title: Hexadecylphosphocholine disrupts cholesterol homeostasis and induces the accumulation of free cholesterol in HepG2 tumour cells.
abstract: Hexadecylphosphocholine (HePC) is a synthetic lipid belonging to the alkylphosphocholines (APC), a new group of antiproliferative agents that are proving to be promising candidates in anticancer therapy. We reported in a previous study that HePC interferes with phosphatidylcholine (PC) synthesis in HepG2 cells via both CDP-choline and phosphatidylethanolamine (PE) methylation. We have subsequently extended our studies to show that HePC interferes with sphingolipid metabolism by hindering the formation of sphingomyelin (SM), an effect accompanied by a substantial increase in the incorporation of the exogenous lipogenic precursors into ceramides. Interestingly, we demonstrate for the first time that HePC strongly inhibits the esterification of free cholesterol (FC) by acting at the level of acyl CoA:cholesterol acyltransferase (ACAT) (EC 2.3.1.26) activity. This effect is accompanied by a considerable increase in the synthesis of cholesterol, which leads to a rise in the levels of FC in cells. We are left in no doubt that the imbalance in the metabolism of membrane-lipid components vital to cell survival may well be responsible for the observed DNA fragmentation and activation of caspase-3, an enzyme involved in the cell apoptosis found in this study.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Jiménez-López
authors.forename: María P
authors.initials: MP
authors.lastname: Carrasco
authors.forename: Carmen
authors.initials: C
authors.lastname: Marco
authors.forename: Josefa L
authors.initials: JL
authors.lastname: Segovia
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000096:biosynthesis*; D002788:Cholesterol Esters / Q000096:biosynthesis; D053938:DNA Fragmentation / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013109:Sphingomyelins / Q000378:metabolism; D014709:Vero Cells
chemical_list: D000970:Antineoplastic Agents; D002518:Ceramides; D002788:Cholesterol Esters; D013109:Sphingomyelins; D010767:Phosphorylcholine; C039128:miltefosine; D002784:Cholesterol; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases