Role of phosphatidylinositol 3-kinase in anti-IgM- and anti-IgD-induced apoptosis in B cell lymphomas.

Cross-linking of surface Ig receptors with anti IgM (anti-mu heavy chain, anti-mu), but not anti-IgD (anti-delta heavy chain, anti-delta), Abs leads to growth arrest and apoptosis in several extensively characterized B cell lymphomas. By poorly understood mechanisms, both Igs transiently stimulate c-Myc protein expression. However, ultimately, only anti-mu causes a severe loss in c-Myc and a large induction of p27(Kip1) protein expression. Because phosphatidylinositol 3-kinase (PI3K) has been established as a major modulator of cellular growth and survival, we investigated its role in mediating anti-Ig-stimulated outcomes. Herein, we show that PI3K pathways regulate cell cycle progression and apoptosis in the ECH408 B cell lymphoma. Anti-mu and anti-delta driven c-Myc protein changes precisely follow their effects on the PI3K effector, p70(S6K). Upstream of p70(S6K), signaling through both Ig receptors depresses PI3K pathway phospholipids below control with time, which is followed by p27(Kip1) induction. Conversely, anti-delta, but not anti-mu stimulated PI3K-dependent phospholipid return to control levels by 4-8 h. Abrogation of the PI3K pathway with specific inhibitors mimics anti-mu action, potentiates anti-mu-induced cell death and, importantly, converts anti-delta to a death signal. Transfection with active PI3K kinase construct induces anti-mu resistance, whereas transfection with dominant negative PI3K augments anti-mu sensitivity. Our results show that prolonged disengagement of PI3K or down-regulation of its products by anti-mu (and not anti-delta) determines B cell fate.
AuthorsG B Carey, D W Scott
JournalJournal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 166 Issue 3 Pg. 1618-26 (Feb 1 2001) ISSN: 0022-1767 [Print] United States
PMID11160203 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Antibodies, Anti-Idiotypic
  • Cdkn1b protein, mouse
  • Cell Cycle Proteins
  • Chromones
  • Enzyme Inhibitors
  • Growth Inhibitors
  • Immunoglobulin D
  • Immunoglobulin M
  • Immunoglobulin delta-Chains
  • Immunoglobulin mu-Chains
  • Microtubule-Associated Proteins
  • Morpholines
  • Proto-Oncogene Proteins c-myc
  • Tumor Suppressor Proteins
  • anti-IgD
  • anti-IgM
  • Cyclin-Dependent Kinase Inhibitor p27
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Phosphatidylinositol 3-Kinases
  • Ribosomal Protein S6 Kinases
  • Animals
  • Antibodies, Anti-Idiotypic (pharmacology)
  • Apoptosis (immunology)
  • Cell Cycle Proteins
  • Chromones (pharmacology)
  • Cyclin-Dependent Kinase Inhibitor p27
  • Enzyme Activation (drug effects, immunology)
  • Enzyme Inhibitors (pharmacology)
  • Growth Inhibitors (pharmacology)
  • Immunoglobulin D (immunology)
  • Immunoglobulin M (immunology)
  • Immunoglobulin delta-Chains (immunology)
  • Immunoglobulin mu-Chains (immunology)
  • Lymphoma, B-Cell (enzymology, immunology, metabolism, pathology)
  • Mice
  • Microtubule-Associated Proteins (biosynthesis, metabolism)
  • Morpholines (pharmacology)
  • Phosphatidylinositol 3-Kinases (antagonists & inhibitors, genetics, metabolism, physiology)
  • Proto-Oncogene Proteins c-myc (biosynthesis, metabolism)
  • Ribosomal Protein S6 Kinases (antagonists & inhibitors, metabolism)
  • Signal Transduction (immunology)
  • Transfection
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins

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