title: Toxicity of oxidized phosphatidylcholines in cultured human melanoma cells.
abstract: The oxidized phospholipids (oxPL) 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) and 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC) are generated from 1-palmitoyl-2-arachidonoyl-phosphatidylcholine under conditions of oxidative stress. These oxPL are components of oxidized low density lipoprotein. They are cytotoxic in cells of the arterial wall thus playing an important role in the development and progression of atherosclerosis. The toxic lipid effects include inflammation and under sustained exposure apoptosis. The aim of this study was to find out whether such toxic effects, especially apoptosis, are also elicited by oxPL in melanocytic cells in order to assess their potential for therapeutic intervention. FACS analysis after staining with fluorescent markers was performed to identify the mode of lipid-induced cell death. Activation of sphingomyelinase which generates apoptotic ceramide was measured using an established fluorescence assay. Ceramide profiles were determined by mass spectrometry. We found that 50μM POVPC induce cell death in human melanoma cells isolated from different stages of tumor progression but affect primary human melanocytes to a much lesser extent. In contrast, 50μM PGPC was only apoptotic in two out of four cell lines used in this study. The toxicity of both compounds was associated with efficient lipid uptake into the tumor cells and activation of acid sphingomyelinase. In several but not all melanoma cell lines used in this study, activation of the sphingomyelin degrading enzyme correlated with an increase in the concentration of the apoptotic mediator ceramide. The individual patterns of the newly formed ceramide species were also cell line-specific. PGPC and POVPC may be considered potential drug candidates for topical skin cancer treatment. They are toxic in malignant cells. The respective oxidized phospholipids are naturally formed in the body and resistance to these compounds is not likely to occur.
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Graz, Austria. Electronic address: clramprecht@gmail.com.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ramprecht
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Graz, Austria. Electronic address: h.m.jaritz@gmail.com.
authors.forename: Hannah
authors.initials: H
authors.lastname: Jaritz
authors.affiliation: Institute of Molecular Biosciences, Karl-Franzens University Graz, Graz, Austria. Electronic address: ingo.streith@uni-graz.at.
authors.forename: Ingo
authors.initials: I
authors.lastname: Streith
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Graz, Austria. Electronic address: elfriede.zenzmaier@tugraz.at.
authors.forename: Elfriede
authors.initials: E
authors.lastname: Zenzmaier
authors.affiliation: Core Facility for Mass Spectrometry, Center for Medical Research, Medical University of Graz, Graz, Austria. Electronic address: harald.koefeler@klinikum-graz.at.
authors.forename: Harald
authors.initials: H
authors.lastname: Köfeler
authors.affiliation: Department of Dermatology, Medical University of Graz, Graz, Austria. Electronic address: rainer.hofmann@medunigraz.at.
authors.forename: Rainer
authors.initials: R
authors.lastname: Hofmann-Wellenhof
authors.affiliation: Dermatology Research Centre, Translational Research Institute (TRI), School of Medicine, The University of Queensland, Brisbane, Queensland, Australia. Electronic address: h.schaider@uq.edu.au.
authors.forename: Helmut
authors.initials: H
authors.lastname: Schaider
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Graz, Austria. Electronic address: albin.hermetter@tugraz.at.
authors.forename: Albin
authors.initials: A
authors.lastname: Hermetter
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001896:Boron Compounds / Q000737:chemistry; D045744:Cell Line, Tumor; D002518:Ceramides / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000633:toxicity*; D008545:Melanoma / Q000378:metabolism / Q000473:pathology; D008856:Microscopy, Fluorescence; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000737:chemistry*; D010742:Phospholipid Ethers / Q000737:chemistry / Q000633:toxicity; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism
chemical_list: C400184:1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphorylcholine; C400185:1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphorylcholine; C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D002518:Ceramides; D008077:Lipoproteins, LDL; D010713:Phosphatidylcholines; D010742:Phospholipid Ethers; C099252:oxidized low density lipoprotein; D013108:Sphingomyelin Phosphodiesterase
keywords: Aldehydophospholipid; Apoptosis; Ceramide; PGPC; POVPC; Skin cancer