It is noteworthy that many deregulated genes were common to 20 μM amiodarone after 24-hour BAY 80-6946 molecular weight and 14-day treatments and to 100 μM tetracycline after 24-hour treatment. Two genes involved in fatty acid transport were up-regulated, SLC27A4 by both drugs and FABP1 by tetracycline after repeat treatments. Only one gene involved in mitochondrial biogenesis, PPARGC1A, was overexpressed by both amiodarone and tetracycline. By contrast, several genes involved in de novo lipogenesis were modulated by the two
drugs. Transcripts of SREBP1, THRSP, ACLY, FASN, and SCD1 were significantly augmented after 24-hour and/or 14-day treatments by amiodarone. SREBP1 and PPARG were also up-regulated, whereas THRSP was down-regulated by 100 μM tetracycline after 24-hour treatment. MLN0128 in vivo However, THRSP was overexpressed after 14-day exposure to 10 μM tetracycline. Expression of genes involved in cholesterol metabolism was also altered; thus, transcript levels of LSS were increased after 24-hour amiodarone and 14-day tetracycline treatments. In addition, SOAT1 and LPIN1 were induced by 20 μM amiodarone after both short- and long-term treatments.
Moreover, genes involved in the formation of lipid droplets, particularly PLIN4 and ADFP, were overexpressed by high concentrations of both drugs, regardless of the duration of treatment. In addition, LPL as well as GDPD3 and ASML3A, two genes involved in phospholipids degradation, were up-regulated after long-term exposure to amiodarone. Finally, the two test CYP genes were also Miconazole modulated: transcripts of CYP2E1 were decreased by both drugs, whereas those of CYP3A4 were induced only by amiodarone. No changes were noticed in ALB or ALDB transcripts regardless of the drug treatment. Comparison with oleic acid–overloaded HepaRG cells revealed that, as observed with the two drugs, genes involved in the formation of lipid droplets (ADFP and PLIN4) were up-regulated by 500 μM oleic acid at the two time points. However,
genes involved in de novo lipogenesis were markedly (FASN, THRSP) or slightly (SCD1) down-regulated, whereas CPT1A involved in FAO was increased. In addition, CYP3A4 transcripts were reduced after 24 hours and CYP2E1 levels were increased after 14 days of oleic acid overload. ALDB transcripts were also decreased after repeat oleic acid exposure. Importantly, the expression of several genes was also analyzed at the protein level by way of western blotting (Fig. 6). For all of them (PPARG, ADFP, CYP2E1, and CYP3A4), changes in protein content followed messenger RNA (mRNA) modifications after treatment with either drug or oleic acid. Liver steatosis is characterized by excessive accumulation of neutral lipids, mainly TG, into intracytoplasmic macrovesicles and microvesicles that are induced by various factors, including several drugs.