benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Hodgkin-Disease

In Hodgkin's lymphoma, F-18-fluoro-deoxy-d-glucose positron emission tomography (FDG-PET) is used for staging and response evaluation after chemotherapy. However, drug-mediated downregulation of glucose uptake in viable Hodgkin's lymphoma cells might limit the use of FDG-PET.. We analyzed the effect of etoposide on cell viability and uptake of F-18-fluoro-deoxy-D-glucose or the glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) in vitro.. Etoposide induced a dose-dependent cytotoxicity in HDLM-2 cells which was significantly correlated with reduced FDG uptake. However, it also significantly increased the portion of viable cells which did not take up 2-NBDG. Interestingly, etoposide-induced cytotoxicity was mainly mediated via caspase-dependent mechanisms, whereas the cell death induced by deprivation of glucose was mediated via caspase-independent mechanisms.. Etoposide-mediated reduction of glucose uptake by Hodgkin's lymphoma cells is mainly caused by cell death. In a small fraction of viable cells, etoposide might downregulate glucose transporters and/or hexokinase activity and by that inhibit glucose uptake. This, however, might not lead to false-negative results of response evaluation in Hodgkin's lymphoma patients after chemotherapy, because inhibition of glucose uptake itself seems to be a strong inducer of cell death. Altogether, this study provides important in vitro evidence to clarify the mechanisms by which FDG-PET monitors the effect of anti-cancer treatment in Hodgkin's lymphoma patients.

Topics: 4-Chloro-7-nitrobenzofurazan; Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; B-Lymphocytes; Caspases; Cell Death; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Deoxyglucose; Energy Metabolism; Etoposide; False Negative Reactions; Hodgkin Disease; Humans; Neoplasm Proteins

We investigated whether cell-permeable, synthetic ceramide (C6 ceramide) could induce apoptosis in Fas-resistant Hodgkin's disease (HD)-derived cell lines. Despite strongly expressing the Fas-receptor, two of three HD-derived cell lines were resistant to Fas-mediated apoptosis. This resistance to Fas could not be attributed to differential Fas isoform generation patterns between the Fas-resistant and the Fas-sensitive cell lines. The Fas-resistant cell lines did not demonstrate the presence of Fas exon 8 deletion. Bcl-2 and BclxL levels were comparable between the Fas-resistant and the Fas-sensitive cell lines. C6 ceramide could induce apoptosis in both Fas-resistant cell lines and this was associated with a decrease in BclxL level. Caspase-1, caspase-3, or pan-caspase inhibitors could not prevent ceramide-induced apoptosis. Furthur, ceramide treatment did not lead to cleavage of caspase 3 or poly(ADP-ribose) polymerase, but caused a loss in mitochondrial transmembrane potential which could not be prevented by caspase inhibitors. Thus, we conclude that ceramide-induced apoptosis in Fas-resistant HD cell lines is caspase independent.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; bcl-X Protein; Caspase 1; Caspase 3; Caspase Inhibitors; Caspases; CD40 Antigens; Cell Membrane Permeability; Ceramides; Cysteine Proteinase Inhibitors; Enzyme Inhibitors; Fas Ligand Protein; fas Receptor; Gene Expression; Hodgkin Disease; Humans; Membrane Glycoproteins; Okadaic Acid; Oligopeptides; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured; Up-Regulation