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  • 1. Abu-Bakar, A'edah
    et al.
    Lämsä, Virpi
    Arpiainen, Satu
    Moore, Michael R.
    Lang, Matti A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Hakkola, Jukka
    Regulation of CYP2A5 gene by the transcription factor nuclear factor (erythroid-derived 2)-like 22007In: Drug Metabolism And Disposition, ISSN 0090-9556, E-ISSN 1521-009X, Vol. 35, no 5, p. 787-794Article in journal (Refereed)
    Abstract [en]

    We have previously shown that cadmium, a metal that alters cellular redox status, induces CYP2A5 expression in nuclear factor (erythroid-derived 2)-like 2 wild-type (Nrf2(-/-)) mice but not in the knockout (Nrf2(-/-)) mice. In the present studies, the potential role of Nrf2 in cadmium-mediated regulation of Cyp2a5 gene was investigated in mouse primary hepatocytes. Cadmium chloride (CdCl2) caused a time-dependent induction of the CYP2A5 at mRNA, protein, and activity levels, with a substantial increase observed within 3 h of exposure. Immunoblotting showed cadmium-dependent nuclear accumulation of Nrf2 within 1 h of exposure. Cotransfection of mouse primary hepatocytes with Cyp2a5 promoter-luciferase reporter plasmids and Nrf2 expression plasmid resulted in a 3-fold activation of Cyp2a5 promoter-mediated transcription relative to the control. Deletion analysis of the promoter localized the Nrf2 responsive region to an area from -2656 to -2339 base pair. Computer-based sequence analysis identified two putative stress response elements (StRE) within the region at positions -2514 to -2505 and -2386 to -2377. Chromatin immunoprecipitation and electrophoretic mobility shift assays showed that interaction of the more proximal StRE with Nrf2 was stimulated by CdCl2. Finally, site-directed mutagenesis of the proximal StRE in Cyp2a5 promoter-luciferase reporter plasmids abolished Nrf2 mediated induction. Collectively, the results indicate that Nrf2 activates Cyp2a5 transcription by directly binding to the StRE in the 5'-flanking region of the gene. This acknowledges Cyp2a5 as the first phase I xenobiotic-metabolizing gene identified under the control of the StRE-Nrf2 pathway with a potential role in adaptive response to cellular stress.

  • 2. Arpiainen, Satu
    et al.
    Jarvenpaa, Sanna-Mari
    Manninen, Aki
    Viitala, Pirkko
    Lang, Matti A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Pelkonen, Olavi
    Hakkola, Jukka
    Coactivator PGC-1 alpha regulates the fasting inducible xenobiotic-metabolizing enzyme CYP2A5 in mouse primary hepatocytes2008In: Toxicology and Applied Pharmacology, ISSN 0041-008X, E-ISSN 1096-0333, Vol. 232, no 1, p. 135-141Article in journal (Refereed)
    Abstract [en]

    The nutritional state of organisms and energy balance related diseases such as diabetes regulate the metabolism of xenobiotics such as drugs, toxins and carcinogens. However, the mechanisms behind this regulation are mostly unknown. The xenobiotic-metabolizing cytochrome P450 (CYP) 2A5 enzyme has been shown to be induced by fasting and by glucagon and cyclic AMP (cAMP), which mediate numerous fasting responses. Peroxisome proliferator-activated receptor gamma coactivator (PGC)-1 alpha triggers many of the important hepatic fasting effects in response to elevated cAMP levels. In the present study, we were able to show that cAMP causes a coordinated induction of PGC-1 alpha expression level by adenovirus mediated gene transfer increased CYP2A5 transcription, Co-transfection of Cyp2a5' promoter constructs with PGC-1 alpha expression vector demonstrated that PGC-1 alpha is able to activate Cyp2a5 transcription through the hepatocyte nuclear factor (HNF)-4 alpha response element in the proximal promoter of the Cyp2a5 gene. Chromartin immunoprecipitation assays showed that PGC-1 alpha binds, together with HNF-4 alpha, to the same region at the Cyp2a5 proximal promoter. In conclusion, PGC-1 alpha mediates the expression of Cyp2A5 induced by cAMP in mouise hepatocytes throuch coactivation of transcription factor HNF-4 alpha. This strongly suggests that PGC-1 alpha is the major factor mediating the fasting response of CYP2A5.

  • 3.
    Christian, Kyle J.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Lang, Matti A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Raffalli-Mathieu, Francoise
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Interaction of heterogeneous nuclear ribonucleoprotein C1/C2 with a novel cis-regulatory element within p53 mRNA as a response to cytostatic drug treatment2008In: Molecular Pharmacology, ISSN 0026-895X, E-ISSN 1521-0111, Vol. 73, no 5, p. 1558-1567Article in journal (Refereed)
    Abstract [en]

    We describe a novel cis-element in the 5' coding region of p53 mRNA and its interaction with heterogeneous nuclear ribonucleoprotein (hnRNP) C1/C2. This element is located in a putative hairpin loop structure, within the first 101 nucleotides downstream of the start codon. The binding of hnRNPC1/C2 is strongly enhanced in response to the DNA-damaging drug cisplatin [cis-diamminedichloroplatinum(II)] and the cytostatic transcriptional inhibitor actinomycin D (dactinomycin), both known inducers of apoptosis and p53. Strongly stimulated binding is observed in both nuclear and cytoplasmic compartments, and it is accompanied by a cytoplasmic increase of hnRNPC1/C2. Changes in hnRNPC1/C2 protein levels are not proportional to binding activity, suggesting qualitative changes in hnRNPC1/C2 upon activation. Phosphorylation studies reveal contrasting characteristics of the cytoplasmic and nuclear hnRNPC1/C2 interaction with p53 mRNA. Results from chimeric p53-luciferase reporter constructs suggest that hnRNPC1/C2 regulates p53 expression via this binding site. Our results are consistent with a mechanism in which the interaction of hnRNPC1/C2 with a cis-element within the coding region of the p53 transcript regulates the expression of p53 mRNA before and during apoptosis. In addition, we report that preapoptotic signals induced by transcriptional inhibition trigger the appearance of a truncated, exclusively cytoplasmic 43-kDa variant of p53 before apoptosis.

  • 4.
    Ellfolk, Maria
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Regulation of Vitamin D 25-hydroxylases: Effects of Vitamin D Metabolites and Pharmaceutical Compounds on the Bioactivation of Vitamin D2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A 700bp portion of the promoter of CYP2D25, the porcine microsomal vitamin D 25-hydroxylase was isolated and sequenced. The computer analysis of the sequence revealed the existence of a putative VDRE at 220 bp upstream of the transcription start site. A CYP2D25 promoter-luciferase reporter plasmid was constructed in order to study the transcriptional regulation of the gene. Treatment with the vitamin D metabolites calcidiol and calcitriol suppressed the promoter, provided that the nuclear receptors VDR and RXR were overexpressed. Phenobarbital was also capable of suppressing the promoter if the nuclear receptors PXR or CAR were overexpressed.

    The 25-hydroxylases are not expressed solely in liver but in a wide array of other organs as well. It is therefore possible at least in theory to study the vitamin D 25-hydroxylation in human subjects using cells from extrahepatic organs, from which biopsy retrieval is easier than from the liver. Dermal fibroblasts are frequently used to study different pathological conditions in human subjects and they are easy to come by. Dermal fibroblasts were shown to express two vitamin D 25-hydroxylases: CYP27A1 and CYP2R1. The expression pattern of CYP2R1 displayed considerable interindividual variation. The fibroblasts were also capable of measurable vitamin D 25-hydroxylation, which makes dermal fibroblasts a possible tool in studying vitamin D 25-hydroxylation in human subjects.

    Little is known about the regulation of expression and activity of the human vitamin D 25-hydroxylases. Therefore dermal fibroblasts – expressing CYP2R1 and CYP27A1 – and human prostate cancer LNCaP cells, that express CYP2R1 and CYP2J2, were treated with calcitriol and phenobarbital and efavirenz, two drugs that give rise to vitamin D deficiency. Treatment decreased the mRNA levels of CYP2R1 and CYP2J2 provided that the treated cells also expressed the necessary nuclear receptors. CYP27A1 did not respond to any of the treatments. The treatments also managed to decrease the 25-hydroxylating activity of the cells.

    The results show that vitamin D 25-hydroxylases can be regulated by both endogenous and xenobiotic compounds.

    List of papers
    1. Isolation and properties of the CYP2D25 promoter: Transcriptional regulation by vitamin D3 metabolites
    Open this publication in new window or tab >>Isolation and properties of the CYP2D25 promoter: Transcriptional regulation by vitamin D3 metabolites
    2006 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 345, no 2, p. 568-572Article in journal (Refereed) Published
    Abstract [en]

    Previous studies have suggested that hepatic production of 25-hydroxyvitamin D3 may be suppressed by 1α,25-dihydroxyvitamin D3. However, the molecular details of these observations have not been clarified. In the current study, the 5´-flanking DNA sequence of CYP2D25, a porcine microsomal vitamin D 25-hydroxylase, was isolated and analyzed. The CYP2D25 promoter contains a putative vitamin D response element (VDRE). The promoter activity was markedly suppressed by 1α,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 in presence of vitamin D receptor (VDR). The data suggest that VDR-mediated inhibition of 25-hydroxylase(s) by vitamin D3 metabolites at the transcriptional level may play an important role in the regulation of 25-hydroxyvitamin D3 production in liver and other tissues.

    Keywords
    Vitamin D3, 25-Hydroxylase, CYP2D25, Promoter, Transcriptional regulation
    National Category
    Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:uu:diva-97879 (URN)10.1016/j.bbrc.2006.04.116 (DOI)16690021 (PubMedID)
    Available from: 2008-11-28 Created: 2008-11-28 Last updated: 2018-01-13Bibliographically approved
    2. Phenobarbital suppresses vitamin D3 25-hydroxylase expression: A potential new mechanism for drug-induced osteomalacia
    Open this publication in new window or tab >>Phenobarbital suppresses vitamin D3 25-hydroxylase expression: A potential new mechanism for drug-induced osteomalacia
    2007 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 357, no 3, p. 603-607Article in journal (Refereed) Published
    Abstract [en]

