Expression Of Multidrug Resistance-associated Protein Research Articles

Effect of Magnesium Supplementation to Prevent Nephrotoxicity on the Antitumor Activity of Cisplatin

Background: Cisplatin (CDDP) is one of the most widely used anticancer drugs, but CDDP often leads to nephrotoxicity, which limits its clinical effectiveness. Magnesium (Mg) supplementation is recommended for the avoidance of CDDP-induced nephrotoxicity. However, there is a concern that exposing cancer cells to Mg may suppress the antitumor effect of CDDP. Methods: Transporter expression, intracellular platinum and Mg levels, and cytotoxicity of CDDP after Mg exposure were assessed in human hepatocellular carcinoma (HepG2) and human ovarian carcinoma (2008) cells. Results: In HepG2 cells, Mg exposure significantly increased mRNA levels of multidrug and toxin extrusion 1 (MATE1), which mediates the renal excretion of CDDP, but did not alter its protein levels, including those of organic cation transporter 1 (OCT1), which mediates CDDP uptake in renal tubular and cancer cells, and multidrug resistance-associated protein 2 (MRP2), which mediates CDDP efflux in cancer cells. In 2008 cells, MATE1 protein expression could not be detected, but a slight increase in MRP2 and OCT1 protein expression was observed after Mg exposure. Intracellular Mg levels were significantly increased due to Mg exposure in both cells. However, intracellular platinum levels and cytotoxicity of CDDP were not affected in both cells, even with 2 mM Mg co-exposure. Conclusion: This study found that Mg exposure only slightly changed transporter expression and did not affect intracellular platinum levels and CDDP cytotoxicity in HepG2 and 2008 cells. Thus, Mg supplementation can be used to avoid CDDP-induced renal toxicity without affecting the accumulation of CDDP in cancer cells and its cytotoxicity.

Nobiletin Enhances Chemosensitivity to Adriamycin through Modulation of the Akt/GSK3β/β⁻Catenin/MYCN/MRP1 Signaling Pathway in A549 Human Non-Small-Cell Lung Cancer Cells.

Drug resistance is a major problem in the treatment of non-small-cell lung cancer (NSCLC). In this study, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was performed to identify the differentially expressed genes in Adriamycin (ADR)-resistant NSCLC A549/ADR cells compared with parental A549 cells. Among the tested phytochemicals, nobiletin (NBT) is able to overcome the ADR resistance of A549/ADR cells. NBT treatment decreased the expression of a neuroblastoma-derived MYC (MYCN) and multidrug resistance-associated protein 1 (MRP1) as well as downregulating Akt, GSK3β, and β-catenin. Consistent with these results, NBT treatment resulted in the accumulation of intracellular ADR. A combination index (CI) assay confirmed the synergistic effect of combined treatment with NBT and ADR in reducing the viability of A549/ADR cells (CI = 0.152). Combined treatment with NBT and ADR enhanced apoptosis in A549/ADR cells, as evidenced by increased caspase-3 activation, poly (ADP-ribose) polymerase (PARP) cleavage, and sub-G1 population compared to treatment with ADR alone. In vivo experiments using a mouse xenograft model revealed that combination therapy with NBT and ADR significantly reduced tumor volume by 84.15%. These data suggest that NBT can sensitize ADR-induced cytotoxicity against A549/ADR cells by inhibiting MRP1 expression, indicating that NBT could serve as an effective adjuvant agent for ADR-based chemotherapy in lung cancer.

Expression of LRP Gene in Breast Cancer Patients Correlated with MRP1 as Two Independent Predictive Biomarkers in Breast Cancer

Background:Breast cancer is the most common malignancy in women. Multidrug resistance (MDR) is still a great obstacle of breast cancer chemotherapy. We have previously shown that multidrug resistance-associated protein 1 (MRP1) is associated with response to neoadjuvant chemotherapy. The lung resistance-related protein (LRP) is identified as a prognostic marker and response to treatment factor which has been studied mainly in hematological malignancy and leukemia. In this study, we aimed to analyze LRP expression and possible correlation between the expression level of this gene with MRP1 as a candidate marker for chemotherapy resistance.Materials and Methods:We collected 54 breast tumors and adjacent normal tissues from Iranian breast cancer patients and Real time RT-PCR was employed to measure the gene expression level in our samples.Results:MRP1 and LRP expression level were significantly lower in tumor tissues of the patients responding to chemotherapy compared to non-responding patients. No relation between the expression level of either of these genes and clinicopathology markers was found.Conclusion:Our results suggest that LRP gene expression is correlated to MRP1 in human breast cancer cells and may affect the clinical response to treatment.

Expression of multidrug-resistance associated proteins in human retinoblastoma treated by primary enucleation.

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. 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. 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). RB intrinsically expresses GSTπ, P-gp and LRP. GSTπ expression is positive in 100% well-differentiation 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.

Quercetin and kaempferol increase the intestinal absorption of isorhamnetin coexisting in Elaeagnus rhamnoides (L.) A. Nelson (Elaeagnaceae) extracts via regulating multidrug resistance-associated protein 2

BackgroundIsorhamnetin (IS) is a flavonoid component with many biological activities such as antioxidant, anti-inflammatory, and anticancer, which is also the main active component in total flavones of Elaeagnus rhamnoides (L.) A. Nelson (Elaeagnaceae) (TFH); however, the interaction between IS and other components in TFH is unclear. PurposeThe aim of the present study was to investigate the enhancement of quercetin (QU) or kaempferol (KA) on the intestinal absorption of IS coexisting in TFH, and then preliminarily illuminate the related mechanisms. MethodsFirstly, the intestinal absorption of IS in the presence or absence of QU or KA was conducted by in vivo pharmacokinetics model, in situ single-pass intestinal perfusion model (SPIP), and MDCK II-MRP2 monolayer cell model to confirm the enhancement of QU or KA on IS absorption. Secondly, the effects of multidrug resistance-associated protein 2 (MRP2) inhibitors on the IS intestinal absorption were investigated to ascertain the mediation of MRP2 on IS absorption. Finally, the effects of QU or KA on MRP2 activity, protein expression, and mRNA level were performed by SPIP, everted-gut sacs, western blotting, and real-time polymerase chain reaction experiments to elucidate the related mechanisms. ResultsQU or KA increased IS intestinal absorption according to the increased AUC0–96h, Cmax, and Peff of IS after co-administrated with QU or KA to rats; the oral absorption of IS was mediated by MRP2 based on the facts that the average plasma concentration, AUC0–96h, and Peff of IS were increased when co-administrated with PR or MK571 (MRP2 inhibitors) as well as the Pratio(BL/AP) of IS was decreased by MK571 in MDCK II-MRP2 cell monolayer; the activity, protein expression, and mRNA level of MRP2 were inhibited or down-regulated by QU or KA because of the increased Peff of MRP2 substrate calcein (CA) and the down-regulated relative protein and mRNA intensity after co-treated with QU or KA. ConclusionQU and KA increased the intestinal absorption of IS in TFH by regulating the activity and expression of MRP2, which provides useful information for the investigation of the transporter-mediated interaction of flavonoid components in herbal extracts.

Mutation analysis of the ABCC2 gene in Chinese patients with Dubin-Johnson syndrome.

