The protein kinase C activators phorbol esters and phosphatidylserine inhibit neutral sphingomyelinase activation, ceramide generation, and apoptosis triggered by daunorubicin.
To address the role of protein kinase C (PKC) in the regulation of ceramide production, we evaluated the impact of the PKC activators 12-O-tetradecanoylphorbol-13-acetate and phosphatidylserine on the apoptotic signaling pathway triggered by the chemotherapeutic drug daunorubicin. Treatment of U937 and HL-60 cells with 0.5-1 microM daunorubicin induced a greater than 30% activation of neutral sphingomyelinase activity within 4-10 min with concomitant sphingomyelin hydrolysis and ceramide generation. Activation of PKC by 12-O-tetradecanoylphorbol-13-acetate and phosphatidylserine inhibited daunorubicin-induced neutral sphingomyelinase activation, sphingomyelin hydrolysis, ceramide generation, and apoptosis. The apoptotic response could be restored by the addition of 25 microM cell-permeant C6-ceramide. In conclusion, PKC emerges as a potentially critical negative regulator of the anthracycline-activated sphingomyelin-ceramide apoptotic pathway.
Mansat
V
V
Contrat Jeune Formation, Institut National de la Santé et de la Recherche Médicale 9503, Centre Claudius Régaud, Toulouse, France.
Laurent
G
G
Levade
T
T
Bettaïeb
A
A
Jaffrézou
J P
JP
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002518:Ceramides / Q000096:biosynthesis*; D003630:Daunorubicin / Q000494:pharmacology*; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D010718:Phosphatidylserines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D002518:Ceramides; D010718:Phosphatidylserines; D011493:Protein Kinase C; D013108:Sphingomyelin Phosphodiesterase; D013755:Tetradecanoylphorbol Acetate; D003630:Daunorubicin