title: Cycloheximide-mediated sensitization to TNF-alpha-induced apoptosis in human colorectal cancer cell line COLO 205; role of FLIP and metabolic inhibitors.
abstract: Current efforts are focused on revealing the cellular factors that determine the "immune escape" of cancer cells. As an example in our study human colorectal cancer cell line COLO 205 was resistant to TNF-alpha - a death inducing ligand. Nonetheless, co-incubation TNF-alpha (10 ng/ml) with cycloheximide (5 micro g/ml, CHX) caused time-dependent (6, 12, 24 hours) cell death even though, at that concentration cycloheximide did not exert cytotoxic effect unless 24 hour of treatment. After additional pretreatment it is concluded that CHX sensitizes cells to TNF-alpha-induced apoptosis. The aim of this study was to investigate the role and properties of cellular proteins that granted COLO 205 cells survival as well as to assess the effect of several metabolic inhibitors on cell viability at the above-mentioned time-points. PKCs inhibitor staurosporine (5 microM) did not influence, whereas cPKC activator PMA (100 microM) prevented TNF-alpha-induced apoptosis in the presence of CHX. Although EDTA (2 mM) and to a lesser degree EGTA (5 mM) were individually cytotoxic, they exerted protective effect at 6 and partially at 12 hour of combined TNF-alpha and CHX treatment. Ionophore A23187 (1 microM) protected cells against cell death at 12 and 24 but only partially at 6 hour of treatment. On the other hand, AD (10 ng/ml) acted synergistically with TNF-alpha and CHX at 6 and 12 hour. It appears that resistance of COLO 205 cells is determined on genomic level by a few reaction steps in which both Ca(2+)-dependent and antiapoptotic proteins are involved. Further studies revealed that CHX treatment reduces the level of FLIP but not other members of TNF-alpha-dependent death signalosome.
authors.affiliation: Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw Agricultural University, Warsaw, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Pajak
authors.forename: B
authors.initials: B
authors.lastname: Gajkowska
authors.forename: A
authors.initials: A
authors.lastname: Orzechowski
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D002614:Chelating Agents / Q000494:pharmacology; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D003513:Cycloheximide / Q000494:pharmacology*; D003609:Dactinomycin / Q000494:pharmacology; D004357:Drug Synergism; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D019139:Tumor Escape; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002614:Chelating Agents; D020536:Enzyme Activators; D007476:Ionophores; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D000001:Calcimycin; D004533:Egtazic Acid; D003513:Cycloheximide; D004492:Edetic Acid; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium