ABSTRACT
The authors report the case of a 74-years-old woman treated by immunotherapy for a metastatic renal cell carcinoma and having developed an important cholestasis with thrombocytosis, increased CRP, leucocytosis and hypoalbuminemia. Liver remained free of metastases at medical imaging. The diagnosis of a Stauffer syndrome was confirmed by the hepatic biopsy. A complete response of liver disorders was obtained after nephrectomy. From literature survey, Stauffer syndrome should be kept in mind in cancer patients, especially those suffering from a renal cell carcinoma, presenting with cholestasis with no underlying cause.
Subject(s)
Carcinoma, Renal Cell , Cholestasis , Kidney Neoplasms , Liver Diseases , Female , Humans , Aged , Carcinoma, Renal Cell/complications , Carcinoma, Renal Cell/diagnosis , Kidney Neoplasms/complications , Kidney Neoplasms/diagnosis , Kidney Neoplasms/pathology , Syndrome , Liver Diseases/diagnosis , Cholestasis/complicationsABSTRACT
BACKGROUND: Late recurrences in postmenopausal women with hormone receptor-positive breast cancers remain an important challenge. Avoidance or delayed development of resistance represents the main objective in extended endocrine therapy (ET). In animal models, resistance was reversed with restoration of circulating estrogen levels during interruption of letrozole treatment. This phase III, randomized, open-label Study of Letrozole Extension (SOLE) studied the effect of extended intermittent letrozole treatment in comparison with continuous letrozole. In parallel, the SOLE estrogen substudy (SOLE-EST) analyzed the levels of estrogen during the interruption of treatment. PATIENTS AND METHODS: SOLE enrolled 4884 postmenopausal women with hormone receptor-positive, lymph node-positive, operable breast cancer between December 2007 and October 2012 and among them, 104 patients were enrolled in SOLE-EST. They must have undergone local treatment and have completed 4-6 years of adjuvant ET. Patients were randomized between continuous letrozole (2.5 mg/day orally for 5 years) and intermittent letrozole treatment (2.5 mg/day for 9 months followed by a 3-month interruption in years 1-4 and then 2.5 mg/day during all of year 5). RESULTS: Intention-to-treat population included 4851 women in SOLE (n = 2425 in the intermittent and n = 2426 in the continuous letrozole groups) and 103 women in SOLE-EST (n = 78 in the intermittent and n = 25 in the continuous letrozole groups). After a median follow-up of 84 months, 7-year disease-free survival (DFS) was 81.4% in the intermittent group and 81.5% in the continuous group (hazard ratio: 1.03, 95% confidence interval: 0.91-1.17). Reported adverse events were similar in both groups. Circulating estrogen recovery was demonstrated within 6 weeks after the stop of letrozole treatment. CONCLUSIONS: Extended adjuvant ET by intermittent administration of letrozole did not improve DFS compared with continuous use, despite the recovery of circulating estrogen levels. The similar DFS coupled with previously reported quality-of-life advantages suggest intermittent extended treatment is a valid option for patients who require or prefer a treatment interruption.
Subject(s)
Breast Neoplasms , Aromatase Inhibitors/therapeutic use , Breast Neoplasms/drug therapy , Chemotherapy, Adjuvant , Disease-Free Survival , Estrogens , Female , Humans , Letrozole , Nitriles/therapeutic use , Postmenopause , Receptors, Estrogen , Receptors, Progesterone , Tamoxifen/therapeutic use , Triazoles/therapeutic useABSTRACT
A young patient consulted in our physical and rehabilitation medicine department following the onset of pain on the scapula area and at the base of his right upper limb after carrying a heavy load. After a couple of weeks, the patient also developed cervical pain. Fortuitously, the cervical scanner displayed a right C6 spondylolysis. Further evaluation by bone scan confirmed that this lesion was not recent and so probably not the cause of the symptoms. Cervical isthmic spondylolysis is a rare condition, much more common at the lumbar level and often ignored at the cervical one. The etiology, pahophysiology, imaging and treatment options for this cervical pathology are discussed in this article.
Un jeune patient a consulté en médecine physique pour des douleurs aux niveaux de l'omoplate et de la racine du membre supérieur droit apparues suite au port d'une charge lourde. Après quelques semaines, le patient se plaignait également de cervicalgies. Un scanner du rachis cervical a objectivé fortuitement une spondylolyse C6 droite. Un bilan complémentaire par scintigraphie osseuse a révélé que la lésion était ancienne et qu'elle n'était probablement pas la cause de la symptomatologie. La lyse isthmique cervicale est une pathologie peu répandue. Très connue à l'étage lombaire, la spondylolyse est rare et souvent ignorée au niveau cervical. L'étiologie, la physiopathologie, l'imagerie et la prise en charge de cette pathologie cervicale sont discutées dans cet article.
Subject(s)
Spondylolysis , Tomography, X-Ray Computed , Humans , Lumbar Vertebrae , Neck , Spondylolysis/diagnostic imagingABSTRACT
Recent studies have revealed that particulate matter (PM) exert deleterious effects on vascular function. Pulmonary artery endothelial cells (HPAEC), which are involved in the vasomotricity regulation, can be a direct target of inhaled particles. Modifications in calcium homeostasis and oxidative stress are critical events involved in the physiopathology of vascular diseases. The objectives of this study were to assess the effects of PM2.5 on oxidative stress and calcium signaling in HPAEC. Different endpoints were studied, (i) intrinsic and intracellular production of reactive oxygen species (ROS) by the H2DCF-DA probe, (ii) intrinsic, intracellular and mitochondrial production of superoxide anion (O2-) by electronic paramagnetic resonance spectroscopy and MitoSOX probe, (iii) reactive nitrosative species (RNS) production by Griess reaction, and (vi) calcium signaling by the Fluo-4 probe. In acellular conditions, PM2.5 leads to an intrinsic free radical production (ROS, O2-) and a 4h-exposure to PM2.5 (5-15µg/cm2), induced, in HPAEC, an increase of RNS, of global ROS and of cytoplasmic and mitochondrial O2- levels. The basal intracellular calcium ion level [Ca2+]i was also increased after 4h-exposure to PM2.5 and a pre-treatment with superoxide dismutase and catalase significantly reduced this response. This study provides evidence that the alteration of intracellular calcium homeostasis induced by PM2.5 is closely correlated to an increase of oxidative stress.
Subject(s)
Air Pollutants/toxicity , Calcium Signaling/drug effects , Endothelial Cells/drug effects , Oxidative Stress/drug effects , Particulate Matter/toxicity , Pulmonary Artery/cytology , Adult , Antioxidants/pharmacology , Calcium/metabolism , Cell Survival/drug effects , Humans , Male , Pulmonary Artery/drug effects , Reactive Nitrogen Species/metabolism , Reactive Oxygen Species/metabolism , Superoxides/metabolismABSTRACT
We report the case of a 57-year old man suffering from acute abdominal cramps. Abdominal computed tomography (CT) scanner revealed an isolated dissection of the superior mesenteric artery. The pain decreased within a few days under conservative treatment and monitoring by angioscans showed a stabilization of the dissection. This clinical case report is accompanied by a literature review on this rare pathology.
Ce cas clinique est celui d'un patient de 57 ans souffrant de douleurs abdominales aiguës. La tomodensitométrie abdominale a permis de mettre en évidence une dissection isolée de l'artère mésentérique supérieure. Les douleurs abdominales ont fortement régressé en quelques jours sous traitement conservateur et les angioscanners de suivi ont montré une stabilisation de la dissection. Ce cas clinique permet une revue de la littérature concernant cette pathologie rare.
