Apo2L/TRAIL induction and nuclear translocation of inositol hexakisphosphate kinase 2 during IFN-beta-induced apoptosis in ovarian carcinoma.

Abstract

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.

• Authors: Bei H Morrison, Zhuo Tang, Barbara S Jacobs, Joseph A Bauer, Daniel J Lindner
• Journal: The Biochemical journal (Biochem J) Vol. 385 Issue Pt 2 Pg. 595-603 (Jan 15 2005) ISSN: 1470-8728 [Electronic] England
• PMID: 15634191 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antibodies, Blocking
• Antibodies, Monoclonal
• Apoptosis Regulatory Proteins
• Membrane Glycoproteins
• TNF-Related Apoptosis-Inducing Ligand
• TNFSF10 protein, human
• Tumor Necrosis Factor-alpha
• Interferon-beta
• Phosphotransferases (Phosphate Group Acceptor)
• inositol hexakisphosphate kinase

Topics

• Active Transport, Cell Nucleus (physiology)
• Antibodies, Blocking (pharmacology)
• Antibodies, Monoclonal (pharmacology)
• Apoptosis (drug effects, physiology)
• Apoptosis Regulatory Proteins
• Carcinoma (metabolism, pathology)
• Cell Line, Tumor
• Cell Proliferation
• Female
• Humans
• Interferon-beta (physiology)
• Membrane Glycoproteins (biosynthesis, immunology, metabolism)
• Ovarian Neoplasms (metabolism, pathology)
• Phosphotransferases (Phosphate Group Acceptor) (biosynthesis, metabolism)
• Protein Transport (physiology)
• Signal Transduction (drug effects, physiology)
• TNF-Related Apoptosis-Inducing Ligand
• Tumor Necrosis Factor-alpha (biosynthesis, immunology, metabolism)