Pregnane X receptor activation induces liver enlargement and regeneration and simultaneously promotes the metabolic activity of CYP3A1/2 and CYP2C6/11 in rats.

Human pregnane X receptor (PXR) is critical for regulating the expression of key drug-metabolizing enzymes such as CYP3A and CYP2C. Our recent study revealed that treatment with rodent-specific PXR agonist pregnenolone-16α-carbonitrile (PCN) significantly induced hepatomegaly and promoted liver regeneration after two-thirds partial hepatectomy (PHx) in mice. However, it remains unclear whether PXR activation induces hepatomegaly and liver regeneration and simultaneously promotes metabolic function of the liver. Here, we investigated the metabolism activity of CYP1A2, CYP3A1/2 and CYP2C6/11 during PXR activation-induced liver enlargement and regeneration in rats after cocktail dosing of CYP probe drugs. For PCN-induced hepatomegaly, a notable increase in the metabolic activity of CYP3A1/2 and CYP2C6/11, as evidenced by the plasma exposure of probe substrates and the AUC ratios of the characteristic metabolites to its corresponding probe substrates. The metabolic activity of CYP1A2, CYP3A1/2 and CYP2C6/11 decreased significantly after PHx. However, PCN treatment obviously enhanced the metabolic activity of CYP2C6/11 and CYP3A1/2 in PHx rats. Furthermore, the protein expression levels of CYP3A1/2 and CYP2C6/11 in liver were up-regulated. Taken together, this study demonstrates that PXR activation not only induces hepatomegaly and liver regeneration in rats, but also promotes the protein expression and metabolic activity of the PXR downstream metabolizing enzymes such as CYP3A1/2 and CYP2C6/11 in the body.

Neoadjuvant-Intensive Androgen Deprivation Therapy Selects for Prostate Tumor Foci with Diverse Subclonal Oncogenic Alterations.

Primary prostate cancer can have extensive microheterogeneity, but its contribution to the later emergence of metastatic castration-resistant prostate cancer (mCRPC) remains unclear. In this study, we microdissected residual prostate cancer foci in radical prostatectomies from 18 men treated with neoadjuvant-intensive androgen deprivation therapy (leuprolide, abiraterone acetate, and prednisone) and analyzed them for resistance mechanisms. Transcriptome profiling showed reduced but persistent androgen receptor (AR) activity in residual tumors, with no increase in neuroendocrine differentiation. Proliferation correlated negatively with AR activity but positively with decreased RB1 expression, and whole-exome sequencing (WES) further showed enrichment for RB1 genomic loss. In 15 cases where 2 or 3 tumor foci were microdissected, WES confirmed a common clonal origin but identified multiple oncogenic alterations unique to each focus. These findings show that subclones with oncogenic alterations found in mCRPC are present in primary prostate cancer and are selected for by neoadjuvant-intense androgen deprivation therapy. In particular, this study indicates that subclonal RB1 loss may be more common than previously appreciated in intermediate- to high-risk primary prostate cancer and may be an early event, independent of neuroendocrine differentiation, in the development of mCRPC. Comprehensive molecular analyses of primary prostate cancer may detect aggressive subclones and possibly inform adjuvant strategies to prevent recurrence.Significance: Neoadjuvant androgen deprivation therapy for prostate cancer selects for tumor foci with subclonal genomic alterations, which may comprise the origin of metastatic castration-resistant prostate cancer. Cancer Res; 78(16); 4716-30. ©2018 AACR.

Impaired liver cytochrome P450 2C11 activity after dual antiplatelet therapy with aspirin and clopidogrel in rats.

1. Aspirin (ASA) and clopidogrel (CLP) are used in combination as dual antiplatelet therapy (DAPT) for acute coronary syndrome based on their complementary mechanisms for platelet aggregation inhibition. However, the pharmacokinetics of such drug combination usage has not been thoroughly investigated. 2. In the current study, an LC-MS/MS method was developed to simultaneously determine the plasma concentrations of ASA and its metabolite salicylic acid (SA) with CLP and its metabolites, clopidogrel carboxylic acid (CLPM) and clopidogrel active metabolite derivative (CAMD). The pharmacokinetics of ASA, SA, CLP, CLPM and CAMD in rats receiving two-week DAPT with ASA and CLP were then determined. 3. After two-week DAPT with ASA and CLP in rats, the activities of aspirin esterase and rCyp2c11, enzymes mediating rat metabolism of ASA and CLP, respectively, in prepared rat liver microsomes were measured followed by further determination of rCyp2c11 mRNA expressions. The results demonstrated that DAPT led to minimal impact on aspirin esterase activity but significant decrease in rCyp2c11 activity and mRNA expression. 4. In conclusion, our findings on impairment in rCyp2C11 activity and mRNA expression by DAPT in rats could provide guidance on its safe clinical use with other CYP 2C19 substrates.

