title: Caspase-, cathepsin-, and PERK-dependent regulation of MDA-7/IL-24-induced cell killing in primary human glioma cells.
abstract: 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 defining the mechanism(s) by which a GST-MDA-7 fusion protein inhibits cell survival of primary human glioma cells in vitro. GST-MDA-7 killed glioma cells with diverse genetic characteristics that correlated with inactivation of ERK1/2 and activation of JNK1-3. Activation of JNK1-3 was dependent on protein kinase R-like endoplasmic reticulum kinase (PERK), and GST-MDA-7 lethality was suppressed in PERK-/- cells. JNK1-3 signaling activated BAX, whereas inhibition of JNK1-3, deletion of BAX, or expression of dominant-negative caspase-9 suppressed lethality. GST-MDA-7 also promoted a PERK-, JNK-, and cathepsin B-dependent cleavage of BID; loss of BID function promoted survival. GST-MDA-7 suppressed BAD and BIM phosphorylation and heat shock protein 70 (HSP70) expression. GST-MDA-7 caused PERK-dependent vacuolization of LC3-expressing endosomes whose formation was suppressed by incubation with 3-methyladenine, expression of HSP70 or BiP/GRP78, or knockdown of ATG5 or Beclin-1 expression but not by inhibition of the JNK1-3 pathway. Knockdown of ATG5 or Beclin-1 expression or overexpression of HSP70 reduced GST-MDA-7 lethality. Our data show that GST-MDA-7 induces an endoplasmic reticulum stress response that is causal in the activation of multiple proapoptotic pathways, which converge on the mitochondrion and highlight the complexity of signaling pathways altered by mda-7/IL-24 in glioma cells that ultimately culminate in decreased tumor cell survival.
authors.affiliation: Department of Biochemistry, Virginia Commonwealth University, Richmond, VA 23298-0035, USA.
authors.forename: Adly
authors.initials: A
authors.lastname: Yacoub
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Park
authors.forename: Pankaj
authors.initials: P
authors.lastname: Gupta
authors.forename: Mohammed
authors.initials: M
authors.lastname: Rahmani
authors.forename: Guo
authors.initials: G
authors.lastname: Zhang
authors.forename: Hossein
authors.initials: H
authors.lastname: Hamed
authors.forename: David
authors.initials: D
authors.lastname: Hanna
authors.forename: Devanand
authors.initials: D
authors.lastname: Sarkar
authors.forename: Irina V
authors.initials: IV
authors.lastname: Lebedeva
authors.forename: Luni
authors.initials: L
authors.lastname: Emdad
authors.forename: Moira
authors.initials: M
authors.lastname: Sauane
authors.forename: Nicollaq
authors.initials: N
authors.lastname: Vozhilla
authors.forename: Sarah
authors.initials: S
authors.lastname: Spiegel
authors.forename: Costas
authors.initials: C
authors.lastname: Koumenis
authors.forename: Martin
authors.initials: M
authors.lastname: Graf
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D020169:Caspases / Q000502:physiology*; D002403:Cathepsins / Q000502:physiology*; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005910:Glioma / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D005982:Glutathione Transferase / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007378:Interleukins / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D011993:Recombinant Fusion Proteins / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured; D019892:eIF-2 Kinase / Q000235:genetics / Q000502:physiology*; D000099180:Interleukin-24
chemical_list: D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D020169:Caspases; D002403:Cathepsins; D000091342:Endoplasmic Reticulum Chaperone BiP; D005982:Glutathione Transferase; D049452:Green Fluorescent Proteins; D007378:Interleukins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D019892:eIF-2 Kinase; D000099180:Interleukin-24; C502778:ATG5 protein, human; C491997:BECN1 protein, human; C000717247:HSPA5 protein, human; C477012:MAP1LC3A protein, human