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Yuichi Sugiyama - One of the best experts on this subject based on the ideXlab platform.
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bile salt export pump bsep abcb11 can transport a nonbile acid substrate Pravastatin
Journal of Pharmacology and Experimental Therapeutics, 2005Co-Authors: Masaru Hirano, Kazuya Maeda, Hisamitsu Hayashi, Hiroyuki Kusuhara, Yuichi SugiyamaAbstract:Pravastatin is a well known 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor. Cumulative studies have shown that Pravastatin is taken up into hepatocytes by the organic anion transporting polypeptide family transporters and excreted into the bile as an intact form by multidrug resistance-associated protein 2 (MRP2). It is generally accepted that the bile salt export pump (BSEP/ABCB11) mainly transports bile acids and plays an indispensable role in their biliary excretion. Interestingly, we found that BSEP could accept Pravastatin as a substrate. Significant ATP-dependent uptake of Pravastatin by human BSEP (hBSEP)- and rat BSEP (rBsep)-expressing membrane vesicles was observed, and the ratio of the uptake activity of Pravastatin to that of taurocholic acid (TCA) by hBSEP was 3.3-fold higher than that by rBsep. The K m value of Pravastatin for hBSEP was 124 μM. A mutual inhibition study between TCA and Pravastatin revealed that they competitively interact with hBSEP. Several statins inhibited the hBSEP- and rBsep-mediated uptake of TCA; however, the specific uptake of other statins (cerivastatin, fluvastatin, and pitavastatin) by hBSEP and rBSEP was not detected. The inhibitory effects of hydrophilic statins (Pravastatin and rosuvastatin) on the uptake of TCA by BSEP were relatively lower than those of lipophilic statins. These data suggest that BSEP may be partly involved in the biliary excretion of Pravastatin in both rats and humans.
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functional involvement of rat organic anion transporter 3 roat3 slc22a8 in the renal uptake of organic anions
Journal of Pharmacology and Experimental Therapeutics, 2002Co-Authors: Maki Hasegawa, Hiroyuki Kusuhara, Daisuke Sugiyama, Kousei Ito, Shirou Ueda, Hitoshi Endou, Yuichi SugiyamaAbstract:Our previous kinetic analyses have shown that the transporter responsible for the renal uptake of Pravastatin, an HMG-CoA reductase inhibitor, differs from that involved in its hepatic uptake. Although organic anion transporting polypeptides are now known to be responsible for the hepatic uptake of Pravastatin, the renal uptake mechanism has not been clarified yet. In the present study, the involvement of rat organic anion transporter 3 (rOat3; Slc22a8 ) in the renal uptake of Pravastatin was investigated. Immunohistochemical staining indicates the basolateral localization of rOat3 in the kidney. rOat1- and rOat3-expressed LLC-PK1 cells exhibited specific uptake of p -aminohippurate (PAH) and Pravastatin, respectively, with the Michaelis-Menten constants ( K m values) of 60 μM for rOat1-meditad PAH uptake and 13 μM for rOat3-mediated Pravastatin uptake. Saturable uptake of PAH and Pravastatin was observed in kidney slices with K m values of 69 and 11 μM, respectively. The difference in the potency of PAH and Pravastatin in inhibiting uptake by kidney slices suggests that different transporters are responsible for their renal uptake. This was also supported by the difference in the degree of inhibition by benzylpenicillin, a relatively selective inhibitor of rOat3, for the uptake of PAH and Pravastatin by kidney slices. These results suggest that rOat1 and rOat3 are mainly responsible for the renal uptake of PAH and Pravastatin, respectively.
