A trans 10-18:1 enriched fraction from beef fed a barley grain-based diet induces lipogenic gene expression and reduces viability of HepG2 cells

Payam Vahmani; William J Meadus; Maria L P da Silva; Alec D Mitchell; Cletos Mapiye; Pascale Duff; David C Rolland; Michael E R Dugan

doi:10.1016/j.bbrep.2016.05.018

A trans 10-18:1 enriched fraction from beef fed a barley grain-based diet induces lipogenic gene expression and reduces viability of HepG2 cells

Biochem Biophys Rep. 2016 May 27:7:84-90. doi: 10.1016/j.bbrep.2016.05.018. eCollection 2016 Sep.

Authors

Payam Vahmani¹, William J Meadus¹, Maria L P da Silva², Alec D Mitchell³, Cletos Mapiye⁴, Pascale Duff¹, David C Rolland¹, Michael E R Dugan¹

Affiliations

¹ Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, Alberta, Canada.
² Faculty of Veterinary and Agricultural Sciences, São Paulo State University, Jaboticabal, SP, Brazil.
³ Faculty of Science, University of Alberta, Edmonton, Alberta, Canada.
⁴ Department of Animal Sciences, Faculty of AgriSciences, Stellenbosch University, P. Bag X1, Matieland 7602, South Africa.

Abstract

Beef fat is a natural source of trans (t) fatty acids, and is typically enriched with either t10-18:1 or t11-18:1. Little is known about the bioactivity of individual t-18:1 isomers, and the present study compared the effects of t9-18:1, cis (c)9-18:1 and trans (t)-18:1 fractions isolated from beef fat enriched with either t10-18:1 (HT10) or t11-18:1 (HT11). All 18:1 isomers resulted in reduced human liver (HepG2) cell viability relative to control. Both c9-18:1 and HT11were the least toxic, t9-18:1had dose response increased toxicity, and HT10 had the greatest toxicity (P<0.05). Incorporation of t18:1 isomers was 1.8-2.5 fold greater in triacylglycerol (TG) than phospholipids (PL), whereas Δ9 desaturation products were selectively incorporated into PL. Culturing HepG2 cells with t9-18:1 and HT10 increased (P<0.05) the Δ9 desaturation index (c9-16:1/16:0) compared to other fatty acid treatments. HT10 and t9-18:1 also increased expression of lipogenic genes (FAS, SCD1, HMGCR and SREBP2) compared to control (P<0.05), whereas c9-18:1 and HT11 did not affect the expression of these genes. Our results suggest effects of HT11 and c9-18:1 were similar to BSA control, whereas HT10 and t-9 18:1 (i.e. the predominant trans fatty acid isomer found in partially hydrogenated vegetable oils) were more cytotoxic and led to greater expression of lipogenic genes.

Keywords: ACC, acetyl-CoA carboxylase; Ag+-SPE, silver ion solid phase extraction; BSA, bovine serum albumin; Beef; Cell culture; Cytotoxicity; FAS, fatty acid synthase; Fatty acid metabolism; HMGCR, 3-Hydroxy-3-Methylglutaryl-CoA reductase; HT10, high-t10 fraction; HT11, high-t11 fraction; Liver; MUFA, monounsaturated fatty acids; PHVO, partially hydrogenated vegetable oils; PL, phospholipid; PUFA, polyunsaturated fatty acids; SCD1, stearoyl-CoA desaturase-1; SFA, saturated fatty acid; SREBP1c, sterol regulatory element-binding protein-1c; SREBP2, sterol regulatory element-binding protein-2; TG, triacylglycerol; TLC, thin layer chromatography; Trans fatty acids; c,, cis; t, trans.