The ferroptosis inducing compounds RSL3 and ML162 are not direct inhibitors of GPX4 but of TXNRD1
Dorian M. Cheff,
Chuying Huang,
Karoline C. Scholzen,
Radosveta Gencheva,
Michael H. Ronzetti,
Qing Cheng,
Matthew D. Hall,
Elias S.J. Arnér
Affiliations
Dorian M. Cheff
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden; Early Translation Branch, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States
Chuying Huang
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden
Karoline C. Scholzen
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden
Radosveta Gencheva
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden
Michael H. Ronzetti
Early Translation Branch, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States
Qing Cheng
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden
Matthew D. Hall
Early Translation Branch, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States
Elias S.J. Arnér
Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden; Department of Selenoprotein Research and the National Tumor Biology Laboratory, National Institute of Oncology, Budapest, Hungary; Corresponding author. Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
Ferroptosis is defined as cell death triggered by iron-dependent lipid peroxidation that is preventable by antioxidant compounds such as ferrostatin-1. Endogenous suppressors of ferroptosis include FSP-1 and the selenoprotein GPX4, the latter of which directly enzymatically reduces lipid hydroperoxides. Small molecules that trigger ferroptosis include RSL3, ML162, and ML210; these compounds are often used in studies of ferroptosis and are generally considered as GPX4 inhibitors. Here, we found that RSL3 and ML162 completely lack capacity of inhibiting the enzymatic activity of recombinant selenoprotein GPX4. Surprisingly, these compounds were instead found to be efficient inhibitors of another selenoprotein, TXNRD1. Other known inhibitors of TXNRD1, including auranofin, TRi-1 and TRi-2, are also efficient inducers of cell death but that cell death could not be suppressed with ferrostatin-1. Our results collectively suggest that prior studies using RSL3 and ML162 may need to be reevaluated in the context of ferroptosis with regards to additional enzyme targets and mechanisms of action that may be involved.