Subject(s)
Aortic Dissection/diagnostic imaging , Mesenteric Artery, Superior/diagnostic imaging , Abdominal Pain/etiology , Humans , Male , Middle Aged , Tomography, X-Ray ComputedABSTRACT
Postoperative development or worsening of obstructive sleep apnea is a potential complication of anesthesia. The objective of this study was to study the effects of a premedication with alprazolam on the occurrence of apneas during the immediate postoperative period. Fifty ASA 1 - 2 patients undergoing a colonoscopy were recruited. Patients with a history of obstructive sleep apnea (OSA) were excluded. Recruited patients were randomly assigned to one of two groups: in Group A, they received 0.5 mg of alprazolam orally one hour before the procedure; and in Group C, they received placebo. Anesthesia technique was identical in both groups. Patients were monitored during the first two postoperative hours to establish their AHI (apnea hypopnea index, the number of apneas and hypopneas per hour). Nine patients were excluded (4 in group A and 5 in group C) due to technical problems or refusal. Interestingly, premedication by alprazolam did not change intra-operative propofol requirements. During the first two postoperative hours, the AHI was significantly higher in group A than in group C (Group A: 20.33 ± 10.97 h-1, C: 9.63 ± 4.67 h-1). These apneas did not induce significant arterial oxygen desaturation, or mandibular instability. Our study demonstrates that a premedication with 0.5 mg of alprazolam doesn't modify intra-operative anesthetic requirements during colonoscopy, but is associated with a higher rate of obstructive apneas during at least three and a half hours after ingestion. No severe side effects were observed in our non-obese population. Our results must be confirmed on a larger scale.
Subject(s)
Alprazolam/administration & dosage , Hypnotics and Sedatives/administration & dosage , Sleep Apnea, Obstructive/chemically induced , Adult , Aged , Alprazolam/therapeutic use , Analgesics/therapeutic use , Anesthetics, Intravenous/therapeutic use , Colonoscopy , Double-Blind Method , Drug Administration Schedule , Female , Humans , Hypnotics and Sedatives/therapeutic use , Ketamine/therapeutic use , Male , Middle Aged , Propofol/therapeutic useABSTRACT
Rupture of abdominal aortic aneurysm (AAA) remains a major cause of death in the elderly. Its prediction is a serious challenge for public health. Despite its regular use to identify patients requiring surgical treatment, the diameter of AAA is not a sufficiently precise and reliable parameter for discriminating aneurysms at high risk of rupture. A better targeting of high risk patients needs understanding in deep the processes and mechanisms directing wall rupture. Inflammation is a significant element in the progression ofAAA and can be visualized using medical imaging techniques such as positron emission tomography (PET) using a glucose derivative (FDG) as radiotracer. Studies conducted in our department have established a relationship between PET positivity and the presence of symptoms such as accelerated growth of the aneurysm or pain, signs generally considered as predictive of rupture. Moreover, activation of leukocytes coupled to cellular and molecular alterations of the aneurysmal wall in the sites of FDG uptake may lead to its instability and incompetence to resist blood pressure and rupture. PET therefore represents a new original exploration method to characterize the severity of AAA progression allowing to assess the need for a surgical treatment much better than does the AAA diameter.
Subject(s)
Aortic Aneurysm, Abdominal/diagnostic imaging , Positron-Emission Tomography , Aortic Aneurysm, Abdominal/diagnosis , Humans , PrognosisABSTRACT
A case of ulnar artery aneurysm in an independent roofer is reported. It is a rare disease often associated with the Hammer Hypothenar Syndrome specifically found in manual workers and athletes exposed to repetitive palmar trauma.
Subject(s)
Aneurysm/diagnosis , Thrombosis/diagnosis , Ulnar Artery/surgery , Adult , Aneurysm/surgery , Construction Industry , Humans , Male , Paresthesia/etiology , Radiography , Thrombosis/surgery , Ulnar Artery/diagnostic imaging , UltrasonographyABSTRACT
We report a rare case of single cervical metastasis of breast cancer. Bone metastases are the most frequent in breast cancer. Early diagnosis combined with the new therapeutic advances have considerably improved the quality of life and increased the survival. Imaging plays a great role in the diagnosis, particularly scintigraphy and radiography, but sometimes also CT and MRI. The treatment is currently not standardized and it combines hormone therapy, chemotherapy, radiotherapy, and/or surgery.
