg, Germany; Corresponding author. Institute of Pathology, University of Würzburg, Würzburg, Germany.
The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; BrafCA; Ptenlox/+ melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2.
