title: Specific inhibition of the Akt1 pleckstrin homology domain by D-3-deoxy-phosphatidyl-myo-inositol analogues.
abstract: Activation of Akt (protein kinase B), a Ser/Thr protein kinase that promotes cell survival, has been linked to tumorigenesis. Akt is activated by phosphorylation after binding of its pleckstrin homology (PH) domain to plasma membrane phosphatidyl-myo-inositol-3-phosphates, formed by phosphoinositide-3-kinase. We report a novel strategy to inhibit Akt activation based on the use of D-3-deoxy-phosphatidyl-myo-inositols (DPIs) that cannot be phosphorylated on the 3-position of the myo-inositol ring. We have studied the DPIs, DPI 1-[(R)-2,3-bis(hexadecanoyloxy)propyl hydrogen phosphate], its ether lipid derivative DPI 1-[(R)-2-methoxy-3-octadecyloxypropyl hydrogen phosphate] (DPIEL), and its carbonate derivative DPI 1-[(R)-2-methoxy-3-octadecyloxypropyl carbonate]. We demonstrate in platelet-derived growth factor-stimulated mouse NIH3T3 cells that the DPIs bind to the PH domain of Akt, trapping it in the cytoplasm and thus preventing Akt activation. DPIEL did not inhibit myristylated-Akt, a constitutively active membrane-bound Akt expressed in NIH3T3 cells, and cell growth was not inhibited, unlike in wild-type NIH3T3 cells. Molecular modeling and docking studies show that DPIEL binds with much higher affinity to Akt's PH domain as compared with DPI and DPI 1-[(R)-2-methoxy-3-octadecyloxypropyl carbonate]. This study shows that the DPIs are a novel class of growth inhibitory agents with a novel mechanism of action through binding to the PH domain of Akt and inhibition of Akt activation.
authors.affiliation: Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, USA. emay@azcc.arizona.edu
authors.forename: Emmanuelle J
authors.initials: EJ
authors.lastname: Meuillet
authors.forename: Daruka
authors.initials: D
authors.lastname: Mahadevan
authors.forename: Hariprasad
authors.initials: H
authors.lastname: Vankayalapati
authors.forename: Margareta
authors.initials: M
authors.lastname: Berggren
authors.forename: Ryan
authors.initials: R
authors.lastname: Williams
authors.forename: Amy
authors.initials: A
authors.lastname: Coon
authors.forename: Alan P
authors.initials: AP
authors.lastname: Kozikowski
authors.forename: Garth
authors.initials: G
authors.lastname: Powis
mesh_terms: D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry; D002455:Cell Division; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D050356:Lipid Metabolism; D051379:Mice; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D009227:Myristic Acids / Q000378:metabolism; D041681:NIH 3T3 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010716:Phosphatidylinositols / Q000737:chemistry / Q000494:pharmacology*; D010750:Phosphoproteins / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014162:Transfection
chemical_list: D001798:Blood Proteins; D004791:Enzyme Inhibitors; D009227:Myristic Acids; D019869:Phosphatidylinositol 3-Kinases; D010716:Phosphatidylinositols; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C039077:platelet protein P47