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biliary excretion of Pravastatin in rats contribution of the excretion pathway mediated by canalicular multispecific organic anion transporter cmoat
Drug Metabolism and Disposition, 1997Co-Authors: Masayo Yamazaki, Sayoko Akiyama, Kayoko Niinuma, Ryuichiro Nishigaki, Yuichi SugiyamaAbstract:The biliary excretion of Pravastatin in normal rats and Eisai hyperbiliruminemic rats (EHBRs) was examined in vivo and in vitro using bile canalicular membrane vesicles (CMVs). In vivo , the total body clearances at steady-state ( CL tot ) for both rat strains decreased as the infusion rate increased. At the lowest infusion rate, CL tot for normal rats was 1.6 times higher than that for EHBRs. Under this set of conditions, the biliary excretion clearance ( CL bile ), defined as the biliary excretion rate at steady-state divided by the concentration in the liver ( C liver ), for normal rats was 3-fold higher than that for EHBRs. The CL bile fell markedly with increasing C liver for normal rats and the Michaelis constant ( K M ) for C liver was 180 μM; in contrast, the degree of saturation was slight if any in EHBRs. In vitro , the uptake of Pravastatin by CMVs prepared from normal rats exhibited clear ATP-dependence, whereas only a minimal effect of ATP was observed on the uptake by CMVs from EHBRs. Transport kinetic studies were performed over a wide range of Pravastatin concentration (0.2–10,000 μM) with a tracer tritium-labeled Pravastatin. Saturation was observed both in the ATP-dependent ( K M : 220 μM) and ATP-independent ( K M : 480 μM) uptake by CMVs prepared from normal rats. ATP-dependent uptake of 2,4-dinitrophenyl glutathione, a typical substrate for the canalicular multispecific organic anion transporter (cMOAT), was inhibited by Pravastatin in a concentration-dependent manner and the resultant inhibitory constant of Pravastatin (170 μM) was comparable with the K M value of ATP-dependent Pravastatin uptake itself. In conclusion, biliary excretion of Pravastatin is mediated mainly by cMOAT in normal rats. This can explain the decrease in the biliary excretion of Pravastatin in EHBRs.
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biliary excretion of Pravastatin in rats contribution of the excretion pathway mediated by canalicular multispecific organic anion transporter cmoat
Drug Metabolism and Disposition, 1997Co-Authors: Masayo Yamazaki, Sayoko Akiyama, Kayoko Niinuma, Ryuichiro Nishigaki, Yuichi SugiyamaAbstract:The biliary excretion of Pravastatin in normal rats and Eisai hyperbiliruminemic rats (EHBRs) was examined in vivo and in vitro using bile canalicular membrane vesicles (CMVs). In vivo , the total body clearances at steady-state ( CL tot ) for both rat strains decreased as the infusion rate increased. At the lowest infusion rate, CL tot for normal rats was 1.6 times higher than that for EHBRs. Under this set of conditions, the biliary excretion clearance ( CL bile ), defined as the biliary excretion rate at steady-state divided by the concentration in the liver ( C liver ), for normal rats was 3-fold higher than that for EHBRs. The CL bile fell markedly with increasing C liver for normal rats and the Michaelis constant ( K M ) for C liver was 180 μM; in contrast, the degree of saturation was slight if any in EHBRs. In vitro , the uptake of Pravastatin by CMVs prepared from normal rats exhibited clear ATP-dependence, whereas only a minimal effect of ATP was observed on the uptake by CMVs from EHBRs. Transport kinetic studies were performed over a wide range of Pravastatin concentration (0.2–10,000 μM) with a tracer tritium-labeled Pravastatin. Saturation was observed both in the ATP-dependent ( K M : 220 μM) and ATP-independent ( K M : 480 μM) uptake by CMVs prepared from normal rats. ATP-dependent uptake of 2,4-dinitrophenyl glutathione, a typical substrate for the canalicular multispecific organic anion transporter (cMOAT), was inhibited by Pravastatin in a concentration-dependent manner and the resultant inhibitory constant of Pravastatin (170 μM) was comparable with the K M value of ATP-dependent Pravastatin uptake itself. In conclusion, biliary excretion of Pravastatin is mediated mainly by cMOAT in normal rats. This can explain the decrease in the biliary excretion of Pravastatin in EHBRs.
Taro Tokui - One of the best experts on this subject based on the ideXlab platform.