    Prolonged therapy with phenobarbital may cause vitamin D deficiency or osteomalacia. In the current study, we propose a novel mechanism for drug-induced osteomalacia involving impaired bioactivation of vitamin D3 due to decreased 25-hydroxylation of vitamin D3 in liver. The present data, using the pig as model, demonstrate direct effects by phenobarbital on the expression of CYP27A1 and CYP2D25, two important 25-hydroxylases. Treatment by phenobarbital markedly reduced the rate of 25-hydroxylation by primary hepatocytes and suppressed the cellular CYP27A1 mRNA levels. The rate of 25-hydroxylation by two different purified 25-hydroxylases, microsomal CYP2D25, and mitochondrial CYP27A1, respectively, was dose-dependently inhibited by phenobarbital. Reporter assay experiments in liver-derived HepG2 cells revealed a marked PXR-mediated transcriptional downregulation of the CYP2D25 promoter. In addition, the data indicate that phenobarbital might affect the mRNA stability of CYP2D25. Taken together, the data suggest that vitamin D3 25-hydroxylation may be suppressed by phenobarbital. A downregulation of 25-hydroxylation by phenobarbital may explain, at least in part, the increased risk of osteomalacia, bone loss, and fractures in long-term phenobarbital therapy.

    Keywords
    Bioactivation of vitamin D3, 25-Hydroxylation, Hepatocytes, Expression, Transcriptional regulation, Osteomalacia
    National Category
    Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:uu:diva-97880 (URN)10.1016/j.bbrc.2007.03.177 (DOI)000246382700006 ()17445763 (PubMedID)
    Available from: 2008-11-28 Created: 2008-11-28 Last updated: 2018-01-13Bibliographically approved
    3. Dermal fibroblasts: a possible tool for studies of vitamin D3 25-hydroxylations in humans
    Open this publication in new window or tab >>Dermal fibroblasts: a possible tool for studies of vitamin D3 25-hydroxylations in humans
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-97881 (URN)
    Available from: 2008-11-28 Created: 2008-11-28 Last updated: 2010-01-13Bibliographically approved
    4. Regulation of vitamin D3 25-hydroxylases in dermal fibroblasts and prostate cancer LNCaP cells
    Open this publication in new window or tab >>Regulation of vitamin D3 25-hydroxylases in dermal fibroblasts and prostate cancer LNCaP cells
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-97882 (URN)
    Available from: 2008-11-28 Created: 2008-11-28Bibliographically approved
  • 5.
    Ellfolk, Maria
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Norlin, Maria
    Gustafsson, Jan
    Wikvall, Kjell
    Dermal fibroblasts: a possible tool for studies of vitamin D3 25-hydroxylations in humansManuscript (Other academic)
  • 6.
    Ellfolk, Maria
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Norlin, Maria
    Wikvall, Kjell
    Regulation of vitamin D3 25-hydroxylases in dermal fibroblasts and prostate cancer LNCaP cellsArticle in journal (Refereed)
  • 7.
    Hosseinpour, Fardin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Ellfolk, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Norlin, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Wikvall, Kjell
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Phenobarbital suppresses vitamin D3 25-hydroxylase expression: A potential new mechanism for drug-induced osteomalacia2007In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 357, no 3, p. 603-607Article in journal (Refereed)
    Abstract [en]

    Prolonged therapy with phenobarbital may cause vitamin D deficiency or osteomalacia. In the current study, we propose a novel mechanism for drug-induced osteomalacia involving impaired bioactivation of vitamin D3 due to decreased 25-hydroxylation of vitamin D3 in liver. The present data, using the pig as model, demonstrate direct effects by phenobarbital on the expression of CYP27A1 and CYP2D25, two important 25-hydroxylases. Treatment by phenobarbital markedly reduced the rate of 25-hydroxylation by primary hepatocytes and suppressed the cellular CYP27A1 mRNA levels. The rate of 25-hydroxylation by two different purified 25-hydroxylases, microsomal CYP2D25, and mitochondrial CYP27A1, respectively, was dose-dependently inhibited by phenobarbital. Reporter assay experiments in liver-derived HepG2 cells revealed a marked PXR-mediated transcriptional downregulation of the CYP2D25 promoter. In addition, the data indicate that phenobarbital might affect the mRNA stability of CYP2D25. Taken together, the data suggest that vitamin D3 25-hydroxylation may be suppressed by phenobarbital. A downregulation of 25-hydroxylation by phenobarbital may explain, at least in part, the increased risk of osteomalacia, bone loss, and fractures in long-term phenobarbital therapy.

  • 8. Konstandi, Maria
    et al.
    Harkitis, Panagiotis
    Kostakis, Dimitris
    Marselos, Marios
    Johnson, Elizabeth O
    Lang, Matti A
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    D-2-receptor-linked signaling pathways regulate the expression of hepatic CYP2E12008In: Life Sciences, ISSN 0024-3205, E-ISSN 1879-0631, Vol. 82, no 1-2, p. 1-10Article in journal (Refereed)
    Abstract [en]

