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[Background]:Leishmaniasis is the world's second deadliest parasitic disease after malaria, and current treatment of the different forms of this disease is far from satisfactory. Alkylphospholipid analogs (APLs) are a family of anticancer drugs that show antileishmanial activity, including the first oral drug (miltefosine) for leishmaniasis and drugs in preclinical/clinical oncology trials, but their precise mechanism of action remains to be elucidated., [Methodology/Principal Findings]:Here we show that the tumor cell apoptosis-inducer edelfosine was the most effective APL, as compared to miltefosine, perifosine and erucylphosphocholine, in killing Leishmania spp. promastigotes and amastigotes as well as tumor cells, as assessed by DNA breakdown determined by flow cytometry. In studies using animal models, we found that orally-administered edelfosine showed a potent in vivo antileishmanial activity and diminished macrophage pro-inflammatory responses. Edelfosine was also able to kill Leishmania axenic amastigotes. Edelfosine was taken up by host macrophages and killed intracellular Leishmania amastigotes in infected macrophages. Edelfosine accumulated in tumor cell mitochondria and Leishmania kinetoplast-mitochondrion, and led to mitochondrial transmembrane potential disruption, and to the successive breakdown of parasite mitochondrial and nuclear DNA. Ectopic expression of Bcl-XL inhibited edelfosine-induced cell death in both Leishmania parasites and tumor cells. We found that the cytotoxic activity of edelfosine against Leishmania parasites and tumor cells was associated with a dramatic recruitment of FOF1-ATP synthase into lipid rafts following edelfosine treatment in both parasites and cancer cells. Raft disruption and specific FOF1-ATP synthase inhibition hindered edelfosine-induced cell death in both Leishmania parasites and tumor cells. Genetic deletion of FOF1-ATP synthase led to edelfosine drug resistance in Saccharomyces cerevisiae yeast., [Conclusions/Significance]:The present study shows that the antileishmanial and anticancer actions of edelfosine share some common signaling processes, with mitochondria and raft-located FOF1-ATP synthase being critical in the killing process, thus identifying novel druggable targets for the treatment of leishmaniasis., This work was supported by grants from the Spanish Ministerio de Economia y Competitividad (SAF2014-59716-R and BIO2014-56930-P), Instituto de Salud Carlos III (RD12/0036/0065 from Red TemaÂtica de Investigación Cooperativa en Cáncer, cofunded by the EU's European Regional Development Fund ± FEDER),European Community's Seventh Framework Programme FP7-2007-2013 (grant HEALTH-F2-2011-256986, PANACREAS), and Spain-UK International Joint Project grant from The Royal Society-CSIC (2004GB0032). CG was supported by the RamoÂn y Cajal Program from the Spanish Ministerio de Ciencia e Innovación.AÂCM was recipient of Formación de Profesorado Universitario predoctoral fellowship from the Spanish Ministerio de Ciencia e Innovación.

The nuclear factor κB (NF-κB) transcription factor is a master regulator of inflammation. Short-term NF-κB activation is generally beneficial. However, sustained NF-κB might be detrimental, directly causing apoptosis of cells or leading to a persistent damaging inflammatory response. NF-κB activity in stressed cells needs therefore to be controlled for homeostasis maintenance. In mildly stressed cells, caspase-3 cleaves p120 RasGAP, also known as RASA1, into an N-terminal fragment, which we call fragment N. We show here that this fragment is a potent NF-κB inhibitor. Fragment N decreases the transcriptional activity of NF-κB by promoting its export from the nucleus. Cells unable to generate fragment N displayed increased NF-κB activation upon stress. Knock-in mice expressing an uncleavable p120 RasGAP mutant showed exaggerated NF-κB activation when their epidermis was treated with anthralin, a drug used for the treatment of psoriasis. Our study provides biochemical and genetic evidence of the importance of the caspase-3-p120-RasGAP stress-sensing module in the control of stress-induced NF-κB activation.