Dubin-Johnson syndrome (DJS) is a rare, autosomal recessive disorder characterized by predominantly conjugated hyperbilirubinemia, caused by a mutation in the adenosine triphosphate-binding cassette subfamily C member 2 (ABCC2) gene coding the multidrug resistance-associated protein 2 (MRP2) protein. ABCC2 mutations have been identified in patients with DJS worldwide; however, the mutation pattern of ABCC2 in China is not well studied. In the present study, the mutation pattern of the ABCC2 gene in Chinese patients with DJS was investigated. A total of 7 clinically confirmed patients with DJS were enrolled, and mutation analysis of the ABCC2 gene was performed by Sanger sequencing of genomic DNA extracted from whole blood. All 32 exons and the adjacent splice junction areas were sequenced. All cases were identified to harbor at least one non-synonymous variant in the ABCC2 gene, including three known mutations in 3 cases and three novel variants (p.G693R, p.G808V and p.E647X) in the other 4 cases, with the known p.R393W and the novel p.G693R and p.E647X variants identified in 2 of the 7 cases (28.6%), respectively. All the identified mutations were heterozygous, and 1 case presented with a compound heterozygous mutation, namely p.G693R/p.G808V, while the other cases carried only one single mutation. The loss of membrane expression of MRP2 caused by the novel nonsense variant, p.E647X, was confirmed by immunohistochemical analysis of liver biopsy. The present study provided the first report on the mutation patterns of the ABCC2 gene in Chinese patients with DJS, and the clinical association of these mutations with the syndrome.

Valproate sensitizes human glioblastoma cells to 3-bromopyruvate-induced cytotoxicity

Glioblastoma (GBM) is the most common brain tumor; however, no effective treatment for it is available yet. Monocarboxylate transporters, which are highly expressed in GBM, play a role in transporting antitumor agents, such as 3-bromopyruvate (3-BrPA). Valproate, primarily used to treat epilepsy, has been considered a possible treatment option for malignant GBM. In this study, we aimed to investigate the combined effects of 3-BrPA and valproate on GBM cell growth and elucidate the underlying mechanisms. Valproate enhanced 3-BrPA-induced cell death in T98G cells, used as a GBM model. Multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP) mRNA levels significantly increased after valproate treatment. 3-BrPA-induced cell death, which was enhanced by valproate, was inhibited in the presence of MK571, a MRP inhibitor, or Ko143, a BCRP inhibitor. In addition, treatment with 3-BrPA and valproate for 48 h reduced cellular ATP levels compared to those in the 3-BrPA alone treatment group. However, cellular ATP levels were recovered in the presence of MK571 or Ko143, compared to those in the 3-BrPA and valproate treatment groups.In conclusion, we suggested that valproate enhanced 3-BrPA-induced cell death. This might be attributable to the increase in cellular ATP consumption owing to valproate-induced MRP2 or BCRP expression.

Platinum(IV) complex-based two-in-one polyprodrug for a combinatorial chemo-photodynamic therapy

A combinatorial therapy that utilizes two or more therapeutic modalities is more effective in overcoming the limitations than each individual method used alone. Despite great advances have been achieved, the combination of chemotherapy and photodynamic therapy (PDT) still cannot satisfy the clinic requirements as the antitumor efficacy could be severely affected by tumor-associated hypoxia. Herein, for the first time, we reported a platinum(IV) complex-based polyprodrug that can in situ generate the highly toxic platinum(II) species as chemotherapeutics and simultaneously induce a high level of reactive oxygen species (ROS) in a PDT-like process without the use of photosensitizer and consumption of oxygen. By in situ polymerizing the platinum(IV) complex-based prodrug monomer (PPM) and 2-methacryloyloxy ethyl phosphorylcholine (MPC), nanosized hydrogel-like polyprodrug could be synthesized. Upon being exposed to light, Pt(IV) moieties in this photoactivable polyprodrug were reduced to generate Pt(II) species. At the meantime, a high level of ROS was generated without the presence of endogenous oxygen, which was confirmed by electron spin resonance (ESR) and fluorescence probes. With the unique nanosized architecture and photoresponsive feature, the as-synthesized polyprodrug exhibited the advantages of sustained drug release, long-term circulation, preferable tumor accumulation, and reversing drug resistance by downregulating the expression of multidrug resistance-associated protein 1 (MRP1) in the anticancer treatment.

Prognostic role of multidrug resistance-associated protein 1 expression and platelet count in operable non-small cell lung cancer.

The overall survival rate of patients with non-small cell lung cancer (NSCLC) following resection remains poor due to the high rates of recurrence and metastasis. The investigation of novel biomarkers is clinically necessary to improve treatment strategies. Multidrug resistance-associated protein 1 (MRP1) and platelet count are linked to a poor prognosis in various types of cancer. However, it is unknown whether MRP1 or platelet count is a suitable prognostic indicator of NSCLC. In the present study, 427 patients with operable NSCLC were enlisted. The association of MRP1 expression and platelet count with clinical pathological factors and patient outcome was evaluated. MRP1 expression was found to be significantly associated with sex, histological type and tumor differentiation, while platelet count was significantly associated with smoking behavior, histological type and clinical stage. Platelet count was significantly higher in patients with negative MRP1 expression than in those with positive MRP1 expression. Survival analysis indicated that there was no association between MRP1 expression and disease-free survival (DFS) or overall survival (OS) time. In the patients with no lymph node metastasis, the OS time was significantly longer in patients with positive MRP1 expression than in those with negative expression. However, in the patients with lymph node metastasis, the DFS time was significantly shorter in patients with positive MRP1 expression than in those with negative expression. There was an association between the platelet count and DFS and OS times, which were significantly longer in patients with a normal platelet count than in those with thrombocytosis. In conclusion, MRP1 expression and platelet count are valuable independent prognostic biomarkers for survival in operable NSCLC.

Knockdown of SIRT1 inhibits proliferation and promotes apoptosis of paclitaxel-resistant human cervical cancer cells

Cervical cancer (CC), a common gynecological cancer, is a primary cause of cancer-related death in women, worldwide. This study investigates the role of Sirtuin 1 (SIRT1) in paclitaxel (PTX)-resistant CC lines. We used qPCR and Western blots to measure SIRT1 mRNA and protein expressions in 10 matched clinical cancer tissues. We compared the expression levels of SIRT1 between sensitive CC cell lines and PTX-resistant cell lines. Subsequently, we used SIRT1 siRNA to knockdown the expression of SIRT1, and then measured cell proliferation, cell apoptosis rate, cell cycle distribution, and expression levels of Bcl-2 and Bax in PTX-sensitive Hela cell line, PTX-resistant Hela and Sila-resistant cell lines. Finally, we detected the location and expression of MRP (multidrug resistance-associated proteins) using immunofluorescence. We found that SIRT1 expression was higher in PTX-sensitive CC tissues than in normal tissues, and significantly higher in PTX-resistant CC tissues than in PTX-sensitive CC tissues. We further demonstrated that knockdown of SIRT1 in PTX-resistant CC cell lines and PTX-sensitive CC cell line inhibited cell proliferation and promoted cell apoptosis. In addition, we observed that blocking SIRT1 expression in PTX-resistant CC cell lines significantly decreased MRP expression. SIRT1 exhibited high expression levels in both PTX-resistant cell lines and patients. Our results suggest that SIRT1 serves as a potential therapeutic target in PTX-resistant CC.

IL-8 regulates the doxorubicin resistance of colorectal cancer cells via modulation of multidrug resistance 1 (MDR1).

Cytokines play important roles in tumorigenesis and progression of cancer cells, while their functions in drug resistance remain to be illustrated. We successfully generated doxorubicin (Dox)-resistant CRC HCT-116 and SW480 cells (namely HCT-116/Dox and SW480/Dox, respectively). Cytokine expression analysis revealed that IL-8, while not FGF-2, EGF, TGF-β, IL-6, or IL-10, was significantly increased in Dox-resistant CRC cells as compared with their corresponding parental cells. Targeted inhibition of IL-8 via siRNAs or its inhibitor reparixin can increase the Dox sensitivity of HCT-116/Dox and SW480/Dox cells. The si-IL-8 can decrease the mRNA and protein expression of multidrug resistance 1 (MDR1, encoded by ABCB1), while has no effect on the expression of multidrug resistance-associated protein 1 (ABCC1), in CRC Dox-resistant cells. IL-8 can increase the phosphorylation of p65 and then upregulate the binding between p65 and promoter of ABCB1. BAY 11-7082, the inhibitor of NF-κB, suppressed the recombination IL-8 (rIL-8) induced upregulation of ABCB1. It confirmed that NF-κB is involved in IL-8-induced upregulation of ABCB1. rIL-8 also increased the phosphorylation of IKK-β, which can further activate NF-κB, while specific inhibitor of IKK-β (ACHP) can reverse rIL-8-induced phosphorylation of p65 and upregulation of MDR1. These results suggested that IL-8 regulates the Dox resistance of CRC cells via modulation of MDR1 through IKK-β/p65 signals. The targeted inhibition of IL-8 might be an important potential approach to overcome the clinical Dox resistance in CRC patients.

ARID1A ablation leads to multiple drug resistance in ovarian cancer via transcriptional activation of MRP2

Multiple Drug Resistance (MDR) of ovarian cancer is a severe trouble for clinical treatment and always contributes to a bad prognosis. AT-rich interaction domain 1 A (ARID1A) has been recognized as a bona fide tumor suppressor gene in recent years, with the highest mutation rate in ovarian cancer. Previous study illustrated that ARID1A expression is negatively correlated with chemoresistance of ovarian cancer cases. However, the specific role of ARID1A in chemoresistance of ovarian cancer remains elusive. In this study, we showed that ARID1A knockdown in ovarian cancer cells significantly reduced their apoptosis rate and led to MDR, while ectopic expression of ARID1A showed opposite effects. ARID1A depletion transcriptionally activates the expression of multidrug resistance-associated protein 2 (MRP2) following chromatin remodeling. Furthermore, IHC analysis of ovarian cancer samples confirmed that ARID1A expression was strong negatively correlated with MRP2 expression. Both ARID1A and MRP2 expression levels are correlated with sensitivity to platinum. Collectively, our results illustrated that ARID1A loss in ovarian cancer leads to MDR through upregulation of MRP2, providing an opportunity to overcome the ARID1A loss induced chemoresistance of ovarian cancer by targeting MRP2.

Altered Function and Expression of ABC Transporters at the Blood–Brain Barrier and Increased Brain Distribution of Phenobarbital in Acute Liver Failure Mice

This study investigated alterations in the function and expression of P-glycoprotein (P-GP), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 2 (MRP2) at the blood–brain barrier (BBB) of acute liver failure (ALF) mice and its clinical significance. ALF mice were developed using intraperitoneal injection of thioacetamide. P-GP, BCRP, and MRP2 functions were determined by measuring the ratios of brain-to-plasma concentration of rhodamine 123, prazosin, and dinitrophenyl-S-glutathione, respectively. The mRNA and proteins expression levels of P-GP, BCRP, and MRP2 were evaluated with quantitative real-time PCR and western blot, respectively. MDCK-MDR1 and HCMEC/D3 cells were used to document the effects of the abnormally altered components in serum of ALF mice on the function and expression of P-GP. The clinical significance of alteration in P-GP function and expression was investigated by determining the distribution of the P-GP substrate phenobarbital (60 mg/kg, intravenous administration) in the brain and loss of righting reflex (LORR) induced by the drug (100 mg/kg). The results showed that ALF significantly downregulated the function and expression of both P-GP and BCRP, but increased the function and expression of MRP2 in the brain of mice. Cell study showed that increased chenodeoxycholic acid may be a reason behind the downregulated P-GP function and expression. Compared with control mice, ALF mice showed a significantly higher brain concentration of phenobarbital and higher brain-to-plasma concentration ratios. In accordance, ALF mice showed a significantly larger duration of LORR and shorter latency time of LORR by phenobarbital, inferring the enhanced pharmacological effect of phenobarbital on the central nervous system (CNS). In conclusion, the function and expression of P-GP and BCRP decreased, while the function and expression of MRP2 increased in the brain of ALF mice. The attenuated function and expression of P-GP at the BBB might enhance phenobarbital distribution in the brain and increase phenobarbital efficacy on the CNS of ALF mice.