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inhibition of human organic anion transporter 3 mediated Pravastatin transport by gemfibrozil and the metabolites in humans
Xenobiotica, 2007Co-Authors: Rie Nakagomihagihara, Daisuke Nakai, Taro TokuiAbstract:Coadministration of gemfibrozil (600 mg, b.i.d., 3 days) with Pravastatin (40 mg/day) decreased the renal clearance of Pravastatin by approximately 40% in healthy volunteers. To investigate the mechanism of this drug–drug interaction in the renal excretion process, we undertook an uptake study of Pravastatin using human organic anion transporters (hOATs)-expressing S2 cells. hOAT3 and hOAT4 transported Pravastatin in a saturatable manner with Michaelis--Menten constants of 27.7 µM and 257 µM respectively. On the other hand, hOAT1 and hOAT2 did not transport Pravastatin. Gemfibrozil and its glucuronide and carboxylic metabolite forms inhibited the uptake of Pravastatin by hOAT3 with IC50 values of 6.8 µM, 19.7 µM and 5.4 µM, respectively. Considering the plasma concentrations of gemfibrozil and its metabolites in humans, the inhibition of hOAT3-mediated Pravastatin transport by gemfibrozil and its metabolites would lead to a decrease in the renal clearance of Pravastatin in clinical settings.
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Gemfibrozil and its glucuronide inhibit the hepatic uptake of Pravastatin mediated by OATP1B1
Xenobiotica; the fate of foreign compounds in biological systems, 2007Co-Authors: Rie Nakagomi-hagihara, Daisuke Nakai, Taro Tokui, Takaaki Abe, Toshihiko IkedaAbstract:When Pravastatin (40 mg/day) was co-administered with gemfibrozil (600 mg, b.i.d., 3 days) to man, the AUC of Pravastatin increased approximately 2-fold. We have clarified that OATP1B1 is a key determinant of the hepatic uptake of Pravastatin in humans. Thus, we hypothesized that gemfibrozil and the main plasma metabolites, a glucuronide (gem-glu) and a carboxylic acid metabolite (gem-M3), might inhibit the hepatic uptake of Pravastatin and lead to the elevation of the plasma concentration of Pravastatin. Gemfibrozil and gem-glu inhibited the uptake of 14C-Pravastatin by human hepatocytes with Ki values of 31.7 µM and 15.7 µM, respectively and also inhibited Pravastatin uptake by OATP1B1-expressing Xenopus laevis oocytes with Ki values of 15.1 µM and 7.6 µM. Additionally, we examined the biliary transport of Pravastatin and demonstrated that Pravastatin was transported by MRP2 using both human canalicular membrane vesicles (hCMVs) and human MRP2-expressing vesicles. However, gemfibrozil, gem-glu and gem-M...
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na+-independent and reached saturation with a Michaelis constant ( K m) of 11.5 ± 2.2 μM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17β-d-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p -aminohippurate. Estradiol-17β-d-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K m value for estradiol-17β-d-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17β-d-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na+-independent uptake of Pravastatin and estradiol-17β-d-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na(+)-independent and reached saturation with a Michaelis constant (K(m)) of 11.5 +/- 2.2 microM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17beta-D-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p-aminohippurate. Estradiol-17beta-D-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K(m) value for estradiol-17beta-D-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17beta-D-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na(+)-independent uptake of Pravastatin and estradiol-17beta-D-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
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Carrier-mediated uptake of Pravastatin by rat hepatocytes in primary culture
Biochemical pharmacology, 1992Co-Authors: Toru Komai, Taro Tokui, Eiji Shigehara, Teiichiro Koga, Michi Ishigami, Chitose Kuroiwa, Seikoh HoriuchiAbstract:Abstract The transport mechanism of Pravastatin, a new cholesterol-lowering drug, was compared in vitro with rat hepatocyte primary culture and mouse skin fibroblasts (L-cells). The uptake of 14C-labeled Pravastatin by cultured hepatocytes was temperature- and dose-dependent. The temperature-dependent uptake as a function of [14C]Pravastatin concentration showed saturation kinetics with Km = 32.2 μM and a maximal uptake rate of 68 pmol/mg protein/min. The uptake of Pravastatin was inhibited significantly by metabolic inhibitors such as rotenone, oligomycin A, antimycin A, 2, 4-dinitrophenol and KCN. Unlabeled Pravastatin as well as R-416 and R-195, structural analogues of Pravastatin, effectively competed for the hepatic uptake of [14C]Pravastatin at 37°. These results indicate that Pravastatin is taken up by the liver by an active transport. In contrast, the transport of Pravastatin by L-cells was temperature-independent and non-saturable, suggesting that the uptake of Pravastatin by L-cells is mediated by passive diffusion. The marked difference in the uptake mechanism of Pravastatin between hepatocytes and L-cells may account for a unique feature of this drug in that the uptake and inhibition of cholesterol biosynthesis occur selectively in the liver.
