BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK...BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.展开更多
AIM： To study the expression and phosphorylation of extracellular signal-regulated kinase （ERK） i and ERK2 in multidrug resistant （MDR） hepatocellular carcinoma （HCC） cells.METHODS： MDR HCC cell lines, HepG2/a...AIM： To study the expression and phosphorylation of extracellular signal-regulated kinase （ERK） i and ERK2 in multidrug resistant （MDR） hepatocellular carcinoma （HCC） cells.METHODS： MDR HCC cell lines, HepG2/adriamycin （ADM） and SMMC7721/ADM, were developed by exposing parental cells to stepwise increasing concentrations of ADM. MTT assay was used to determine drug sensitivity. Flow cytometry was employed to analyze cell cycle distribution and measure cell P-glycoprotein （P-gp） and multidrug resistant protein 1 （MRP1） expression levels. ERK1 and ERK2 mRNA expression lev-ls were measured by quantitative real-time PCR （QRTPCR）. Expression and phosphorylation of ERK1 and ERK2 were analyzed by Western blot.RESULTS： MTT assay showed that HepG2/ADM andSMMC7721/ADM were resistant not only to ADM, but also to multiple anticancer drugs. The P-gp expression was over 10-fold higher in HepG2/ADM cells than in HepG2 cells （8.92% ±0.22% vs 0.88% ± 0.05%, P 〈 0.001） and over 4-fold higher in SMMC7721/ADM cells than in SMMC7721 cells （7.37% ± 0.26% vs 1.74% ± 0.25%, P 〈 0.001）. However, the MRP1 expression was not significantly higher in HepG2/ADM and SMMC7721/ADM cells than in parental cells. In addition, the percentage of MDR HepG2/ADM and SMMC7721/ADM cells was significantly decreased in the G0/G1 phase and increased in the the S phase or G2/M phase. QRT-PCR analysis demonstrated that the ERK1 and ERK2 mRNA expression increased apparently in HepG2/ADM cells and decreased significantly in SMMC7721/ADM cells. Compared with the expression of parental cells, ERK1 and ERK2 protein expressions were markedly decreased in SMMC7721/ADM cells. However, ERK2 protein expression was markedly increased while ERK1 protein expression had no significant change in HepG2/ADM cells. Phosphorylation of ERK1 and ERK2 was markedly decreased in both HepG2/ADM and SMMC7721/ADM MDR cells.CONCLUSION： ERK1 and ERK2 activities are downregulated in P-gp-mediated MDR HCC cells. ERK1 or ERK2 might be a potential drug target for circumventing MDR HCC cells,展开更多
AIM： To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein （PGP） and p53 protein in advanced hepatocellular carcinoma （HCC）. METHODS： The study was condu...AIM： To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein （PGP） and p53 protein in advanced hepatocellular carcinoma （HCC）. METHODS： The study was conducted on 41 patients with advanced HCC who were treated by repeated arterial infusion chemotherapy. Biopsy specimens from the tumor were collected before the start of treatment in all the patients, and the specimens were stored frozen until immunohistochemical staining, which was performed after the start of treatment, to detect PGP and p53 protein expressions. Twenty of the fortyone patients were treated with an anthracycline drug （epirubicin hydrochloride; anthracycline group）, and the remaining 21 were treated with a non-anthracycline drug （mitoxantrone hydrochloride in 11 patients and carboplatin in 10 patients; non-anthracycline group）. The relationship between the chemotherapeutic efficacy and the results of immunostaining were compared between the two groups. RESULTS： Before the start of the treatment, PGPpositive rate was 90.2% （strongly-positive, 36.6%） and p53 protein-positive rate was 34.1% （strongly-positive, 19.5%）. In the anthracycline group, the response rate was 40.0%. The number of patients showing poor response to the treatment was significantly larger in the patients with strongly positive PGP expression （P= 0.005）, and their prognoses were poor （P= 0.001）. in the nonanthracycline group, the response rate was 42.9%,and there was no significant relationship between the chemotherapeutic drug efficacy and the PGP or p53 protein expression. When only the data from the 11 patients treated with anthraquinone drug, mitoxantrone, were analyzed, however, the number of patients who showed poor response to treatment was significantly higher among the p53-positive patients （P= 0.012）, irrespective of the survival outcome. CONCLUSION： The chemotherapeutic efficacy with an anthracycline drug for advanced HCC can be predicted by immunohistochemical analysis of PGP expression. Similarly, immunostaining to evaluate p53 protein may be useful to predict the response in patients treated with an anthraquinone drug.展开更多
AIM： To reveal the expression of multidrug-resistance associated proteins： glutathione-S-transferase π（GSTπ）, P-glycoprotein（P-gp） and vault protein lung resistance protein（LRP） in retinoblastoma（RB） witho...AIM： To reveal the expression of multidrug-resistance associated proteins： glutathione-S-transferase π（GSTπ）, P-glycoprotein（P-gp） and vault protein lung resistance protein（LRP） in retinoblastoma（RB） without any conservative treatment before primary enucleation and to correlate this expression with histopathological tumor features. METHODS： A total of 42 specimens of RB undergone primary enucleation were selected for the research. Sections from the formalin-fixed, paraffin-embedded specimens were stained with HE and immunohistochemistry to detect the expression of GSTπ, P-gp and LRP.RESULTS： GSTπ was expressed in 39/42（92.86%） RBs and in 9/9（100%） well-differentiated RBs. P-gp/GSTπ was found in 30（71.42%） of 42 RBs. Totally 9（21.43%） tumors were well differentiated and 33（78.57%） were poorly differentiated. Totally 15（35.71%） eyes had optic nerve（ON） tumor invasion, 36（85.71%） had choroidal tumor invasion, and 14（33.33%） had simultaneous choroidal and ON invasion. There was no statistically significant relationship between P-gp, GSTπ, LRP positivity and the degree of ocular layer tumor invasion and ON tumor invasion（P〉0.05）. CONCLUSION： RB intrinsically expresses GSTπ, P-gp and LRP. GSTπ expression is positive in 100% welldifferentiation ones, so in which way it is correlated with differentiation. But the other two proteins expressions are not related to tumor differentiation and to the degree of tumor invasion. GSTπ may be a new target of chemotherapy in RB.展开更多
The barriers present in the interfaces between the blood and the central nervous system form a major hurdle for the pharmacological treatment of central nervous system injuries and diseases.The family of ATP-binding c...The barriers present in the interfaces between the blood and the central nervous system form a major hurdle for the pharmacological treatment of central nervous system injuries and diseases.The family of ATP-binding cassette(ABC)transporters has been widely studied regarding efflux of medications at blood-central nervous system barriers.These efflux transporters include P-glycoprotein(abcb1),‘breast cancer resistance protein'(abcg2)and the various‘multidrug resistance-associated proteins'(abccs).Understanding which efflux transporters are present at the blood-spinal cord,blood-cerebrospinal fluid and cerebrospinal fluid-spinal cord barriers is necessary to determine their involvement in limiting drug transfer from blood to the spinal cord tissue.Recent developments in the blood-brain barrier field have shown that barrier systems are dynamic and the profile of barrier defenses can alter due to conditions such as age,disease and environmental challenge.This means that a true understanding of ABC efflux transporter expression and localization should not be one static value but instead a range that represents the complex patient subpopulations that exist.In the present review,the blood-central nervous system barrier literature is discussed with a focus on the impact of ABC efflux transporters on:(i)protecting the spinal cord from adverse effects of systemically directed drugs,and(ii)limiting centrally directed drugs from accessing their active sites within the spinal cord.展开更多
Quercetin is a biologically active flavonoid that has been used as a popular health supplement.It is reported that quercetin may cause flavonoid-drug interaction mediated by P-glycoprotein,the most predominant efflux ...Quercetin is a biologically active flavonoid that has been used as a popular health supplement.It is reported that quercetin may cause flavonoid-drug interaction mediated by P-glycoprotein,the most predominant efflux transporter.In this study,we comprehensively evaluated the potential of the pharmacokinetic interaction of quercetin mediated by multidrug resistance-associated protein 2(MRP2),another major efflux transporter.MRP2-transfected MDCKII cells and LS174T cells were used to evaluate the potential inhibition and induction of MRP2 by quercetin in vitro.To evaluate the induction effect of quercetin on Mrp2 in vivo,Mrp2 mRNA expression in rat liver,kidney,and small intestinal tissues was determined after the oral administration of quercetin(50,100,or 250 mg/kg)for seven days.Mrp2-mediated interaction potential was also evaluated by the pharmacokinetic study of phenolsulfonphthalein in rats after single or multiple doses of quercetin.Additionally,the effect of quercetin on absorption of docetaxel,a P-glycoprotein and CYP3A4 substrate,was also evaluated.Quercetin inhibited the function of MRP2 at 10μM and induced the mRNA expression of MRP2 at 50μM in vitro.Additionally,at 100 mg/kg,quercetin markedly increased Mrp2 expression in the small intestine of rats.However,there was no significant change in phenolsulfonphthalein pharmacokinetics due to single-(50,100,or 250 mg/kg)or multiple-dose(50,100,or 250 mg/kg for seven days)quercetin co-administration.By contrast,a significant interaction caused by quercetin(100 mg/kg)was observed in the absorption of docetaxel.The results suggested that although quercetin modulates the function and expression of MRP2 in vitro,it may have a low potential of Mrp2-mediated interaction and present negligible safety concerns related to the interaction.展开更多
Heavy metals, including cadmium (Cd), are widespread pollutants of great environmental concern because of their ac- cumulation and toxicity. Environmental conditions can affect the accumulation and elimination of Cd i...Heavy metals, including cadmium (Cd), are widespread pollutants of great environmental concern because of their ac- cumulation and toxicity. Environmental conditions can affect the accumulation and elimination of Cd in organisms. The aim of this study is to understand the respective responses of metallothioneins (MTs), P-glycoprotein (P-gp), and heat shock protein 70 (hsp70) genes in the mantle and digestive gland of the oyster Crassostrea gigas exposed to 10 g L 1 Cd for 28 days, followed by a depura- tion period of 35 days under different feeding strategies. The MT expression in the digestive gland was higher than in mantle, and was induced in a fluctuating pattern throughout the time of the whole experiment when the oyster was exposed to Cd. The results indicated an enhanced MT activity is required for Cd detoxification. Expression levels of P-gp in the mantle of Cd-exposed oysters fed with algae increased in the first two weeks of the accumulation phase. Then the induction weakened, but the expression still in- creased significantly compared with the control group fed without algae. The P-gp levels in the digestive gland were under-regulated during both the contamination and decontamination periods except in the group fed with Dicrateria inornata at day 0.083. The in- duction of P-gp is possibly related to the important role of pumping Cd out of the cell, while a major implication of P-gp expression inhibition would be a disruption of the protein synthesis. Hsp70 expression exhibited an overall decreasing trend. The highest relative hsp70 inhibition occurred during day 42 to day 63, with approximately 4-fold and 10-fold lower hsp70 levels as compared to the C.gigas feeding with no algae in the mantle and digestive gland, respectively. The induction of hsp70 may be explained by the re- folding of protein in presence of Cd, followed by the inhibition of hsp70 when the protein synthesis was disrupted.展开更多
Objective： To study the effect of arsenic trioxide （As203） on the expression of drug transporting molecules in multidrug resistance malignant neoplasma acute promyelocytic leukemia （APL） MR2 cell line. Methods： ...Objective： To study the effect of arsenic trioxide （As203） on the expression of drug transporting molecules in multidrug resistance malignant neoplasma acute promyelocytic leukemia （APL） MR2 cell line. Methods： MR2 resistant to alltrans retinoic acid （ATRA） and non-ATRA resistant APL cell line NB4 were used. Expressions of P-glycoprotein （Pgp）, multidrug resistance protein （MRP） and lung resistance-related protein （LRP） were detected by immunocytochemical assay. Results： The expression of Pgp was significantly higher in MR2（30%-40%） than that in NB4（10%-20%） （P 〈 0.001）, and the expression of MRP was also higher in MR2 （56.9 ± 3.4 - 21.2 ± 1.1） than that in NB4 （20.6 ± 5.3 - 16.7 ± 1.2） （P 〈 0.001）. As2O3 ranging from 0.5-2.0 μmol/L, could significantly decrease the expressions of Pgp and MRP. The expression of Pgp and MRP in MR.2 cell line were negatively correlated with the dose and duration of action of As2O3. Conclusion： Pgp and MRP may be the sensitive targets of As2O3 to overcome drug-resistance. ATRA might be the substrates of Pgp and MRP.展开更多