Growth hormone: a newly identified developmental organizer.

The sexually dimorphic expression of cytochromes P450 (CYP) drug-metabolizing enzymes has been reported in all species examined. These sex differences are only expressed during adulthood and are solely regulated by sex differences in circulating growth hormone (GH) profiles. Once established, however, the different male- and female-dependent CYP isoform profiles are permanent and immutable, suggesting that adult CYP expression requires imprinting. As the hormone that regulates an adult function is likely the same hormone that imprints the function, we selectively blocked GH secretion in some newborn male rats, whereas others received concurrent physiologic replacement of rat GH. The results demonstrate that adult male GH activation of the signal transduction pathway regulating expression of the principal CYP2C11 isoform is obligatorily dependent on perinatal GH imprinting, without which CYP2C11 and drug metabolism would be permanently and profoundly suppressed. As there are other adult metabolic functions also regulated by GH, pediatric drug therapy known to disrupt GH secretion could unintentionally impair adult health.

A new in vivo analysis model to detect sexually dimorphic rat liver cytochrome P450 gene expression dependent on growth hormone secretory patterns.

Several drug-metabolizing cytochrome P450 (CYP) enzymes exhibit sexual dimorphism depending on the pituitary growth hormone (GH) secretory patterns. However, the mechanism underlying CYP sexual dimorphism remains unclear. We previously established a transgenic (Alb-DsRed2 Tg) rat that expressed red fluorescent DsRed2 protein, particularly in hepatocytes, to visualize cell differentiation and multiplication and found that hepatic DsRed2 expression exhibited sexual dimorphism that was limited to adult males. In this study, we compared the expression patterns between sexual dimorphic Cyps and DsRed2 in Tg rats after experimentally reversing the GH secretory patterns in males and females. Postnatal day 1 male and female Tg rats were gonadectomized and then testosterone propionate (0.25 mg/rat) was subcutaneously administered to ovariectomized females immediately after surgery. Cyp mRNA and DsRed2 expression levels were quantified using RT-PCR and an in vivo imaging system, respectively. GH-dependent Cyps and hepatic DsRed2 expression patterns were reversed in males and females at 9 weeks after birth and were significantly correlated (P<0.05). This suggested that DsRed2 expression in these Tg rats depended on GH secretory patterns. Based on DsRed2 fluorescence, this Tg rat model could become a tool to readily and effectively evaluate changes in GH-dependent Cyp expression.

Differential Effects of Sunitinib on the Expression Profiles of Xenobiotic-Metabolizing Enzymes and Transporters in Rat Liver and Kidneys.

Sunitinib (SUN) is a multi-targeted tyrosine kinase inhibitor that was recently approved for the treatment of gastrointestinal tract and renal cancers. To date, very little is known about the effects of SUN on the expression of hepatic and renal xenobiotic-metabolizing enzymes (XMEs) and transporters. The present study was designed to investigate the capacity of chronic SUN treatment to modulate the mRNA and protein expression levels of phase I cytochrome P450 (CYP), phase II conjugating enzymes, and phase III transporters in rat liver and kidneys. For this purpose, SUN (25, 50 and 100 mg/kg) was injected IP into Wistar albino rats for 4 weeks; thereafter, the mRNA and protein expression levels of several XMEs and transporters were determined by RT-PCR and Western blot analysis, respectively. Real-time PCR analysis showed that SUN significantly induced the hepatic and renal CYP1A1, 1A2, 1B1, 2E1 and 4F4, whereas it inhibited CYP2C11 and 4A2. Furthermore, SUN specifically induced renal, but not hepatic, CYP2J3 and 3A2, while it induced only hepatic CYP4A1. With regard to phase II, SUN induced hepatic GSTA1 and UGT1A and renal NQO1 and UGT1A mRNA levels, whereas it inhibited renal GST1A expression. On the other hand, both renal and hepatic P-gp, MRP2 and BCRP transporters were significantly induced by SUN at the mRNA and protein expression levels. Importantly, these differential effects were associated with changes in oxidative stress genes and lipid peroxidation levels. In conclusion, SUN can serve as XME and transporters modulator, which potentially may counteract the efficacy of the treatment, adverse reactions and drug interactions in SUN treatment.

Permanent uncoupling of male-specific CYP2C11 transcription/translation by perinatal glutamate.

Perinatal exposure of rats and mice to the typically reported 4mg/g bd wt dose of monosodium glutamate (MSG) results in a complete block in GH secretion as well as obesity, growth retardation and a profound suppression of several cytochrome P450s, including CYP2C11, the predominant male-specific isoform--all irreversible effects. In contrast, we have found that a lower dose of the food additive, 2mg/g bd wt on alternate days for the first 9days of life results in a transient neonatal depletion of plasma GH, a subsequent permanent overexpression of CYP2C11 as well as subnormal (mini) GH pulse amplitudes in an otherwise normal adult masculine episodic GH profile. The overexpressed CYP2C11 was characterized by a 250% increase in mRNA, but only a 40 to 50% increase in CYP2C11 protein and its catalytic activity. Using freshly isolated hepatocytes as well as primary cultures exposed to the masculine-like episodic GH profile, we observed normal induction, activation, nuclear translocation and binding to the CYP2C11 promoter of the GH-dependent signal transducers required for CYP2C11 transcription. The disproportionately lower expression levels of CYP2C11 protein were associated with dramatically high expression levels of an aberrant, presumably nontranslated CYP2C11 mRNA, a 200% increase in CYP2C11 ubiquitination and a 70-80% decline in miRNAs associated, at normal levels, with a suppression of CYP2C expression. Whereas the GH-responsiveness of CYP2C7 and CYP2C6 as well as albumin was normal in the MSG-derived hepatocytes, the abnormal expression of CYP2C11 was permanent and irreversible.

Changes of hepatic lipid mediators associated with intake of high-fat diet for 12 weeks in endotoxemic rats using LC-ESI-MS/MS.

BACKGROUND & AIMS: It has recently been reported that anti-inflammatory lipid mediators are increased in the late phase of acute inflammation, whereas proinflammatory lipid mediators are regulated at the initiation of inflammation. The purpose of this study was to evaluate changes of hepatic lipid mediators due to high-fat diet (HFD) feeding in endotoxemic rats. METHODS: Male Wistar rats were fed either HFD or control diet for 12 weeks, and were then killed 0, 1.5, and 6 h after lipopolysaccharide (LPS) injection. Analyses included lipidomics assessment of mediators using liquid chromatography-electrospray ionization/multi-stage mass spectrometry; measuring expression of hepatic polyunsaturated fatty acid (PUFA)-oxidizing enzyme, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and inducible nitric oxide synthase mRNA levels; blood biochemical tests; and liver histology. RESULTS: HFD feeding worsened liver injury, increased expression of TNF-α and IL-6 mRNA, and increased oxidative stress after LPS injection. PUFA-oxidizing enzymes were higher in HFD-fed rats after LPS injection. The proinflammatory prostaglandin (PG)E2 and thromboxane B2 were increased 1.5 h after LPS injection, and had decreased by 6 h in HFD-fed rats. In contrast, potent pro-resolving resolvins derived from eicosapentaenoic acid and docosahexaenoic acid were not detected, but anti-inflammatory epoxyeicosatrienoic acids, lipoxin A4, and 15-deoxy-PGJ2 were increased after LPS injection in HFD-fed rats. CONCLUSIONS: HFD feeding for 12 weeks enhanced proinflammatory lipid mediators 1.5 h after LPS injection suggesting relation to liver injury.

Intestinal and hepatic expression of cytochrome P450s and mdr1a in rats with indomethacin-induced small intestinal ulcers.

BACKGROUND: Non-steroidal anti-inflammatory drugs induce the serious side effect of small intestinal ulcerations (SIUs), but little information is available regarding the consequences to drug metabolism and absorption. AIM: We examined the existence of secondary hepatic inflammation in rats with indomethacin (INM)-induced SIUs and assessed its relationship to the cytochrome P450 (CYP) and P-glycoprotein (mdr1a), the major drug-metabolizing factors in the small intestine and the liver. METHODS: Gene expression of the CYP family of enzymes and mdr1a was measured with quantitative real-time polymerase chain reaction (qPCR). Vancomycin (VCM), a poorly absorbed drug, was administered intraduodenally to rats with SIUs. RESULTS: INM induced SIUs predominantly in the lower region of the small intestine with high expression of inflammatory markers. Liver dysfunction was also observed, which suggested a secondary inflammatory response in rats with SIUs. In the liver of rats with SIUs, the expression of CYP2C11, CYP2E1, and CYP3A1 was significantly decreased, and loss of CYP3A protein was observed. Although previous studies have shown a direct effect of INM on CYP3A activity, we could not confirm any change in hepatic CY3A4 expression (major isoform of human CYP3A) in vitro. The plasma VCM concentration was increased in rats with SIUs due to partial absorption from the mucosal injury, but not in normal mucosa. CONCLUSIONS: INM-induced SIUs had a subtle effect on intestinal CYP expression, but had an apparent action on hepatic CYP, which was influenced, at least in part, by the secondary inflammation. Furthermore, drug absorption was increased in rats with SIUs.

Rhythmic expression of cytochrome P450 epoxygenases CYP4x1 and CYP2c11 in the rat brain and vasculature.

Mammals have circadian variation in blood pressure, heart rate, vascular tone, thrombotic tendency, and cerebral blood flow (CBF). These changes may be in part orchestrated by circadian variation in clock gene expression within cells comprising the vasculature that modulate blood flow (e.g., fibroblasts, cerebral vascular smooth muscle cells, astrocytes, and endothelial cells). However, the downstream mechanisms that underlie circadian changes in blood flow are unknown. Cytochrome P450 epoxygenases (Cyp4x1 and Cyp2c11) are expressed in the brain and vasculature and metabolize arachidonic acid (AA) to form epoxyeicosatrienoic acids (EETs). EETs are released from astrocytes, neurons, and vascular endothelial cells and act as potent vasodilators, increasing blood flow. EETs released in response to increases in neural activity evoke a corresponding increase in blood flow known as the functional hyperemic response. We examine the hypothesis that Cyp2c11 and Cyp4x1 expression and EETs production vary in a circadian manner in the rat brain and cerebral vasculature. RT-PCR revealed circadian/diurnal expression of clock and clock-controlled genes as well as Cyp4x1 and Cyp2c11, within the rat hippocampus, middle cerebral artery, inferior vena cava, hippocampal astrocytes and rat brain microvascular endothelial cells. Astrocyte and endothelial cell culture experiments revealed rhythmic variation in Cyp4x1 and Cyp2c11 gene and protein expression with a 12-h period and parallel rhythmic production of EETs. Our data suggest there is circadian regulation of Cyp4x1 and Cyp2c11 gene expression. Such rhythmic EETs production may contribute to circadian changes in blood flow and alter risk of adverse cardiovascular events throughout the day.

Irreversible perinatal imprinting of adult expression of the principal sex-dependent drug-metabolizing enzyme CYP2C11.

We proposed to determine whether, like other sexual dimorphisms, drug metabolism is permanently imprinted by perinatal hormones, resulting in its irreversible sex-dependent expression. We treated newborn male rats with monosodium glutamate (MSG), a total growth hormone (GH) blocker, and, using cultured hepatocytes, examined expression of adult CYP2C11, the predominant cytochrome-P450 expressed only in males, as well as the signal transduction pathway by which episodic GH solely regulates the isoform's expression. In addition, adolescent hypophysectomized (hypox) male rats served as controls in which GH was eliminated after the critical imprinting period. Whereas renaturalization of the masculine episodic GH profile restored normal male-like levels of CYP2C11, as well as CYP2C12, in hepatocytes from hypox rats, the cells derived from the MSG-treated rats were completely unresponsive. Moreover, GH exposure of hepatocytes from hypox rats resulted in normal induction, activation, nuclear translocation, and binding to the CYP2C11 promoter of the signal transducers mediating GH regulation of CYP2C11 expression, which dramatically contrasted with the complete unresponsiveness of the MSG-derived hepatocytes, also associated with hypermethylation of GH-response elements in the CYP2C11 promoter. Lastly, neonatal MSG treatment had no adverse effect on postnatal and adult testosterone levels. The results demonstrate that the sexually dimorphic expression of CYP2C11 is irreversibly imprinted shortly after birth by a hormone other than the customary testosterone, but likely by GH.

Protein restoration in low-birth-weight rat offspring derived from maternal low-protein diet leads to elevated hepatic CYP3A and CYP2C11 activity in adulthood.

