title: The novel synthetic ether lipid inositol-C2-PAF inhibits phosphorylation of the tyrosine kinases Src and FAK independent of integrin activation in transformed skin cells.
abstract: New alkyl-phospholipids that are structurally derived from platelet-activating factor are promising candidates for anticancer treatment. The mechanism of action of derivatives of the platelet-activating factor is distinctly different from that of known DNA- or tubulin-targeting anticancer agents because they are incorporated into cell membranes, where they accumulate and interfere with a wide variety of key enzymes. We recently presented evidence of a novel group of alkyl-phospholipids, glycosidated phospholipids that efficiently inhibit cell proliferation. One member of this group, inositol-C2-PAF (Ino-C2-PAF), displays high efficacy and low cytotoxicity in HaCaT-cells, an immortalized non-tumorigenic skin keratinocyte cell line. Here, we show that Ino-C2-PAF also inhibits the motility of the skin-derived transformed cell lines HaCaT and squamous cell carcinoma (SCC)-25. This decrease in motility is accompanied by an altered F-actin cytoskeleton, increased clustering of integrins, and increased cell-matrix adhesion. Despite enhanced integrin clustering and matrix adhesion, we observed less phosphorylation of the cytoplasmic tyrosine kinases focal adhesion kinase (FAK) and Src, key regulators of cellular motility, at focal adhesion sites. Transient transfection of constitutively active variants of FAK and Src could at least in part bybass this inhibitory effect of Ino-C2-PAF. This fact indicates that Ino-C2-PAF interferes with the fine-tuned balance between adhesion and migration. Ino-C2-PAF at least partially uncouples integrin-mediated attachment from subsequent integrin-dependent signaling steps, which inhibits migration in transformed keratinocyte cell lines.
authors.affiliation: Charité-Universitaetsmedizin Berlin, Campus Virchow Klinikum, Institut fuer Biochemie, Oudenarder Str. 16, 13347 Berlin, Germany.
authors.forename: Geo
authors.initials: G
authors.lastname: Semini
authors.forename: Annette
authors.initials: A
authors.lastname: Hildmann
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Reissig
authors.forename: Werner
authors.initials: W
authors.lastname: Reutter
authors.forename: Kerstin
authors.initials: K
authors.lastname: Danker
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects; D005434:Flow Cytometry; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D010742:Phospholipid Ethers / Q000494:pharmacology*; D010766:Phosphorylation; D015398:Signal Transduction; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D016023:Integrins; D010742:Phospholipid Ethers; C026659:edelfosine; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D019061:src-Family Kinases