Multiple Drug Resistance Protein Research Articles

Excessive vincristine exposure in a child being treated for acute lymphoblastic leukaemia with underlying Dubin-Johnson syndrome: a case report.

Dubin-Johnson syndrome is a rare benign autosomal recessive condition that causes an isolated increase of conjugated bilirubin in the serum. Impaired biliary excretion is due to mutation in the multiple drug-resistance protein 2 gene (MRP2). We describe the case of a 4-year-old girl being treated for acute lymphoblastic leukaemia who had a history of conjugated hyperbilirubinaemia and persistently elevated bilirubin levels on initiation of chemotherapy. During treatment for leukaemia, she was diagnosed with Dubin-Johnson syndrome for the underlying condition. Following administration of vincristine at the recommended dose of 1.5mg/m2, an abnormally high vincristine exposure was observed (AUC > 200µg/L*h), approximately 3 times higher than previously reported exposures in a comparable clinical setting. Vincristine dose reductions were applied on subsequent cycles of treatment and resulted in markedly reduced drug exposures, within the normal target range. This case provided a rare opportunity to assess the impact of MRP2 mutations associated with Dubin-Johnson syndrome on the pharmacokinetics of vincristine and strongly indicates that a marked dose reduction should be recommended. Clinicians should be made aware of the potential for altered drug disposition for agents such as vincristine in patients with this rare genetic condition.

Activation of the Anaphase Promoting Complex Reverses Multiple Drug Resistant Cancer in a Canine Model of Multiple Drug Resistant Lymphoma.

Simple SummaryMultiple drug resistant cancers develop all too soon in patients who received successful cancer treatment. A lack of treatment options often leaves palliative care as the last resort. We tested whether the insulin sensitizer, metformin, known to have anti-cancer activity, could impact canines with drug resistant lymphoma when added to chemotherapy. All canines in the study expressed protein markers of drug resistance and within weeks of receiving metformin, the markers were decreased. A microarray was performed, and from four canines assessed, a common set of 290 elevated genes were discovered in tumor cells compared to control cells. This cluster was enriched with genes that stall the cell cycle, with a large component representing substrates of the Anaphase Promoting Complex (APC), which degrades proteins. One canine entered partial remission. RNAs from this canine showed that APC substrates were decreased during remission and elevated again during relapse, suggesting that the APC was impaired in drug resistant canines and restored when remission occurred. We validated our results in cell lines using APC inhibitors and activators. We conclude that the APC may be a vital guardian of the genome and could delay the onset of multiple drug resistance when activated.Like humans, canine lymphomas are treated by chemotherapy cocktails and frequently develop multiple drug resistance (MDR). Their shortened clinical timelines and tumor accessibility make canines excellent models to study MDR mechanisms. Insulin-sensitizers have been shown to reduce the incidence of cancer in humans prescribed them, and we previously demonstrated that they also reverse and delay MDR development in vitro. Here, we treated canines with MDR lymphoma with metformin to assess clinical and tumoral responses, including changes in MDR biomarkers, and used mRNA microarrays to determine differential gene expression. Metformin reduced MDR protein markers in all canines in the study. Microarrays performed on mRNAs gathered through longitudinal tumor sampling identified a 290 gene set that was enriched in Anaphase Promoting Complex (APC) substrates and additional mRNAs associated with slowed mitotic progression in MDR samples compared to skin controls. mRNAs from a canine that went into remission showed that APC substrate mRNAs were decreased, indicating that the APC was activated during remission. In vitro validation using canine lymphoma cells selected for resistance to chemotherapeutic drugs confirmed that APC activation restored MDR chemosensitivity, and that APC activity was reduced in MDR cells. This supports the idea that rapidly pushing MDR cells that harbor high loads of chromosome instability through mitosis, by activating the APC, contributes to improved survival and disease-free duration.

Leonurine Promotes Cisplatin Sensitivity in Human Cervical Cancer Cells Through Increasing Apoptosis and Inhibiting Drug-Resistant Proteins.