Subject(s)
Breast Neoplasms/pathology , Cervical Vertebrae/pathology , Spinal Neoplasms/secondary , Back Pain/etiology , Female , Humans , Middle Aged , Spinal Neoplasms/diagnosisABSTRACT
The multidrug resistance-associated protein 2 (MRP2) is an ATP-binding cassette transporter involved in biliary, renal, and intestinal secretion of numerous organic anions, including endogenous compounds such as bilirubin and exogenous compounds such as drugs and toxic chemicals. Its expression can be modulated in various physiopathological situations, notably being markedly decreased during liver cholestasis and upregulated in some cancerous tissues. In addition, MRP2 levels are altered in hepatocytes in response to hormones such as glucocorticoids and to structurally unrelated drugs such as rifampicin, phenobarbital, ritonavir, and cisplatin. The chemical carcinogen 2-acetylaminofluorene and chemopreventive agents such as oltipraz and sulforaphane also markedly increased MRP2 expression in liver parenchymal cells. Interestingly, most of the chemical inducers of MRP2 act on drug-metabolizing enzymes, indicating a coordinated regulation of these detoxifying proteins; cellular mechanisms involved are, at least partly, common and may be related to nuclear hormone receptors such as the pregnane X receptor. Owing to the major role played by MRP2 in elimination of drugs and endogenous compounds, modulation of its expression may lead to adverse effects or to changes in drug pharmacokinetics.
Subject(s)
Gene Expression Regulation , Membrane Transport Proteins , Multidrug Resistance-Associated Proteins/biosynthesis , Animals , Carcinogens/pharmacology , Cell Membrane/metabolism , Cholestasis/metabolism , Glucocorticoids/pharmacology , Hormones/metabolism , Humans , Liver/cytology , Liver/drug effects , Multidrug Resistance-Associated Protein 2 , Multidrug Resistance-Associated Proteins/genetics , Pregnane X Receptor , RNA, Messenger/metabolism , Rats , Receptors, Cytoplasmic and Nuclear/metabolism , Receptors, Steroid/metabolism , Transcription, Genetic , Xenobiotics/pharmacologyABSTRACT
FDG-PET (18-fluoro-desoxyglucose positron emission tomography) is a fonctionnal imaging method based on the high rate of glycolysis in different types of cancer-cells. We report the first five cases where FDG-PET was used in France for head and neck cancers. The results were analyzed on the basis of data reported to date in the literature, leading to a proposal for rational use of this diagnostic available in only a few centers in France. For primary assessment of cervicofacial carcinomas, different imaging techniques such as CT and MRI have improved tumor staging. Although 18-FDG-PET cannot replace these techniques used to monitor size and structural changes in tumors and lymph nodes, it will be helpful in following their metabolic activity. This diagnostic tool consequently is greatly helpful for detection and post-therapeutic evaluation of head and neck carcinomas and their recurrence. 18-FDG-PET is currently under evaluation as a tool for detecting cervical lymph nodes and early assessment of response to chemotherapy.
