• Toxicological Research
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• v.18 no.3
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• pp.249-257
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• 2002

Cytochrome P450 3As such as 3A4 and 3A5 metabolize a wide range of pharmaceutical compounds. The vectors for the expression of fusion protein containing an N-terminal human P450 3A4 or P450 3A5 sequences and a C-terminal rat NADPH-cytochrome P450 reductase moiety were constructed. These plasmids were used to express the fusion protein in Escherichia coli DH5$\alpha$ cells. High levels of expression were achieved (100~200 nmol/liter) and the expressed fusion protein in E. coli membranes were catalytically active for nifedipine oxidation, a typical enzymatic activity of P450 3A4. The NADPH-P450 reductase activities of these fusion protein were also determined by measuring reduction of cytochrome c. To fine a specific Inhibitor of P450 3A4 from naturally occurring chemicals, a series of isothiocyanate compounds were evaluated for the inhibitory activity of P450 using the fusion proteins in E. coli membranes. Of the five isothiocyanates (phenethyl isothiocyanate, phenyl isothiocyanate, benzol isothiocyanate, benzoyl isothiocyanate and cyclohexyl isothiocyanate) tested, benzoyl isothiocyanate showed a strong inhibition of P450 3A4 with an $IC_{50}$value of 2.8 $\mu\textrm{M}$. Our results indicate that the self-sufficient fusion protein will be very useful tool to study the drug metabolism and benzyl isothiocyanate may be valuable for characterizing the enzymatic properties of P450 3A4.

• Toxicological Research
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• v.12 no.2
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• pp.155-161
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• 1996

The enzymatic properties for NADPH-P450 reductase domain of a fusion protein between human cytochrome P450 1A1 and rat NADPH-P450 reductase expressed in Escherichia coli were investigated. The fusion plasmid pCW/1A1OR-expressed E. coli membrane showed high NADPH-cytochrome c reductase activity ($830.1\pm 85.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$), while pCW control vector and P 450 1A1 expression vector pCW/1A1 showed relatively quite low activity ($4.35\pm 0.49, 3.27\pm 0.50 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively). The kinetic curves for NADPH-cytochrome c reductase followed typical Michaelis-Menten kinetics. The $K_{max}$ and $V_{max}$ for NADPH-dependent reductase activity were $8.24\pm 2.61\mu $and $817.9\pm 60.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively, whereas those for cytochrome c-dependent reductase activity were $19.97\pm 2.86\mu M$ and $1303.5\pm 67.1 nmol\cdot min^{-1}\cdot mg protein^{-1}$. The reductase activities were also compared with those of rat, porcine and human liver microsomes. The activity of pCW/ 1A1OR-expressed E. coli membrane was 15.2-fold higher than that of rat liver microsome. Treatment with benzo(a)pyrene, 7-ethoxyresorufin and $\alpha$-naphthofiavone which are known as specific substrates or inhibitor for human P450 1A1 increased NADPH-cytochrome c reductase activity of fusion protein in E. coli membrane dose-dependently. These results demonstrate that the membrane topology of fused enzyme may be important for activity of its NADPH-P450 reductase domain.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.209.1-209.1
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• 2003

We have previously shown that 2, 3', 4, 5' -tetramethoxystilbene(TMS) from synthetic trans-stilbene analogues, is one of the most potently selective inhibitor of recombinant human cytochrome P450 1B1 in vitro. In the present studies. the effects of TMS on the expression of cytochrome P450 1B1 were investigated in human cancer cell lines such as MCF-7 and HL -60. TCDD-stimulated P450 1B1 protein and mRNA expression was significantly suppressed by TMS in a dose-dependent manner. (omitted)

• YAKHAK HOEJI
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• v.43 no.6
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• pp.834-842
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• 1999

The metabolism and pharmacokinetics of M-l, which is metabolite of pentoxifylline, have been studied in human liver microsomes. Biphasic kinetics was observed from the Eadie-Hofstee plot for the formation of both metabolites of M-l. For the kinetics of pentoxifylline, mean values of $V_{max1}{\;}and{\;}V_{max2}$ were 1,648 and 5,622 nmol/min/mg protein, and the estimated values of $K_{ml}{\;}and{\;}K_{m2}$ were 0.180 and 4.829 mM, respectively. For M-3, mean values of $V_{max1}{\;}and{\;}V_{max2}$ were 0.062 and 0.491 nmol/min/mg protein, and estimated values of $K_{ml}{\;}and{\;}K_{m2}$ were 0.025 and 1.216 mM. The formations of pentoxifylline and M-3 from M-1 were indentified by using several selective inhibitors of cytochrome P450 isoformes at 0.05-5 mM concentration of M-1 in human liver microsomes. For the analysis of low (0.05 mM) concentration of M-1, where the affinity was expected as low, indicated that CYPlA2 and CYP3A4 were major P450 isoforms responsible for pentoxifylline and M-3 formation. CYP3A4 and CYP2A6 appeared to be P450 isoforms responsible for M-3 formation at high (5 mM) concentration of M-1.