Daisuke Nakai - One of the best experts on this subject based on the ideXlab platform.
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inhibition of human organic anion transporter 3 mediated Pravastatin transport by gemfibrozil and the metabolites in humans
Xenobiotica, 2007Co-Authors: Rie Nakagomihagihara, Daisuke Nakai, Taro TokuiAbstract:Coadministration of gemfibrozil (600 mg, b.i.d., 3 days) with Pravastatin (40 mg/day) decreased the renal clearance of Pravastatin by approximately 40% in healthy volunteers. To investigate the mechanism of this drug–drug interaction in the renal excretion process, we undertook an uptake study of Pravastatin using human organic anion transporters (hOATs)-expressing S2 cells. hOAT3 and hOAT4 transported Pravastatin in a saturatable manner with Michaelis--Menten constants of 27.7 µM and 257 µM respectively. On the other hand, hOAT1 and hOAT2 did not transport Pravastatin. Gemfibrozil and its glucuronide and carboxylic metabolite forms inhibited the uptake of Pravastatin by hOAT3 with IC50 values of 6.8 µM, 19.7 µM and 5.4 µM, respectively. Considering the plasma concentrations of gemfibrozil and its metabolites in humans, the inhibition of hOAT3-mediated Pravastatin transport by gemfibrozil and its metabolites would lead to a decrease in the renal clearance of Pravastatin in clinical settings.
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Gemfibrozil and its glucuronide inhibit the hepatic uptake of Pravastatin mediated by OATP1B1
Xenobiotica; the fate of foreign compounds in biological systems, 2007Co-Authors: Rie Nakagomi-hagihara, Daisuke Nakai, Taro Tokui, Takaaki Abe, Toshihiko IkedaAbstract:When Pravastatin (40 mg/day) was co-administered with gemfibrozil (600 mg, b.i.d., 3 days) to man, the AUC of Pravastatin increased approximately 2-fold. We have clarified that OATP1B1 is a key determinant of the hepatic uptake of Pravastatin in humans. Thus, we hypothesized that gemfibrozil and the main plasma metabolites, a glucuronide (gem-glu) and a carboxylic acid metabolite (gem-M3), might inhibit the hepatic uptake of Pravastatin and lead to the elevation of the plasma concentration of Pravastatin. Gemfibrozil and gem-glu inhibited the uptake of 14C-Pravastatin by human hepatocytes with Ki values of 31.7 µM and 15.7 µM, respectively and also inhibited Pravastatin uptake by OATP1B1-expressing Xenopus laevis oocytes with Ki values of 15.1 µM and 7.6 µM. Additionally, we examined the biliary transport of Pravastatin and demonstrated that Pravastatin was transported by MRP2 using both human canalicular membrane vesicles (hCMVs) and human MRP2-expressing vesicles. However, gemfibrozil, gem-glu and gem-M...
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na+-independent and reached saturation with a Michaelis constant ( K m) of 11.5 ± 2.2 μM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17β-d-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p -aminohippurate. Estradiol-17β-d-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K m value for estradiol-17β-d-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17β-d-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na+-independent uptake of Pravastatin and estradiol-17β-d-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na(+)-independent and reached saturation with a Michaelis constant (K(m)) of 11.5 +/- 2.2 microM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17beta-D-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p-aminohippurate. Estradiol-17beta-D-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K(m) value for estradiol-17beta-D-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17beta-D-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na(+)-independent uptake of Pravastatin and estradiol-17beta-D-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
Marie-catherine Vozenin-brotons - One of the best experts on this subject based on the ideXlab platform.
