Exchange of extracellular cystine for intracellular glutamate by the antiporter system xc (-) is implicated in numerous pathologies. Pharmacological agents that inhibit system xc (-) activity with ...high potency have long been sought, but have remained elusive. In this study, we report that the small molecule erastin is a potent, selective inhibitor of system xc (-). RNA sequencing revealed that inhibition of cystine-glutamate exchange leads to activation of an ER stress response and upregulation of CHAC1, providing a pharmacodynamic marker for system xc (-) inhibition. We also found that the clinically approved anti-cancer drug sorafenib, but not other kinase inhibitors, inhibits system xc (-) function and can trigger ER stress and ferroptosis. In an analysis of hospital records and adverse event reports, we found that patients treated with sorafenib exhibited unique metabolic and phenotypic alterations compared to patients treated with other kinase-inhibiting drugs. Finally, using a genetic approach, we identified new genes dramatically upregulated in cells resistant to ferroptosis.DOI: http://dx.doi.org/10.7554/eLife.02523.001.
Apoptosis is one type of programmed cell death. Increasingly, non-apoptotic cell death is recognized as being genetically controlled, or 'regulated'. However, the full extent and diversity of ...alternative cell death mechanisms remain uncharted. Here we surveyed the landscape of pharmacologically accessible cell death mechanisms. In an examination of 56 caspase-independent lethal compounds, modulatory profiling showed that 10 compounds induced three different types of regulated non-apoptotic cell death. Optimization of one of those ten resulted in the discovery of FIN56, a specific inducer of ferroptosis. Ferroptosis has been found to occur when the lipid-repair enzyme GPX4 is inhibited. FIN56 promoted degradation of GPX4. FIN56 also bound to and activated squalene synthase, an enzyme involved in isoprenoid biosynthesis, independent of GPX4 degradation. These discoveries show that dysregulation of lipid metabolism is associated with ferroptosis. This systematic approach is a means to discover and characterize novel cell death phenotypes.
E3 ubiquitin ligases are of interest as drug targets for their ability to regulate protein stability and function. The oncogene Mdm2 is an attractive E3 ligase to target, as it is the key negative ...regulator of the tumor suppressor p53, which controls the transcription of genes involved in cell fate. Overexpression of Mdm2 facilitates tumorigenesis by inactivating p53, and through p53-independent oncogenic effects. We developed a high-throughput cellular Mdm2 auto-ubiquitination assay, which we used to discover a class of small-molecule Mdm2 ligase activity inhibitors. These compounds inhibit Mdm2 and p53 ubiquitination in cells, reduce viability of cells with wild-type p53, and synergize with DNA-damaging agents to cause cell death. We determined that these compounds effectively inhibit the E3 ligase activity of the Mdm2-MdmX hetero-complex. This mechanism may be exploitable to create a new class of anti-tumor agents.
Precision medicine in oncology requires not only identification of cancer-associated mutations but also effective drugs for each cancer genotype, which is still a largely unsolved problem. One ...approach for the latter challenge has been large-scale testing of small molecules in genetically characterized cell lines. We hypothesized that compounds with high cell-line-selective lethality exhibited consistent results across such pharmacogenomic studies. We analyzed the compound sensitivity data of 6,259 lethal compounds from the NCI-60 project. A total of 2,565 cell-line-selective lethal compounds were identified and grouped into 18 clusters based on their median growth inhibitory GI50 profiles across the 60 cell lines, which were shown to represent distinct mechanisms of action. Further transcriptome analysis revealed a biomarker, NADPH abundance, for predicting sensitivity to ferroptosis-inducing compounds, which we experimentally validated. In summary, incorporating cell-line-selectivity filters improves the predictive power of pharmacogenomic analyses and enables discovery of biomarkers that predict the sensitivity of cells to specific cell death inducers.
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•Cell-line-selective lethal compounds are consistent across pharmacogenomic studies•Compounds with distinct sensitivity profiles indicate distinct mechanisms of action•The GI50 profiles of ferroptosis inducers are cell-line selective and unique•Basal NADP(H) level correlates with sensitivity to ferroptosis inducers
Large-scale compound profiling across cancer cell lines has been of interest, but discrepancies between different projects have been suggested. The methodology of Shimada et al. allows for consistent analyses of such data and identifies robust biomarkers for drug sensitivity, including NADPH as a biomarker for ferroptosis-inducing compounds.
A series of Pictet–Spengler condensation derivatives (tetrahydro-β-carbolines) was designed, synthesized and evaluated for lethality against a panel of seven cancer cell lines. Seven compounds (2a, ...13, 20, 21, 27, 29 and 34) showed lethality in at least five cell lines. Among these, compound 27 showed a unique selectivity towards oncogenic-RAS expressing BJ-TERT/LT/ST/RASV12 tumor cells, compared to non-transformed BJ-TERT cells. Further investigation revealed that 27 induces cell death without activation of caspases. This represents a useful new probe of non-apoptotic cell death and oncogenic-RAS synthetic lethality.
