Apo2L/TRAIL induction and nuclear translocation of inositol hexakisphosphate kinase 2 during IFN-beta-induced apoptosis in ovarian carcinoma.
Previously, we have reported that overexpression of IHPK2 (inositol hexakisphosphate kinase 2) sensitized NIH-OVCAR-3 ovarian carcinoma cell lines to the growth-suppressive and apoptotic effects of IFN-beta (interferon-beta) treatment and gamma-irradiation. In the present study, we demonstrate that Apo2L/TRAIL (Apo2L/tumour-necrosis-factor-related apoptosis-inducing ligand) is a critical mediator of IFN-induced apoptosis in these cells. Compared with IFN-alpha2, IFN-beta is a more potent inducer of Apo2L/TRAIL and IHPK2 activity. Overexpression of IHPK2 converts IFN-alpha2-resistant cells into cells that readily undergo apoptosis in response to IFN-alpha2. In untreated cells transfected with IHPK2-eGFP (where eGFP stands for enhanced green fluorescent protein), the fusion protein is localized to the cytoplasm and perinuclear region. After treatment with IFN-beta, IHPK2-eGFP translocated to the nucleus. In cells transfected with mutant IHPK2-NLS-eGFP (where NLS stands for nuclear localization sequence), containing point mutations in the NLS, the fusion protein remained trapped in the cytoplasm, even after IFN-beta treatment. Cells expressing mutant NLS mutation were more resistant to IFN-beta. The IC50 value of IHPK2-expressing cells was 2-3-fold lower than vector control. The IC50 value of NLS-mutant-expressing cells was 3-fold higher than vector control. Blocking antibodies to Apo2L/TRAIL or transfection with a dominant negative Apo2L/TRAIL receptor (DR5Delta) inhibited the antiproliferative effects of IFN-beta. Thus overexpression of IHPK2 enhanced apoptotic effects of IFN-beta, and expression of the NLS mutant conferred resistance to IFN-beta. Apo2L/TRAIL expression and nuclear localization of IHPK2 are both required for the induction of apoptosis by IFN-beta in ovarian carcinoma.
Morrison
Bei H
BH
Center for Cancer Drug Development and Discovery, Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Tang
Zhuo
Z
Jacobs
Barbara S
BS
Bauer
Joseph A
JA
Lindner
Daniel J
DJ
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D019138:Antibodies, Blocking / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D016899:Interferon-beta / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000378:metabolism* / Q000473:pathology; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000096:biosynthesis / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*
D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D016899:Interferon-beta; D017856:Phosphotransferases (Phosphate Group Acceptor); C099438:inositol hexakisphosphate kinase