Clinical, Pathologic, and Genetic Features of Neonatal Dubin-Johnson Syndrome: A Multicenter Study in Japan

To clarify the clinical, pathologic, and genetic features of neonatal Dubin-Johnson syndrome. Ten patients with neonatal Dubin-Johnson syndrome were recruited from 6 pediatric centers in Japan between September 2013 and October 2016. Clinical and laboratory course, macroscopic and microscopic liver findings, and molecular genetic findings concerning ATP-binding cassette subfamily C member 2 (ABCC2) were retrospectively and prospectively examined. All neonates exhibited cholestasis, evident as prolonged jaundice with or without acholic stools and elevations of serum direct bilirubin as well as γ-glutamyltransferase or total bile acids. Only 38% (3 of 8) of patients who underwent liver biopsy showed a grossly black liver or melanin-like pigment deposits in hepatocytes; their biopsies were performed in early infancy. Immunohistochemically, all liver specimens showed no expression of multidrug resistance-associated protein 2 but increased expression of the bile salt export pump protein. Homozygous or compound heterozygous pathogenic variants of ABCC2 were identified in all patients, representing 11 distinct pathogenic variants including 2 not previously reported. Immunohistochemical staining of the liver for multidrug resistance-associated protein 2 and molecular genetic analysis of ABCC2 are crucial for accurate diagnosis of neonatal Dubin-Johnson syndrome.

Effect of YHHJ on the expression of the hepatocellular bile acid transporters multidrug resistance-associated protein 2 and bile salt export pump in ethinylestradiol-induced cholestasis.

The herbal medicine Yin Huang Mixture (YHHJ; patent no. 200910031240.7) is an aqueous extract composed from various herbs, including Artemisia capillaries Thunb, Hypericum japonicum Thunb, Eucommia ulmoides Oliver, Rheum officinale Baill, Gardenia jasminoides Ellis, Poria cocos Wolf and Dictamnus dasycarpus Turcz. Previous studies have indicated that YHHJ treatment has a beneficial effect on ameliorating itching and reducing serum bile acid levels in patients with intrahepatic cholestasis of pregnancy (ICP). However, the molecular mechanisms of action of YHHJ in ICP have not been fully elucidated. Therefore, the present study investigated an experimental hepatocellular cholestasis model to explore the regulatory role of YHHJ on the expression of the bile acid carriers, multidrug resistance-associated protein 2 (MRP2) and the bile salt export pump (BSEP). Initially, 5 mg/kg/day 17-α ethinylestradiol (EE) was used to induce cholestasis in rats and primary isolated rat hepatocytes. Subsequently, 9 or 36 g/kg/day YHHJ water extract was administrated. Blood samples were collected and serum biochemical parameters of total bile acids (TBA), total bilirubin (TBil), alanine transaminase and aspartate aminotransferase levels were determined. Rat livers and primary isolated rat hepatocytes were obtained and the protein and mRNA expression levels of MRP2 and BSEP were analyzed by western blot analysis and reverse transcription-quantitative polymerase chain reaction, respectively. Results revealed that EE-induced hepatocellular cholestasis was associated with a significant increase in serum TBA and TBil levels, whereas, YHHJ treatment significantly reversed this effect (P<0.01). Further experiments on the molecular mechanism revealed that EE significantly decreased the expression of MRP2 and BSEP compared with the control group, whereas YHHJ treatment significantly upregulated MRP2 and BSEP expression in vivo and in vitro compared with no YHHJ treatment (P<0.01). In addition, to establish whether upregulation of MRP2 and BSEP protein expression levels resulted from increased expression of their respective mRNA, the mRNA expression levels were determined. Results indicated that YHHJ treatment significantly increased MRP2 and BSEP mRNA expression levels in EE-induced hepatocellular cholestasis compared with no YHHJ treatment (P<0.01). In conclusion, the present findings suggest that YHHJ effects EE-induced cholestasis and this process may be mediated through regulating hepatobiliary transporters, MRP2 and BSEP.

