Environmental nutrient levels impact cancer cell metabolism, resulting in context-dependent gene essentiality1,2. Here, using loss-of-function screening based on RNA interference, we show that environmental oxygen levels are a major driver of differential essentiality between in vitro model systems and in vivo tumours. Above the 3–8% oxygen concentration typical of most tissues, we find that cancer cells depend on high levels of the iron–sulfur cluster biosynthetic enzyme NFS1. Mammary or subcutaneous tumours grow despite suppression of NFS1, whereas metastatic or primary lung tumours do not. Consistent with a role in surviving the high oxygen environment of incipient lung tumours, NFS1 lies in a region of genomic amplification present in lung adenocarcinoma and is most highly expressed in well-differentiated adenocarcinomas. NFS1 activity is particularly important for maintaining the iron–sulfur co-factors present in multiple cell-essential proteins upon exposure to oxygen compared to other forms of oxidative damage. Furthermore, insufficient iron–sulfur cluster maintenance robustly activates the iron-starvation response and, in combination with inhibition of glutathione biosynthesis, triggers ferroptosis, a non-apoptotic form of cell death. Suppression of NFS1 cooperates with inhibition of cysteine transport to trigger ferroptosis in vitro and slow tumour growth. Therefore, lung adenocarcinomas select for expression of a pathway that confers resistance to high oxygen tension and protects cells from undergoing ferroptosis in response to oxidative damage.
We thank members of the laboratories of D.M.S., K.B. and R.P.; G. Georgiou and E. Stone for cyst(e)inase; C. Moraes, and I. F. M. de Coo for wild-type 143B and CYTB 143B cells; P. Thiru for bioinformatic support; C. Loomis, L. Chiriboga, and B. Zeck for histology. Research was supported by a gift from Agios Pharmaceuticals to D.M.S., National Institutes of Health (NIH) (T32GM007308 and T32GM115313 supporting V.O.S.; CA168940 to R.P., CA193660 to K.B., and CA103866, CA129105, and AI07389 to D.M.S.), Starr Cancer Consortium and Broad Institute SPARC to D.M.S., Leukemia and Lymphoma Society Special Fellow Award to K.B., V Foundation to R.P., Pew-Stewart Scholar Grant to R.P., Susan G. Komen for the Cure to R.P. D.M.S. is an investigator of the Howard Hughes Medical Institute. Experimental Pathology Resource Center supported by the NIH (P30CA016087, S10 OD010584-01, and S10 OD018338). Immune Monitoring Core supported by the NIH (S10 OD016304).
Extended data figures
This table contains simultaneous in vivo and in vitro screening data.
This table contains a curated list of 25 common metabolites utilized by the enzymes screened.
This table contains primary screening data, 21% oxygen and 3% oxygen.
This table shows overlap of shRNAs scoring in both screens.