Expression of CAR in SW480 and HepG2 cells during G1 is associated with cell proliferation

Osabe, Makoto; Sugatani, Junko; Takemura, Akiko; Yamazaki, Yoji; Ikari, Akira; Kitamura, Naomi; Negishi, Masahiko; Miwa, Masao

doi:10.1016/j.bbrc.2008.02.140

Cited by 19 publications

(17 citation statements)

References 16 publications

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“…HGF was first demonstrated to repress mRNA expression of CAR in primary human hepatocytes by a 3.8-fold factor (Fig. 7A), which agrees with previous data from human hepatoma HepG2 cells (Osabe et al, 2008). HGF was next shown to markedly inhibit induction of the CAR prototypical target CYP2B6 occurring in phenobarbital-exposed human hepatocytes (Fig.…”

Section: Le Vee Et Alsupporting

confidence: 89%

“…These data most likely illustrate the fact that HGF down-regulates the CAR-related signaling pathway, which has been shown to be involved in phenobarbital-mediated MRP2 induction in hepatocytes (Kast et al, 2002). This down-regulation of the CAR-related regulatory pathway in primary human hepatocytes, clearly demonstrated by the inhibition of phenobarbital-mediated upregulation of the CAR prototypical target CYP2B6, is probably due to the repression of CAR expression by HGF, initially reported in human hepatoma HepG2 cells (Osabe et al, 2008) and now extended to primary normal human hepatocytes in the present study. In addition, HGF may also impair the CAR-related pathway through inhibiting ligand-induced nuclear accumulation of this drug-sensing receptor, as recently described in mouse primary hepatocytes (Koike et al, 2007).…”

Section: Regulation Of Human Hepatic Transporters By Hgfsupporting

confidence: 67%

“…at ASPET Journals on May 11, 2018 dmd.aspetjournals.org Downloaded from cells (Kakizaki et al, 2007;Osabe et al, 2008), and 3) phenobarbital appears to be one of the most robust inducers of drug transporters such as MDR1, MRP2, and BCRP in primary human hepatocytes (Jigorel et al, 2006). HGF was first demonstrated to repress mRNA expression of CAR in primary human hepatocytes by a 3.8-fold factor (Fig.…”

Section: Le Vee Et Almentioning

confidence: 97%

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Differential Regulation of Drug Transporter Expression by Hepatocyte Growth Factor in Primary Human Hepatocytes

Vée¹,

Lecureur²,

Moreau³

et al. 2009

Drug Metab Dispos

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ABSTRACT:Hepatocyte growth factor (HGF) is known to down-regulate expression of drug-detoxifying proteins such as cytochromes P450 (P450s) in human hepatocytes. The present study was designed to determine whether HGF may also impair expression of uptake and efflux drug transporters, which constitute important determinants of the liver detoxification pathway, such as P450s. Exposure of primary human hepatocytes to 20 ng/ml HGF for 48 h was found to down-regulate mRNA levels of major sinusoidal uptake transporters, including sodium taurocholate-cotransporting polypeptide (NTCP), organic anion-transporting polypeptide (OATP) 2B1, OATP1B1, organic cation transporter (OCT) 1, and organic anion transporter 2. HGF concomitantly reduced NTCP, OATP2B1, and OATP1B1 protein expression and NTCP, OATP, and OCT1 transport activities. With respect to efflux pumps, HGF decreased mRNA expression of the canalicular bile salt export pump, whereas that of the multidrug resistance (MDR) 1 gene was transiently increased. Moreover, Western blot analysis indicated that HGF up-regulated expressions of MDR1/P-glycoprotein and breast cancer resistance protein in human hepatocytes, whereas those of multidrug resistance gene-associated protein (MRP) 2 and MRP3 were unchanged. However, HGF prevented constitutive androstane receptor-related up-regulation of MRP2 occurring in phenobarbital-treated hepatocytes. Taken together, these data demonstrate that HGF differentially regulates transporter expression in human hepatocytes, i.e., it represses most of the sinusoidal uptake transporters, whereas expression of most of the efflux transporters is unchanged or increased. Such changes probably contribute to alterations of pharmacokinetics in patients with diseases associated with increased plasma levels of HGF such as fulminant hepatitis.