Immunohistochemical Assessment of the Expression of Biliary Transportation Proteins MRP2 and MRP3 in Hepatocellular Carcinoma and in Cholangiocarcinoma

Multidrug resistance-associated protein 2 (MRP2) is a multi-specific organic anion transporter predominantly expressed in the canalicular membrane of hepatocytes, epithelial cells from gallbladder and apical membranes of proximal tubular kidney epithelium whereas multidrug resistance-associated protein 3 (MRP3) is present in the basolateral membrane of hepatocytes and cholangiocytes. This study aims to detect the expression of these transporters in hepatocellular carcinoma (HCC) and in cholangiocarcinoma (CC), searching for evidences for future studies on differential diagnosis and on clinical essays. The immunohistochemical reactivity (IHC) of these transporters was assessed in tissue microarrays of 80 HCC and 56 CC cases using monoclonal antibodies and compared with anatomopathological (AP) variables. The positivity of MRP2 was observed in 92.3% of HCC and in 96.3% of CC. The detection of high MRP2 expression in HCC was not significantly different (p > 0.05) according to the size, number of nodules architectural pattern and growth pattern of HCC and CC. Regarding histological grades, 22/22 well moderately differentiated HCC versus 50/56 poorly differentiated HCC were positive for MRP2. A trend for lower expression in poor differentiation HCC was found. And 50/50 well/moderately differentiated CC versus 2/4 poorly/undifferentiated CC were positive for MRP2. This result showed a reduced expression (p = 0,0004) in poorly differentiated CC. MRP3 positivity was observed in 18.8% of HCC and was not significantly different according to AP parameters. MRP3 was expressed in 44.5% CC, with a trend for lower expression in less differentiated CC and significantly lower rates in the ductular histological subtype (p = 0.023). The high expression of MRP2 in HCC and in CC is conserved regardless most of the anatomopathological parameters, except for a trend of lower expression in less differentiated HCC and CC. The observation of lower MRP3 expression in less differentiated CC and, especially, in the histological subtype with expression of hepatic progenitor cell phenotypes leads to future opportunities to evaluate the expression of this marker in cholangiocarcinomas.

Study of peripheral blood multidrug resistance-associated protein 1 expression of children intractable epilepsy.

The aim of this study was to analyze multidrug resistance-associated protein 1 (MRP1) expression of peripheral blood of children intractable epilepsy. Sixty children with epilepsy admitted to outpatient and inpatient services of Xuzhou Children's Hospital between November 2010 and October 2011 were divided into a refractory epilepsy group and a drug-controlled epilepsy group, with 30 cases each. Thirty healthy children who went to the hospital in the same year for health examination were enrolled as a control group. Reverse transcriptase polymerase chain reaction and Western blot method were used to determine peripheral blood MRP1 level, mRNA, and protein content of the 3 groups. MRP1 expression in the refractory epilepsy group was significantly higher than those of the epilepsy group with good drug control and of the control group. All differences had statistical significance (P<0.05), except for the comparison between the drug-controlled epilepsy group and the control group (P>0.05). Peripheral blood MRP1 expression in patients with refractory epilepsy increases.

Celecoxib enhances sensitivity to chemotherapy drugs of T-cell lymphoma.

Celecoxib is a newly-identified nonsteroidal anti-inflammatory drug, which has been used to treat fever in clinical practice. Celecoxib has been demonstrated to suppress the viability of various human tumor cells. However, the effect of celecoxib on response of T-cell lymphoma to chemotherapy agents remains unclear. The aim of the present study was to investigate the effect of celecoxib on chemosensitivity of human T-cell lymphoma, and to address the underlying mechanism of action. The cytotoxicity of CDDP, epirubicin and VCR on Jurkat and Hut-78 cells treated with celecoxib was assessed by MTT assay, and the half-maximal inhibitory concentration (IC50) value was calculated by Origin 75 software. The effect of celecoxib on apoptosis and intracellular concentration of Rhodamine-123 in Jurkat and Hut-78 cells was analyzed by flow cytometry. The expression of transcription factor p65 (p65), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), multidrug resistance 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1) at mRNA and protein levels were detected by reverse transcription quantitative polymerase chain reaction and western blotting, respectively. Proliferation suppression rates and apoptosis levels were significantly increased in Jurkat and Hut-78 cells combined with celecoxib compared with those without celecoxib, when treated with CDDP, epirubicin and VCR. The IC50 values of the chemotherapy agents were lower in Jurkat and Hut-78 cells treated with celecoxib compared with those that were not. The apoptosis level, expression of Bax and the intracellular concentration of Rhodamine-123 were increased, whereas the expression of p65, Bcl-2, MDR1 and MRP1 were decreased, in celecoxib-treated Jurkat and Hut-78 cells compared with those without celecoxib treatment. These results indicated that celecoxib may enhance the sensitivity of T-cell lymphoma to chemotherapy drugs by inhibiting the expression of multidrug resistance (MDR)-associated proteins via downregulating the activity of the nuclear factor-κB signaling pathway, suggesting that celecoxib may improve the curative effect of chemotherapy drugs in T-cell lymphoma.

