Anthocyanins are plant pigments occurring in flowers and berry fruits. Since a phenomenon of food-drug interactions is increasingly emerging, we examined the effects of 21 major anthocyanins and the extracts from 3 food supplements containing anthocyanins on the aryl hydrocarbon receptor (AhR)-cytochrome P450 CYP1A1 signaling pathway in human hepatocytes and human hepatic HepG2 and intestinal LS174T cancer cells. Pelargonidin-3-O-rutinoside (PEL-2) and cyanidin-3,5-O-diglucoside (CYA-3) dose-dependently activated AhR, as revealed by gene reporter assay. PEL-2 and CYA-3 induced CYP1A1 mRNA but not protein in HepG2 and LS174T cells. Neither compounds induced CYP1A1 mRNA and protein in four different primary human hepatocytes cultures. The effects of PEL-2 and CYA-3 on AhR occurred by ligand-dependent and ligand-independent mechanisms, respectively, as demonstrated by ligand binding assay. In a direct enzyme inhibition assay, none of the antocyanins tested inhibited the CYP1A1 marker activity to less than 50% even at 100 μM concentration. PEL-2 and CYA-3 at 100 μM inhibited CYP1A1 to 79% and 65%, respectively. In conclusion, with exception of PEL-2 and CYA-3, there were no effects of 19 major anthocyanins and 3 food supplements containing anthocyanins on AhR-CYP1A1 signaling, implying zero potential of these compounds for food-drug interactions with respect to AhR-CYP1A1 pathway.

• Klíčová slova
• 2,3,7,8-tetrachlorodibenzo-p-dioxin, AhR, Anthocyanins, Aryl hydrocarbon receptor, Cytochrome P450, Food supplements, Food–drug interactions, TCDD, aryl hydrocarbon receptor,
• MeSH
• anthokyaniny chemie   toxicita   MeSH
• buňky Hep G2 MeSH
• cytochrom P-450 CYP1A1 metabolismus   MeSH
• dospělí MeSH
• glukosidy chemie   toxicita   MeSH
• hepatocyty účinky léků   metabolismus   MeSH
• inhibitory enzymů toxicita   MeSH
• interakce mezi potravou a léky MeSH
• jaterní mikrozomy účinky léků   enzymologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• potravní doplňky MeSH
• receptory aromatických uhlovodíků účinky léků   metabolismus   MeSH
• regulace genové exprese enzymů účinky léků   MeSH
• signální transdukce účinky léků   MeSH
• vazba proteinů MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• anthokyaniny MeSH
• cyanidin-3-O-beta-glucopyranoside MeSH Prohlížeč
• cytochrom P-450 CYP1A1 MeSH
• glukosidy MeSH
• inhibitory enzymů MeSH
• pelargonidin MeSH Prohlížeč
• receptory aromatických uhlovodíků MeSH

We examined the effects of anthocyanidins (cyanidin, delphinidin, malvidin, peonidin, petunidin, pelargonidin) on the aryl hydrocarbon receptor (AhR)-CYP1A1 signaling pathway in human hepatocytes, hepatic HepG2 and intestinal LS174T cancer cells. AhR-dependent reporter gene expression in transfected HepG2 cells was increased by pelargonidin in a concentration-dependent manner at 24h. Similarly, pelargonidin induced the expression of CYP1A1 mRNA up to 5-fold in HepG2 and LS174T cells relative to the induction by 5 nM 2,3,7,8-tetrachlorodibenzodioxin (TCDD), the most potent activator of AhR. CYP1A1 and CYP1A2 mRNAs were also increased by pelargonidin in three primary human hepatocytes cultures (approximately 5% of TCDD potency) and the increase in CYP1A1 protein in HepG2 and LS174T cells was comparable to the increase in catalytic activity of CYP1A1 enzyme. Ligand binding analysis demonstrated that pelargonidin was a weak ligand of AhR. Enzyme kinetic analyses using human liver microsomes revealed inhibition of CYP1A1 activity by delphinidin (IC50 78 μM) and pelargonidin (IC50 33 μM). Overall, although most anthocyanidins had no effects on AhR-CYP1A1 signaling, pelargonidin can bind to and activate the AhR and AhR-dependent gene expression, and pelargonidin and delphinidin inhibit the CYP1A1 catalytic activity.

• MeSH
• aktivace transkripce účinky léků   MeSH
• anthokyaniny farmakologie   MeSH
• buňky Hep G2 MeSH
• cytochrom P-450 CYP1A1 biosyntéza   MeSH
• enzymová indukce MeSH
• hepatocyty účinky léků   enzymologie   MeSH
• jaterní mikrozomy enzymologie   MeSH
• kinetika MeSH
• lidé MeSH
• ligandy MeSH
• messenger RNA biosyntéza   MeSH
• nádory jater enzymologie   MeSH
• polychlorované dibenzodioxiny farmakologie   MeSH
• primární buněčná kultura MeSH
• promotorové oblasti (genetika) účinky léků   MeSH
• receptory aromatických uhlovodíků účinky léků   metabolismus   MeSH
• signální transdukce účinky léků   MeSH
• střevní nádory enzymologie   MeSH
• transfekce MeSH
• transkripční faktory bHLH účinky léků   metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• AHR protein, human MeSH Prohlížeč
• anthokyaniny MeSH
• CYP1A1 protein, human MeSH Prohlížeč
• cytochrom P-450 CYP1A1 MeSH
• ligandy MeSH
• messenger RNA MeSH
• pelargonidin MeSH Prohlížeč
• polychlorované dibenzodioxiny MeSH
• receptory aromatických uhlovodíků MeSH
• transkripční faktory bHLH MeSH

