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Supplementary key words ceramide • metastasis • inhibitorsCancer cells develop a lipogenic phenotype that supports the energy and membrane synthesis requirements associated with the enhanced proliferation and survival under stress inherent to malignant progression ( 1, 2 ). The recognition of the importance of this phenotype in cancer has led to the use of enzymes of lipid metabolism as markers to monitor neoplastic progression and response to therapy, as well as to the development of drugs targeted at key lipogenic enzymes, such as fatty acid synthase (FASN) ( 2, 3 ). The excess fatty acid synthesis that results from the coordinated activation of lipogenic enzymes in many types of cancer leads to the accumulation of palmitate, which needs to be further processed by the cells due to the toxic effects of its accumulation. One pathway that Abstract Acid ceramidase (AC) catalyzes the hydrolysis of ceramide into sphingosine, in turn a substrate of sphingosine kinases that catalyze its conversion into the mitogenic sphingosine-1-phosphate. AC is expressed at high levels in several tumor types and has been proposed as a cancer therapeutic target. Using a model derived from PC-3 prostate cancer cells, the highly tumorigenic, metastatic, and chemoresistant clone PC-3/Mc expressed higher levels of the AC ASAH1 than the nonmetastatic clone PC-3/S. Stable knockdown of ASAH1 in PC-3/Mc cells caused an accumulation of ceramides, inhibition of clonogenic potential, increased requirement for growth factors, and inhibition of tumorigenesis and lung metastases. We developed de novo ASAH1 inhibitors, which also caused a dose-dependent accumulation of ceramides in PC-3/Mc cells and inhibited their growth and clonogenicity. Finally, immunohistochemical analysis of primary prostate cancer samples showed that higher levels of ASAH1 were associated with more advanced stages of this neoplasia. These observations confi rm ASAH1 as a therapeutic target in advanced and chemoresistant forms of prostate cancer and suggest that our new potent and specifi c AC inhibitors could act by counteracting critical growth properties of SAF2008-00706 and SAF2011-22444 (to G.F.) Press, February 18, 2013 DOI 10.1194 Acid ceramidase as a therapeutic target in metastatic prostate cancer Abbreviations: AC, acid ceramidase; CMH, ceramide monohexoside; MDR1, multidrug resistant protein 1; NC, neutral ceramidase; PC, prostate cancer; PIN, prostate intraepithelial neoplasia; S1P, sphingosine-1-phosphate. This work was supported by Ministry of Science and Innovation Grants ; Agència de Gestió d'Ajuts Universitaris i de Recerca de la Generalitat de Catalunya Grant 2009SGR1072 (to G.F.); Ministry of Science and Innovation Grants SAF2008-04136-C02-01 and SAF2011-24686 (to T.M.T.); Ministry of Economy and Competitivity Grant SAF2012-40017-C02-01 (to T.M.T.); Agència de Gestió d'Ajuts Universitaris i de Recerca de la Generalitat de Catalunya Grant 2009SGR1482 (to T.M.T.); Xarxa de Bancs de Tumours de Catalunya-Pla Director d'Oncologia and Fondo Europeo de Desarrollo...

This article is available online at http://www.jlr.org hydrolase encoded by the ASAH1 gene. The main clinical features include painful and progressively deformed joints, subcutaneous nodules, a hoarse cry due to laryngeal involvement, and premature death. Hepatosplenomegaly and nervous system dysfunction may also occur ( 1, 2 ). Although the pathogenesis of FD is still unclear in terms of the molecular lesions caused by ceramide storage, the involvement of aCDase defi ciency is unquestionable. Recent interest in aCDase also stems from the fact that this enzyme appears to modulate cell functions by controlling the levels of ceramide and sphingoid bases, which are both considered as putative bioactive molecules ( 3 ).Diagnosis of FD must be biochemically confi rmed by the demonstration of defi cient activity of aCDase, which can then be further documented by characterization of the ASAH1 molecular defects. Although aCDase is a very well known enzyme, existing methods for determining its activity and for FD diagnosis still exhibit many disadvantages. The methods that have been used for FD diagnostic purposes can be classifi ed into three groups: i ) aCDase enzymatic assays ( 4-16 ), classically performed with radiolabeled substrates ( 4-13 ), which are rather water-insoluble and require at least one detergent (see Table 1 ) ; ii ) loading tests, consisting of the addition of exogenous radiolabeled sphingolipids, e.g., ceramide ( 17, 18 ), sulfatide ( 19,20 ), or sphingomyelin ( 21 ), on cultured living cells and the study of their metabolism; and iii ) determination of accumulated ceramide, either by sophisticated chromatographic methods ( 22,23 ) or through the use of the diacylglycerol kinase assay in the presence of ␥ [ Farber disease (FD) is a rare inherited lipid storage disorder, also known as lipogranulomatosis, which is characterized by accumulation of ceramide in the cells and tissues of patients ( 1, 2 ). This accumulation is the consequence of a defi cient intracellular activity of aCDase, a lysosomal

Inflammatory bowel disease (IBD) describes different illnesses characterized by chronic inflammation of the gastrointestinal tract. Although the pathogenic mechanisms leading to IBD are poorly understood, immune system disturbances likely underlie its development. Sphingolipids (SLs) have been identified as important players and promising therapeutic targets to control inflammation in IBD. Interestingly, it seems that microorganisms of the normal gut microbiota and probiotics are involved in sphingolipid function. However, there is a great need to investigate the role of SLs as intermediates in the crosstalk between intestinal immunity and microorganisms. This review focuses on recent investigations that describe some mechanisms involved in the regulation of cytokine profiles by SLs. We also describe the importance of gut microbiota in providing signaling molecules that favor the communication between resident bacteria and intestinal cells. This, in turn, modulates the immune response in the bowel and likely in other peripheral organs. The potential of SLs and gut microbiota as targets or therapeutic agents for IBD is also discussed.

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