title: Linker for activation of T-cell family member2 (LAT2) a lipid raft adaptor protein for AKT signaling, is an early mediator of alkylphospholipid anti-leukemic activity.
abstract: Lipid rafts are highly ordered membrane domains rich in cholesterol and sphingolipids that provide a scaffold for signal transduction proteins; altered raft structure has also been implicated in cancer progression. We have shown that 25 μm 10-(octyloxy) decyl-2-(trimethylammonium) ethyl phosphate (ODPC), an alkylphospholipid, targets high cholesterol domains in model membranes and induces apoptosis in leukemia cells but spares normal hematopoietic and epithelial cells under the same conditions. We performed a quantitative (SILAC) proteomic screening of ODPC targets in a lipid-raft-enriched fraction of leukemic cells to identify early events prior to the initiation of apoptosis. Six proteins, three with demonstrated palmitoylation sites, were reduced in abundance. One, the linker for activation of T-cell family member 2 (LAT2), is an adaptor protein associated with lipid rafts in its palmitoylated form and is specifically expressed in B lymphocytes and myeloid cells. Interestingly, LAT2 is not expressed in K562, a cell line more resistant to ODPC-induced apoptosis. There was an early loss of LAT2 in the lipid-raft-enriched fraction of NB4 cells within 3 h following treatment with 25 μm ODPC. Subsequent degradation of LAT2 by proteasomes was observed. Twenty-five μm ODPC inhibited AKT activation via myeloid growth factors, and LAT2 knockdown in NB4 cells by shRNA reproduced this effect. LAT2 knockdown in NB4 cells also decreased cell proliferation and increased cell sensitivity to ODPC (7.5×), perifosine (3×), and arsenic trioxide (8.5×). Taken together, these data indicate that LAT2 is an early mediator of the anti-leukemic activity of alkylphospholipids and arsenic trioxide. Thus, LAT2 may be used as a target for the design of drugs for cancer therapy.
authors.affiliation: Instituto Nacional de Ciência e Tecnologia em Células-Tronco e Terapia Celular, Fundação Hemocentro de Ribeirão Preto, 14051-140, Ribeirão Preto, SP, Brazil.
authors.forename: Carolina H
authors.initials: CH
authors.lastname: Thomé
authors.forename: Guilherme A
authors.initials: GA
authors.lastname: dos Santos
authors.forename: Germano A
authors.initials: GA
authors.lastname: Ferreira
authors.forename: Priscila S
authors.initials: PS
authors.lastname: Scheucher
authors.forename: Clarice
authors.initials: C
authors.lastname: Izumi
authors.forename: Andreia M
authors.initials: AM
authors.lastname: Leopoldino
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Simão
authors.forename: Pietro
authors.initials: P
authors.lastname: Ciancaglini
authors.forename: Kleber T
authors.initials: KT
authors.lastname: de Oliveira
authors.forename: Alice
authors.initials: A
authors.lastname: Chin
authors.forename: Samir M
authors.initials: SM
authors.lastname: Hanash
authors.forename: Roberto P
authors.initials: RP
authors.lastname: Falcão
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Rego
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: Greene
authors.forename: Vitor M
authors.initials: VM
authors.lastname: Faça
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation; D002784:Cholesterol / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000378:metabolism; D021962:Membrane Microdomains; D010087:Oxides / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects; D010743:Phospholipids / Q000378:metabolism / Q000494:pharmacology*; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D020543:Proteome / Q000032:analysis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C552819:10-(octyloxy)decyl-2-(trimethylammonium)ethyl phosphate; D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D001152:Arsenicals; C419196:LAT2 protein, human; D010087:Oxides; D010743:Phospholipids; D020543:Proteome; D034741:RNA, Small Interfering; D010767:Phosphorylcholine; C105905:perifosine; D002784:Cholesterol; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D000077237:Arsenic Trioxide