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Pravastatin Inhibits the Rho/CCN2/Extracellular Matrix Cascade in Human Fibrosis Explants and Improves Radiation-Induced Intestinal Fibrosis in Rats
Clinical Cancer Research, 2007Co-Authors: Valerie Haydont, C Bourgier, Marc Pocard, A Lusinchi, Jocelyne Aigueperse, Denis Mathe, Jean Bourhis, Marie-catherine Vozenin-brotonsAbstract:Purposes: Intestinal complications after radiotherapy are caused by transmural fibrosis and impair the quality of life of cancer survivors. Radiation fibrosis was considered permanent and irreversible, but recently, its dynamic nature was shown, providing new opportunities for the development of antifibrotic therapies. Among these new targets, we identified the Rho/ROCK pathway and thought to investigate whether Pravastatin treatment inhibits Rho pathway activation and elicits an antifibrotic action. Experimental Design: Rho and ROCK activities were monitored in human explants presenting radiation fibrosis remodeling after incubation with Pravastatin. Subsequent modulation of CCN2, type I collagen, and fibronectin expression were assessed ex vivo and in intestinal smooth muscle cells derived from radiation enteropathy. Then, the therapeutic relevance of the antifibrotic action of Pravastatin was explored in vivo in a rat model of chronic radiation fibrosis (19 Gy X-rays) treated with 30 mg/kg/d Pravastatin in the drinking water. Results: The results obtained with human explants show that Pravastatin specifically inhibits Rho activity in submucosal mesenchymal cells. Pravastatin also elicits ROCK inhibition, and subsequent CCN2 production in human explants and smooth muscle cells isolated from radiation enteropathy. Inhibition of type I collagen and fibronectin does occur, showing that Pravastatin modulates the secretory phenotype of mesenchymal cells. Lastly, curative Pravastatin administration improves radiation enteropathy in rats. This structural improvement is associated with decreased deposition of CCN2 and subsequent decreased extracellular matrix deposition. Conclusion: Targeting established fibrosis with Pravastatin is an efficient and safe antifibrotic strategy in radiation-induced enteropathy, and is easily transferable into the clinic.
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Pravastatin Inhibits the Rho/CCN2/extracellular matrix cascade in human fibrosis explants and improves radiation-induced intestinal fibrosis in rats.
Clinical cancer research : an official journal of the American Association for Cancer Research, 2007Co-Authors: Valerie Haydont, C Bourgier, Marc Pocard, A Lusinchi, Jocelyne Aigueperse, Denis Mathe, Jean Bourhis, Marie-catherine Vozenin-brotonsAbstract:Intestinal complications after radiotherapy are caused by transmural fibrosis and impair the quality of life of cancer survivors. Radiation fibrosis was considered permanent and irreversible, but recently, its dynamic nature was shown, providing new opportunities for the development of antifibrotic therapies. Among these new targets, we identified the Rho/ROCK pathway and thought to investigate whether Pravastatin treatment inhibits Rho pathway activation and elicits an antifibrotic action. Rho and ROCK activities were monitored in human explants presenting radiation fibrosis remodeling after incubation with Pravastatin. Subsequent modulation of CCN2, type I collagen, and fibronectin expression were assessed ex vivo and in intestinal smooth muscle cells derived from radiation enteropathy. Then, the therapeutic relevance of the antifibrotic action of Pravastatin was explored in vivo in a rat model of chronic radiation fibrosis (19 Gy X-rays) treated with 30 mg/kg/d Pravastatin in the drinking water. The results obtained with human explants show that Pravastatin specifically inhibits Rho activity in submucosal mesenchymal cells. Pravastatin also elicits ROCK inhibition, and subsequent CCN2 production in human explants and smooth muscle cells isolated from radiation enteropathy. Inhibition of type I collagen and fibronectin does occur, showing that Pravastatin modulates the secretory phenotype of mesenchymal cells. Lastly, curative Pravastatin administration improves radiation enteropathy in rats. This structural improvement is associated with decreased deposition of CCN2 and subsequent decreased extracellular matrix deposition. Targeting established fibrosis with Pravastatin is an efficient and safe antifibrotic strategy in radiation-induced enteropathy, and is easily transferable into the clinic.