Subject(s)
Head and Neck Neoplasms/diagnostic imaging , Tomography, Emission-Computed , Fluorodeoxyglucose F18 , Humans , Laryngeal Neoplasms/diagnostic imaging , Lymphatic Metastasis/diagnostic imaging , Male , Neoplasm Recurrence, Local/diagnostic imaging , Neoplasms, Unknown Primary/diagnostic imaging , Pharyngeal Neoplasms/diagnostic imaging , Prognosis , RadiopharmaceuticalsABSTRACT
Biliary elimination of endogenous compounds and xenobiotics usually requires carrier-mediated systems allowing movement across the canalicular membrane of hepatocytes. The major systems implicated belong to the ATP binding cassette transporter family: P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2), principally mediate the passage into the bile of cationic and anionic compounds, respectively, whereas the bile salt export pump (BSEP) handles biliary acids and also some anticancer drugs. Expression of these canalicular proteins can be altered in response to various hormones and structurally unrelated xenobiotics. Indeed, glucocorticoids up-regulate expression of both MRP2 and BSEP in rat hepatocytes, whereas insulin induces P-gp. P-gp expression is also up-regulated by numerous chemical carcinogens, such as polycyclic aromatic hydrocarbons and 2-acetylaminofluorene and by some anticancer drugs, such as anthracyclins. 2-Acetylaminofluorene also induces MRP2; in addition, expression of this transporter in liver cells is increased in response to various drugs, such as the barbiturate phenobarbital, the chemopreventive agent, oltipraz and the anticancer drug, cisplatin. Most of the chemical inducers acting on canalicular transporter levels are well-known to up-regulate some hepatic drug metabolizing enzymes, suggesting a coordinate regulation of liver detoxifying proteins in response to these compounds.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/biosynthesis , ATP-Binding Cassette Transporters/biosynthesis , Carrier Proteins/biosynthesis , Hormones/physiology , Membrane Transport Proteins , Multidrug Resistance-Associated Proteins , Xenobiotics/pharmacology , ATP Binding Cassette Transporter, Subfamily B/biosynthesis , ATP Binding Cassette Transporter, Subfamily B/genetics , ATP Binding Cassette Transporter, Subfamily B/metabolism , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , ATP Binding Cassette Transporter, Subfamily B, Member 11 , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Animals , Anion Transport Proteins , Carrier Proteins/genetics , Carrier Proteins/metabolism , Gene Expression Regulation/drug effects , Glucocorticoids/physiology , Humans , Insulin/physiology , Multidrug Resistance-Associated Protein 2 , Up-Regulation/physiologySubject(s)
Carotid Artery, Internal, Dissection/diagnosis , Hypoglossal Nerve Diseases/etiology , Magnetic Resonance Imaging , Adult , Aged , Carotid Artery, Internal/diagnostic imaging , Carotid Artery, Internal/pathology , Carotid Artery, Internal, Dissection/complications , Cerebral Angiography , Humans , Hypoglossal Nerve Diseases/diagnosis , Male , Middle Aged , Ultrasonography, DopplerABSTRACT
Expression of multidrug resistance-associated protein 2 (MRP2), an efflux pump contributing to biliary secretion of xenobiotics, was investigated in primary rat and human hepatocytes exposed to sulforaphane, a naturally-occurring chemopreventive agent. Northern blot indicated that sulforaphane increased MRP2 mRNA levels in primary rat hepatocytes; it also induced expression of drug metabolizing enzymes such as glutathione S-transferase A1/2 isoforms and NAD(P)H:quinone oxidoreductase in a dose-response and time-course manner similar to that observed for the upregulation of MRP2 transcripts. This sulforaphane-related increase of MRP2 mRNAs paralleled increased expression of 190 kD MRP2 protein as assessed by Western blotting; it was fully abolished by the transcription inhibitor actinomycin D. MRP2 induction was associated with increased cellular production of reactive oxygen species (ROS) and addition of dimethyl sulfoxide, that reduced sulforaphane-related formation of ROS, and also decreased MRP2 mRNA levels in sulforaphane-treated primary rat hepatocytes; this suggests that sulforaphane-mediated production of ROS may contribute to MRP2 induction. This link between ROS and MRP2 regulation was further supported by the increase of MRP2 expression occurring in response to t-butylhydroquinone, known to regulate drug metabolizing enzymes through ROS formation. In addition to rat cells, primary human hepatocytes exposed to sulforaphane also displayed induced MRP2 expression evidenced at both mRNA and protein levels. All these observations strongly support the conclusion that the export pump MRP2 can be classified among the detoxifying proteins that are regulated by sulforaphane and that are thought to contribute, at least in part, to its anticarcinogenic properties.