The World Health Organization has identified hypercholesterolemia to be one of the major symptoms encompassing the metabolic syndrome. Moreover, epidemiologic evidence indicates that low-birth-weight offspring are at greater risk of developing the metabolic syndrome. Previous work in our laboratory demonstrated that maternal protein restriction (MPR) results in impaired fetal growth and hypercholesterolemia in adulthood. This was attributed to repression of hepatic CYP7A1, a rate-limiting enzyme that catabolizes cholesterol to bile acids. Another important function of hepatic cytochrome P450 enzymes is the phase I oxidative metabolism of drugs (i.e., statins for hypercholesterolemia), which can significantly impact pharmacokinetics. We hypothesized that MPR offspring may have altered ability to metabolize drugs in adulthood. To address this hypothesis, we maintained Wistar rats on a 20% protein diet (control) or a low 8% protein diet throughout prenatal and postnatal life (LP1) or exclusively during prenatal life and weaning (LP2). Intriguingly CYP3A and CYP2C11 intrinsic clearance (Vmax/Km) was significantly increased exclusively in LP2 offspring at postnatal day 130 compared with control or LP1 offspring, as evaluated by testosterone enzyme kinetics in liver microsomes. The increase in activity was secondary to an increase in CYP3A23 and CYP2C11 mRNA. Collectively, these findings suggest that a low-birth-weight offspring with postnatal catch-up growth may have a diminished response to xenobiotics metabolized by CYP3A and CYP2C11 enzymes.

Disturbed balance between phase I and II metabolizing enzymes in ovarian endometriosis: a source of excessive hydroxy-estrogens and ROS?

Oxidative metabolism of estrogens was studied in 31 ovarian endometriosis and 29 normal endometrium samples, by qPCR. Expression was monitored for genes encoding five estrogen hydroxylating, five hydroxy (OH)-estrogen conjugating, and three estrogen quinone detoxifying enzymes. CYP1B1, COMT, NQO1, and GSTP1 protein levels were determined using Western blotting and immunohistochemistry staining. Increased expression of CYP1A1, CYP3A7 and COMT, and higher levels of MB-COMT were seen in endometriosis, as compared to normal endometrium. Expression of CYP1B1, CYP3A5, SULT1A1 and NQO2 was unchanged, with comparable CYP1B1 protein levels. Expression of SULT1E1, SULT2B1, UGT2B7, NQO1, and GSTP1 was decreased. Three NQO1 isoforms were detected; NQO1c appears to be endometriosis-specific. Our data indicate a disturbed balance between phase I and II metabolizing enzymes in endometriosis, potentially leading to excessive OH-estrogen and altered ROS formation, and stimulation of proliferation of ectopic endometrium. This is the first report on disturbed expression of estrogen oxidative metabolism genes in ovarian endometriosis.

Noncanonical suppression of GH-dependent isoforms of cytochrome P450 by the somatostatin analog octreotide.

Octreotide is a potent somatostatin analog therapeutically used to treat several conditions including hyper GH secretion in patients with acromegaly. We infused, over 30 s, octreotide into male rats every 12 h for 6 days at levels considerably greater than typical human therapeutic doses. Unexpectedly, resulting circulating GH profile was characterized by pulses of higher amplitudes, longer durations, and greater total content than normal, but still contained an otherwise male-like episodic secretory profiles. In apparent disaccord, the normally elevated masculine expression levels (protein and/or mRNA) of CYP2C11 (accounting for >50% of the total hepatic cytochrome P450 content), CYP3A2, CYP2C7, and IGF1, dependent on the episodic GH profile, were considerably downregulated. We explain this contradiction by proposing that the requisite minimal GH-devoid interpulse durations in the masculine profile that solely regulate expression of at least CYP2C11 and IGF1 may be sufficiently reduced to suppress transcription of the hepatic genes. Alternatively, we observed that octreotide infusion may have acted directly on the hepatocytes to induce expression of immune response factors postulated to suppress CYP transcription and/or upregulate expression of several negative regulators (e.g. phosphatases and SOCS proteins) of the JAK2/STAT5B signaling pathway that normally mediates the upregulation of CYP2C11 and IGF1 by the masculine episodic GH profile.

Neonatal xenoestrogen exposure alters growth hormone-dependent liver proteins and genes in adult female rats.

