proapoptotic sphingosine (So) and ceramide (Cer). Thus, as central enzymes in modulating the Cer/S1P balance, SKs are attractive targets for cancer therapy ( 1 ). Two SKs exist in humans, SK1 and SK2. SK1 has been extensively studied and there is a large body of evidence that proves its role in promoting cell survival, proliferation, and neoplastic transformation ( 2-5 ). SK1 is also elevated in many human cancers, which appears to contribute to carcinogenesis, chemotherapeutic resistance, and poor patient outcome. SK2, however, has not been as well-characterized, and there are contradictions in the key physiological functions that have been proposed for this isoform. Despite this, many studies are now emerging that implicate SK2 in key roles in a variety of diseases, including the development of a range of solid tumors ( 6 ).The potential of SKs as therapeutic targets has boosted the development of small molecule inhibitors ( 4,(7)(8)(9)(10)(11)(12)(13)(14). A detailed characterization of their pharmacology, particularly their selectivity against human SK1 and SK2, has been published ( 15 ). The fi rst known SK inhibitors were long chain base analogs such as N , N -dimethyl-D-erythro-sphingosine (DMS) ( 16,17 ) and L-threo-dihydrosphingosine (safi ngol) ( 18-21 ). While DMS inhibits both SK1 and SK2 by (SGR 2009(SGR 1072, and the Fundació la Marató de TV3 (112130 and 112132 Abbreviations: CB5R, NADH-cytochrome b5 reductase; C16dhCer, N -hexadecanoyldihydrosphingosine ; CDH, ceramide dihexoside (lactosylceramide); Cer, ceramide; CerC6NBD, N -[6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl]-D-erythro-sphingosine; CMH, ceramide monohexoside (glucosyl and galactosylceramide); Des1, dihydroceramide desaturase; dhCDH, dihydroceramide dihexoside (lactosyldihydroceramide); dhCer, dihydroceramide; dhCerC6NBD, N -[6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl]-D-erythro-dihydrosphingosine; dhSM, dihydrosphingomyelin; DMS, N , N -dimethyl-D-erythro-sphingosine; FAD, fl avin adenine dinucleotide; LC3, microtubule-associated protein 1-light chain 3; MTT, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; NBD, 4-nitro-2,1,3-benzoxadiazole; PDB, Protein Data Bank; S1P, sphingosine-1-phosphate; SK, sphingosine kinase; SKI, sphingosine kinase inhibitor; So, sphingosine; TBST, TBS with 0.1% Tween 20; UPLC, ultraperformance LC . This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (SAF2011-22444), the Generalitat de Catalunya

Sphingolipids (SLs) have been extensively investigated in biomedical research due to their role as bioactive molecules in cells. Here, we describe the effect of a SL analog, jaspine B (JB), a cyclic anhydrophytosphingosine found in marine sponges, on the gastric cancer cell line, HGC-27. JB induced alterations in the sphingolipidome, mainly the accumulation of dihydrosphingosine, sphingosine, and their phosphorylated forms due to inhibition of ceramide synthases. Moreover, JB provoked atypical cell death in HGC-27 cells, characterized by the formation of cytoplasmic vacuoles in a time and dose-dependent manner. Vacuoles appeared to originate from macropinocytosis and triggered cytoplasmic disruption. The pan-caspase inhibitor, z-VAD, did not alter either cytotoxicity or vacuole formation, suggesting that JB activates a caspase-independent cell death mechanism. The autophagy inhibitor, wortmannin, did not decrease JB-stimulated LC3-II accumulation. In addition, cell vacuolation induced by JB was characterized by single-membrane vacuoles, which are different from double-membrane autophagosomes. These findings suggest that JB-induced cell vacuolation is not related to autophagy and it is also independent of its action on SL metabolism.

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The use of intact cells in medical research offers a number of advantages over employing cell-free systems. In diagnostic, cells isolated from liquid biopsies can be directly used, speeding up...

New fluorogenic sensors with suitable kinetic parameters and sensitivity have been developed for the determination of sphingosine-1-phosphate lyase activity in cell lysates. The probe RBM148 can be efficiently loaded into cationic liposomes and used to determine S1PL activity in intact cells.

The suitability as FRET probes of the bichromophoric 1-deoxydihydroceramides RBM5-160 and RBM5 161, containing NBD spisulosine as sphingoid base and a terminal MCC or NR tagged palmitic acid, respectively, has...