RIPK3 upregulation confers robust proliferation and collateral cystine-dependence on breast cancer recurrence

We used synthetic lethal high-throughput screening to interrogate 23,550 compounds for their ability to kill engineered tumorigenic cells but not their isogenic normal cell counterparts. We identified known and novel compounds with genotype-selective activity, including doxorubicin, daunorubicin, mitoxantrone, camptothecin, sangivamycin, echinomycin, bouvardin, NSC146109, and a novel compound that we named erastin. These compounds have increased activity in the presence of hTERT, the SV40 large and small T oncoproteins, the human papillomavirus type 16 (HPV) E6 and E7 oncoproteins, and oncogenic HRAS. We found that overexpressing hTERT and either E7 or LT increased expression of topoisomerase 2alpha and that overexpressing RAS(V12) and ST both increased expression of topoisomerase 1 and sensitized cells to a nonapoptotic cell death process initiated by erastin.

Ferrostatin-1 (Fer-1) inhibits ferroptosis, a form of regulated, oxidative, nonapoptotic cell death. We found that Fer-1 inhibited cell death in cellular models of Huntington’s disease (HD), periventricular leukomalacia (PVL), and kidney dysfunction; Fer-1 inhibited lipid peroxidation, but not mitochondrial reactive oxygen species formation or lysosomal membrane permeability. We developed a mechanistic model to explain the activity of Fer-1, which guided the development of ferrostatins with improved properties. These studies suggest numerous therapeutic uses for ferrostatins, and that lipid peroxidation mediates diverse disease phenotypes.

DNA-damaging agents signal to p53 through as yet unidentified posttranscriptional mechanisms. Here we show that phosphorylation of human p53 at serine 15 occurs after DNA damage and that this leads to reduced interaction of p53 with its negative regulator, the oncoprotein MDM2, in vivo and in vitro. Furthermore, using purified DNA-dependent protein kinase (DNA-PK), we demonstrate that phosphorylation of p53 at serines 15 and 37 impairs the ability of MDM2 to inhibit p53-dependent transactivation. We present evidence that these effects are most likely due to a conformational change induced upon phosphorylation of p53. Our studies provide a plausible mechanism by which the induction of p53 can be modulated by DNA-PK (or other protein kinases with similar specificity) in response to DNA damage.