title: Endothelin-1 inhibits apoptosis through a sphingosine kinase 1-dependent mechanism in uterine leiomyoma ELT3 cells.
abstract: Uterine leiomyomas, or fibroids, are the most common tumors of the myometrium. The ELT3 cell line, derived from Eker rat leiomyoma, has been successfully used as a model for the study of leiomyomas. We have demonstrated previously the potent mitogenic properties of the peptidic hormone endothelin (ET)-1 in this cell line. Here we investigated the antiapoptotic effect of ET-1 in ELT3 cells. We found that 1) serum starvation of ELT3 cells induced an apoptotic process characterized by cytochrome c release from mitochondria, caspase-3/7 activation, nuclei condensation and DNA fragmentation; 2) ET-1 prevented the apoptotic process; and 3) this effect of ET-1 was fully reproduced by ETB agonists. In contrast, no antiapoptotic effect of ET-1 was observed in normal myometrial cells. A pharmacological approach showed that the effect of ET-1 on caspase-3/7 activation in ELT3 cells was not dependent on phosphatidylinositol 3-kinase, ERK1/2, or phospholipase D activities. However, inhibitors of sphingosine kinase-1 (SphK1), dimethylsphingosine and threo-dihydrosphingosine, reduced the effect of ET-1 by about 50%. Identical results were obtained when SphK1 expression was down-regulated in ELT3 cells transfected with SphK1 small interfering RNA. Furthermore, serum starvation induced a decrease in SphK1 activity that was prevented by ET-1 without affecting the level of SphK1 protein expression. Finally, sphingosine 1-phosphate, the product of SphK activity, was as efficient as ET-1 in inhibiting serum starvation-induced caspase-3/7 activation. Together, these results demonstrate that ET-1 possesses a potent antiapoptotic effect in ELT3 cells that involves sphingolipid metabolism through the activation of SphK1.
authors.affiliation: Signalisation et Régulations Cellulaires, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8619, Bâtiment 430, Université Paris Sud, 91 S/R/C 405 Orsay Cedex, France.
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Raymond
authors.forename: Christine
authors.initials: C
authors.lastname: Bole-Feysot
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Banno
authors.forename: Zahra
authors.initials: Z
authors.lastname: Tanfin
authors.forename: Philippe
authors.initials: P
authors.lastname: Robin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D019610:Cytoprotection / Q000187:drug effects; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D007889:Leiomyoma / Q000201:enzymology* / Q000473:pathology; D009215:Myometrium / Q000166:cytology / Q000187:drug effects; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology*; D051381:Rats; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000201:enzymology* / Q000473:pathology; D000099157:Sphingosine Kinase
chemical_list: D016895:Culture Media, Serum-Free; D019332:Endothelin-1; D017853:Phosphotransferases (Alcohol Group Acceptor); D000099157:Sphingosine Kinase