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Section: Le Vee Et Alsupporting

confidence: 89%

Section: Regulation Of Human Hepatic Transporters By Hgfsupporting

confidence: 67%

Section: Le Vee Et Almentioning

confidence: 97%

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Differential Regulation of Drug Transporter Expression by Hepatocyte Growth Factor in Primary Human Hepatocytes

Vée¹,

Lecureur²,

Moreau³

et al. 2009

Drug Metab Dispos

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“…The biological implication of growth signal-mediated regulation of CAR in the absence of exogenous CAR activators can only be speculated on at the present time. Upon drug activation, CAR is known to repress TNF␣-induced death of mouse primary hepatocytes (12) and also appears to regulate cell cycles (8,13). Through these and additional unknown functions, CAR activation may cause various effects on growth factor-mediated signals.…”

Section: Discussionmentioning

confidence: 99%

Active ERK1/2 Protein Interacts with the Phosphorylated Nuclear Constitutive Active/Androstane Receptor (CAR; NR1I3), Repressing Dephosphorylation and Sequestering CAR in the Cytoplasm

Osabe

Negishi

2011

Journal of Biological Chemistry

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The nuclear constitutive active/androstane receptor (CAR) is inactivated and sequestered in the cytoplasm when Thr-38 is phosphorylated. Here, we have demonstrated that activated ERK1/2 interacts with phosphorylated CAR to repress dephosphorylation of Thr-38. The phosphorylation-dependent interaction between CAR and ERK1/2 was examined by co-immunoprecipitation experiments of ectopically expressed FLAG-tagged CAR T38A and CAR T38D mutants with endogenous phospho-ERK1/2 in Huh-7 cells. Phospho-ERK1/2 coprecipitated only the phosphorylation-mimicking CAR T38D mutant; this coprecipitation was mediated by the interaction with the xenochemical response signal peptide near the C terminus of CAR. This interaction increased after EGF treatment and decreased after treatment with the MEK inhibitor U0126 as well as after knockdown of MEK1/2 by shRNA in Huh-7 cells. The phosphorylation levels of Thr-38 of CAR decreased in U0126-treated Huh-7 cells. Thus, activated ERK1/2 interacts with CAR and represses dephosphorylation of Thr-38, providing a cell signal-regulated mechanism for CAR activation.

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“…Besides ubiquitous expression in normal tissues, Rfc is expressed in various human tumor cell lines including leukemic blasts [2]. Moreover, expression of nuclear receptor CAR was shown in various human cancer cells including brain tumor stem cells [58] and hepatoma or colon carcinoma cells [59]. Concerning the clinical relevance for patients with ALL receiving MTX and PB, recent studies demonstrated expression of CAR in human peripheral blood mononuclear cells [60] as well as expression and inducibility of CYP 2B6 by PB-type CYP450 inducers in the human leukemia HL-60 cell line [61].…”

Section: Discussionmentioning

confidence: 99%

Antiepileptic Drugs Reduce the Efficacy of Methotrexate Chemotherapy through Accelerated Degradation of the Reduced Folate Carrier by the Ubiquitin-Proteasome Pathway

Halwachs

Schaefer²,

Seibel³

et al. 2011

Chemotherapy

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Background/Aims: Concurrent treatment with methotrexate (MTX) and enzyme-inducing antiepileptic drugs including phenobarbital (PB) reduces the efficacy of MTX chemotherapy in cancer patients. We have shown that Reduced folate carrier (Rfc1)-mediated uptake of MTX, an essential determinant of MTX chemotherapy, is significantly reduced by PB via protein kinase C (PKC). However, whether PB treatment affects Rfc1 activity through regulation of carrier protein stability and the mechanisms involved remain unclear. Methods/Results: Protein turnover assays using hepatocytoma cells demonstrated that Rfc1 is a long-lived protein that is mainly degraded by the ubiquitin-proteasome proteolytic pathway under basal conditions. Pretreatment with PB significantly reduced Rfc1-mediated MTX uptake and shortened the carrier protein half-life. This effect was abolished by the specific PKC inhibitor Gö6976. Inhibition of proteasomes with MG-132 significantly elevated Rfc1 protein levels and induced colocalization of Rfc1 and ubiquitin particularly in submembranous cellular compartments. Finally, we demonstrated that PB treatment resulted in enhanced levels of Rfc1 polyubiquitin conjugates. Conclusions: Our results demonstrate that PB treatment causes downregulation of Rfc1 activity through PKC-dependent accelerated degradation of the Rfc1 protein by the ubiqutin-proteasome pathway. This regulatory mechanism may therefore involve clinically relevant drug resistance in patients concurrently receiving MTX and enzyme-inducing antiepileptic drugs.

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Expression of CAR in SW480 and HepG2 cells during G1 is associated with cell proliferation

Cited by 19 publications

References 16 publications

Differential Regulation of Drug Transporter Expression by Hepatocyte Growth Factor in Primary Human Hepatocytes

Differential Regulation of Drug Transporter Expression by Hepatocyte Growth Factor in Primary Human Hepatocytes

Active ERK1/2 Protein Interacts with the Phosphorylated Nuclear Constitutive Active/Androstane Receptor (CAR; NR1I3), Repressing Dephosphorylation and Sequestering CAR in the Cytoplasm

Antiepileptic Drugs Reduce the Efficacy of Methotrexate Chemotherapy through Accelerated Degradation of the Reduced Folate Carrier by the Ubiquitin-Proteasome Pathway

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