BackgroundCisplatin-based neoadjuvant chemotherapy and concurrent radiotherapy and chemotherapy are the main treatment for advanced cervical cancer. However, the development of multidrug resistance (MDR) leads to chemotherapy failure, tumor recurrence and poor survival. In this research, we investigated the effect and corresponding mechanism of leonurine on cisplatin sensitivity of cervical cancer cells.MethodsAnti-cervical cancer efficacy of leonurine and leonurine combined with cisplatin was examined in C33A and Ms751 cells. The cell counting kit-8 assay and bromodeoxyuridine assay were applied for measuring cell proliferation. CompuSyn software was used to calculate the combination index and assess the synergistic effect of leonurine and cisplatin on cell proliferation. The cell cycle distribution and cell apoptosis were analyzed by flow cytometry. The expression of cleaved caspase-3, poly ADP-ribose polymerase (PARP), B-cell lymphoma-2 associated X (BAX), B-cell lymphoma-2 (BCL-2), P glycoprotein (P-Gp) protein and multiple drug resistance protein 1 (MRP1) was analyzed by Western blotting.ResultsLeonurine had time- and dose-dependent anti-proliferative effects on C33A and MS751 cells. Leonurine and cisplatin combination was more efficacious in inhibiting the growth of cervical cancer cells than either of the two drugs. The combined application has shown that the cervical cancer cells were arrested at G1 phase after treatments. Moreover, flow cytometry analysis indicated that the combined treatment could cause more cell apoptosis than the single drug treatment. Consistently, combined treatment elevated BAX/BCL-2 ratio, and the expression of BAX, PARP and cleaved caspase-3 proteins. Mechanistic investigations uncovered that the tumor-inhibiting effects of the co-treatment were mediated by repressing MDR, including MRP1 and P-Gp protein, thereby enhancing the efficiency of cisplatin.ConclusionLeonurine and cisplatin have synergistic antitumorigenic effects on cervical cancer. Combination with leonurine may serve as a novel strategy for enhancing cisplatin sensitivity via the inhibition of the expression of MRP1 and P-Gp.

Tripartite motif protein 25 is associated with epirubicin resistance in hepatocellular carcinoma cells via regulating PTEN/AKT pathway.

Tripartite motif protein 25 (TRIM25) expression was altered in various human cancers. Herein, we found that the expression of TRIM25 was elevated in hepatocellular carcinoma (HCC) tissues and cell lines. Knockdown of TRIM25 increased the sensitivity of HCC HepG2 cells to epirubicin (EPI), as indicated by reduced cell viability, enhanced cell apoptosis, and downregulated P-glycoprotein (P-gp) and multiple drug-resistance protein 1 (MRP1). Moreover, TRIM25 knockdown strengthened the effects of EPI on phosphatase and tensin homolog (PTEN) and phosphorylated (p)-AKT. However, overexpression of TRIM25 exerted an opposite effect, weakening the sensitivity of Huh7 to EPI, and obviously increasing PTEN and reducing p-AKT. Most important, all the changes induced by TRIM25 overexpression in Huh7 were reversed with additional treatment of LY294002 (an AKT pathway inhibitor). Notably, coimmunoprecipitation experiments confirmed the interaction between TRIM25 and PTEN. Knockdown of TRIM25 resulted in reduced ubiquitination of PTEN protein. Collectively, our data suggested that TRIM25 enhanced EPI resistance via modulating PTEN/AKT pathway, and targeting TRIM25 may enhance the sensitivity of HCC cells toward chemotherapy drugs.

The Effects Of Sevoflurane On The Progression And Cisplatinum Sensitivity Of Cervical Cancer Cells.

