title: Dual effects of IGFBP-3 on endothelial cell apoptosis and survival: involvement of the sphingolipid signaling pathways.
abstract: Insulin-like growth factor binding protein (IGFBP)-3 has both growth-inhibiting and growth-promoting effects at the cellular level. The cytotoxic action of several anticancer drugs is linked to increased ceramide generation through sphingomyelin hydrolysis or de novo biosynthesis. Herein, we investigated the role of IGFBP-3 on apoptosis of human umbilical vein endothelial cells (HUVEC) and its relationship with ceramide levels. We report that IGFBP-3 exerts dual effects on HUVEC, potentiating doxorubicin-induced apoptosis but enhancing survival in serum-starved conditions. Ceramide was increased by IGFBP-3 in the presence of doxorubicin and decreased when IGFBP-3 was added alone to cells cultured in serum-free medium. The protection exerted by the ceramide synthase inhibitor fumonisin B1 over doxorubicin-induced apoptosis was enhanced by IGFBP-3 with concomitant reduction of ceramide levels. IGFBP-3 alone activated sphingosine kinase (SK) and increased SK1 mRNA; the SK inhibitor N,N-dimethylsphingosine (DMS) blocked IGFBP-3 antiapoptotic effect. Moreover, IGFBP-3 increased IGF-I mRNA and dramatically enhanced IGF-I release. IGF-I receptor (IGF-IR) and its downstream signaling pathways Akt and ERK were phosphorylated by IGFBP-3, whereas inhibition of IGF-IR phosphorylation with tyrphostin AG1024 suppressed the antiapopoptic effect of IGFBP-3. Finally, IGFBP-3 increased endothelial cell motility in all experimental conditions. These findings provide evidence that IGFBP-3 differentially regulates endothelial cell apoptosis by involvement of the sphingolipid signaling pathways. Moreover, the survival effect of IGFBP-3 seems to be mediated by the IGF-IR.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, C.so Dogliotti 14-10126 Turin, Italy.
authors.forename: Riccarda
authors.initials: R
authors.lastname: Granata
authors.forename: Letizia
authors.initials: L
authors.lastname: Trovato
authors.forename: Giovanni
authors.initials: G
authors.lastname: Garbarino
authors.forename: Marina
authors.initials: M
authors.lastname: Taliano
authors.forename: Renata
authors.initials: R
authors.lastname: Ponti
authors.forename: Giusy
authors.initials: G
authors.lastname: Sala
authors.forename: Riccardo
authors.initials: R
authors.lastname: Ghidoni
authors.forename: Ezio
authors.initials: E
authors.lastname: Ghigo
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D037341:Fumonisins / Q000494:pharmacology; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013107:Sphingolipids / Q000378:metabolism*; D014470:Umbilical Cord / Q000166:cytology; D015854:Up-Regulation / Q000187:drug effects; D000099157:Sphingosine Kinase
chemical_list: D002518:Ceramides; D016895:Culture Media, Serum-Free; D004317:Doxorubicin; D048049:Extracellular Signal-Regulated MAP Kinases; D037341:Fumonisins; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D017526:Receptor, IGF Type 1; D013107:Sphingolipids; D000099157:Sphingosine Kinase; C056933:fumonisin B1; C494918:AKT1 protein, human