Subject(s)
Hepatocytes/drug effects , Mitochondrial Proteins , Reactive Oxygen Species , Ribosomal Proteins/metabolism , Saccharomyces cerevisiae Proteins , Thiocyanates/pharmacology , Animals , Glutathione Transferase/genetics , Glutathione Transferase/metabolism , Hepatocytes/metabolism , Isothiocyanates , Male , RNA, Messenger/genetics , Rats , Rats, Sprague-Dawley , Ribosomal Proteins/genetics , SulfoxidesABSTRACT
1. Glibenclamide, a sulphonylurea widely used for the treatment of non-insulin-dependent diabetes mellitus, has been shown to inhibit the activities of various ATP-binding cassette (ABC) transporters. In the present study, its effects towards multidrug resistance protein 1 (MRP1), an ABC efflux pump conferring multidrug resistance and handling organic anions, were investigated. 2. Intracellular accumulation of calcein, an anionic dye substrate for MRP1, was strongly increased by glibenclamide in a dose-dependent manner in MRP1-overexpressing lung tumour GLC4/Sb30 cells through inhibition of MRP1-related calcein efflux. By contrast, glibenclamide did not alter calcein levels in parental control GLC4 cells. Another sulphonylurea, tolbutamide, was however without effect on calcein accumulation in both GLC4/Sb30 and GLC4 cells. 3. Glibenclamide used at 12.5 microM was, moreover, found to strongly enhance the sensitivity of GLC4/Sb30 cells towards vincristine, an anticancer drug handled by MRP1. 4. Efflux of carboxy-2',7'-dichlorofluorescein, an anionic dye handled by the ABC transporter MRP2 sharing numerous substrates with MRP1 and expressed at high levels in liver, was also strongly inhibited by glibenclamide in isolated rat hepatocytes. 5. In summary, glibenclamide reversed MRP1-mediated drug resistance likely through inhibiting MRP1 activity and blocked organic anion efflux from MRP2-expressing hepatocytes. Such effects associated with the known inhibitory properties of glibenclamide towards various others ABC proteins suggest that this sulphonylurea is a general inhibitor of ABC transporters.
Subject(s)
ATP-Binding Cassette Transporters/antagonists & inhibitors , Glyburide/pharmacology , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , Analysis of Variance , Antineoplastic Agents, Phytogenic/pharmacology , Cell Survival , Drug Interactions , Drug Screening Assays, Antitumor , Humans , Hypoglycemic Agents/pharmacology , Lung Neoplasms/pathology , Multidrug Resistance-Associated Proteins , Tumor Cells, Cultured , Vincristine/pharmacologyABSTRACT
Oltipraz (OPZ) is a potent chemopreventive agent against chemically-induced carcinogenesis in several animal models. It affects the expression and/or activity of xenobiotic-metabolizing enzymes and its effects are altered in the course of inflammation in liver. The present study was undertaken to analyse the effect of OPZ alone or in combination with Escherichia coli lipopolysaccharide (LPS) on the expression and activities of glutathione S-transferases (GSTs) and cytochrome P450 (CYPs) in rat lung and kidney. Male Wistar rats were fed a diet containing OPZ for 1-5 days. LPS was injected 24 h before the end of OPZ treatment (from 48 to 72 h). Total GST activity, measured using 1-chloro-2,4-dinitrobenzene as a substrate, increased slightly in both lung and kidney during OPZ treatment. As previously demonstrated in the liver, OPZ induced rat GSTP1 in both kidney and lung and this effect was totally (kidney) or partially (lung) inhibited by co-treatment with LPS. CYP1A expression and activity were strongly increased in both tissues 24 h after starting OPZ treatment and maintained for 5 days. This increase was suppressed during the acute-phase response to endotoxin. OPZ has no effect on CYP2B1 mRNA expression in the lung, but it dramatically decreased the amount and activity of the corresponding apoprotein. The OPZ-dependent decrease in the CYP2B1 apoprotein was abolished and its corresponding activity partially reversed during LPS treatment. In reconstitution experiments using cytosol from OPZ-treated or control rat lungs and microsomal fractions, CYP2B1 apoprotein was rapidly degraded in the presence of cytosol from treated rats. This effect was partially reversed in the presence of MG132, a proteasome inhibitor. These observations support the conclusion that the decrease of CYP2B1 by OPZ involves proteasome-dependent degradation and represents a new mechanism of regulation by this compound.
