Modulatory actions of o-coumaric acid on carcinogen-activating cytochrome P450 isozymes and the potential for drug interactions in human hepatocarcinoma cells.

CONTEXT: Although humans are exposed to o-coumaric acid (OCA) in their diet, there is no available literature related to drug interaction and the carcinogen-activating potential of OCA in the HepG2 cell line. OBJECTIVE: This study was undertaken to determine the effects of OCA on the cytochrome P450 (CYP) 1A2, CYP2E1, CYP2C9, and CYP3A4 enzymes, which are primarily involved in carcinogen and drug metabolism. MATERIALS AND METHODS: The cytotoxicity of OCA in HepG2 cells was investigated by measuring the cleavage of WST-1. The protein and mRNA levels of CYPs were determined by western blotting and RT-PCR, respectively. RESULTS: The EC10, EC25, and EC50 values of OCA were calculated to be 1.84, 3.91 and 7.39 mM, respectively. A sublethal dose of 5 mM was used throughout this study. The CYP1A2 protein and mRNA levels were increased by 52 and 40% (p < 0.05), as were the CYP2E1 levels by 225 and 424%, respectively (p < 0.05). However, OCA treatment caused 52 and 60% decreases in the levels of CYP3A4 protein and mRNA (p < 0.05), respectively. In contrast to CYP3A4, the CYP2C9 protein and mRNA levels increased by 110 and 130%, respectively. DISCUSSION AND CONCLUSION: Co-administration of OCA with some drugs may lead to undesirable food-drug interactions due to modulatory effects on CYP isozymes involved in drug metabolism. Moreover, exposure to OCA may cause an increase in carcinogenicity and toxicity due to the induction of the CYP isozymes involved in chemical carcinogenesis. Therefore, serious precautions should be taken when using OCA as a supplement.

Cyclamen Trochopteranthum: Cytotoxic activity and possible adverse interactions including drugs and carcinogens.

OBJECTIVE: To examine the effect of water extracts of cyclamen tubers on the expression of main cytochrome P450 (CYP450s) including CYP1A1, CYP1A2 CYP2E1, CYP2B6, CYP2C9 and CYP3A4 that participate in the metabolism of both drugs and carcinogens and cytotoxic activity in human cancer cell lines, namely HepG2 and Caco-2. METHODS: Cyclamen trochopteranthum tubers were extracted with dH(2)O and then lyophilized under vacuum. Infrared spectral study was made for extracts by Fourier transform infrared spectroscopy (FT-IR). Cytotoxic activity of cyclamen was determined by crystal violet staining in HepG2 and Caco-2 cells. CYP expression was determined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Cyclamen water extract had moderate cytotoxic activity. It was found that lethal concentration (LC50) value of the cyclamen extract was 50 and 125 µg/mL in HepG2 and Caco-2 cell lines, respectively. Moreover, it caused induction and suppression of CYP450s mRNA levels in HepG2 and Caco-2 cells. CONCLUSION: Cyclamen may have a potential not only inhibition and/or induction of the metabolism of certain co-administered drugs but also development of toxicity, mutagenesis and malignant transformation due to induction or suppression of the CYP450s dependent drug metabolizing enzymes.

Diverse action of acrylamide on cytochrome P450 and glutathione S-transferase isozyme activities, mRNA levels and protein levels in human hepatocarcinoma cells.

Humans are exposed to acrylamide in their diet and cigarette smoke. Acrylamide is metabolized into glycidamide by CYP2E1. However, very few studies regarding the effects of acrylamide on cytochrome P450 and Glutathione S-Transferase (GST) isozymes have been pursued. The aim of this study is to elucidate the effects of acrylamide on cytochrome P450 and GST isozymes in HepG2 cell line. Treatment with 1.25 and 2.5 mM acrylamide caused 9.5- and 3.7-fold increases and 4.0- and 3.3-fold increases in CYP1A-associated ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities, respectively. These increases were consistent with increases in mRNA and protein levels of these isozymes. Similarly, CYP2E1-associated aniline 4-hydroxylase (ANH) activity, protein levels, and mRNA levels increased 2.1- and 2.6-fold, 2.4- and 3.2-fold, and 1.4- and 1.9-fold following 1.25 and 2.5 mM acrylamide treatments, respectively. In addition, GST-mu activity was increased 2.4- and 5.1-fold by acrylamide. Moreover, GST-mu mRNA and protein levels increased twofold as a result of acrylamide treatment. In contrast, GST-pi protein and mRNA levels decreased significantly. In conclusion, human cell exposure to acrylamide causes an increase in the levels of carcinogenicity and toxicity and a disturbance in drug metabolism, possibly due to complex effects on P450 and GST isozymes.