Involvement of ceramide in the mechanism of Cr(VI)-induced apoptosis of CHO cells.
Mitochondria reduce Cr(VI) to Cr(V) with concomitant generation of reactive oxygen species, thereby exhibiting cytotoxic effects leading to apoptosis in various types of cells. To clarify the mechanism by which Cr(VI) induces apoptosis, we examined the effect of Cr(VI) on Chinese hamster ovary (CHO) cells. Cr(VI) increased cellular levels of ceramide by activating acid sphingomyelinase (ASMase) and inhibiting the phosphorylation of pleckstrin homology domain-containing protein kinase B (Akt). Cr(VI) also induced cyclosporin A- and trifluoperazine-sensitive depolarization of mitochondria and activated caspase-3, 8 and 9, thereby causing fragmentation of cellular DNA. The presence of desipramine, an inhibitor of ASMase, and membrane permeable pCPT-cAMP suppressed the Cr(VI)-induced activation of caspases and DNA fragmentation. These results suggested that accumulation of ceramide play an important role in the Cr(VI)-induced apoptosis of CHO cells through activation of mitochondrial membrane permeability transition.
Muranaka
Shikibu
S
Institute of Medical Science, Kurashiki Medical Center, Kurashiki 710-8522, Japan.
Kanno
Tomoko
T
Fujita
Hirofumi
H
Kobuchi
Hirotsugu
H
Akiyama
Jitsuo
J
Yasuda
Tatsuji
T
Utsumi
Kozo
K
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D016466:CHO Cells; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology; D002857:Chromium / Q000633:toxicity*; D006224:Cricetinae; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D003891:Desipramine / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D013108:Sphingomyelin Phosphodiesterase / Q000187:drug effects / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology; D014191:Tranylcypromine / Q000494:pharmacology
D002518:Ceramides; D011518:Proto-Oncogene Proteins; D013873:Thionucleotides; D002857:Chromium; C074702:chromium hexavalent ion; D014191:Tranylcypromine; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D016572:Cyclosporine; D004247:DNA; D000242:Cyclic AMP; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D013108:Sphingomyelin Phosphodiesterase; D020169:Caspases; D003891:Desipramine