title: Caspase-3-dependent activation of calcium-independent phospholipase A2 enhances cell migration in non-apoptotic ovarian cancer cells.
abstract: Calcium-independent phospholipase A(2) (iPLA(2)) plays a pivotal role in phospholipid remodeling and many other biological processes, including inflammation and cancer development. iPLA(2) can be activated by caspase-3 via a proteolytic process in apoptotic cells. In this study we identify novel signaling and functional loops of iPLA(2) activation leading to migration of non-apoptotic human ovarian cancer cells. The extracellular matrix protein, laminin-10/11, but not collagen I, induces integrin- and caspase-3-dependent cleavage and activation of overexpressed and endogenous iPLA(2). The truncated iPLA(2) (amino acids 514-806) generates lysophosphatidic acid and arachidonic acid. Arachidonic acid is important for enhancing cell migration toward laminin-10/11. Lysophosphatidic acid activates Akt that in turn acts in a feedback loop to block the cleavage of poly-(ADP-ribose) polymerase and DNA fragmentation factor as well as prevent apoptosis. By using pharmacological inhibitors, blocking antibodies, and genetic approaches (such as point mutations, dominant negative forms of genes, and siRNAs against specific targets), we show that beta(1), but not beta(4), integrin is involved in iPLA(2) activation and cell migration to laminin-10/11. The role of caspase-3 in iPLA(2) activation and cell migration are supported by several lines of evidence. 1) Point mutation of Asp(513) (a cleavage site of caspase-3 in iPLA(2)) to Ala blocks laminin-10/11-induced cleavage and activation of overexpressed iPLA(2), whereas mutation of Asp(733) to Ala has no such effect, 2) treatment of inhibitors or a small interfering RNA against caspase-3 results in decreased cell migration toward laminin-10/11, and 3) selective caspase-3 inhibitor blocks cleavage of endogenous iPLA(2) induced by laminin-10/11. Importantly, small interfering RNA-mediated down-regulation of endogenous iPLA(2) expression in ovarian carcinoma HEY cells results in decreased migration toward laminin, suggesting that our findings are pathophysiologically important.
authors.affiliation: Department of Cancer Biology, The Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors.forename: Xiaoxian
authors.initials: X
authors.lastname: Zhao
authors.forename: Dongmei
authors.initials: D
authors.lastname: Wang
authors.forename: Zhenwen
authors.initials: Z
authors.lastname: Zhao
authors.forename: Yingyi
authors.initials: Y
authors.lastname: Xiao
authors.forename: Saubhik
authors.initials: S
authors.lastname: Sengupta
authors.forename: Yijin
authors.initials: Y
authors.lastname: Xiao
authors.forename: Renliang
authors.initials: R
authors.lastname: Zhang
authors.forename: Kirsten
authors.initials: K
authors.lastname: Lauber
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wesselborg
authors.forename: Li
authors.initials: L
authors.lastname: Feng
authors.forename: Tyler M
authors.initials: TM
authors.lastname: Rose
authors.forename: Yue
authors.initials: Y
authors.lastname: Shen
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhang
authors.forename: Glenn
authors.initials: G
authors.lastname: Prestwich
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism*; D002465:Cell Movement; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D016023:Integrins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D008954:Models, Biological; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2
chemical_list: D016023:Integrins; D007797:Laminin; D008246:Lysophospholipids; C119013:laminin 10; C474559:laminin 11 protein, human; D010741:Phospholipases A; D054467:Phospholipases A2; D053148:Caspase 3; C032881:lysophosphatidic acid; D002118:Calcium