The World Health Organisation recommends exclusive breastfeeding for the first six months of an infant’s life and in combination with solid food thereafter. This recommendation was introduced based on research showin...The World Health Organisation recommends exclusive breastfeeding for the first six months of an infant’s life and in combination with solid food thereafter. This recommendation was introduced based on research showing numerous health benefits of breastfeeding for both the mother and the infant. However, there is always concern regarding the transfer of medications from mother to their breastfed baby via milk. Pharma-cokinetic properties of a drug are usually used to pre-dict its transferability into breast milk. Although most drugs are compatible with breastfeeding, cases of toxic drug exposure have been reported. This is thought to be due to active transport mechanisms whereby effux transporter proteins expressed in the epithelial cells of the mammary gland actively secrete drugs into milk. An example of such effux transporters including the breast cancer resistance protein which is strongly induced during lactation and this could result in contamination of milk with the substrates of this transporter which may place the suckling infant at risk of toxicity. Furthermore, there is little known about the substrate specifcity of most effux transporters as we have highlighted in this review. There also exists some degree of contradiction between in vivo and in vitro studies which makes it difficult to conclusively predict outcomes and drug-drug interactions.展开更多
P-glycoprotein(P-gp)highly expressed in cancer cells can lead to multidrug resistance(MDR)and the combination of anti-cancer drugs with P-gp inhibitor has been a promising strategy to reverse MDR in cancer treatment.I...P-glycoprotein(P-gp)highly expressed in cancer cells can lead to multidrug resistance(MDR)and the combination of anti-cancer drugs with P-gp inhibitor has been a promising strategy to reverse MDR in cancer treatment.In this study,we established a label-free and detergent-free system combining surface plasmon resonance(SPR)biosensor with styrene maleic acid(SMA)polymer membrane proteins(MPs)stabilization technology to screen potential P-gp inhibitors.First,P-gp was extracted from MCF-7/ADR cells using SMA polymer to form SMA liposomes(SMALPs).Following that,SMALPs were immobilized on an SPR biosensor chip to establish a P-gp inhibitor screening system,and the affinity between P-gp and small molecule ligand was determined.The methodological investigation proved that the screening system had good specificity and stability.Nine P-gp ligands were screened out from 50 natural products,and their affinity constants with P-gp were also determined.The in vitro cell verification experiments demonstrated that tetrandrine,fangchinoline,praeruptorin B,neobaicalein,and icariin could significantly increase the sensitivity of MCF-7/ADR cells to Adriamycin(Adr).Moreover,tetrandrine,praeruptorin B,and neobaicalein could reverse MDR in MCF-7/ADR cells by inhibiting the function of P-gp.This is the first time that SMALPs-based stabilization strategy was applied to SPR analysis system.SMA polymer can retain P-gp in the environment of natural lipid bilayer and thus maintain the correct conformation and physiological functions of P-gp.The developed system can quickly and accurately screen small molecule ligands of complex MPs and obtain affinity between complex MPs and small molecule ligands without protein purification.展开更多
基金supported by grants from the Medical Innovation Fundation of Fujian Province(No.2007-CXB-7)the Natural Science Foundation of Fujian Province(No.2009D010)
文摘BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.
基金Supported by Innovation Fund of Fujian Province,No.2007-CXB-7Key Science and Technology Project of Xiamen,No.3502Z20077045
文摘AIM： To study the expression and phosphorylation of extracellular signal-regulated kinase （ERK） i and ERK2 in multidrug resistant （MDR） hepatocellular carcinoma （HCC） cells.METHODS： MDR HCC cell lines, HepG2/adriamycin （ADM） and SMMC7721/ADM, were developed by exposing parental cells to stepwise increasing concentrations of ADM. MTT assay was used to determine drug sensitivity. Flow cytometry was employed to analyze cell cycle distribution and measure cell P-glycoprotein （P-gp） and multidrug resistant protein 1 （MRP1） expression levels. ERK1 and ERK2 mRNA expression lev-ls were measured by quantitative real-time PCR （QRTPCR）. Expression and phosphorylation of ERK1 and ERK2 were analyzed by Western blot.RESULTS： MTT assay showed that HepG2/ADM andSMMC7721/ADM were resistant not only to ADM, but also to multiple anticancer drugs. The P-gp expression was over 10-fold higher in HepG2/ADM cells than in HepG2 cells （8.92% ±0.22% vs 0.88% ± 0.05%, P 〈 0.001） and over 4-fold higher in SMMC7721/ADM cells than in SMMC7721 cells （7.37% ± 0.26% vs 1.74% ± 0.25%, P 〈 0.001）. However, the MRP1 expression was not significantly higher in HepG2/ADM and SMMC7721/ADM cells than in parental cells. In addition, the percentage of MDR HepG2/ADM and SMMC7721/ADM cells was significantly decreased in the G0/G1 phase and increased in the the S phase or G2/M phase. QRT-PCR analysis demonstrated that the ERK1 and ERK2 mRNA expression increased apparently in HepG2/ADM cells and decreased significantly in SMMC7721/ADM cells. Compared with the expression of parental cells, ERK1 and ERK2 protein expressions were markedly decreased in SMMC7721/ADM cells. However, ERK2 protein expression was markedly increased while ERK1 protein expression had no significant change in HepG2/ADM cells. Phosphorylation of ERK1 and ERK2 was markedly decreased in both HepG2/ADM and SMMC7721/ADM MDR cells.CONCLUSION： ERK1 and ERK2 activities are downregulated in P-gp-mediated MDR HCC cells. ERK1 or ERK2 might be a potential drug target for circumventing MDR HCC cells,
文摘AIM： To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein （PGP） and p53 protein in advanced hepatocellular carcinoma （HCC）. METHODS： The study was conducted on 41 patients with advanced HCC who were treated by repeated arterial infusion chemotherapy. Biopsy specimens from the tumor were collected before the start of treatment in all the patients, and the specimens were stored frozen until immunohistochemical staining, which was performed after the start of treatment, to detect PGP and p53 protein expressions. Twenty of the fortyone patients were treated with an anthracycline drug （epirubicin hydrochloride; anthracycline group）, and the remaining 21 were treated with a non-anthracycline drug （mitoxantrone hydrochloride in 11 patients and carboplatin in 10 patients; non-anthracycline group）. The relationship between the chemotherapeutic efficacy and the results of immunostaining were compared between the two groups. RESULTS： Before the start of the treatment, PGPpositive rate was 90.2% （strongly-positive, 36.6%） and p53 protein-positive rate was 34.1% （strongly-positive, 19.5%）. In the anthracycline group, the response rate was 40.0%. The number of patients showing poor response to the treatment was significantly larger in the patients with strongly positive PGP expression （P= 0.005）, and their prognoses were poor （P= 0.001）. in the nonanthracycline group, the response rate was 42.9%,and there was no significant relationship between the chemotherapeutic drug efficacy and the PGP or p53 protein expression. When only the data from the 11 patients treated with anthraquinone drug, mitoxantrone, were analyzed, however, the number of patients who showed poor response to treatment was significantly higher among the p53-positive patients （P= 0.012）, irrespective of the survival outcome. CONCLUSION： The chemotherapeutic efficacy with an anthracycline drug for advanced HCC can be predicted by immunohistochemical analysis of PGP expression. Similarly, immunostaining to evaluate p53 protein may be useful to predict the response in patients treated with an anthraquinone drug.