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Pravastatin inhibits the Rho/CCN2/extracellular matrix cascade in human fibrosis explants and improves radiation-induced intestinal fibrosis in rats
Clinical Cancer Research, 2007Co-Authors: Valerie Haydont, C Bourgier, Marc Pocard, A Lusinchi, Jocelyne Aigueperse, Denis Mathe, Jean Bourhis, Marie-catherine Vozenin-brotonsAbstract:Purposes: Intestinal complications after radiotherapy are caused by transmural fibrosis and impair the quality of life of cancer survivors. Radiation fibrosis was considered permanent and irreversible, but recently, its dynamic nature was shown, providing new opportunities for the development of antifibrotic therapies. Among these new targets, we identified the Rho/ROCK pathway and thought to investigate whether Pravastatin treatment inhibits Rho pathway activation and elicits an antifibrotic action. Experimental Design: Rho and ROCK activities were monitored in human explants presenting radiation fibrosis remodeling after incubation with Pravastatin. Subsequent modulation of CCN2, type I collagen, and fibronectin expression were assessed ex vivo and in intestinal smooth muscle cells derived from radiation enteropathy. Then, the therapeutic relevance of the antifibrotic action of Pravastatin was explored in vivo in a rat model of chronic radiation fibrosis (19 Gy X-rays) treated with 30 mg/kg/d Pravastatin in the drinking water. Results: The results obtained with human explants show that Pravastatin specifically inhibits Rho activity in submucosal mesenchymal cells. Pravastatin also elicits ROCK inhibition, and subsequent CCN2 production in human explants and smooth muscle cells isolated from radiation enteropathy. Inhibition of type I collagen and fibronectin does occur, showing that Pravastatin modulates the secretory phenotype of mesenchymal cells. Lastly, curative Pravastatin administration improves radiation enteropathy in rats. This structural improvement is associated with decreased deposition of CCN2 and subsequent decreased extracellular matrix deposition. Conclusion: Targeting established fibrosis with Pravastatin is an efficient and safe antifibrotic strategy in radiation-induced enteropathy, and is easily transferable into the clinic. © 2007 American Association for Cancer Research.
Kenji Nishimura - One of the best experts on this subject based on the ideXlab platform.
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na+-independent and reached saturation with a Michaelis constant ( K m) of 11.5 ± 2.2 μM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17β-d-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p -aminohippurate. Estradiol-17β-d-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K m value for estradiol-17β-d-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17β-d-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na+-independent uptake of Pravastatin and estradiol-17β-d-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
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human liver specific organic anion transporter lst 1 mediates uptake of Pravastatin by human hepatocytes
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Daisuke Nakai, Rie Nakagomi, Yoshitake Furuta, Taro Tokui, Takaaki Abe, Toshihiko Ikeda, Kenji NishimuraAbstract:Involvement of LST-1 (a human liver-specific transporter, also called OATP2) as the major transporter in the uptake of Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, by human liver was demonstrated. The hepatic uptake of Pravastatin evaluated using human hepatocytes was Na(+)-independent and reached saturation with a Michaelis constant (K(m)) of 11.5 +/- 2.2 microM. The uptake of Pravastatin was temperature-dependent and was inhibited by estradiol-17beta-D-glucuronide, taurocholic acid, bromosulfophthalein, and simvastatin acid, but not by p-aminohippurate. Estradiol-17beta-D-glucuronide competitively inhibited Pravastatin uptake with an inhibition constant comparable to the K(m) value for estradiol-17beta-D-glucuronide transport, indicating that a common transporter mediates the transport of Pravastatin and estradiol-17beta-D-glucuronide in human hepatocytes. The results obtained with human hepatocytes agreed with those obtained with LST-1 expressing Xenopus oocytes. Oocytes microinjected with human liver polyadenylated mRNA showed Na(+)-independent uptake of Pravastatin and estradiol-17beta-D-glucuronide. A simultaneous injection of LST-1 antisense oligonucleotides completely abolished this uptake. Expression of LST-1 was immunohistochemically demonstrated in the human hepatocytes, but not in Hep G2 cells, which showed very low uptake of Pravastatin. Therefore, LST-1 was regarded as a key molecule for Pravastatin in liver-specific inhibition of cholesterol synthesis, making Pravastatin accessible to the target enzyme, which would otherwise not be inhibited by this hydrophilic drug.