Subject(s)
Anticarcinogenic Agents/pharmacology , Aryl Hydrocarbon Hydroxylases , Cytochrome P-450 CYP1A1/metabolism , Cytochrome P-450 Enzyme System/metabolism , Lung/drug effects , Oxidoreductases, N-Demethylating/metabolism , Proteasome Endopeptidase Complex , Pyrazines/pharmacology , Animals , Cytochrome P-450 CYP1A1/biosynthesis , Cytochrome P-450 CYP1A1/genetics , Cytochrome P-450 CYP2B1/biosynthesis , Cytochrome P-450 CYP2B1/genetics , Cytochrome P-450 CYP2B1/metabolism , Cytochrome P-450 CYP2B6 , Cytochrome P-450 Enzyme System/biosynthesis , Cytochrome P-450 Enzyme System/genetics , Cytosol/enzymology , Glutathione Transferase/biosynthesis , Glutathione Transferase/genetics , Glutathione Transferase/metabolism , Isoenzymes/biosynthesis , Isoenzymes/genetics , Isoenzymes/metabolism , Kidney/drug effects , Kidney/enzymology , Lipopolysaccharides/pharmacology , Lung/enzymology , Male , Oxidoreductases, N-Demethylating/biosynthesis , Oxidoreductases, N-Demethylating/genetics , Peptide Hydrolases/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Rats, Wistar , Thiones , ThiophenesABSTRACT
Rat liver epithelial cells resistant to the chemical carcinogen 3MC, termed F258/3MC cells and generated by long-term exposure of parental F258 cells to the PAH, were characterized, especially with respect to expression of multidrug resistance transporters such as P-glycoprotein, MRP1 and MRP2. F258/3MC cells were found to be cross-resistant to other PAHs such as BP and dimethylbenz(a)anthracene but remained sensitive to known substrates of multidrug resistance efflux pumps such as doxorubicin and vincristine. They did not display either decreased cellular PAH accumulation or increased PAH efflux. In addition, P-glycoprotein and MRP2 mRNA levels were not, or only barely detected, in F258/3MC cells and in their parental counterparts whereas these PAH-resistant and sensitive cells showed closed levels of MRP1 mRNAs and activity. Moreover, P-gp- and MRP1-overexpressing cells were shown to display similar accumulation and efflux of BP than those found in P-gp- and MRP1-negative control cells. These data therefore suggest that multidrug resistance transporters do not contribute to PAH resistance in PAH-selected liver cells.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Carcinogens/toxicity , Hepatocytes/metabolism , Membrane Transport Proteins , Polycyclic Aromatic Hydrocarbons/toxicity , 9,10-Dimethyl-1,2-benzanthracene/toxicity , ATP Binding Cassette Transporter, Subfamily B/genetics , ATP Binding Cassette Transporter, Subfamily B/metabolism , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Animals , Benzopyrenes/toxicity , Cells, Cultured , Cytochrome P-450 CYP1A1/biosynthesis , Cytochrome P-450 CYP1A1/genetics , DNA Adducts/analysis , DNA Adducts/drug effects , Doxorubicin/pharmacology , Drug Resistance, Multiple , Hepatocytes/cytology , Hepatocytes/drug effects , Methylcholanthrene/toxicity , Multidrug Resistance-Associated Protein 2 , Multidrug Resistance-Associated Proteins , RNA, Messenger/metabolism , Rats , Up-Regulation , Vincristine/pharmacologyABSTRACT
Organic anion secretion by human hepatocytes was characterized using primary liver parenchymal cell cultures and the anionic fluorescent dye carboxy-2',7'-dichlorofluorescein (CF). Probenecid, a well-known common blocker of the membrane transport process for anions, was shown to increase CF accumulation in primary human hepatocytes by inhibiting cellular CF efflux in a dose-dependent manner, thereby establishing the presence of an efflux system for organic anions in cultured hepatocytes. Outwardly directed transport of CF from hepatocytes was found to be temperature-dependent; it was not altered by changes in the