• Archives of Pharmacal Research
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• v.26 no.8
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• pp.631-637
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• 2003

Chloroquine has been used for many decades in the prophylaxis and treatment of malaria. It is metabolized in humans through the N-dealkylation pathway, to desethylchloroquine (DCQ) and bisdesethylchloroquine (BDCQ), by cytochrome P450 (CYP). However, until recently, no data are available on the metabolic pathway of chloroquine. Therefore, the metabolic pathway of chloroquine was evaluated using human liver microsomes and cDNA-expressed CYPs. Chloroquine is mainly metabolized to DCQ, and its Eadie-Hofstee plots were biphasic, indicating the involvement of multiple enzymes, with apparent $K_m and V_{max}$ values of 0.21 mM and 1.02 nmol/min/mg protein 3.43 mM and 10.47 nmol/min/mg protein for high and low affinity components, respectively. Of the cDNA-expressing CYPs examined, CYP1A2, 2C8, 2C19, 2D6 and 3A4/5 exhibited significant DCQ formation. A study using chemical inhibitors showed only quercetin (a CYP2C8 inhibitor) and ketoconazole (a CYP3A4/5 inhibitor) inhibited the DCQ formation. In addition, the DCQ formation significantly correlated with the CYP3A4/5-catalyzed midazolam 1-hydroxylation (r=0.868) and CYP2C8-catalyzed paclitaxel 6$\alpha$-hydroxylation (r = 0.900). In conclusion, the results of the present study demonstrated that CYP2C8 and CYP3A4/5 are the major enzymes responsible for the chloroquine N-deethylation to DCQ in human liver microsomes.

• Analytical Science and Technology
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• v.8 no.2
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• pp.117-124
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• 1995

To Purify hemoproteins showing from 218nm absorbance, crude liver extract of human with hepatocirrhosis was treated with Triton N-101. Hemoproteins were purified by modification of Mohamed's method. This crude extract was applied to Octyl-Sepharose CL-4B column and the step elution was performed with 0.06% Lubrol PX and 0.25% Lubrol PX. The absorption of effluents were examined at 418nm and two peaks were appeared(Fig. 2). Hemoproteins were purified from Hyydroxyapatite and DEAE-Sephadex A-25 columns which the first peak was applied to(Fig. 3, 4). In death with suddenly, purified hemoproteins with 62 and 45kDa were obtained from 12.5% SDS-PAGE. In death with hepatocirrhosis, purified hemoprotein with 54kDa was obtainded from 12.5% SDS-PAGE(Fig. 5). Cytochrome P450 was purified to a specific content of 20.8nmol/mg protein with a recovery of about 4.1%. Absorbance maximum of these hemoproteins were 446nm at UV spectruum(Fig. 6).

• Archives of Pharmacal Research
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• v.27 no.7
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• pp.693-712
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• 2004

The rats with protein-calorie malnutrition (PCM, 5％ casein diet for a period of 4-week) were reported to exhibit 60 and 80％ suppression in the hepatic microsomal cytochrome P450 (CYP) 1 A2 and CYP2C11 levels, respectively, and 40-50％ decreases in CYP2E1 and CYP3A 1/2 levels compared to control (23％ casein diet for a period of 4-week) based on Western blot analysis. In addition, Northern blot analysis showed that CYP1 A2, CYP2E1, CYP2C11, and CYP3A1/2 mRNAs decreased in the state of PCM as well. Hence, pharmacokinetic changes of the drugs in rats with PCM [especially the area under the plasma concentration-time curve from time zero to time infinity (AUC) changes of metabolite(s)] reported from literatures were tried to explain in terms of CYP isozyme changes in the rats. Otherwise, the time-averaged nonrenal clearance ($CL_{NR}$) of parent drug was compared. Pharmacokinetic changes of the drugs in other types of malnutritional state, such as kwashiorkor and marasmus, in both human and animal models were also compared. The drugs reviewed are as follows： diuretics, antibiotics, anticancer agents, antiepileptics, antiarrythmics, analgesics, xanthines, antimalarials, and miscellaneous.