The hypothalamic-growth hormone (GH)-liver axis represents a new concept in endocrine regulation of drug toxicity. Preponderant sex differences are found in liver gene expression, mostly dependent on the sexually dimorphic pattern of GH secretion which is set during the neonatal period by gonadal steroids. We tested if GH-dependent sexually dimorphic liver enzymes and proteins was perturbed by neonatal Bisphenol A (BPA) treatment in female rats. Female rats were sc injected with BPA (50 or 500 µg/50 µl) or castor oil vehicle from postnatal day 1 to 10. At five months serum prolactin, pituitary GH, and serum and liver insulin growth factor-I (IGF-I) were measured by RIA. Major urinary proteins (MUPs) were determined by electrophoresis. Liver Cyp2c11, Cyp2c12, Adh1, Hnf6, and Prlr mRNA levels were determined by real time PCR. Pituitary GH content and liver IGF-I concentration were increased by neonatal BPA treatment, indicating partial masculinization of the GH axis in treated females. GH-dependent female predominant liver enzyme genes (Cyp2c12 and Adh1) and a transcription factor (Hnf6) were downregulated or defeminized, while there were no changes in a male predominant gene (Cyp2c11) or protein (MUP). Our findings indicate that perinatal exposure to BPA may compromise the sexually dimorphic capacity of the liver to metabolize drugs and steroids.

Stress is a critical player in CYP3A, CYP2C, and CYP2D regulation: role of adrenergic receptor signaling pathways.

Stress is a critical player in the regulation of the major cytochrome P-450s (CYPs) that metabolize the majority of the prescribed drugs. Early in life, maternal deprivation (MD) stress and repeated restraint stress (RS) modified CYP expression in a stress-specific manner. In particular, the expression of CYP3A1 and CYP2C11 was increased in the liver of MD rats, whereas RS had no significant effect. In contrast, hepatic CYP2D1/2 activity was increased by RS, whereas MD did not affect it. The primary effectors of the stress system, glucocorticoids and epinephrine, highly induced CYP3A1/2. Epinephrine also induced the expression of CYP2C11 and CYP2D1/2. Further investigation indicated that AR-agonists may modify CYP regulation. In vitro experiments using primary hepatocyte cultures treated with the AR-agonists phenylephrine, dexmedetomidine, and isoprenaline indicated an AR-induced upregulating effect on the above-mentioned CYPs mediated by the cAMP/protein kinase A and c-Jun NH2-terminal kinase signaling pathways. Interestingly though, in vivo pharmacological manipulations of ARs using the same AR-agonists led to a suppressed hepatic CYP expression profile, indicating that the effect of the complex network of central and peripheral AR-linked pathways overrides that of the hepatic ARs. The AR-mediated alterations in CYP3A1/2, CYP2C11, and CYP2D1/2 expressions are potentially connected with those observed in the activation of signal transducer and activator of transcription 5b. In conclusion, stress and AR-agonists may modify the expression of the major CYP genes involved in the metabolism of drugs used in a wide range of diseases, thus affecting drug efficacy and toxicity.

Maternal exposure to low doses of DES altered mRNA expression of hepatic microsomal enzymes in male rat offspring.

Our previous studies demonstrated that prenatal diethylstilbestrol (DES) treatment disrupts steroidogenesis but induces high-level expression of androgen receptor (AR) mRNA to inhibit the disruption of spermatogenesis. This study examined which prenatal DES treatment influenced hepatic microsomal enzymes, CYP3A1, CYP2B1/2, CYP2C11, UGT2B1 (UDP-glucuronosyltransferase 2B1), and IGF-1 (insulin-like growth factor-1), in male rat offspring. DES treatment decreased the mRNA expression levels of CYP3A1 and CYP2B1/2, but did not alter the expression of CYP2C11. At 6 weeks, DES treatment increasd the mRNA expression levels of UGT2B1 and IGF-1. These results suggest that prenatal DES treatment alters two hepatic enzymes (CYP3A1 and CYP2B1/2) and IGF-1 mRNA expression levels to counteract the low level of testosterone, but this disrupted UGT2B1 mRNA expression reduces the testosterone level.

CYP2C76 non-synonymous variants in cynomolgus and rhesus macaques.

