Butyrylcholinesterase expression is regulated by fatty acids in HepG2 cells Muslum Gok a , N. Dilara Zeybek b , Ebru Bodur a, * a Hacettepe University, Faculty of Medicine, Department of Medical Biochemistry, 06100, Ankara, Turkey b Hacettepe University, Faculty of Medicine, Department of Histology and Embryology, 06100, Ankara, Turkey article info Article history: Received 30 December 2015 Received in revised form 5 April 2016 Accepted 18 April 2016 Available online xxx Keywords: Butyrylcholinesterase HepG2 Lipid metabolism Linoleic acid a-Linolenic acid Expression abstract Butyrylcholinesterase (BChE) is mostly associated with the detoxification of xenobiotics. In this study to analyze the involvement of BChE in lipid metabolism, linoleic acid (LA) and a-linolenic acid (ALA) were applied to HepG2 cells along with expression of wild type human BChE. After 48 h of these treatments WST-1 cell proliferation assay, FACS analysis, RT-PCR, Oil Red O staining and activity assays were per- formed. Application of high concentrations of LA to HepG2 cells without BChE transfection lead to detachment of the cells. The IC 50 value LA was found as 149.3 mM whereas the IC 50 value for ALA could not be calculated. Hence, in order to display minimal effects on cell viability, 5 mM was chosen as appropriate concentration for LA and ALA application to HepG2 cells. Transfection of wild-type BChE plasmid to HepG2 cells yielded increased BChE expression. Application of 5 mM ALA after BChE trans- fection to HepG2 cells resulted in increased expression of BChE. Although with this low concentration the number of apoptotic cells was decreased with ALA treatments, LA application did not cause a similar result with the same dose. Moreover ghost cell like property was observed in LA-treated cells. Appli- cation of ALA, on the other hand, led to an overall increase in cell numbers, BChE expression and activity. Our results indicate that BChE expression might be regulated by ALA in HepG2 cells. © 2016 Published by Elsevier Ireland Ltd. 1. Introduction Cholinesterases (ChEs) are classified into two subtypes through their genetic location, substrate-inhibitor specificity and response to carbamates, organophosphates, and xenobiotics as acetylcho- linesterase (AChE) and butyrylcholinesterase (BChE) [1e8]. Furthermore, there seems to be a counter-regulation between ChEs, which is reflected in proliferation and differentiation related signaling [7,8]. BChE is a major plasma enzyme released from liver [9]. Numerous reports link BChE activity with obesity, coronary artery disease, adiposity, type-2 diabetes mellitus and the hepatic fat content [10e14]. There is also a report on BChE knockout mice, which becomes obese on a high-fat diet [14]. We have previously shown a link between lipoprotein lipase, plasma free fatty acid levels and BChE along with exercise and conjugated linoleic acid (CLA) supplementation [15]. Recently, it has also been reported that pure human BChE is capable of hydrolyzing octanoyl ghrelin to desacyl ghrelin [16]. Linoleic acid (LA, u-6, 18:2, cis,cis-9,12-octadecadienoic acid) and a-linolenic acid (ALA, u-3, 18:3, cis,cis,cis-9,12,15- octadecatrienoic acid) are two fatty acids which cannot be syn- thesized in mammalian cells due to lack of the desaturase enzyme. Hence, dietary intake is essential. These polyunsaturated fatty acids (PUFAs) engage in regulation of immune function through eicosa- noid synthesis and alter plasma lipids as well as nuclear receptor activation [17,18]. In this study, this link between lipid metabolism and BChE was investigated in HepG2 cells. Essential fatty acids, linoleic acid (LA) and a-linolenic acid (ALA) were applied to HepG2 cells. For better evaluation HepG2 cells were also transfected with wild-type BChE. Our results display that expression of BChE in HepG2 cells treated with LA and ALA is increased as displayed by RT-PCR and protein studies. Furthermore ALA treatment of wt-BChE transfected cells increased the number of healthy HepG2 cells. We surmise that BChE expression might be regulated by ALA treatment, which in turn aids cell viability. * Corresponding author. E-mail address: ebodur@hacettepe.edu.tr (E. Bodur). Contents lists available at ScienceDirect Chemico-Biological Interactions journal homepage: www.elsevier.com/locate/chembioint http://dx.doi.org/10.1016/j.cbi.2016.04.029 0009-2797/© 2016 Published by Elsevier Ireland Ltd. Chemico-Biological Interactions xxx (2016) 1e6 Please cite this article in press as: M. Gok, et al., Butyrylcholinesterase expression is regulated by fatty acids in HepG2 cells, Chemico-Biological Interactions (2016), http://dx.doi.org/10.1016/j.cbi.2016.04.029