Cathepsin B mediates tumor necrosis factor-induced arachidonic acid release in tumor cells.
Arachidonic acid (AA) generated by cytosolic phospholipase A2 (cPLA2) has been suggested to function as a second messenger in tumor necrosis factor (TNF)-induced death signaling. Here, we show that cathepsin B-like proteases are required for the TNF-induced AA release in transformed cells. Pharmaceutical inhibitors of cathepsin B blocked TNF-induced AA release in human breast (MCF-7S1) and cervix (ME-180as) carcinoma as well as murine fibrosarcoma (WEHI-S) cells. Furthermore, TNF-induced AA release was significantly reduced in cathepsin B-deficient immortalized murine embryonic fibroblasts. Employing cPLA2-deficient MCF-7S1 cells expressing ectopic cPLA2 or cPLA2-deficient immortalized murine embryonic fibroblasts, we showed that cPLA2 is dispensable for TNF-induced AA release and death in these cells. Furthermore, TNF-induced cathepsin B-dependent AA release could be dissociated from the cathepsin B-independent cell death in MCF-7S1 cells, whereas both events required cathepsin B activity in other cell lines tested. These data suggest that cathepsin B inhibitors may prove useful not only in the direct control of cell death but also in limiting the damage-associated inflammation.
Apoptosis Laboratory, Institute of Cancer Biology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark.
Lasse
L
Foghsgaard
Ulrik
U
Lademann
Dorte
D
Wissing
Birgit
B
Poulsen
Marja
M
Jaattela
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism*; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007249:Inflammation; D051379:Mice; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000378:metabolism
D018076:DNA, Complementary; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D016718:Arachidonic Acid; D010741:Phospholipases A; D054467:Phospholipases A2; D002403:Cathepsins; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L; C534278:Ctsl protein, mouse