    This study investigated the role of catecholamine-related signaling pathways in the regulation of hepatic cytochrome P450 (CYP2E1). Central and peripheral catecholamine depletion with reserpine down-regulated CYP2E1. On the other hand, selective peripheral catecholamine depletion with guanethidine increased CYP2E1 apoprotein levels. Enrichment of peripheral catecholamines with adrenaline suppressed p-nitrophenol hydroxylase activity (PNP). PNP activity was also markedly suppressed by L-DOPA. Stimulation of D-2-receptors with bromocriptine up-regulated CYP2E1, as assessed by enzyme activity and protein levels, whereas blockade of D-2-dopaminergic receptors with sulpiride down-regulated this isozyme. These findings indicate that central and peripheral catecholamines have different effects on CYP2E1. Central catecholamines appear related to the up-regulation, whereas the role of peripheral catecholamines is clearly related to the type and location of adrenoceptors involved. D-2-receptor-linked signaling pathways have an up-regulating effect on CYP2E1, while D-1-receptor pathways may down-regulate this isozyme. It is worth noting that the widespread environmental pollutant benzo(alpha)pyrene (13(alpha)P) altered the modulating effect of catecholaminergic systems on CYP2E1 regulation. In particular, whereas stimulation or blockade of adrenoceptors had no effect on constitutive PNP activity, exposure to B(alpha)P modified the impact of central and peripheral catecholamines and alpha(2)-adrenoceptors on CYP2E1 expression. It appears that under the influence of B(alpha)P, alpha(2)-adrenergic receptor-linked signaling pathways increased CYP2E1 apoprotein levels. Given that a wide range of xenobiotics and clinically used drugs are activated by CYP2E1 to toxic metabolites, including the production of reactive oxygen species (ROS), it is possible that therapies challenging dopaminergic receptor- and/or alpha(2)-adrenoceptor-linked signaling pathways may alter the expression of CYP2E1, thus affecting the progress and development of several pathologies.

  • 9. Konstandi, Maria
    et al.
    Lang, Matti A
    Kostakis, Dimitris
    Johnson, Elizabeth O
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Marselos, Marios
    Predominant role of peripheral catecholamines in the stress-induced modulation of CYP1A2 inducibility by benzo(alpha)pyrene2008In: Basic & Clinical Pharmacology & Toxicology, ISSN 1742-7835, E-ISSN 1742-7843, Vol. 102, no 1, p. 35-44Article in journal (Refereed)
    Abstract [en]

    The potential involvement of catecholamines and in particular of alpha(2)-adrenoceptor-related signalling pathways, in the regulation of drug-metabolizing enzymes by stress was investigated in Wistar rats after exposure to the environmental pollutant benzo(alpha)pyrene. For this purpose, total cytochrome P450 content, the CYP1A2 mRNA levels, 7-methoxyresorufin-O-dealkylase (MROD), 7-pentoxyresorufin-O-dealkylase (PROD) and p-nitrophenol hydroxylase activity levels were determined in the livers of rats exposed to repeated restraint stress after treatment with benzo(alpha)pyrene coupled with pharmacological manipulations of peripheral and/or central catecholamines and alpha(2)-adrenoceptors. The data show that stress is a significant factor in the regulation of CYP1A2 induction and that catecholamines play a central role in the stress-mediated modulation of hepatic CYP1A2 inducibility by benzo(alpha)pyrene. The up-regulating effect of stress on benzo(alpha)pyrene-induced CYP1A2 gene expression was eliminated after a generalized catecholamine depletion with reserpine. Similarly, in a state where only peripheral catecholamines were depleted and central catecholamines remained intact after guanethidine administration, the up-regulating effect of stress was eliminated. It is apparent that stress up-regulates the induction of CYP1A2 by benzo(alpha)pyrene mainly via peripheral catecholamines, while central catecholamines hold a minor role in the regulation. Pharmacological manipulations of alpha(2)-adrenoceptors appear to interfere with the effect of stress on the regulation of CYP1A2 inducibility. Either blockade or stimulation of alpha(2)-adrenoceptors with atipamezole and dexmedetomidine respectively, eliminated the up-regulating effect of stress on CYP1A2 benzo(alpha)pyrene-induced expression, while it enhanced MROD activity. In contrast, stress and pharmacological manipulations of catecholamines and alpha(2)-adrenoceptors did not affect total P450 content, the CYP2B1/2-dependent PROD and the CYP2E1-dependent p-nitrophenol hydroxylase activities. In conclusion, stress is a significant factor in the regulation of the CYP1A2 inducibility by benzo(alpha)pyrene, which in turn is involved in the metabolism of a large spectrum of toxicants, drugs and carcinogenic agents. Although the mechanism underlying the stress effect on CYP1A2 induction has not been clearly elucidated, it appears that peripheral catecholamines hold a predominant role, while central catecholamines and in particular, central noradrenergic pathways hold a minor role.

  • 10.
    Lindell, Monica
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Expression of Genes Encoding for Drug Metabolism in the Small Intestine2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This investigation focused on the mRNA expression of drug metabolising Cytochromes P-450 (CYP) and UDP-glucuronosyltransferases (UGT) and the transport protein P-glycoprotein (Pgp) in the small intestine of humans and rats.

    The mRNA expression of the investigated genes in the human small intestine (duodenum) varies between individuals giving each one of us personal profile. In general, the most dominant forms are Pgp, CYPs 2C9, 2D6, 3A4, and UGTs 1A1, 1A10, 2B7. However, which of these is the highest expressed one varies between individuals.

    The correlation in expression between some CYP forms and UGT forms respectively is relatively high, which indicates that they have some regulatory mechanisms in common. It was also shown that the mRNA expression of both CYPs and UGTs may be affected by endogenous and exogenous factors. Sex and ethnic background, affected the mRNA expression of CYP2A6 and 2E1 respectively. Commonly used drugs such as acetylsalicylicacid (ASA) and omeprazole (omep) affect CYP2A6, CYP2E1 (ASA) and CYP3A4, UGT1A4 (omep). The expression of UGT1A4 is also affected by smoking. All these factors are commonly used and can therefore lead to important drug-drug interactions.

    It was also shown that the human small intestinal CYP mRNA expression pattern differs from that found in the rat. The rat CYP expression is rather constant between the different individuals, and the main rat intestinal forms are CYP1A1, CYP2C, CYP2D6 and CYP3A1. The expression is the same for females and males and no difference can be seen between the different segments of the rat small intestine. As metabolic studies have often been done with rat liver we compared the mRNA expression in the two organs. We found that the mRNA expression of 1A1 was absent in the liver and that the CYP2B1, CYP2Cs, CYP2D1 and Pgp all had a stronger mRNA expression in the small intestine compared to the liver. It is therefore important to realise that results from metabolic studies on liver may not be directly extrapolated to the small intestine.

    Artemisinin is an orally used drug in multidrug treatment of malaria in Southeast Asia. It has been suggested that artemisinin can induce drug metabolism and therefore be involved in drug-drug interactions. This study shows that artemisinin induces mainly the CYP2B via nuclear receptor CAR.

    List of papers
    1. Expression of Genes Encoding for Drug Metabolising Cytochrome P450 Enzymes and P-glycoprotein in the Rat Small Intestine: Comparison to the Liver
    Open this publication in new window or tab >>Expression of Genes Encoding for Drug Metabolising Cytochrome P450 Enzymes and P-glycoprotein in the Rat Small Intestine: Comparison to the Liver
    2003 In: Eur. J. Drug Metab. Pharmacokin., Vol. 28, no 1, p. 41-48Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-90892 (URN)
    Available from: 2003-10-01 Created: 2003-10-01Bibliographically approved
    2. Variable Expression of CYP and Pgp Genes in the Human Small Intestine
    Open this publication in new window or tab >>Variable Expression of CYP and Pgp Genes in the Human Small Intestine
    Show others...
    2003 (English)In: European Journal of Clinical Investigation, ISSN 0014-2972, E-ISSN 1365-2362, Vol. 33, no 6, p. 493-499Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND:

    The small intestine is receiving increased attention for its importance in drug metabolism. However, knowledge of the intervariability and regulation of the enzymes involved, cytochrome p450 and P-Glycoproteins (CYP and Pgp), is poor when compared with the corresponding hepatic enzymes.

    METHODS:

    The expression of eight different CYP genes and the Pgp were determined by reverse transcription polymerase chain reaction (RT-PCR) in 51 human duodenum biopsies. And the variability and correlation of expression was analyzed.

    RESULTS:

    Extensive interindividual variability was found in the expression of most of the genes. Only CYP2C9, CYP3A4 and Pgp were found in all samples. CYP1A2, CYP2A6 and CYP2E1 exhibited the highest interindividual variability. No strong correlation of expression existed between the genes. But a highly significant correlation was found between CYP2D6/1A2, 2D6/2E1, 1A2/2E1 and 2B6/2C9. Acetylsalicylic acid and omeprazole significantly increased the expression of CYPs 2A6, 2E1 and 3A4, respectively.

    CONCLUSIONS:

    Extensive interindividual variability is characteristic for the expression of drug-metabolizing CYP and Pgp genes in human duodenum, and external factors such as drugs may further increase the variability. It is possible that the large interindividual variability may lead to variable bioavailability of orally used drugs and hence complicate optimal drug therapy, especially for drugs with a small therapeutic window. Elucidation of factors contributing to clinically important variances warrants further investigation.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-90893 (URN)10.1046/j.1365-2362.2003.01154.x (DOI)12795646 (PubMedID)
    Available from: 2003-10-01 Created: 2003-10-01 Last updated: 2017-12-14Bibliographically approved
    3. Expression of UDP-Glucuronosyltransferase Genes (UGTs) in Human Duodenum
    Open this publication in new window or tab >>Expression of UDP-Glucuronosyltransferase Genes (UGTs) in Human Duodenum
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-90894 (URN)
    Available from: 2003-10-01 Created: 2003-10-01 Last updated: 2011-03-01
    4. In vivo and mechanistic evidence of nuclear receptor CAR induction by artemisinin
    Open this publication in new window or tab >>In vivo and mechanistic evidence of nuclear receptor CAR induction by artemisinin
    Show others...
    2006 (English)In: European Journal of Clinical Investigation, ISSN 0014-2972, E-ISSN 1365-2362, Vol. 36, no 9, p. 647-653Article in journal (Refereed) Published
    Abstract [en]

    Backround Artemisinin (a sesquiterpene lactone endoperoxide) has become important in multi-drug treatment of malaria. There is evidence that artemisinin induces drug metabolism which could result in drug-drug interactions. The objective of this study was to characterize the inductive properties of artemisinin on drug-metabolizing cytochrome P450 (CYP450) enzymes. Materials and methods The possibility of artemisinin to induce CYP450 was studied in artemisinin-treated (orally for four days) and vehicle-treated rats using reverse transcriptase polymerase chain reaction (RT-PCR). The effect on enzymatic activities in mouse microsomes from multiple artemisinin administration (intraperitonally) to mice were also studied as well as the effect on the expression in mouse primary hepatocytes and HEK293 cells. Results Increased CYP2B1 mRNA levels in rats could be seen after artemisinin treatment as well as a weak but reproducible increase in the intensity of CYP1A2. Administration of artemisinin to mice up-regulated hepatic CYP2B10-dependent, and to a lesser extent, CYP2A5-dependent enzyme activities. In primary hepatocyte culture, artemisinin significantly increased the CYP2B10 mRNA levels whereas the CYP2A5 mRNA levels were increased to a lesser extent. No significant changes were seen in the levels of other CYP enzymes. Artemisinin was an activator of constitutive androstane receptor (CAR) but not pregnane X receptor (PXR) in HEK293 cells. Conclusions The results demonstrate that the drug exerts its effects on drug metabolism via the CAR receptor that results in up-regulation of genes such as the Cyp2b. The weaker up-regulation of CYP2A5 might also be CAR-dependent or alternatively, a consequence of artemisinin toxicity. The results of this study are of importance when predicting potential drug-drug interactions in multi-drug therapies with artemisinin.

    Keywords
    CAR receptor; CYP450; drug-drug interactions; induction; malaria
    National Category
    General Practice
    Identifiers
    urn:nbn:se:uu:diva-90895 (URN)10.1111/j.1365-2362.2006.01700.x (DOI)000239636000008 ()
    Available from: 2003-10-01 Created: 2003-10-01 Last updated: 2018-01-13Bibliographically approved
  • 11.
    Lindell, Monica
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Karlsson, Mats O.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Division of Pharmacokinetics and Drug Therapy.
    Lennernäs, Hans
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Påhlman, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Colorectal Surgery.
    Lang, Matti A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Variable Expression of CYP and Pgp Genes in the Human Small Intestine2003In: European Journal of Clinical Investigation, ISSN 0014-2972, E-ISSN 1365-2362, Vol. 33, no 6, p. 493-499Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    The small intestine is receiving increased attention for its importance in drug metabolism. However, knowledge of the intervariability and regulation of the enzymes involved, cytochrome p450 and P-Glycoproteins (CYP and Pgp), is poor when compared with the corresponding hepatic enzymes.

    METHODS:

    The expression of eight different CYP genes and the Pgp were determined by reverse transcription polymerase chain reaction (RT-PCR) in 51 human duodenum biopsies. And the variability and correlation of expression was analyzed.

    RESULTS:

    Extensive interindividual variability was found in the expression of most of the genes. Only CYP2C9, CYP3A4 and Pgp were found in all samples. CYP1A2, CYP2A6 and CYP2E1 exhibited the highest interindividual variability. No strong correlation of expression existed between the genes. But a highly significant correlation was found between CYP2D6/1A2, 2D6/2E1, 1A2/2E1 and 2B6/2C9. Acetylsalicylic acid and omeprazole significantly increased the expression of CYPs 2A6, 2E1 and 3A4, respectively.

    CONCLUSIONS:

    Extensive interindividual variability is characteristic for the expression of drug-metabolizing CYP and Pgp genes in human duodenum, and external factors such as drugs may further increase the variability. It is possible that the large interindividual variability may lead to variable bioavailability of orally used drugs and hence complicate optimal drug therapy, especially for drugs with a small therapeutic window. Elucidation of factors contributing to clinically important variances warrants further investigation.

  • 12.
    Lindell, Monica
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Karlsson, Mats O.
    Påhlman, Lars
    Lennernäs, Hans
    Lang, Matti A.
    Expression of UDP-Glucuronosyltransferase Genes (UGTs) in Human DuodenumManuscript (Other academic)
  • 13.
    Lindell, Monica
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Lang, Matti
    Lennernäs, Hans
    Expression of Genes Encoding for Drug Metabolising Cytochrome P450 Enzymes and P-glycoprotein in the Rat Small Intestine: Comparison to the Liver2003In: Eur. J. Drug Metab. Pharmacokin., Vol. 28, no 1, p. 41-48Article in journal (Refereed)
  • 14.
    Mahteme, Haile
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Larsson, B
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Toxicology.
    Sundin, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Khamis, Harry
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Information Science.
    Graf, Wilhelm
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Uptake of 5-fluorouracil (5-FU) in peritoneal metastases in relation to the route of drug administration and tumour debulking surgery: an autoradiographic study in the rat2004In: European Journal of Cancer, ISSN 0959-8049, E-ISSN 1879-0852, Vol. 40, no 1, p. 142-147Article in journal (Refereed)
    Abstract [en]

