title: Caspase-independent apoptosis induced by differentiation-inducing factor of Dicytostelium discoideum in INS-1 cells.
abstract: Differentiation-inducing factor (DIF) is a lipophilic hormone of Dicytostelium discoideum and has been shown to exert diverse effects in mammalian cells. We investigated the effect of DIF on cell viability in insulin-secreting INS-1 cells. DIF induced cell death in a dose-dependent manner. In DIF-treated cells, nuclear condensation and shrinkage of the cell body were observed. After 6 h of DIF treatment, cells became Tdt-mediated dUTP-biotin nick end-labeling-positive, and DNA ladder formation was detected, indicating that DIF induced apoptosis in these cells. DIF did not activate caspase-3, a key enzyme mediating apoptotic signals generated by various agents. Furthermore, DIF-induced cell death was not affected by Z-asp-2, 6-dichlorobenzoyloxymethylketone, a broad inhibitor of the caspases. As is the case in other types of cells, DIF increased cytoplasmic free calcium concentration in INS-1 cells. However, DIF-induced cell death was not affected by chelating intracellular free calcium by 1, 2-bis(2-aminoophenoxy)ethane-N, N, N, N-tetra acetic acid (BAPTA). These results indicate that DIF induces apoptosis in INS-1 cells by a mechanism independent of caspase-3. DIF-induced elevation of cytoplasmic calcium does not mediate the effect of DIF on cell death.
authors.affiliation: Department of Laboratory Medicine, Gunma University School of Medicine, 371-8512, Maebashi, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Fujimaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kubohara
authors.forename: I
authors.initials: I
authors.lastname: Kobayashi
authors.forename: I
authors.initials: I
authors.lastname: Kojima
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006588:Hexanones / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D002614:Chelating Agents; D006588:Hexanones; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; D004533:Egtazic Acid; D015759:Ionomycin; D019869:Phosphatidylinositol 3-Kinases; D053148:Caspase 3; D020169:Caspases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium