Apoptosis induced by N-hexanoylsphingosine in CHP-100 cells associates with accumulation of endogenous ceramide and is potentiated by inhibition of glucocerebroside synthesis

We report that apoptosis induced by N-hexanoylsphingosine (C₆-Cer)in CHP-100 human neuroepithelioma cells associates with accumulation of monohexosylsphingolipids produced not only by short-chain ceramide glycosylation but also through glycosylation of a ceramide pool endogenously produced. By high-performance thin layer chromatography on berate silica gel plates, newly formed monohexosylsphingolipids were identified as glucosylceramides (GluCer); however, accumulation of lactosylceramide or higher-order glycosphingolipids was not observed. GluCer accumulation was fully suppressed by D-threo-1- phenyl-2-decanoylamino-3-morpholino-1-propanol; moreover, while this inhibitor had no effect on cell viability when administered alone, it markedly potentiated the apoptotic effect of C₆-Cer. These results provide evidence that activation of GluCer synthesis is an important mechanism through which CHP-100 cells attempt to escape ceramide-induced apoptosis.