The small/short heterodimer partner (SHP, NR0B2) is a nuclear receptor corepressor lacking a DNA binding domain. SHP is induced by bile acid-activated farnesoid X receptor (FXR) resulting in CYP7A1 gene suppression. In contrast, Pregnane X receptor (PXR) activation by its ligands was recently suggested to inhibit SHP gene transactivation to maximize the induction of PXR target genes. However, there are also conflicting reports in literature whether PXR or rodent Pxr activation down-regulates SHP/Shp expression. Moreover, the PXR-mediated regulation of the SHP gene has been studied only at the SHP mRNA and transactivation (gene reporter assay) levels. In this study, we studied the effect of rifampicin, a prototype PXR ligand, on SHP mRNA, and protein expression in three primary human hepatocyte cultures. We found that SHP mRNA is not systematically down-regulated in hepatocyte in culture after 24 h treatment with rifampicin. Consistently, we did not observe down-regulation of SHP protein in primary human hepatocytes after 24 and 48 h of incubation with rifampicin. We can conclude that although we observed slight down-regulation of SHP mRNA and protein in several hepatocyte preparations, the phenomenon is unlikely critical for PXR-mediated induction of its target genes.

• Klíčová slova
• CYP3A4, PXR, SHP, cytochrome P450, induction,
• Publikační typ
• časopisecké články MeSH

Metformin is widely used in the treatment of type-2 diabetes. The pleotropic effects of metformin on glucose and lipid metabolism have been proposed to be mediated by the activation of AMP-activated protein kinase (AMPK) and the subsequent up-regulation of small heterodimer partner (SHP). SHP suppresses the functions of several nuclear receptors involved in the regulation of hepatic metabolism, including pregnane X receptor (PXR), which is referred to as a "master regulator" of drug/xenobiotic metabolism. In this study, we hypothesize that metformin suppresses the expression of CYP3A4, a main detoxification enzyme and a target gene of PXR, due to SHP up-regulation. We employed various gene reporter assays in cell lines and qRT-PCR in human hepatocytes and in Pxr(-/-) mice. We show that metformin dramatically suppresses PXR-mediated expression of CYP3A4 in hepatocytes. Consistently, metformin significantly suppressed the up-regulation of Cyp3a11 mRNA in the liver and intestine of wild-type mice, but not in Pxr(-/-) mice. A mechanistic investigation of the phenomenon showed that metformin does not significantly up-regulate SHP in human hepatocytes. We further demonstrate that AMPK activation is not involved in this process. We show that metformin disrupts PXR's interaction with steroid receptor coactivator-1 (SRC1) in a two-hybrid assay independently of the PXR ligand binding pocket. Metformin also inhibited vitamin D receptor-, glucocorticoid receptor- and constitutive androstane receptor (CAR)-mediated induction of CYP3A4 mRNA in human hepatocytes. We show, therefore, a suppressive effect of metformin on PXR and other ligand-activated nuclear receptors in transactivation of the main detoxification enzyme CYP3A4 in human hepatocytes.

• MeSH
• aktivace transkripce MeSH
• cytochrom P-450 CYP3A genetika   metabolismus   MeSH
• hepatocyty účinky léků   metabolismus   MeSH
• hypoglykemika farmakologie   MeSH
• koaktivátory jaderných receptorů metabolismus   MeSH
• konstitutivní androstanový receptor MeSH
• kultivované buňky MeSH
• lidé MeSH
• membránové proteiny genetika   metabolismus   MeSH
• messenger RNA metabolismus   MeSH
• metformin farmakologie   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• polohový reflex účinky léků   MeSH
• pregnanový X receptor MeSH
• proteinkinasy aktivované AMP fyziologie   MeSH
• receptory cytoplazmatické a nukleární metabolismus   fyziologie   MeSH
• receptory glukokortikoidů fyziologie   MeSH
• receptory kalcitriolu fyziologie   MeSH
• reportérové geny MeSH
• signální transdukce MeSH
• steroidní receptory genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• Cyp3a11 protein, mouse MeSH Prohlížeč
• cytochrom P-450 CYP3A MeSH
• hypoglykemika MeSH
• koaktivátory jaderných receptorů MeSH
• konstitutivní androstanový receptor MeSH
• membránové proteiny MeSH
• messenger RNA MeSH
• metformin MeSH
• nuclear receptor subfamily 0, group B, member 2 MeSH Prohlížeč
• pregnanový X receptor MeSH
• proteinkinasy aktivované AMP MeSH
• receptory cytoplazmatické a nukleární MeSH
• receptory glukokortikoidů MeSH
• receptory kalcitriolu MeSH
• steroidní receptory MeSH