Effects of Combined EPA, DHA and Cd2+ on Fatty Acids and Phospholipid Classes in Human Hep G2 Cells 
Linhartova P.,*1 and Sampels S.1
1University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research Institute of Aquaculture and Protection of Waters, Husova tř. 458/102, 370 05,České Budějovice, Czech Republic, email*: linhap01@frov.jcu.cz

Human Hep G2 hepatocellular cells were used to mimic the effects of consumption of contaminated fish. Cells were incubated with eicosapentaenoic acid (EPA) and docosahexaenioc acid (DHA), important fatty acids (FA) in fish and subsequently with cadmium chloride (Cd2+) as a relevant and carcinogenic contaminant. The aim of this study was to investigate the uptake of FA and the impact of cadmium chloride (Cd2+) on the lipid metabolism in the cells.
The results showed that 2 h incubations with EPA or DHA repeated three times (total 6h of FA duration on cell with changing culture medium) significantly increased the amount of these FA plus DPA (docosapentaenoic acid),  compared to all other treatments, indicating that an increased amount of substrate enhances metabolism from EPA towards the longer chain n-3 FA.
In opposite to incubations for 24h with FA only, a combined incubation of 24h FA and subsequently with cadmium at 5µM also resulted in increased levels of DPA but not EPA and DHA, in the total lipid content of the cells, which then could either be a sign for increased metabolism from EPA to DPA or increased ß-oxidation DHA to DPA induced by the cadmium. Also we found that incubation with cadmium decreased cardiolipin, which is an essential phospholipid class in the mitochondria. These findings correlate with the decreased cell viability shown by the cytotoxic assay and indicate that cadmium affects mitochondrial function.  

Acknowledgements: The study was financially supported by the Ministry of Education, Youth and Sports of the Czech Republic - projects „CENAKVA“(No. CZ.1.05/2.1.00/01.0024) and “CENAKVA II“(No. LO1205 under the NPU I program),  by the Grant Agency of Czech Republic (GACR No. 13-01543S) and by the Grant Agency of the University of South Bohemia in Ceske Budejovice (GAJU No. 134/2013/Z ).