    Patients with peritoneal metastases from colorectal cancer have a poor prognosis. Aggressive treatment by debulking surgery and intraperitoneal (i.p.) chemotherapy has been suggested as an alternative therapy. However, the drug penetrance into the tumour in relation to the administration route and surgical reduction of the tumour is not well known. We compared locoregional administration with intravenous (i.v.) injection. Thirty-four in-bred rats with peritoneal metastases were randomly allocated into eight groups and injected with 14C-labelled 5-fluorouracil (5-FU) either through the i.v. or i.p. route, with or without a preceding tumour debulking, and were sacrificed after 2 or 8 h. Tumour radioactivity was visualised by autoradiography and quantified by a computer-based image analysis. After 8 h, 19 debulked and i.p.-injected tumours had a higher drug uptake, 63.2+/-28 (mean+/-standard deviation (SD)) kBq/g than 62 native i.p.-injected tumours (32.8+/-14) or 22 debulked and i.v.-injected tumours (18.5+/-18, P=0.002). After 8 h, 9 small tumours (<median 571 pixels) which underwent i.p. injection and tumour reduction had a higher drug uptake (77.4+/-26) than 29 non-debulked and i.p.-injected (35.1+/-17) or eight debulked and i.v. injected tumours (23.0+/-16, P=0.004). For larger tumours (>/=median 571 pixels), 16 debulked and i.p.-injected tumours had a higher radioactivity (drug uptake) (150.7+/-63) at 2 h than 49 i.p.-injected native tumours (48.5+/-59) or 11 reduced and i.v.-injected tumours (19.9+/-13, P=0.03). At 8 h, 10 debulked and i.p.-injected tumours had a higher drug uptake (50.3+/-24) than 33 native and i.p.-injected (30.8+/-10) or 14 debulked and i.v.-injected tumours (16.0+/-19, P=0.001). These results indicate that a debulking procedure and locoregional treatment of peritoneal metastases is associated with an increased level of 5-FU in the tumours.

  • 15.
    Pettersson, Hanna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Norlin, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Andersson, Ulla
    Avd. för klinisk kemi, KI, Huddinge, Sverige.
    Pikuleva, Irina
    Department of clinical chemistry and toxicology, University of Texas medical branch, Galveston, USA.
    Björkhem, Ingemar
    Avd. för klinisk kemi. KI, Huddinge, Sverige.
    Misharin, Alexander Yu
    Inst. of biomedical chemisrty, Russian academy of medical sciences, Moscow, Russia.
    Wikvall, Kjell
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Metabolism of a novel side chain modified Delta 8(14)-15-ketosterol, a potential cholesterol lowering drug: 28-hydroxylation by CYP27A12008In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, ISSN 1388-1981, E-ISSN 1879-2618, Vol. 1781, no 8, p. 383-390Article in journal (Refereed)
    Abstract [en]

    The synthetic inhibitors of sterol biosynthesis, 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one and 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one, are of interest as potential cholesterol lowering drugs. Rapid metabolism of synthetic 15-ketosterols may lead to a decrease, or loss, of their potency to affect lipid metabolism. 3beta-Hydroxy-5alpha-cholest-8(14)-en-15-one is reported to be rapidly side chain oxygenated by rat liver mitochondria. In an attempt to reduce this metabolism, the novel side chain modified 15-ketosterol 3beta-Hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one was synthesized. We have examined the metabolism by recombinant human CYP27A1 of this novel side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one and compared the rate of metabolism with that of the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. Both sterols were found to be efficiently metabolized by recombinant human CYP27A1. None of the two 15-ketosterols was significantly metabolized by microsomal 7alpha-hydroxylation. Interestingly, CYP27A1-mediated product formation was much lower with the side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one than with the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. A surprising finding was that this novel side chain modified sterol was metabolized mainly in the C-28 position by CYP27A1. The data on 28-hydroxylation by human CYP27A1 provide new insights on the catalytic properties and substrate specificity of this enzyme. The finding that 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one with a modified side chain is metabolized at a dramatically slower rate than the previously described 15-ketosterol with unmodified side chain may be important for future development of synthetic cholesterol lowering sterols.

  • 16.
    Simonsson, Ulrika S.H.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Lindell, Monica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Raffalli-Mathieu, Francoise
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Lannerbro, Angela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Honkakoski, Paavo
    University of Kuopio, Kuopio, Finland .
    Lang, Matti A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    In vivo and mechanistic evidence of nuclear receptor CAR induction by artemisinin2006In: European Journal of Clinical Investigation, ISSN 0014-2972, E-ISSN 1365-2362, Vol. 36, no 9, p. 647-653Article in journal (Refereed)
    Abstract [en]

    Backround Artemisinin (a sesquiterpene lactone endoperoxide) has become important in multi-drug treatment of malaria. There is evidence that artemisinin induces drug metabolism which could result in drug-drug interactions. The objective of this study was to characterize the inductive properties of artemisinin on drug-metabolizing cytochrome P450 (CYP450) enzymes. Materials and methods The possibility of artemisinin to induce CYP450 was studied in artemisinin-treated (orally for four days) and vehicle-treated rats using reverse transcriptase polymerase chain reaction (RT-PCR). The effect on enzymatic activities in mouse microsomes from multiple artemisinin administration (intraperitonally) to mice were also studied as well as the effect on the expression in mouse primary hepatocytes and HEK293 cells. Results Increased CYP2B1 mRNA levels in rats could be seen after artemisinin treatment as well as a weak but reproducible increase in the intensity of CYP1A2. Administration of artemisinin to mice up-regulated hepatic CYP2B10-dependent, and to a lesser extent, CYP2A5-dependent enzyme activities. In primary hepatocyte culture, artemisinin significantly increased the CYP2B10 mRNA levels whereas the CYP2A5 mRNA levels were increased to a lesser extent. No significant changes were seen in the levels of other CYP enzymes. Artemisinin was an activator of constitutive androstane receptor (CAR) but not pregnane X receptor (PXR) in HEK293 cells. Conclusions The results demonstrate that the drug exerts its effects on drug metabolism via the CAR receptor that results in up-regulation of genes such as the Cyp2b. The weaker up-regulation of CYP2A5 might also be CAR-dependent or alternatively, a consequence of artemisinin toxicity. The results of this study are of importance when predicting potential drug-drug interactions in multi-drug therapies with artemisinin.

