title: 4-Hydroxyhexenal and 4-hydroxynonenal are mediators of the anti-cachectic effect of n-3 and n-6 polyunsaturated fatty acids on human lung cancer cells.
abstract: Cachexia, the most severe paraneoplastic syndrome, occurs in about 80% of patients with advanced cancer; it cannot be reverted by conventional, enteral, or parenteral nutrition. For this reason, nutritional interventions must be based on the use of substances possessing, alongside nutritional and energetic properties, the ability to modulate production of the pro-inflammatory factors responsible for the metabolic changes characterising cancer cachexia. In light of their nutritional and anti-inflammatory properties, polyunsaturated fatty acids (PUFAs), and in particular n-3, have been investigated for treating cachexia; however, the results have been contradictory. Since both n-3 and n-6 PUFAs can affect cell functions in several ways, this research investigated the possibility that the effects of both n-3 and n-6 PUFAs could be mediated by their major aldehydic products of lipid peroxidation, 4-hydroxyhexenal (HHE) and 4-hydroxynonenal (HNE), and by their anti-inflammatory properties. An "in vitro" cancer cachexia model, consisting of human lung cancer cells (A427) and murine myoblasts (C2C12), was used. The results showed that: 1) both n-3 and n-6 PUFAs reduced the growth of lung cancer cells without causing cell death, increased lipid peroxidation and Peroxisome Proliferator-Activated Receptor (PPAR)α, and decreased TNFα; 2) culture medium conditioned by A427 cells grown in the absence of PUFAs blocked myosin production and the differentiation of C2C12 muscle cells; conversely, muscle cells grown in culture medium conditioned by the same cells in the presence of PUFAs showed myosin expression and formed myotubes; 3) adding HHE or HNE directly to C2C12 cells maintained in culture medium conditioned by A427 cells in the absence of PUFAs stimulated myosin production and myotube formation; 4) putative consensus sequences for (PPARs) have been found in genes encoding fast isoforms of myosin heavy chain, by a bioinformatics approach. The overall results show, first, the ability of both n-3 and n-6 PUFAs and their lipid peroxidation products to prevent the blocking of myosin expression and myotube formation caused in C2C12 cells by medium conditioned by human lung tumour cells. The C2C12 cell differentiation can be due to direct effect of lipid peroxidation products, as evidenced by treating C2C12 cells with HHE and HNE, and to the decrease of pro-inflammatory TNFα in A427 cell culture medium. The presence of consensus sequences for PPARs in genes encoding the fast isoforms of myosin heavy chain suggests that the effects of PUFAs, HHE, and HNE are PPAR-mediated.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Corso Raffaello 30, 10125 Turin, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Muzio
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Corso Raffaello 30, 10125 Turin, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ricci
authors.affiliation: Department of Experimental Medicine, University of Genoa, Via Leon Battista Alberti 2, 16132 Genoa, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Traverso
authors.affiliation: Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132 Genoa, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Monacelli
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Corso Raffaello 30, 10125 Turin, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Oraldi
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Corso Raffaello 30, 10125 Turin, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Maggiora
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Corso Raffaello 30, 10125 Turin, Italy. Electronic address: rosangela.canuto@unito.it.
authors.forename: R A
authors.initials: RA
authors.lastname: Canuto
mesh_terms: D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D005786:Gene Expression Regulation; D006801:Humans; D015227:Lipid Peroxidation; D051379:Mice; D032342:Muscle Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D000447:Aldehydes; D017077:Culture Media, Conditioned; D047493:PPAR alpha; D014409:Tumor Necrosis Factor-alpha; C063409:4-hydroxyhexenal; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D018995:Myosin Heavy Chains; C027576:4-hydroxy-2-nonenal
keywords: Cachexia; HHE; HNE; Lung cancer; Muscle cells; Myosin; PPARs; PPRE; TNFα; n-3 PUFAs; n-6 PUFAs, lipid peroxidation