SignificanceNonapoptotic cell death-induced tissue damage has been implicated in a variety of diseases, including neurodegenerative disorder, inflammation, and stroke. In this study, we demonstrate that ferroptosis, a newly defined iron-dependent cell death, mediates both chemotherapy- and ischemia/reperfusion-induced cardiomyopathy. RNA-sequencing analysis revealed up-regulation of heme oxygenase 1 by doxorubicin as a major mechanism of ferroptotic cardiomyopathy. As a result, heme oxygenase 1 degrades heme and releases free iron in cardiomyocytes, which in turn leads to generation of oxidized lipids in the mitochondria membrane. Most importantly, both iron chelation therapy and pharmacologically blocking ferroptosis could significantly alleviate cardiomyopathy in mice. These findings suggest targeting ferroptosis as a strategy for treating deadly heart disease.

Metastasis is responsible for the majority of prostate cancer-related deaths; however, little is known about the molecular mechanisms that underlie this process. Here we identify an oncogene-tumor suppressor cascade that promotes prostate cancer initiation and metastasis by coordinately activating Ras and NF-κB. Specifically, we show that loss of the RasGAP gene DAB2IP induces metastatic prostate cancer in a murine model. Notably, DAB2IP functions as a signaling scaffold that coordinately regulates Ras and NF-κB through distinct domains to promote tumor initiation and metastasis, respectively. DAB2IP is suppressed in human prostate cancer where expression inversely correlates with tumor grade and predicts prognosis. Moreover, we report that epigenetic silencing of DAB2IP is a key mechanism by which the polycomb-group protein EZH2 activates Ras, NF-κB, and triggers metastasis. These studies define the mechanism by which two major pathways can be simultaneously activated in metastatic prostate cancer and establish EZH2 as a driver of metastasis.

Ferroptosis is a recently identified iron‐dependent form of nonapoptotic cell death implicated in brain, kidney, and heart pathology. However, the biological roles of iron and iron metabolism in ferroptosis remain poorly understood. Here, we studied the functional role of iron and iron metabolism in the pathogenesis of ferroptosis. We found that ferric citrate potently induces ferroptosis in murine primary hepatocytes and bone marrow–derived macrophages. Next, we screened for ferroptosis in mice fed a high‐iron diet and in mouse models of hereditary hemochromatosis with iron overload. We found that ferroptosis occurred in mice fed a high‐iron diet and in two knockout mouse lines that develop severe iron overload (Hjv–/– and Smad4Alb/Alb mice) but not in a third line that develops only mild iron overload (Hfe –/– mice). Moreover, we found that iron overload–induced liver damage was rescued by the ferroptosis inhibitor ferrostatin‐1. To identify the genes involved in iron‐induced ferroptosis, we performed microarray analyses of iron‐treated bone marrow–derived macrophages. Interestingly, solute carrier family 7, member 11 (Slc7a11), a known ferroptosis‐related gene, was significantly up‐regulated in iron‐treated cells compared with untreated cells. However, genetically deleting Slc7a11 expression was not sufficient to induce ferroptosis in mice. Next, we studied iron‐treated hepatocytes and bone marrow–derived macrophages isolated from Slc7a11–/– mice fed a high‐iron diet. Conclusion: We found that iron treatment induced ferroptosis in Slc7a11–/– cells, indicating that deleting Slc7a11 facilitates the onset of ferroptosis specifically under high‐iron conditions; these results provide compelling evidence that iron plays a key role in triggering Slc7a11‐mediated ferroptosis and suggest that ferroptosis may be a promising target for treating hemochromatosis‐related tissue damage. (Hepatology 2017;66:449–465).