MDA-7/IL-24-induced cell killing in malignant renal carcinoma cells occurs by a ceramide/CD95/PERK-dependent mechanism.
Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) is a novel cytokine displaying selective apoptosis-inducing activity in transformed cells without harming normal cells. The present studies focused on clarifying the mechanism(s) by which glutathione S-transferase (GST)-MDA-7 altered cell survival of human renal carcinoma cells in vitro. GST-MDA-7 caused plasma membrane clustering of CD95 and the association of CD95 with procaspase-8. GST-MDA-7 lethality was suppressed by inhibition of caspase-8 or by overexpression of short-form cellular FLICE inhibitory protein, but only weakly by inhibition of cathepsin proteases. GST-MDA-7-induced CD95 clustering (and apoptosis) was blocked by knockdown of acidic sphingomyelinase or, to a greater extent, ceramide synthase-6 expression. GST-MDA-7 killing was, in parallel, dependent on inactivation of extracellular signal-regulated kinase 1/2 and on CD95-induced p38 mitogen-activated protein kinase and c-jun NH(2)-terminal kinase-1/2 signaling. Knockdown of CD95 expression abolished GST-MDA-7-induced phosphorylation of protein kinase R-like endoplasmic reticulum kinase. GST-MDA-7 lethality was suppressed by knockout or expression of a dominant negative protein kinase R-like endoplasmic reticulum kinase that correlated with reduced c-jun NH(2)-terminal kinase-1/2 and p38 mitogen-activated protein kinase signaling and maintained extracellular signal-regulated kinase-1/2 phosphorylation. GST-MDA-7 caused vacuolization of LC3 through a mechanism that was largely CD95 dependent and whose formation was suppressed by knockdown of ATG5 expression. Knockdown of ATG5 suppressed GST-MDA-7 toxicity. Our data show that in kidney cancer cells GST-MDA-7 induces ceramide-dependent activation of CD95, which is causal in promoting an endoplasmic reticulum stress response that activates multiple proapoptotic pathways to decrease survival.
Park
Margaret A
MA
Department of Biochemistry and Molecular Biology, Massey Cancer Center, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0035, USA
Walker
Teneille
T
Martin
Aditi Pandya
AP
Allegood
Jeremy
J
Vozhilla
Nicollaq
N
Emdad
Luni
L
Sarkar
Devanand
D
Rahmani
Mohammed
M
Graf
Martin
M
Yacoub
Adly
A
Koumenis
Costas
C
Spiegel
Sarah
S
Curiel
David T
DT
Voelkel-Johnson
Christina
C
Grant
Steven
S
Fisher
Paul B
PB
Dent
Paul
P
D017209:Apoptosis / Q000187:drug effects; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D053181:Caspase 8 / Q000378:metabolism; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D002518:Ceramides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007378:Interleukins / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D019892:eIF-2 Kinase / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000099180:Interleukin-24
D053181:Caspase 8; D002518:Ceramides; D007378:Interleukins; D048031:JNK Mitogen-Activated Protein Kinases; D011993:Recombinant Fusion Proteins; D019892:eIF-2 Kinase; D019014:fas Receptor; D048051:p38 Mitogen-Activated Protein Kinases; D000099180:Interleukin-24