title: Intracellular sphingosine kinase 2-derived sphingosine-1-phosphate mediates epidermal growth factor-induced ezrin-radixin-moesin phosphorylation and cancer cell invasion.
abstract: The bioactive sphingolipid sphingosine-1-phosphate (S1P) mediates cellular proliferation, mitogenesis, inflammation, and angiogenesis. These biologies are mediated through S1P binding to specific GPCRs [sphingosine-1-phosphate receptor (S1PR)1-5] and some other less well-characterized intracellular targets. Ezrin-radixin-moesin (ERM) proteins, a family of adaptor molecules linking the cortical actin cytoskeleton to the plasma membrane, are emerging as critical regulators of cancer invasion via regulation of cell morphology and motility. Recently, we identified S1P as an acute ERM activator (via phosphorylation) through its action on S1PR2. In this work, we dissect the mechanism of S1P generation downstream of epidermal growth factor (EGF) leading to ERM phosphorylation and cancer invasion. Using pharmacologic inhibitors, small interfering RNA technologies, and genetic approaches, we demonstrate that sphingosine kinase (SK)2, and not SK1, is essential and sufficient in EGF-mediated ERM phosphorylation in HeLa cells. In fact, knocking down SK2 decreased ERM activation 2.5-fold. Furthermore, we provide evidence that SK2 is necessary to mediate EGF-induced invasion. In addition, overexpressing SK2 causes a 2-fold increase in HeLa cell invasion. Surprisingly, and for the first time, we find that this event, although dependent on S1PR2 activation, does not generate and does not require extracellular S1P secretion, therefore introducing a potential novel model of autocrine/intracrine action of S1P that still involves its GPCRs. These results define new mechanistic insights for EGF-mediated invasion and novel actions of SK2, therefore setting the stage for novel targets in the treatment of growth factor-driven malignancies.
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Mohamad M
authors.initials: MM
authors.lastname: Adada
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Canals
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Nara
authors.initials: N
authors.lastname: Jeong
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Ashwin D
authors.initials: AD
authors.lastname: Kelkar
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Hernandez-Corbacho
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pulkoski-Gross
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Jane C
authors.initials: JC
authors.lastname: Donaldson
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA.
authors.forename: Yusuf A
authors.initials: YA
authors.lastname: Hannun
authors.affiliation: *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA lina.obeid@stonybrookmedicine.edu.
authors.forename: Lina M
authors.initials: LM
authors.lastname: Obeid
mesh_terms: D019898:Autocrine Communication / Q000235:genetics; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008246:Lysophospholipids / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D000081025:Sphingosine-1-Phosphate Receptors; D000099149:Ezrin; D000099157:Sphingosine Kinase
chemical_list: D003598:Cytoskeletal Proteins; D004815:Epidermal Growth Factor; D008246:Lysophospholipids; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D049349:Receptors, Lysosphingolipid; D013110:Sphingosine; D000081025:Sphingosine-1-Phosphate Receptors; D000099149:Ezrin; C477522:S1PR2 protein, human; C071058:moesin; C071776:radixin; C060506:sphingosine 1-phosphate; C000594250:sphingosine kinase 2, human; D000099157:Sphingosine Kinase
keywords: Spns2; alkaline ceramidase 2; cell adhesion