title: Prolactin upregulates sphingosine kinase-1 expression and activity in the human breast cancer cell line MCF7 and triggers enhanced proliferation and migration.
abstract: Sphingosine kinases (SK) catalyze the formation of sphingosine-1-phosphate (S1P) which plays a crucial role in cell growth and survival. Here, we show that prolactin (PRL) biphasically activates the SK-1, but not the SK-2 subtype, in the breast adenocarcinoma cell-line MCF7. A first peak occurs after minutes of stimulation and is followed by a second delayed activation after hours of stimulation. A similar biphasic effect on SK-1 activity is seen for 17beta-estradiol (E(2)). The delayed activation of SK-1 derives from an upregulated mRNA and protein expression and is due to increased SK-1 promoter activity and mechanistically involves STAT5 activation as well as protein kinase C and the classical mitogen-activated protein kinases. Furthermore, glucocorticoids also block both hormone-induced SK-1 expression and activity. Functionally, long-term stimulation of MCF7 cells with PRL or E(2) is well known to trigger increased cell proliferation and migration. Both hormone-induced cell responses critically involve SK-1 activation since the depletion of SK-1, but not SK-2, by siRNA transfection abolishes the hormone-induced cell proliferation and migration. In summary, our data show that PRL and E(2) cause a pronounced delayed SK-1 activation which is due to increased gene transcription, and critically determines the capability of cells to grow and move. Thus, the SK-1 may represent a novel attractive target for anti-tumor therapy.
authors.affiliation: Pharmazentrum frankfurt/ZAFES, Klinikum der J W Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany.
authors.forename: Frauke
authors.initials: F
authors.lastname: Döll
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeilschifter
authors.forename: Andrea
authors.initials: A
authors.lastname: Huwiler
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D006801:Humans; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D015854:Up-Regulation; D000099157:Sphingosine Kinase
chemical_list: D004815:Epidermal Growth Factor; D004958:Estradiol; D017853:Phosphotransferases (Alcohol Group Acceptor); D011388:Prolactin; D034741:RNA, Small Interfering; D000099157:Sphingosine Kinase