基金Supported by the National Natural Science Foundation of China(No.30371515)
文摘AIM： To reveal the expression of multidrug-resistance associated proteins： glutathione-S-transferase π（GSTπ）, P-glycoprotein（P-gp） and vault protein lung resistance protein（LRP） in retinoblastoma（RB） without any conservative treatment before primary enucleation and to correlate this expression with histopathological tumor features. METHODS： A total of 42 specimens of RB undergone primary enucleation were selected for the research. Sections from the formalin-fixed, paraffin-embedded specimens were stained with HE and immunohistochemistry to detect the expression of GSTπ, P-gp and LRP.RESULTS： GSTπ was expressed in 39/42（92.86%） RBs and in 9/9（100%） well-differentiated RBs. P-gp/GSTπ was found in 30（71.42%） of 42 RBs. Totally 9（21.43%） tumors were well differentiated and 33（78.57%） were poorly differentiated. Totally 15（35.71%） eyes had optic nerve（ON） tumor invasion, 36（85.71%） had choroidal tumor invasion, and 14（33.33%） had simultaneous choroidal and ON invasion. There was no statistically significant relationship between P-gp, GSTπ, LRP positivity and the degree of ocular layer tumor invasion and ON tumor invasion（P〉0.05）. CONCLUSION： RB intrinsically expresses GSTπ, P-gp and LRP. GSTπ expression is positive in 100% welldifferentiation ones, so in which way it is correlated with differentiation. But the other two proteins expressions are not related to tumor differentiation and to the degree of tumor invasion. GSTπ may be a new target of chemotherapy in RB.
文摘The barriers present in the interfaces between the blood and the central nervous system form a major hurdle for the pharmacological treatment of central nervous system injuries and diseases.The family of ATP-binding cassette(ABC)transporters has been widely studied regarding efflux of medications at blood-central nervous system barriers.These efflux transporters include P-glycoprotein(abcb1),‘breast cancer resistance protein'(abcg2)and the various‘multidrug resistance-associated proteins'(abccs).Understanding which efflux transporters are present at the blood-spinal cord,blood-cerebrospinal fluid and cerebrospinal fluid-spinal cord barriers is necessary to determine their involvement in limiting drug transfer from blood to the spinal cord tissue.Recent developments in the blood-brain barrier field have shown that barrier systems are dynamic and the profile of barrier defenses can alter due to conditions such as age,disease and environmental challenge.This means that a true understanding of ABC efflux transporter expression and localization should not be one static value but instead a range that represents the complex patient subpopulations that exist.In the present review,the blood-central nervous system barrier literature is discussed with a focus on the impact of ABC efflux transporters on:(i)protecting the spinal cord from adverse effects of systemically directed drugs,and(ii)limiting centrally directed drugs from accessing their active sites within the spinal cord.
