title: Insulin-like growth factor I induces migration and invasion of human multiple myeloma cells.
abstract: Multiple myeloma (MM) is an incurable form of cancer characterized by accumulation of malignant plasma cells in the bone marrow. During the course of this disease, tumor cells cross endothelial barriers and home to the bone marrow. In latter stages, myeloma cells extravasate through blood vessels and may seed a variety of organs. Insulin-like growth factor I (IGF-I) is one of several growth factors shown to promote the growth of MM cells. In the current study, we have assessed the ability of IGF-I to serve additionally as a chemotactic factor affecting the mobility and invasive properties of these cells. Results indicate that IGF-I promotes transmigration through vascular endothelial cells and bone marrow stromal cell lines. Analysis of endogenous signaling pathways revealed that protein kinase D/protein kinase Cmicro (PKD/PKCmicro) and RhoA were both activated in a phosphatidylinositol 3-kinase (PI-3K)-dependent manner. Inhibition of PI-3K, PKCs, or Rho-associated kinase by pharmacologic inhibitors abrogated migration, whereas mitogen-activated protein kinase (MAPK), Akt, and p70S6 kinase inhibitors had no effect. These results suggest that IGF-I promotes myeloma cell migration by activation of PI-3K/PKCmicro and PI-3K/RhoA pathways independent of Akt. The identification of IGF-I as both a proliferative and migratory factor provides a rational basis for the development of targeted therapeutic strategies directed at IGF-I in the treatment of MM.
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology*; D009361:Neoplasm Invasiveness / Q000503:physiopathology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D020742:rhoA GTP-Binding Protein / Q000096:biosynthesis
chemical_list: D004791:Enzyme Inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; C089212:protein kinase D; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D064413:3-Phosphoinositide-Dependent Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020742:rhoA GTP-Binding Protein