title: Ligation of cell surface GRP78 with antibody directed against the COOH-terminal domain of GRP78 suppresses Ras/MAPK and PI 3-kinase/AKT signaling while promoting caspase activation in human prostate cancer cells.
abstract: We have previously shown that treatment of prostate cancer and melanoma cells expressing GRP78 on their cell surface with antibody directed against the COOH-terminal domain of GRP78 upregulates and activates p53 causing decreased cell proliferation and upregulated apoptosis. In this report, we demonstrate that treatment of 1-LN prostate cancer cells with this antibody decreases cell surface expression of GRP78, Akt(Thr308) and Akt(Ser473) kinase activities and reduces phosphorylation of FOXO, and GSK3beta. This treatment also suppresses activation of ERK1/2, p38 MAPK and MKK3/6; however, it upregulates MKK4 activity. JNK, as determined by its phosphorylation state, is subsequently activated, triggering apoptosis. Incubation of cells with antibody reduced levels of anti-apoptotic Bcl-2, while elevating pro-apoptotic BAD, BAX and BAK expression as well as cleaved caspases-3, -7, -8 and -9. Silencing GRP78 or p53 gene expression by RNAi prior to antibody treatment abrogated these effects. We conclude that antibody directed against the COOH-terminal domain of GRP78 may prove useful as a pan suppressor of proliferative/survival signaling in cancer cells expressing GRP78 on their cell surface.
authors.affiliation: Department of Pathology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Uma K
authors.initials: UK
authors.lastname: Misra
authors.forename: Salvatore V
authors.initials: SV
authors.lastname: Pizzo
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D011494:Protein Kinases / Q000502:physiology*; D017434:Protein Structure, Tertiary; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D020169:Caspases; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt; C000717247:HSPA5 protein, human; C494918:AKT1 protein, human