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.
Department of Biochemistry and Molecular Biology, Massey Cancer Center, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0035, USA
Margaret A
MA
Park
Teneille
T
Walker
Aditi Pandya
AP
Martin
Jeremy
J
Allegood
Nicollaq
N
Vozhilla
Luni
L
Emdad
Devanand
D
Sarkar
Mohammed
M
Rahmani
Martin
M
Graf
Adly
A
Yacoub
Costas
C
Koumenis
Sarah
S
Spiegel
David T
DT
Curiel
Christina
C
Voelkel-Johnson
Steven
S
Grant
Paul B
PB
Fisher
Paul
P
Dent
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