Cynomolgus CYP2C76, not orthologous to any human cytochrome P450, partly accounts for species differences in drug metabolism between cynomolgus macaques and humans. To discover the CYP2C76 variants, we previously surveyed cynomolgus macaque genomes and found several non-synonymous variants, including a null allele. However, the analysis was limited to cynomolgus macaques, and the number of genomes was relatively small. In this study, therefore, further screening was conducted using 74 cynomolgus and 30 rhesus macaques. A total of 18 non-synonymous variants was found, among which 7 were in substrate recognition sites, important for protein function, and 14 (74%) were shared by both macaque lineages. In cynomolgus macaques, 3 (16%) non-synonymous variants were unique to Indochinese animals, whereas all the variants found in Indonesian animals were shared by Indochinese animals. Among the 18 variants, as compared with the wild type, in progesterone 16α-hydroxylation, L65F, M310L, and N364S variants showed lower metabolic activity and lower intrinsic clearance by kinetic analysis. Molecular modeling indicated that the reduced catalytic activity of the L65F variant in progesterone 16α-hydroxylation possibly resulted from a longer distance of progesterone to the heme in the active site of the CYP2C76 protein. L65F, M310L, and N364S variants might partly influence inter-animal variations of CYP2C76 metabolic activities.

Effects of Lactobacillus casei on the expression and the activity of cytochromes P450 and on the CYP mRNA level in the intestine and the liver of male rats.

OBJECTIVES: The aim of the study was to find whether probiotic Lactobacillus casei influences the expression or the activity of cytochromes P450 (CYP) and whether it has an influence on the level of CYP mRNA in male rats. DESIGN: Live bacterial suspension of L. casei was administered orally (gavage) to healthy male Wistar rats daily for 7 days. Control group of rats was treated with the saline solution. Sections of the duodenum, jejunum, ileum, caecum and colon were dissected from each experimental animal. In all individual samples, the expression of selected CYPs was determined by Western blotting. The levels of expression of CYPs were also evaluated by mRNA using the real-time PCR method. RESULTS: There were changes observed in the expression of CYP enzymes and in the CYP mRNA levels along the intestine after application of L. casei. The expression of CYP1A1 enzyme was found to be decreased in the proximal part of the jejunum and colon, CYP1A1 mRNA level was decreased in the distal part of the jejunum, ileum and caecum. Thus, the changes in CYP1A1 protein or mRNA were observed along the intestine of male rats. Similarly, a decreased expression of the caecal CYP2E1 mRNA and of the duodenal CYP3A9 mRNA after treatment of rats with L. casei was found. CONCLUSION: Probiotic L. casei might be able to contribute to prevention against colorectal cancer by decreasing levels of certain forms of xenobiotic-metabolizing enzymes; moreover, in general, there is a possibility of interactions with concomitantly taken pharmacotherapeutic agents.

Effects of brucine combined with glycyrrhetinic acid or liquiritin on rat hepatic cytochrome P450 activities in vivo.

Abstract: The activities of four CYP450 enzymes (CYP3A, 1A2, 2El and 2C) and the mRNA expression levels of CYP1A2, 2El, 2Cll and 3A1 in rat liver were determined after Wistar rats were orally administered with brucine (BR) at three dosage levels (3, 15 and 60 mg.kg-1 per day) and the high dose of BR combined with glycyrrhetinic acid (GA, 25 mg.kg-1 per day) or liquiritin (LQ, 20 mg.kg-1 per day) for 7 consecutive days. Compared with the control, brucine caused 24.5% and 34.6% decrease of CYP3A-associated testosterone 6beta-hydroxylation (6betaTesto-OH) and CYP2C-associated tolbutamide hydroxylation (Tol-OH), respectively, and 146.1% increase of CYP2El-associated para-nitrophenol hydroxylation (PNP-OH) at the high dose level. On the other hand, (BR+GA) caused 51.4% and 33.5% decrease, respectively, of CYP2El-associated PNP-OH and CYP1A2-associated ethoxyresorufin-O-de-ethylation (EROD) as compared with the high dose of BR group. Meanwhile, (BR+LQ) caused 41.1% decrease of CYP2El-associated PNP-OH and 37.7% increase of CYP2C-associated Tol-OH. The results indicated that the co-administration of BR with GA or LQ had effect on mRNA expression and activities of the CYP450 enzymes mentioned above to some extent, and the in vivo antagonism of LQ on BR-induced CYPs adverse effects and the in vivo inhibitory action of GA on CYP2E1 and 1A2 might play an important role in the detoxification of Radix Glycyrrhizae against Strychnos nux-vomica L.