MYCN upregulates the transsulfuration pathway to suppress the ferroptotic vulnerability in MYCN-amplified neuroblastoma
Authors:Konstantinos V. Floros1, Ayesha T. Chawla1, Mia O. Johnson-Berro1, Rishabh Khatri1, Angeliki M. Stamatouli2, Sosipatros A. Boikos3, Mikhail G. Dozmorov4, L. Ashley Cowart5,6 and Anthony C. Faber1
1 Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA.
2 Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
3 Division of Hematology, Oncology and Palliative Care, Virginia Commonwealth University and Massey Cancer Center, Richmond, VA, USA.
4 Department of Biostatistics, Virginia Commonwealth University, Richmond, VA, USA.
5 Department of Biochemistry and Molecular Biology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA.
6 Hunter Holmes McGuire Veteran’s Affairs Medical Center, Richmond, VA, USA.
Keywords:
MYCN-amplified neuroblastoma, ferroptosis, cystathionine, transsulfuration pathway, methionine, cysteine.
Abbreviations:
BSO – buthionine sulfoximine,
CBS – cystathionine-beta-synthase,
FPN – ferroportin,
GSH – glutathione,
MTA – methylthioadenosine,
MTAP – MTA phosphorylase,
NB – neuroblastoma,
PAG – propargylglycine,
ROS – reactive oxygen species,
SAH – S-adenosyl-homocysteine,
SAM – S-adenosyl-methionine.
Corresponding Author(s):
Conflict of interest statement:
A.C.F. has served as a paid consultant for AbbVie.
Please cite this article as:
Konstantinos V. Floros, Ayesha T. Chawla, Mia O. Johnson-Berro, Rishabh Khatri, Angeliki M. Stamatouli, Sosipatros A. Boikos, Mi-khail G. Dozmorov, L. Ashley Cowart and Anthony C. Faber (2022). MYCN upregulates the transsulfuration pathway to suppress the ferroptotic vulnerability in MYCN-amplified neuroblastoma. Cell Stress 6(2): 21-29. doi: 10.15698/cst2022.02.264
© 2022 Floros et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduc-tion in any medium, provided the original author and source are acknowledged.
Abstract:
Ferroptosis is an iron-dependent, oxidative form of cell death that is countered mainly by glutathione peroxidase 4 (GPX4) and the production of glutathione (GSH), which is formed from cysteine. The identification of the cancers that may benefit from pharmacological ferroptotic induction is just emerging. We recently demonstrated that inducing ferroptosis genetically or pharmacologically in MYCN-amplified neuroblastoma (NB) is a novel and effective way to kill these cells. MYCN increases iron metabolism and subsequent hydroxyl radicals through increased expression of the transferrin receptor 1 (TfR1) and low levels of the ferroportin receptor. To counter increased hydroxyl radicals, MYCN binds to the promoter of SLC3A2 (solute carrier family 3 member 2). SLC3A2 is a subunit of system Xc-, which is the cysteine-glutamate antiporter that exports glutamate and imports cystine. Cystine is converted to cysteine intracellularly. Here, we investigated other ways MYCN may increase cysteine levels. By performing metabolomics in a syngeneic NB cell line either expressing MYCN or GFP, we demonstrate that the transsulfuration pathway is activated by MYCN. Furthermore, we demonstrate that MYCN-amplified NB cell lines and tumors have higher levels of cystathionine beta-synthase (CBS), the rate-limiting enzyme in transsulfuration, which leads to higher levels of the thioether cystathionine (R-S-(2-amino-2-carboxyethyl)-l-homocysteine). In addition, MYCN-amplified NB tumors have high levels of methylthioadenosine phosphorylase (MTAP), an enzyme that helps salvage methionine following polyamine metabolism. MYCN directly binds to the promoter of MTAP. We propose that MYCN orchestrates both enhanced cystine uptake and enhanced activity of the transsulfuration pathway to counteract increased reactive oxygen species (ROS) from iron-induced Fenton reactions, ultimately contributing to a ferroptosis vulnerability in MYCN-amplified neuroblastoma.