Khellin and visnagin differentially modulate AHR signaling and downstream CYP1A activity in human liver cells.
Khellin and visnagin are two furanochromones that can be frequently found in ethnomedical formulations in Asia and the Middle East. Both compounds possess anti-inflammatory and analgesic properties, therefore modern medicine uses these compounds or structurally related derivatives for treatment of vitiligo, bronchial asthma and renal colics. Despite their frequent usage, the potential toxic properties of visnagin and khellin are not well characterized up-to-now. Many natural compounds modulate the expression and activity of cytochrome P450 1A1 (CYP1A1), which is well-known to bioactivate pro-carcinogens. The expression of this enzyme is controlled by the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor and regulator of drug metabolism. Here, we investigated the influence of both furanochromones on AHR signaling in human HepG2 hepatocarcinoma cells and primary human hepatocytes. Both compounds transactivated xenobiotic response element (XRE)-driven reporter gene activity in a dose-dependent manner and induced CYP1A1 transcription in HepG2 cells and primary hepatocytes. The latter was abolished in presence of a specific AHR antagonist. CYP1A enzyme activity assays done in HepG2 cells and primary hepatocytes revealed an inhibition of enzyme activity by both furanochromones, which may become relevant regarding the metabolism of xenobiotics and co-administered therapeutic drugs. The observed induction of several other members of the AHR gene battery, whose gene products are involved in regulation of cell growth, differentiation and migration, indicates that a further toxicological characterization of visnagin and khelllin is urgently required in order to minimize potential drug-drug interactions and other toxic side-effects that may occur during therapeutic usage of these furanochromones.
Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic.
Radim
R
Vrzal
Katrin
K
Frauenstein
Peter
P
Proksch
Josef
J
Abel
Zdenek
Z
Dvorak
Thomas
T
Haarmann-Stemmann
D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D002460:Cell Line; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007666:Khellin / Q000494:pharmacology*; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
D018336:Receptors, Aryl Hydrocarbon; D007666:Khellin; D001189:Aryl Hydrocarbon Hydroxylases; D019363:Cytochrome P-450 CYP1A1; C044999:visnagin