ionic composition of the incubation medium used in efflux experiments. In addition to probenecid, various structurally and functionally unrelated xenobiotics such as glibenclamide, rifampicin, vinblastine, MK-571, indomethacin, and cyclosporin A were shown to inhibit secretion of CF by primary human hepatocytes, thus suggesting that organic anion excretion by human liver may be impaired by various drugs. Northern blot and Western blot analyses of the expression of multidrug resistance proteins (MRP), such as MRP1 and MRP2, which are known to mediate cellular outwardly directed transport of organic anions indicated that MRP2 was present at substantial levels in cultured human hepatocytes as well as in their in vivo counterparts, whereas MRP1 expression was only barely detectable. These results therefore suggest that MRP2, unlike MRP1, may contribute to the organic anion efflux system displayed by primary human hepatocytes and inhibited by a wide range of xenobiotics.
Subject(s)
Fluoresceins/metabolism , Hepatocytes/drug effects , Xenobiotics/pharmacology , Anion Transport Proteins , Anions/metabolism , Biological Transport/drug effects , Carrier Proteins/metabolism , Cells, Cultured , Hepatocytes/metabolism , HumansABSTRACT
Transport across hepatocyte plasma membranes is a key parameter in hepatic clearance and usually occurs through different carrier-mediated systems. Sinusoidal uptake of compounds is thus mediated by distinct transporters, such as Na(+)-dependent or Na(+)-independent anionic transporters and by some cationic transporters. Similarly, several membrane proteins located at the apical pole of hepatocytes have been incriminated in the excretion of compounds into the bile. Indeed, biliary elimination of anionic compounds, including glutathione S-conjugates, is mediated by MRP2, whereas bile salts are excreted by a bile salt export pump (BSEP) and Class I-P-glycoprotein (P-gp) is involved in the secretion of amphiphilic cationic drugs, whereas class II-P-gp is a phospholipid transporter. The expression of hepatic transporters and their activity are regulated in various situations, such as ontogenesis, carcinogenesis, cholestasis, cellular stress and after treatment by hormones and xenobiotics. Moreover, a direct correlation between a defect and the absence of transporter with hepatic disease has been demonstrated for BSEP, MDR3-P-gp and MRP2.
Subject(s)
Bile Acids and Salts/metabolism , Carrier Proteins/metabolism , Hydroxysteroid Dehydrogenases , Liver/metabolism , Membrane Glycoproteins , Animals , Carrier Proteins/biosynthesis , Humans , Liver Neoplasms/metabolismABSTRACT
Expression of the canalicular multispecific organic anion transporter (cMOAT), an efflux pump involved in biliary secretion of xenobiotics, was investigated in rat hepatocytes exposed to the chemopreventive agent oltipraz. Northern blotting indicated that this compound increased cMOAT mRNA levels in primary cultured hepatocytes. Such an induction of cMOAT transcripts was demonstrated to be dose-dependent and started as early as 4 h treatment; in addition, western blotting showed increased levels of 190 kDa cMOAT in oltipraz-treated primary rat hepatocytes when compared with their untreated counterparts. In contrast, administration of oltipraz to rats failed to enhance hepatic cMOAT mRNA and protein amounts whereas it was found to induce liver expression of glutathione S-transferase P1, a well-known oltipraz-regulated drug metabolizing enzyme. These data therefore suggest that cMOAT up-regulation occurring in rat hepatocytes in response to oltipraz may be restricted to in vitro situations and is therefore unlikely to be directly involved in the in vivo chemopreventive properties of oltipraz.