Ciclosporin A as a Reversal Agent Against Concurrent Multidrug Resistance in Tumors with Nanobubbles.

The purpose of this work was to challenge the multidrug resistance (MDR) in tumor through nanobubbles (NB) co-loaded reversal agent and chemotherapeutic drug layer by layer. The core/shell NB structure contains Doxorubicin (Dox) as anticancer drug in the core and Ciclosporin A (CsA), a cyclic polypeptide composed of 11 amino acids, as a reversal agent in the shell. The drug was designed to work against concurrent MDR processes and was defined as CsA/Dox/NB. HL60/ADM cells with typical high expression of multidrug resistance associated protein 1 (MRP1) were assessed by flow cytometer, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, and Western blot analysis to observe the in vitro and in vivo anticancer efficacy and reversal ability of MDR. Results demonstrated that the function and expression of MRP1 could be successfully inhibited by CsA as a reversal agent from the pharmaceutical preparation, leading to dramatic increase of intracellular concentration of Dox. The accumulation of anticancer drug in the MDR cancer cells enhanced inhibition of cell proliferation through G2/M arrest and tumor growth of nude mice xenograft model. It was therefore concluded that the CsA/Dox/NB can be a promising drug candidate in overcoming tumor MDR.

Association of DNA Repair and Drug Transporter in Relation to Chemosensitivity in Primary Culture of Thai Gastric Cancer Patients

Acquired resistance is a major reason for poor clinical outcomes in cancer chemotherapy patients. The aim of this study was to determine the sensitivity to anticancer drugs and to identify the alterations of DNA repair and drug transporter in a model of primary culture obtained from pre- and post-platinum-based anticancer treatments in nine Thai gastric cancer patients. Ex vivo sensitivity to anti-cancer drugs (cisplatin, oxaliplatin, 5-fluorouracil (5-FU) and irinotecan) was analysed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression of the drug transporter (multidrug resistance-associated protein 1 (MRP1), P-glycoprotein (P-gp)) and DNA repair (X-ray cross-complementing gene 1 (XRCC1) and excision repair cross-complementing 1 (ERCC1)) were examined by RT-PCR. The IC50 to cisplatin and oxaliplatin of the cells obtained from gastric cancer patients after clinical drug treatments were administered to five patients (55.5%) revealed a significant increase when compared with prior treatments. The basal expression values of XRCC1, ERCC1 and MRP1 obtained from the treated patients were in correlation with those of IC50. Ex vivo platinum drug treatment of the primary culture obtained from naïve patients over seven days also revealed a significant increase in MRP1 (7/9), XRCC1 (4/9) and ERCC1 (4/9). These observations have also been observed in the KATOIII cell line. Clinical treatment by platinum-based anti-cancer drug can develop acquired drug resistance in Thai gastric cancer patients through upregulation in the expression of drug transporter MRP1 and DNA repair XRCC1 and ERCC1. In cell culture model, cisplatin-resistant gastric cancer cell line KATOIII/diamminedichloroplatinum (KATOIII/DDP) significantly increased the expression level of these genes when compared to its parental cells (KATOIII).