title: Ceramide mediates nanovesicle shedding and cell death in response to phosphatidylinositol ether lipid analogs and perifosine.
abstract: Anticancer phospholipids that inhibit Akt such as the alkylphospholipid perifosine (Per) and phosphatidylinositol ether lipid analogs (PIAs) promote cellular detachment and apoptosis and have a similar cytotoxicity profile against cancer cell lines in the NCI60 panel. While investigating the mechanism of Akt inhibition, we found that short-term incubation with these compounds induced rapid shedding of cellular nanovesicles containing EGFR, IGFR and p-Akt that occurred in vitro and in vivo, while prolonged incubation led to cell detachment and death that depended on sphingomyelinase-mediated generation of ceramide. Pretreatment with sphingomyelinase inhibitors blocked ceramide generation, decreases in phospho-Akt, nanovesicle release and cell detachment in response to alkylphospholipids and PIAs in non-small cell lung cancer cell lines. Similarly, exogenous ceramide also decreased active Akt and induced nanovesicle release. Knockdown of neutral sphingomyelinase decreased, whereas overexpression of neutral or acid sphingomyelinase increased cell detachment and death in response to the compounds. When transferred in vitro, PIA or Per-induced nanovesicles increased ceramide levels and death in recipient cells. These results indicate ceramide generation underlies the Akt inhibition and cytotoxicity of this group of agents, and suggests nanovesicle shedding and uptake might potentially propagate their cytotoxicity in vivo.
authors: Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892-4254, USA.
authors: J J
authors: JJ
authors: Gills
authors: C
authors: C
authors: Zhang
authors: M S
authors: MS
authors: Abu-Asab
authors: S S
authors: SS
authors: Castillo
authors: C
authors: C
authors: Marceau
authors: J
authors: J
authors: LoPiccolo
authors: A P
authors: AP
authors: Kozikowski
authors: M
authors: M
authors: Tsokos
authors: T
authors: T
authors: Goldkorn
authors: P A
authors: PA
authors: Dennis
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D018129:Phosphatidylinositol Phosphates / Q000633:toxicity*; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000627:therapeutic use / Q000633:toxicity; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000627:therapeutic use / Q000633:toxicity; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D002518:Ceramides; D018129:Phosphatidylinositol Phosphates; D011725:Pyridines; D034741:RNA, Small Interfering; C443645:ethyl-7-(3-nitrophenyl)-5,8a-dimethyl-6-methoxycarbonyl-2,3,8,8a-tetrahydro-7H-oxazolo(3,2-a)pyridin-8-carboxylate; D010767:Phosphorylcholine; C105905:perifosine; D066246:ErbB Receptors; D017526:Receptor, IGF Type 1; D051057:Proto-Oncogene Proteins c-akt; D013108:Sphingomyelin Phosphodiesterase