Increase of ceramide in adriamycin-induced HL-60 cell apoptosis: detection by a novel anti-ceramide antibody

We recently raised an IgM class of monoclonal antibody (Ab) for ceramide (NHCER-2), and examined its specificity and sensitivity. Enzyme-linked immunosorbent assay (ELISA) and thin-layer chromatography (TLC) showed that NHCER-2 recognized ceramides but not other sphingolipids such as sphingosine, sphinganine, sphingomyelin, sphingosine-1-phosphate, ceramide-1-phosphate, glucosylceramide and cerebroside. In addition, N-hexanoyl, N-octanoyl and N-palmitoylsphingosine were detected by NHCER-2, but N-acetylsphingosine and dihydroceramide were not. Densities of ceramide detected by NHCER-2 were proportional to the amounts of ceramide standard up to 250 ng. When various concentrations of adriamycin (ADR) was added to induce apoptosis, the amounts of ceramide detected by NHCER-2 time- and dose-dependently increased in apoptosis-sensitive HL-60 cells as well as by DGK assay, but not in apoptosis-resistant HL-60/ADR cells. After cell fractionation, ceramide levels judged not only by diacylglycerol kinase (DGK) assay but also by NHCER-2 were shown to increase in the microsomal and the nuclear fraction in apoptosis-sensitive cells, but not in apoptosis-resistant cells. Moreover, absolute amounts of ceramide determined by NHCER-2 were well correlated with those by DGK assay. These results suggest that increase of ceramide in the nuclear fraction as well as in the microsomal fraction may play a role in ADR-induced apoptosis and that a novel anti-ceramide Ab NHCER-2 could be beneficial to investigate changes of ceramide content in the cells. (C) 2002 Published by Elsevier Science B.V.