Effects of cigarette smoke on cell viability, linoleic acid metabolism and cholesterol synthesis, in THP-1 cells.
Cigarette smoke (CS) contains thousands of substances, mainly free radicals that have as a target the polyunsaturated fatty acids (PUFA). Long chain PUFA are produced through elongation and desaturation reactions from their precursors; the desaturation reactions are catalyzed by different enzymes: the conversion of 18:2n-6 (linoleic acid, LA) to 18:3n-6 by Delta6 desaturase, while that of 20:3n-6 to 20:4n-6 by Delta5 desaturase. The aim of this work is to evaluate the effect of serum exposed to cigarette smoke (SE-FBS) on (1) cell viability and proliferation, (2) [1-(14)C] LA conversion and desaturase activities in THP-1 cells, a monocytic cell line. In THP-1, CS inhibits cell proliferation dose-dependently, by producing a modification in the cell cycle with a reduced number of cells in synthesis and mitosis phases at higher concentrations. CS also decreases [1-(14)C] LA conversion to its derivatives in a concentration-dependent manner, inhibiting the activities of Delta6 and mainly Delta5 desaturase. In addition, CS does not modify the incorporation of LA into various lipid classes but it reduces cholesterol synthesis from radiolabelled acetate, and increases free fatty acid, TG and CE levels. In conclusion, CS affects lipid metabolism, inhibiting LA conversion and desaturase activities. CS also shifts the "de novo" lipid synthesis from free cholesterol to TG and CE, where LA is preferentially esterified.
Ghezzi
Silvia
S
Department of Pharmacological Sciences, University of Milan, via Balzaretti 9, 20133 Milan, Italy.
Risé
Patrizia
P
Ceruti
Stefania
S
Galli
Claudio
C
D000818:Animals; D002417:Cattle; D002470:Cell Survival; D002784:Cholesterol / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005419:Flavonoids / Q000032:analysis; D006801:Humans; D019787:Linoleic Acid / Q000378:metabolism*; D050602:Linoleoyl-CoA Desaturase / Q000378:metabolism; D050356:Lipid Metabolism; D009000:Monocytes / Q000378:metabolism; D010636:Phenols / Q000032:analysis; D059808:Polyphenols; D014028:Tobacco Smoke Pollution / Q000032:analysis; D014407:Tumor Cells, Cultured
D005231:Fatty Acids, Unsaturated; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D014028:Tobacco Smoke Pollution; D002784:Cholesterol; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase