title: Melanoma differentiation associated gene-7/interleukin-24 potently induces apoptosis in human myeloid leukemia cells through a process regulated by endoplasmic reticulum stress.
abstract: Melanoma differentiation associated gene-7 (mda-7)/interleukin-24 (IL-24), a member of the IL-10 cytokine gene family, preferentially induces cell death in neoplastic epithelial cells types while sparing their normal counterparts. The effects of mda-7/IL-24 in acute myeloid leukemia (AML) cells have not been extensively characterized. Treatment with recombinant GST-MDA-7/IL-24 potently induced apoptosis in diverse myeloid leukemia cell types including U937, HL60, MV4-11, EOL-1, and MLL/ENL cells. MDA-7/IL-24 also markedly induced apoptosis in and suppressed the colony-forming capacity of primary AML blasts but exerted minimal toxicity toward normal CD34(+) hematopoietic progenitor cells. MDA-7/IL-24 lethality was associated with pronounced endoplasmic reticulum (ER) stress induction in leukemia cell lines and primary AML blasts, manifested by the accumulation of growth arrest and DNA damage-inducible protein 34 (GADD34), 78-kDa glucose-regulated protein (GRP78)/BiP, inositol-requiring enzyme 1α (IRE1α), and eukaryotic initiation factor 2α phosphorylation. It is noteworthy that short hairpin RNA (shRNA) knockdown of IRE1α, GADD34, or GRP78/BiP significantly enhanced MDA-7/IL-24-mediated apoptosis, indicating a protective role for these molecules against MDA-7/IL-24 lethality. MDA-7/IL-24 also down-regulated the antiapoptotic protein Mcl-1 and sharply increased expression of the proapoptotic proteins Bim and Noxa. Ectopic Mcl-1 expression or shRNA knockdown of Bim or Noxa significantly attenuated MDA-7/IL-24-mediated leukemia cell death. Finally, knockdown of Bax or Bak significantly reduced MDA-7/IL-24 lethality. Together, these findings indicate that MDA-7/IL-24 potently induces apoptosis in human myeloid leukemia cells through a process regulated by ER stress induction, Mcl-1 down-regulation, and Bim and Noxa up-regulation. They also suggest that MDA-7/IL-24 warrants further investigation in myeloid leukemia.
authors.affiliation: Department of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Rahmani
authors.forename: Mandy
authors.initials: M
authors.lastname: Mayo
authors.forename: Rupesh
authors.initials: R
authors.lastname: Dash
authors.forename: Upneet Kaur
authors.initials: UK
authors.lastname: Sokhi
authors.forename: Igor P
authors.initials: IP
authors.lastname: Dmitriev
authors.forename: Devanand
authors.initials: D
authors.lastname: Sarkar
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000473:pathology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D018922:HL-60 Cells; D006801:Humans; D007378:Interleukins / Q000502:physiology*; D007951:Leukemia, Myeloid / Q000378:metabolism / Q000473:pathology*; D013234:Stem Cells / Q000473:pathology; D013312:Stress, Physiological / Q000502:physiology*; D020298:U937 Cells; D000099180:Interleukin-24
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D007378:Interleukins; D000099180:Interleukin-24; C000717247:HSPA5 protein, human