N-Acylated Serinol Is a Novel Ceramide Mimic Inducing Apoptosis in Neuroblastoma Cells

Abstract

A novel structural analog of ceramide was synthesized by N-acylation of serinol (2-amino-1,3-propanediol) and studied for its effects on glycolipid biosynthesis and cell differentiation of neuroblastoma cells. Incubation with N-palmitoylated serinol (C16-serinol) increased the concentration of endogenous ceramide by 50 -80% and caused apoptosis in rapidly dividing low density cells but not in confluent cells. Cell death was not suppressed by simultaneous incubation with phorbol ester, known to antagonize ceramide-induced apoptosis by activation of protein kinase C (PKC). Purification of potential target proteins of C16-serinol was achieved by affinity chromatography of a protein preparation from rat brain on immobilized C16-serinol. A gel activity assay revealed that the eluate from C16-serinol-Sepharose contained three serine/threonine-specific protein kinases with molecular masses of 50, 70, and 95 kDa. The 70-kDa protein was immunostained on a Western blot using a PKC-specific antibody. The purified PKC could be activated directly by C16-serinol in an in vitro phosphorylation assay. Induction of apoptosis in neuroblastoma cells was suppressed by inhibition of PKC with Gö 6983. Our overall results indicate that apoptosis in neuroblastoma cells induced by C16-serinol was at least partially mediated by activation of PKC on condition of ongoing cell division. N-Acylated serinols may thus be useful for induction of apoptosis in mitotic cells and may be of therapeutic potential for treatment of cancer in the nervous system.

Ceramide Induces Apoptosis and Growth Arrest of Human Glioblastoma Cells by Inhibiting Akt Signaling Pathways

“…The effect of several chemotherapeutic agents are linked to the induction of apoptosis and associated with an increase of cellular ceramide (Bieberich et al, 2000;Macchia et al, 2001). In the present study, we found that ceramide induced apoptotic cell death in U373MG cells, detected by decrease of mitochondrial membrane potential or phosphatidylserine exposure measured by Annexin V binding.…”

Caspase-dependent and -independent cell death of Jurkat human leukemia cells induced by novel synthetic ceramide analogs

“…Sustained elevation of ceramide was observed after treatment with our analogs: a finding also described with other ceramide mimics, including Nacylated-serinol, B13 and diene-ceramides. 8,9,14 Interestingly, the present study shows that ceramide accumulation occurs upstream of the mitochondrial events since, in contrast to execution of the cell death program, it was not suppressed by Bcl-xL overexpression. Several mechanisms could account for ceramide elevation : inhibition of SM and GlcCer synthases (present study), inhibition of ceramide degradation by cerami- Ceramide analogs trigger Jurkat cell death T Granot et al dase, 9 or ceramide-induced 'self-accumulation'.…”

“…25 N-acylated derivatives of serinol also caused apoptosis of neuroblastoma or breast cancer cells. 8,26 Further analogs exhibited cytotoxicity against cancer cells, including compounds containing a thiouracil ring, 27 benzene, 28 or 4,6-diene-ceramides. 14 In addition to the numerous effects reported on different cell culture models, several ceramide analogs proved to be effective in vivo, some of them having been administered as liposomes.…”

“…Several hypotheses have been proposed, including activation of serine-threonine kinases, for example, PKCz, 8,12 mitochondrial events, that is, disruption of mitochondrial membrane potential, production of reactive oxygen species, and cytochrome c release, 14 drop in glutathione levels 13 or Rb dephosphorylation. 7 Positively charged ceramides also appear to trigger mitochondrial permeabilization.…”

“…Addition of synthetic short-chain ceramides, ceramines, C16-or C18-serinols, cationic ceramides as well as some other analogs was reported to mimic ceramide in inducing apoptosis in various cancer or leukemia cell lines, and, in some instances, to reduce the mass of xenografted tumors. [6][7][8][9][10][11][12][13][14][15] These observations have emphasized the potential usefulness of developing novel, ceramide-based chemotherapeutic agents for anticancer treatment.…”