基金supported by Basic Science Research Pro-gram through the National Research Foundation of Korea funded by the Ministry of Science,ICT and Future Planning(NRF-2015R1A2A2A01002673)
文摘Quercetin is a biologically active flavonoid that has been used as a popular health supplement.It is reported that quercetin may cause flavonoid-drug interaction mediated by P-glycoprotein,the most predominant efflux transporter.In this study,we comprehensively evaluated the potential of the pharmacokinetic interaction of quercetin mediated by multidrug resistance-associated protein 2(MRP2),another major efflux transporter.MRP2-transfected MDCKII cells and LS174T cells were used to evaluate the potential inhibition and induction of MRP2 by quercetin in vitro.To evaluate the induction effect of quercetin on Mrp2 in vivo,Mrp2 mRNA expression in rat liver,kidney,and small intestinal tissues was determined after the oral administration of quercetin(50,100,or 250 mg/kg)for seven days.Mrp2-mediated interaction potential was also evaluated by the pharmacokinetic study of phenolsulfonphthalein in rats after single or multiple doses of quercetin.Additionally,the effect of quercetin on absorption of docetaxel,a P-glycoprotein and CYP3A4 substrate,was also evaluated.Quercetin inhibited the function of MRP2 at 10μM and induced the mRNA expression of MRP2 at 50μM in vitro.Additionally,at 100 mg/kg,quercetin markedly increased Mrp2 expression in the small intestine of rats.However,there was no significant change in phenolsulfonphthalein pharmacokinetics due to single-(50,100,or 250 mg/kg)or multiple-dose(50,100,or 250 mg/kg for seven days)quercetin co-administration.By contrast,a significant interaction caused by quercetin(100 mg/kg)was observed in the absorption of docetaxel.The results suggested that although quercetin modulates the function and expression of MRP2 in vitro,it may have a low potential of Mrp2-mediated interaction and present negligible safety concerns related to the interaction.
基金supported by the Earmarked Fund for Modern Agro-industry Technology Research System in Shandong Province (No. SDAIT-14)the major Agricultural Applied Technological Innovation Program in Shandong Province: Construction and Demonstration of Ecological Farming Model of Monomeric Triploid Oyster
文摘Heavy metals, including cadmium (Cd), are widespread pollutants of great environmental concern because of their ac- cumulation and toxicity. Environmental conditions can affect the accumulation and elimination of Cd in organisms. The aim of this study is to understand the respective responses of metallothioneins (MTs), P-glycoprotein (P-gp), and heat shock protein 70 (hsp70) genes in the mantle and digestive gland of the oyster Crassostrea gigas exposed to 10 g L 1 Cd for 28 days, followed by a depura- tion period of 35 days under different feeding strategies. The MT expression in the digestive gland was higher than in mantle, and was induced in a fluctuating pattern throughout the time of the whole experiment when the oyster was exposed to Cd. The results indicated an enhanced MT activity is required for Cd detoxification. Expression levels of P-gp in the mantle of Cd-exposed oysters fed with algae increased in the first two weeks of the accumulation phase. Then the induction weakened, but the expression still in- creased significantly compared with the control group fed without algae. The P-gp levels in the digestive gland were under-regulated during both the contamination and decontamination periods except in the group fed with Dicrateria inornata at day 0.083. The in- duction of P-gp is possibly related to the important role of pumping Cd out of the cell, while a major implication of P-gp expression inhibition would be a disruption of the protein synthesis. Hsp70 expression exhibited an overall decreasing trend. The highest relative hsp70 inhibition occurred during day 42 to day 63, with approximately 4-fold and 10-fold lower hsp70 levels as compared to the C.gigas feeding with no algae in the mantle and digestive gland, respectively. The induction of hsp70 may be explained by the re- folding of protein in presence of Cd, followed by the inhibition of hsp70 when the protein synthesis was disrupted.