  • 17.
    Syvänen, Stina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Eriksson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Genchel, Tove
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Lindhe, Örjan
    Antoni, Gunnar
    Långström, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Synthesis of two potential NK1-receptor ligands using [1-11C]ethyl iodide and [1-11C]propyl iodide and initial PET-imaging2007In: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 7, p. 6-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    The previously validated NK1-receptor ligand [O-methyl-11C]GR205171 binds with a high affinity to the NK1-receptor and displays a slow dissociation from the receptor. Hence, it cannot be used in vivo for detecting concentration changes in substance P, the endogenous ligand for the NK1-receptor. A radioligand used for monitoring these changes has to enable displacement by the endogenous ligand and thus bind reversibly to the receptor. Small changes in the structure of a receptor ligand can lead to changes in binding characteristics and also in the ability to penetrate the blood-brain barrier. The aim of this study was to use carbon-11 labelled ethyl and propyl iodide with high specific radioactivity in the synthesis of two new and potentially reversible NK1-receptor ligands with chemical structures based on [O-methyl-11C]GR205171.

    METHODS:

    [1-11C]Ethyl and [1-11C]propyl iodide with specific radioactivities of 90 GBq/μmol and 270 GBq/μmol, respectively, were used in the synthesis of [O-methyl-11C]GR205171 analogues by alkylation of O-desmethyl GR205171. The brain uptake of the obtained (2S,3S)-N-(1-(2- [1-11C]ethoxy-5-(3-(trifluoromethyl)-4H-1,2,4-triazol-4-yl)phenyl)ethyl)-2-phenylpiperidin-3-amine (I) and (2S,3S)-2-phenyl-N-(1-(2- [1-11C]propoxy-5-(3-(trifluoromethyl)-4H-1,2,4-triazol-4-yl)phenyl)ethyl)piperidin-3-amine (II) was studied with PET in guinea pigs and rhesus monkeys and compared to the uptake of [O-methyl-11C]GR205171.

    RESULTS:

    All ligands had similar uptake distribution in the guinea pig brain. The PET-studies in rhesus monkeys showed that (II) had no specific binding in striatum. Ligand (I) had moderate specific binding compared to the [O-methyl-11C]GR205171. The ethyl analogue (I) displayed reversible binding characteristics contrary to the slow dissociation rate shown by [O-methyl-11C]GR205171.

    CONCLUSION:

    The propyl-analogue (II) cannot be used for detecting changes in NK1-ligand levels, while further studies should be performed with the ethyl-analogue (I).

  • 18.
    Tang, Wanjin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Pettersson, Hanna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Norlin, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Pharmaceutical Biochemistry.
    Involvement of the PI3K/Akt pathway in estrogen-mediated regulation of human CYP7B1: identification of CYP7B1 as a novel target for PI3K/Akt and MAPK signalling2008In: Journal of Steroid Biochemistry and Molecular Biology, ISSN 0960-0760, E-ISSN 1879-1220, Vol. 112, no 1-3, p. 63-73Article in journal (Refereed)
    Abstract [en]

    The steroid hydroxylase CYP7B1 metabolizes neurosteroids, cholesterol derivatives, and estrogen receptor (ER) ligands. Previous studies identified CYP7B1 as a target for regulation by estrogen. The present study examines the mechanism for estrogen-mediated regulation of the human CYP7B1 gene promoter. Treatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), abolished ER-mediated up-regulation of a CYP7B1 promoter-luciferase reporter in HepG2 cells, whereas overexpression of PI3K or Akt significantly increased estrogenic up-regulation of CYP7B1. Overexpression of dominant-negative mutant Akt abolished ER-mediated stimulation of CYP7B1 in HepG2 cells. Data indicated no binding of ER to CYP7B1 promoter sequences, suggesting that ER interacts with the PI3K/Akt pathway without binding to the gene. At low ER levels, overexpression of Akt suppressed CYP7B1 promoter activity, suggesting that its effect on CYP7B1 is different when estrogens are absent. In HEK293 cells, CYP7B1 transcription was much less affected by Akt, indicating that the mechanism for up-regulation of CYP7B1 is different in different cell types. Other experiments indicated that MAPK signalling may affect basal CYP7B1 levels. The current results, indicating that regulation of CYP7B1 by ER can be mediated via the PI3K/Akt signal pathway, a regulatory pathway important for cellular survival and growth, suggest an important role for CYP7B1 in cellular growth, particularly in connection with estrogenic signalling.

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