The purpose of these studies was to investigate effect of selenate (Se6), selenized yeast (SeYe) and carnosic acid (CA) supplementation to the diet containing fish oil (F-O) and rapeseed oil (R-O) on contents of fatty acids (FA), malondialdehyde (MDA), tocopherols (Ts) and total cholesterol (TCh) in lambs’ spleens. 24 male lambs (4 groups per 6 animals) have been fed: the control diet - the basal diet (BD) enriched in F-O and R-O; the CA diet - BD enriched in F-O, R-O and CA; the SeYeCA diet - BD enriched in F-O, R-O, CA and SeYe; the Se6CA diet - BD enriched in F-O, R-O, CA and Se6. Dietary modifications affected profiles of FA in spleens. The SeYeCA and Se6CA diets increased the docosapentaenoic acid preference in Δ4-desaturase, hence the higher content of docosahexaenoic acid was found in spleens of SeYe- or Se6-treated lambs than in spleens of animals receiving the CA and control diets. Experimental diets reduced the level of atherogenic FA in the spleen in comparison with the control diet. The experimental diets supplemented with SeYe or Se6 increased levels of TCh and Ts in spleens in comparison with the CA and control CA diets. The present studies documented that Se6, SeYe and CA influenced the metabolism of FA, Ts and cholesterol in spleens.

Active vitamin D derivatives (VDDs) – 1α,25-dihydroxyvitamin D3/D2 and their synthetic analogs – are well-known inducers of cell maturation with the potential for differentiation therapy of acute myeloid leukemia (AML). However, their dose-limiting calcemic activity is a significant obstacle to using VDDs as an anticancer treatment. We have shown that different activators of the NF-E2-related factor-2/Antioxidant Response Element (Nrf2/ARE) signaling pathway, such as the phenolic antioxidant carnosic acid (CA) or the multiple sclerosis drug monomethyl fumarate (MMF), synergistically enhance the antileukemic effects of various VDDs applied at low concentrations in vitro and in vivo. This study aimed to investigate whether glutathione, the major cellular antioxidant and the product of the Nrf2/ARE pathway, can mediate the Nrf2-dependent differentiation-enhancing activity of CA and MMF in HL60 human AML cells. We report that glutathione depletion using L-buthionine sulfoximine attenuated the enhancing effects of both Nrf2 activators concomitant with downregulating vitamin D receptor (VDR) target genes and the activator protein-1 (AP-1) family protein c-Jun levels and phosphorylation. On the other hand, adding reduced glutathione ethyl ester to dominant negative Nrf2-expressing cells re-stored both the suppressed differentiation responses and the downregulated expression of VDR protein, VDR target genes, as well as c-Jun and P-c-Jun levels. Finally, using the transcription factor decoy strategy, we demonstrated that AP-1 is necessary for the enhancement by CA and MMF of 1α,25-dihydroxyvitamin D3-induced VDR and RXRα protein expression, transactivation of the vitamin D response element, and cell differentiation. Collectively, our findings suggest that glutathione mediates, at least in part, the potentiating effect of Nrf2 activators on VDDs-induced differentiation of AML cells, likely through the positive regulation of AP-1.