Spisulosine (ES-285) induces prostate tumor PC-3 and LNCaP cell death by de novo synthesis of ceramide and PKCζ activation

Ceramide synthase inhibition by fumonisin B1 causes accumulation of 1-deoxysphinganine: a novel category of bioactive 1-deoxysphingoid bases and 1-deoxydihydroceramides biosynthesized by mammalian cell lines and animals

Fumonisin B(1) (FB(1)) is a mycotoxin that inhibits ceramide synthases (CerS) and causes kidney and liver toxicity and other disease. Inhibition of CerS by FB(1) increases sphinganine (Sa), Sa 1-phosphate, and a previously unidentified metabolite. Analysis of the latter by quadrupole-time-of-flight mass spectrometry assigned an m/z = 286.3123 in positive ionization mode, consistent with the molecular formula for deoxysphinganine (C(18)H(40)NO). Comparison with a synthetic standard using liquid chromatography, electrospray tandem mass spectrometry identified the metabolite as 1-deoxysphinganine (1-deoxySa) based on LC mobility and production of a distinctive fragment ion (m/z 44, CH(3)CH=NH (+)(2)) upon collision-induced dissociation. This novel sphingoid base arises from condensation of alanine with palmitoyl-CoA via serine palmitoyltransferase (SPT), as indicated by incorporation of l-[U-(13)C]alanine into 1-deoxySa by Vero cells; inhibition of its production in LLC-PK(1) cells by myriocin, an SPT inhibitor; and the absence of incorporation of [U-(13)C]palmitate into 1-[(13)C]deoxySa in LY-B cells, which lack SPT activity. LY-B-LCB1 cells, in which SPT has been restored by stable transfection, however, produce large amounts of 1-[(13)C]deoxySa. 1-DeoxySa was elevated in FB(1)-treated cells and mouse liver and kidney, and its cytotoxicity was greater than or equal to that of Sa for LLC-PK(1) and DU-145 cells. Therefore, this compound is likely to contribute to pathologies associated with fumonisins. In the absence of FB(1), substantial amounts of 1-deoxySa are made and acylated to N-acyl-1-deoxySa (i.e. 1-deoxydihydroceramides). Thus, these compounds are an underappreciated category of bioactive sphingoid bases and "ceramides" that might play important roles in cell regulation.

Biodiversity of sphingoid bases ("sphingosines") and related amino alcohols

"Sphingosin" was first described by J. L. W. Thudichum in 1884 and structurally characterized as 2S,3R,4E-2-aminooctadec-4-ene-1,3-diol in 1947 by Herb Carter, who also proposed the designation of "lipides derived from sphingosine as sphingolipides." This category of amino alcohols is now known to encompass hundreds of compounds that are referred to as sphingoid bases and sphingoid base-like compounds, which vary in chain length, number, position, and stereochemistry of double bonds, hydroxyl groups, and other functionalities. Some have especially intriguing features, such as the tail-to-tail combination of two sphingoid bases in the alpha,omega-sphingoids produced by sponges. Most of these compounds participate in cell structure and regulation, and some (such as the fumonisins) disrupt normal sphingolipid metabolism and cause plant and animal disease. Many of the naturally occurring and synthetic sphingoid bases are cytotoxic for cancer cells and pathogenic microorganisms or have other potentially useful bioactivities; hence, they offer promise as pharmaceutical leads. This thematic review gives an overview of the biodiversity of the backbones of sphingolipids and the broader field of naturally occurring and synthetic sphingoid base-like compounds.