文摘Objective： To study the effect of arsenic trioxide （As203） on the expression of drug transporting molecules in multidrug resistance malignant neoplasma acute promyelocytic leukemia （APL） MR2 cell line. Methods： MR2 resistant to alltrans retinoic acid （ATRA） and non-ATRA resistant APL cell line NB4 were used. Expressions of P-glycoprotein （Pgp）, multidrug resistance protein （MRP） and lung resistance-related protein （LRP） were detected by immunocytochemical assay. Results： The expression of Pgp was significantly higher in MR2（30%-40%） than that in NB4（10%-20%） （P 〈 0.001）, and the expression of MRP was also higher in MR2 （56.9 ± 3.4 - 21.2 ± 1.1） than that in NB4 （20.6 ± 5.3 - 16.7 ± 1.2） （P 〈 0.001）. As2O3 ranging from 0.5-2.0 μmol/L, could significantly decrease the expressions of Pgp and MRP. The expression of Pgp and MRP in MR.2 cell line were negatively correlated with the dose and duration of action of As2O3. Conclusion： Pgp and MRP may be the sensitive targets of As2O3 to overcome drug-resistance. ATRA might be the substrates of Pgp and MRP.
文摘The World Health Organisation recommends exclusive breastfeeding for the first six months of an infant’s life and in combination with solid food thereafter. This recommendation was introduced based on research showing numerous health benefits of breastfeeding for both the mother and the infant. However, there is always concern regarding the transfer of medications from mother to their breastfed baby via milk. Pharma-cokinetic properties of a drug are usually used to pre-dict its transferability into breast milk. Although most drugs are compatible with breastfeeding, cases of toxic drug exposure have been reported. This is thought to be due to active transport mechanisms whereby effux transporter proteins expressed in the epithelial cells of the mammary gland actively secrete drugs into milk. An example of such effux transporters including the breast cancer resistance protein which is strongly induced during lactation and this could result in contamination of milk with the substrates of this transporter which may place the suckling infant at risk of toxicity. Furthermore, there is little known about the substrate specifcity of most effux transporters as we have highlighted in this review. There also exists some degree of contradiction between in vivo and in vitro studies which makes it difficult to conclusively predict outcomes and drug-drug interactions.
基金supported by the National Natural Science Foundation of China(No.82173777,81872829,81673386,82174092)the Science and Technology Commission of Shanghai Municipality(21ZR1483000)。
文摘P-glycoprotein(P-gp)highly expressed in cancer cells can lead to multidrug resistance(MDR)and the combination of anti-cancer drugs with P-gp inhibitor has been a promising strategy to reverse MDR in cancer treatment.In this study,we established a label-free and detergent-free system combining surface plasmon resonance(SPR)biosensor with styrene maleic acid(SMA)polymer membrane proteins(MPs)stabilization technology to screen potential P-gp inhibitors.First,P-gp was extracted from MCF-7/ADR cells using SMA polymer to form SMA liposomes(SMALPs).Following that,SMALPs were immobilized on an SPR biosensor chip to establish a P-gp inhibitor screening system,and the affinity between P-gp and small molecule ligand was determined.The methodological investigation proved that the screening system had good specificity and stability.Nine P-gp ligands were screened out from 50 natural products,and their affinity constants with P-gp were also determined.The in vitro cell verification experiments demonstrated that tetrandrine,fangchinoline,praeruptorin B,neobaicalein,and icariin could significantly increase the sensitivity of MCF-7/ADR cells to Adriamycin(Adr).Moreover,tetrandrine,praeruptorin B,and neobaicalein could reverse MDR in MCF-7/ADR cells by inhibiting the function of P-gp.This is the first time that SMALPs-based stabilization strategy was applied to SPR analysis system.SMA polymer can retain P-gp in the environment of natural lipid bilayer and thus maintain the correct conformation and physiological functions of P-gp.The developed system can quickly and accurately screen small molecule ligands of complex MPs and obtain affinity between complex MPs and small molecule ligands without protein purification.