Understanding of cell death mechanisms is important to identifying therapeutic approaches to treat excess cell growth, as seen in tumors, or to inhibit excess cell death, as seen in neurodegenerative ...disease and ischemia. In the first part of this work, we aim to extend the understanding of a non-apoptotic cell death phenotype, ferroptosis, through use of a genome-wide siRNA screen. We identified knockdown of CARS, or cysteinyl-tRNA synthetase, as an inhibitor of erastin-induced ferroptosis. Loss of CARS led to upregulation of the transsulfuration pathway, where methionine is used as the source of sulfur for cysteine synthesis, as a suppressive mechanism. Upregulation of the transsulfuration pathway may serve as a biomarker to identify tumor types that may be insensitive to ferroptosis-inducing therapeutics. On the other hand, induction of the transsulfuration pathway may be beneficial in disease contexts that involve excess cell death. In the second part of this work, we elucidate the mechanism of action of a small molecule Mdm2 inhibitor, or MEL. Mdm2 is a negative inhibitor of p53; therefor, an inhibitor of Mdm2 may be useful in treating tumors driven by Mdm2 overexpression. We found MEL to inhibit the E3-ligase activity of Mdm2/MdmX heterocomplex, proving to be a useful tool to probe the importance of the heterocomplex in normal physiology and disease development. We also explored the structural scaffold of MEL compounds, an indole, and identified a novel ferroptosis inducer, increasing the chemical toolbox available to study ferroptosis.
Understanding of cell death mechanisms is important to identifying therapeutic approaches to treat excess cell growth, as seen in tumors, or to inhibit excess cell death, as seen in neurodegenerative ...disease and ischemia. In the first part of this work, we aim to extend the understanding of a non-apoptotic cell death phenotype, ferroptosis, through use of a genome-wide siRNA screen. We identified knockdown of CARS, or cysteinyl-tRNA synthetase, as an inhibitor of erastin-induced ferroptosis. Loss of CARS led to upregulation of the transsulfuration pathway, where methionine is used as the source of sulfur for cysteine synthesis, as a suppressive mechanism. Upregulation of the transsulfuration pathway may serve as a biomarker to identify tumor types that may be insensitive to ferroptosis-inducing therapeutics. On the other hand, induction of the transsulfuration pathway may be beneficial in disease contexts that involve excess cell death. In the second part of this work, we elucidate the mechanism of action of a small molecule Mdm2 inhibitor, or MEL. Mdm2 is a negative inhibitor of p53; therefor, an inhibitor of Mdm2 may be useful in treating tumors driven by Mdm2 overexpression. We found MEL to inhibit the E3-ligase activity of Mdm2/MdmX heterocomplex, proving to be a useful tool to probe the importance of the heterocomplex in normal physiology and disease development. We also explored the structural scaffold of MEL compounds, an indole, and identified a novel ferroptosis inducer, increasing the chemical toolbox available to study ferroptosis.
Background: Periprocedural anticoagulation using uninterrupted warfarin could reduce the risk of thromboembolic complications of atrial fibrillation (AF) ablation. Few studies, however, have ...evaluated the efficacy and safety of periprocedural dabigatran in AF ablation. Methods and Results: A total of 211 consecutive patients who underwent AF ablation, including 110 patients who received 110mg dabigatran twice daily (group D) and 101 patients who received dose-adjusted warfarin (international normalized ratio, 2.0–3.0; group W), were evaluated. Dabigatran was discontinued on the morning of the procedure, and resumed on the next morning. Warfarin was continued throughout the procedure. During the procedure, heparin infusion was maintained to achieve an activated clotting time of >300s. Postprocedural cerebral magnetic resonance imaging (MRI) was performed in 60 patients (group D, n=31; group W, n=29). No periprocedural deaths or symptomatic thromboembolic complications were observed in either group. MRI indicated a silent cerebral infarction in 1 patient in each group. Five patients in group D and 11 in group W had minor bleeding (P=0.12). Cardiac tamponade occurred in 2 patients in group W, but in none in group D. Total bleeding complications occurred less frequently in group D (4.5%) than in group W (12.9%; P<0.05). Conclusions: Dabigatran at a dose of 110mg twice daily was safe for AF ablation in patients with a relatively low risk of thromboemboli, suggesting that it may become an alternative to warfarin in those patients. (Circ J 2012; 76: 2337–2342)
BigRIPS as a high resolution spectrometer for pionic atoms Nishi, T.; Berg, G.P.A.; Dozono, M. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Letnik:
317
Journal Article
Recenzirano
We are presently working on a new project ‘pionic atom factory project’ at RIBF. The project aims at precision spectroscopy of the energy spectrum of the pionic atom for a wide range of elements, ...using missing-mass spectroscopy of the (d,3He) reaction near the π- emission threshold. For this project, we developed a new ion optics for BigRIPS using the dispersion-matching method. In this optics the BigRIPS beam line is used as a high resolving-power forward angle spectrometer to momentum-analyze 3He. We are aiming for a spectral resolution of <400keV (FWHM). An overview of the new optics and the result of a pilot experiment are reported.
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