The lysophosphatidylcholine analogue edelfosine is a potent antitumor lipid that targets cellular membranes. The underlying mechanisms leading to cell death remain controversial, although two cellular membranes have emerged as primary targets of edelfosine, the plasma membrane (PM) and the endoplasmic reticulum. In an effort to identify conditions that enhance or prevent the cytotoxic effect of edelfosine, we have conducted genome-wide surveys of edelfosine sensitivity and resistance in Saccharomyces cerevisiae presented in this work and the accompanying paper (Cuesta-Marbán, Á., Botet, J., Czyz, O., Cacharro, L. M., Gajate, C., Hornillos, V., Delgado, J., Zhang, H., Amat-Guerri, F., Acuña, A. U., McMaster, C. R., Revuelta, J. L., Zaremberg, V., and Mollinedo, F. (January 23, 2013) J. Biol. Chem. 288,), respectively. Our results point to maintenance of pH homeostasis as a major player in modulating susceptibility to edelfosine with the PM proton pump Pma1p playing a main role. We demonstrate that edelfosine alters PM organization and induces intracellular acidification. Significantly, we show that edelfosine selectively reduces lateral segregation of PM proteins like Pma1p and nutrient H+-symporters inducing their ubiquitination and internalization. The biology associated to the mode of action of edelfosine we have unveiled includes selective modification of lipid raft integrity altering pH homeostasis, which in turn regulates cell growth. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc., This work was supported in part by a Natural Sciences and Engineering Research Council of Canada discovery grant, a seed grant from the University of Calgary, a Natural Sciences and Engineering Research Council of Canada University Faculty award (to V. Z.), Canadian Institutes of Health Research Grant 14124 (to C. R. M.), Spanish Ministerio de Economia y Competitividad Grants SAF2008-02251 and SAF2011-30518, Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, co-funded by the Fondo Europeo de Desarrollo Regional of the European Union Grants RD06/0020/1037 and RD12/0036/0065, European Community's Seventh Framework Programme FP7-2007-2013 Grant HEALTH-F2-2011-256986, (PANACREAS), and Junta de Castilla y León Grants CSI052A11-2 and CSI221A12-2 (to F. M.).

The ether-phospholipid edelfosine, a prototype antitumor lipid (ATL), kills yeast cells and selectively kills several cancer cell types. To gain insight into its mechanism of action, we performed chemogenomic screens in the Saccharomyces cerevisiae gene-deletion strain collection, identifying edelfosine-resistant mutants. LEM3, AGP2, and DOC1 genes were required for drug uptake. Edelfosine displaced the essential proton pump Pma1p from rafts, inducing its internalization into the vacuole. Additional ATLs, including miltefosine and perifosine, also displaced Pma1p from rafts to the vacuole, suggesting that this process is a major hallmark of ATL cytotoxicity in yeast. Radioactive and synthetic fluorescent edelfosine analogues accumulated in yeast plasma membrane rafts and subsequently the endoplasmic reticulum. Although both edelfosine and Pma1p were initially located at membrane rafts, internalization of the drug toward endoplasmic reticulum and Pma1p to the vacuole followed different routes. Drug internalization was not dependent on endocytosis and was not critical for yeast cytotoxicity. However, mutants affecting endocytosis, vesicle sorting, or trafficking to the vacuole, including the retromer and ESCRT complexes, prevented Pma1p internalization and were edelfosineresistant. Our data suggest that edelfosine-induced cytotoxicity involves raft reorganization and retromer- and ESCRT-mediated vesicular transport and degradation of essential raft proteins leading to cell death. Cytotoxicity of ATLs is mainly dependent on the changes they induce in plasma membrane raft-located proteins that lead to their internalization and subsequent degradation. Edelfosine toxicity can be circumvented by inactivating genes that then result in the recycling of internalized cell-surface proteins back to the plasma membrane. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc., This work was supported in part by Spanish Ministerio de Economia y Competitividad Grants SAF2005-04293, SAF2008-02251, and SAF2011-30518, Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, co-funded by the Fondo Europeo de Desarrollo Regional of the European Union Grants RD06/0020/1037 and RD12/0036/0065, European Community's Seventh Framework Programme FP7-2007-2013 Grant HEALTH-F2-2011-256986 (PANACREAS), Fundación “la Caixa” Grant BM05-30-0, Junta de Castilla y León Grants CSI052A11-2 and CSI221A12-2 (to F. M.), Spanish Ministerio de Economia y Competitividad Grants BIO2008-00194 and BIO2011-23901, Junta de Castilla y León Grant GR147 (to J. L. R.), Fondo de Investigación Sanitaria and European Commission (FIS-FEDER) Grants 06/0813 and PS09/01915, Junta de Castilla y León Biomedicine Project 2010-2011 (to C. G.), Spanish Ministerio de Economia y Competitividad Grant CTQ2010-16457 (to A. U. A.), Canadian Institutes of Health Research Grant 14124 (to C. R. M.), a Natural Sciences and Engineering Research Council of Canada discovery grant, a seed grant from the University of Calgary, and an Natural Sciences and Engineering Research Council of Canada University faculty award (to V. Z.).