title: Characterization of heparanase-induced phosphatidylinositol 3-kinase-AKT activation and its integrin dependence.
abstract: Heparanase functions as a heparan sulfate-degrading enzyme and as a ligand for an unidentified signaling receptor(s). Here, several reactions involved in the activation of the PI3K-AKT pathway by latent heparanase were characterized. Protein suppression using specific siRNAs revealed that heparanase-induced phosphorylation of AKT at Ser-473 was RICTOR-mTOR-dependent, whereas ILK and PAK1/2 were dispensable. p110α was the PI3K catalytic isoform preferred by heparanase for AKT activation and cell proliferation because the p110α inhibitor YM024 blocked these processes. Heparanase-induced AKT phosphorylation was low in mouse embryonic fibroblast cells expressing a RAS interaction-defective p110α compared with wild type cells, indicating that RAS has an important role in the PI3K-AKT activation. The response to heparanase was also inefficient in suspension cultures of several cell lines, suggesting a requirement of integrins in this pathway. Adhesion via either αVβ3 or α5β1 promoted heparanase-induced AKT phosphorylation, and a stronger effect was seen when both integrins were engaged. Simultaneous inhibition of FAK and PYK2 using a chemical inhibitor, or suppression of their expression, inhibited heparanase-induced AKT activation and cell proliferation. Stimulation of cells with heparanase enhanced their resistance against oxidative stress- or growth factor starvation-induced apoptosis. These results demonstrate that there is an intimate cross-talk between the heparanase receptor(s) and integrins during induction of the prosurvival PI3K-AKT pathway by heparanase.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, 75123 Uppsala, Sweden.
authors.forename: Anjum
authors.initials: A
authors.lastname: Riaz
authors.forename: Neta
authors.initials: N
authors.lastname: Ilan
authors.forename: Israel
authors.initials: I
authors.lastname: Vlodavsky
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Li
authors.forename: Staffan
authors.initials: S
authors.lastname: Johansson
mesh_terms: D000818:Animals; D016466:CHO Cells; D058534:Class I Phosphatidylinositol 3-Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D019030:Receptors, Vitronectin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013876:Thiophenes / Q000494:pharmacology; D054462:p21-Activated Kinases / Q000235:genetics / Q000378:metabolism; D000099175:Heparanase
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; D004791:Enzyme Inhibitors; D005966:Glucuronidase; D039302:Integrin alphaVbeta3; D009025:Morpholines; D051057:Proto-Oncogene Proteins c-akt; D019030:Receptors, Vitronectin; D013876:Thiophenes; D054462:p21-Activated Kinases; D000099175:Heparanase; C000598597:3-(4-morpholinothieno(3,2-d)pyrimidyl-2-yl)phenol; C094340:integrin alphavbeta1; C509622:1-phosphatidylinositol 3-kinase p110 subunit, mouse; C515903:PAK1 protein, human; C515907:PAK2 protein, human; C515905:Pak1 protein, mouse; C515909:Pak2 protein, mouse