Bacterial ceramides and sphingophospholipids induce apoptosis of human leukaemic cells

Abstract

The genus Sphingobacterium, whose members are Gram-negative non-fermentative rods, possesses ceramides and related sphingophospholipids (SPLs) with isoheptadecasphinganine and 2-hydroxy or non-hydroxy isopentadecanoic acid. This paper reports evidence that ceramides isolated from Sphingobacterium spiritivorum ATCC 33861 induce endonucleolytic DNA cleavage in human myeloid leukaemia HL-60 cells in vitro, which is the primary characteristic biochemical marker for apoptosis or programmed cell death. Ceramides and SPLs also induced DNA fragmentation and caspase-3 activation, followed by changes in morphology, such as alterations in the size of nuclei and cells, and cell cycle shortening. Apoptotic activity correlated with the ceramide structure. Ceramide with a 2-hydroxy fatty acid showed stronger apoptotic activity than ceramide with a non-hydroxy fatty acid. Furthermore, the major five SPLs (ceramide phosphorylethanolamine-1 and -2, ceramide phosphorylinositol-1 and -2, and ceramide phosphorylmannose-1) showed apoptosis-inducing activity in HL-60 cells, indicating that the ceramide moiety of the SPLs plays a crucial role as the intracellular second messenger but that their hydrophilicity is less important in this regard. The hydrophilic part of SPLs may play a role in other cellular response systems. The involvement of Fas antigen was implicated in the apoptotic event since Fas antigen expression was observed after 3 or 4 h stimulation of HL-60 cells with bacterial ceramides. However, a time-course study for caspase-3 activation indicated maximal activity at 1 h after stimulation with bacterial ceramides, suggesting that two (or possibly more) mechanisms of signal transduction, Fas-dependent and Fas-independent, may be involved. Fas antigen expression and caspase-3 activation by five kinds of SPLs were observed after 3 or 4 h. These results indicate that there is a difference in the response of HL-60 cells to bacterial ceramides and SPLs.

Structures and biological activity of phosphorylated dihydroceramides of Porphyromonas gingivalis

“…Neither phosphoglycerol ceramides nor ester-linked fatty acid were reported for Sphingobacterium phosphoceramides (4,17). These bacterial sphingolipids were recently shown to promote apoptosis in several cell types (4). Because of the structural similarities between P. gingivalis phosphoceramides and Sphingobacterium sp.…”

“…Sphingobacterium species are reported to synthesize phosphoethanolamine ceramides containing a 15-methyl hexadecanoic long-chain base in amide linkage to either isoC 15:0 or 2-OH isoC 15:0 (4,17). Neither phosphoglycerol ceramides nor ester-linked fatty acid were reported for Sphingobacterium phosphoceramides (4,17). These bacterial sphingolipids were recently shown to promote apoptosis in several cell types (4).…”

Alkamid database: Chemistry, occurrence and functionality of plant N-alkylamides

“…9Z-octadecenamide was identified in the lichen Stereocaulon alpinum as bioactive NAA (Ingolfsdottir et al, 1997). Ceramides, fatty acid linked sphingosines, are major lipid components in Pseudomonaslike Gram (À ) bacteria and important physiological constituents in eukaryotic cell membranes (Minamino et al, 2003). In human and other mammalian skin, ceramides play a key role against transepidermal water loss and harmful environmental influences (Raith et al, 2004).…”

Downregulation of KDR expression induces apoptosis in breast cancer cells

“…The deregulation of apoptosis is considered one of the characteristics of malignant tumors. Inducing tumor cell apoptosis has become an effective strategy for cancer treatment [14,15]. Most previous studies about KDR have centered on its role in cell proliferation.…”