PT - JOURNAL ARTICLE AU - Mohamed Rahmani AU - Mandy Mayo AU - Rupesh Dash AU - Upneet Kaur Sokhi AU - Igor P. Dmitriev AU - Devanand Sarkar AU - Paul Dent AU - David T. Curiel AU - Paul B. Fisher AU - Steven Grant TI - Melanoma Differentiation Associated Gene-7/Interleukin-24 Potently Induces Apoptosis in Human Myeloid Leukemia Cells through a Process Regulated by Endoplasmic Reticulum Stress AID - 10.1124/mol.110.068007 DP - 2010 Dec 01 TA - Molecular Pharmacology PG - 1096--1104 VI - 78 IP - 6 4099 - http://molpharm.aspetjournals.org/content/78/6/1096.short 4100 - http://molpharm.aspetjournals.org/content/78/6/1096.full SO - Mol Pharmacol2010 Dec 01; 78 AB - 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.