• Biomedical Science Letters
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• v.18 no.1
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• pp.1-9
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• 2012

Differentially expressed genes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were identified in order to evaluate them as dioxin-sensitive markers and crucial signaling molecules to understand dioxin-induced toxic mechanisms in human bronchial cells. Gene expression profiling was analyzed by cDNA microarray and ten genes were selected for further study. They were cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1), S100 calcium binding protein A8 (calgranulin A), S100 calcium binding protein A9 (calgranulin B), aldehyde dehydrogenase 1 family, member A3 (ALDH6) and peroxiredoxin 5 (PRDX5) in up-regulated group. Among them, CYP1B1 was used as a hallmark for dioxin and sharply increased by TCDD exposure. Down-regulated genes were IK cytokine, interferon-induced protein with tetratricopeptide repeats 1 (IFIT1), nuclease sensitive element binding protein 1 (NSEP1), protein tyrosine phosphatase type VI A, member 1 (PTP4A1), ras oncogene family 32 (RAB32). Although up-regulated 4 genes in microarray were coincided with northern hybridization, down-regulated 5 genes showed U-shaped expression pattern which is sharply decreased at lower doses and gradually increased at higher doses. These results introduce some of TCDD-responsive genes can be sensitive markers against TCDD exposure and used as signaling cues to understand toxicity initiated by TCDD inhalation in pulmonary tissues.

• Development and Reproduction
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• v.27 no.3
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• pp.149-157
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• 2023

We investigated the involvement of autophagy with steroidogenesis in testicular Leydig cells. Human chorionic gonadotropin (hCG)-stimulated T production in Leydig cells was not remarkably altered in the presence of an autophagy inhibitor 3-methyladenine (3-MA). Although pretreatment with 3-MA demonstrated a tendency to decrease hCG-induced T production, the differences were significant only at a higher time point of 24 h following hCG. Microtubule associated protein light chain 3 (LC3)-II was detectable in the control cells in all the experiments. The hCG-induced increase in steroidogenic acute regulatory protein (StAR) and cytochrome P450 side chain cleave (P450scc) protein levels were not significantly altered by 3-MA. Leydig cells isolated from immature rat testes 12 h following hCG treatment showed relatively increased levels of LC3-II protein compared to the control group. Furthermore, LC3-II levels shown in these cells reached almost the identical to those from normal adult testes. However, LC3-II protein levels were almost comparable or even slightly lower than the controls at 48 h following hCG. Expression of StAR and P450scc was upregulated at both 12 and 48 h after hCG. We also used MA-10 cells, the mouse Leydig cell line, in this experiment. When dibutyryl cyclic-AMP was treated with MA-10 cells, P4 levels were significantly increased in the cell culture medium. However, P4 levels tended to decrease in the presence of 3-MA, but the difference was not statistically significant. This was consistent with the results of the rat Leydig cell experiments. Together, we believe that although autophagy participates in steroidogenesis and enhances steroidogenic efficacy of Leydig cells, it may not be a decisive cellular process for steroidogenesis, specifically in the mature Leydig cells.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2647-2653
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• 2012

Involvement of cytochrome P450 genes (CYPs) in breast cancer (BCa) may differ between populations, with expression patterns affected by tumorigenesis. This may have an important role in the metabolism of anticancer drugs and in the progression of cancer. The aim of this study was to determine the mRNA expression patterns of four cytochrome P450 genes (CYP2W1, 3A5, 4F11 and 8A1) in Mexican women with breast cancer. Real-time PCR analyses were conducted on 32 sets of human breast tumors and adjacent non-tumor tissues, as well as 20 normal breast tissues. Expression levels were tested for association with clinical and pathological data of patients. We found higher gene expression of CYP2W1, CYP3A5, CYP4F11 in BCa than in adjacent tissues and only low in normal mammary glands in our Mexican population while CYP8A1 was only expressed in BCa and adjacent tissues. We found that Ki67 protein expression was associated with clinicopathological features as well as with CYP2W1, CYP4F11 and CYP8A1 but not with CYP3A5. The results indicated that breast cancer tissues may be better able to metabolize carcinogens and other xenobiotics to active species than normal or adjacent non-tumor tissues.