ObjectiveTo investigate the effect of sevoflurane on the progression of cervical cancer cells, and to explore its effect on the cisplatinum (DDP) sensitivity in cervical cancer cells and underlying mechanism.MethodsSiha and Hela cervical cancer cells were cultured and treated with 3% sevoflurane, 10 μmol/L DDP, or the co-treatment of sevoflurane and DDP, respectively. Cell proliferation was evaluated by the CCK8 assay. Cell apoptosis was assessed by flow cytometry. Cell migration was detected by wound healing assay. The expression of B-cell lymphoma-2 (BCL-2), B-cell lymphoma-2 associated X (BAX), Ezrin, matrix metalloproteinase 2 (MMP2), lung resistance-related protein (LRP), multiple drug resistance protein 1 (MRP1), glutathione-S-transferase-π (GST-π), and P glycoprotein (P-gp) protein was determined by Western blotting.ResultsAfter treated with sevoflurane, cell proliferation and migration rate in Siha and Hela cells were significantly elevated, while cell apoptosis was decreased. In addition, the expression of migration-related protein Ezrin and MMP2 was increased accordingly, apoptotic-related protein BCL-2 expression was also increased while BAX protein expression was decreased after sevoflurane treatment. The proliferation, migration rate, and apoptosis of Siha and Hela cells in sevoflurane plus DDP group were not significantly different with those in DDP group. There was no significant difference in apoptotic-related protein, migration-related protein, and drug resistance-associated proteins expression between DDP treatment group and combined treatment group.ConclusionSevoflurane promotes the progression but has no effect on the cisplatinum sensitivity in cervical cancer cells.

S100A9 regulates cisplatin chemosensitivity of squamous cervical cancer cells and related mechanism.

ObjectiveOur previous research has shown that the expression of S100 calcium-binding protein A9 (S100A9) in tumor cells was associated with neoadjuvant chemotherapy sensitivity in cervical squamous cell carcinoma. In the present study, we altered the expression of S100A9 through infecting lentivirus, investigated its effect on the chemosensitivity to cisplatin of cervical cancer cells and then made a primary exploration of the involved mechanism.Materials and methodsLentivirus was employed to upregulate and downregulate S100A9 expression in SiHa cells. The protein expression level of apoptotic-related proteins Bcl-2 and Bax, drug resistance-related proteins multiple drug resistance protein 1 (MRP1), P glycoprotein (P-gp), glutathione-S-transferase-π (GST-π), lung resistance-related protein (LRP), and FOXO1 signaling pathway related proteins was detected by Western blot. The CCK-8 assay was used to examine chemosensitivity to cisplatin, and the proportion of apoptosis cells was analyzed by the flow cytometry.ResultsS100A9 overexpression could obviously increase the IC50 value of SiHa cells to cisplatin and decrease the apoptosis rate induced by cisplatin. Downregulation of S100A9 led to the opposite results. In S100A9 overexpression SiHa cells, the expression level of Bcl-2, LRP, GST-π, p-AKT, p-ERK, p-FOXO1, and Nanog was significantly increased, while FOXO1 expression was decreased. The opposite results were observed in S100A9 knockdown SiHa cells.ConclusionDownregulation of S100A9 could significantly increase apoptosis rate, resulting in enhancing sensitivity of SiHa cells to cisplatin, which may be related to Bcl-2, GST-π, and LRP protein and by altering the AKT/ERK-FOXO1-Nanog signaling pathway.

Nivolumab in renal cancer

Renal cell carcinoma (RCC) is a chemoresistant tumor, characterized by a poor response and lack of survival benefit with conventional cytotoxic agents. Furthermore, the complexity and heterogeneity of RCC limit the biologic targets for novel agents to manage RCC. Expression of the multiple drug resistance (MDR) protein (ATP-binding cassette P-glycoprotein) is increased in RCC, while the Von Hippel Lindau protein is mutated or silenced in approximately half of sporadic RCC, resulting in high levels of hypoxia inhibiting factor (HIF) and the activation of several genes codifying growth factors and growth factors receptors, such as vascular endothelial growth factor (VEGF), platelet-derived growth factor B (PDGF-B), and transforming growth factor alpha (TGFα). Consequently, immunodrugs targeting pathways related to these proteins have been evaluated for the management of metastatic RCC (mRCC). This review provides an overview of drugs that have been evaluated or are under investigation for the treatment of mRCC, including the multi-tyrosine kinase inhibitors (TKIs) sunitinib, pazopanib, axitinib, the mammalian target of rapamycin (mTOR) inhibitors everolimus and temsirolimus, and nivolumab, which targets the programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) pathway. Promising results have been obtained with nivolumab, alone or in combination with TKIs such as sunitinib and pazopanib, and with ipilimumab, an immune checkpoint inhibitor which acts on the CTLA-4 pathway. Although much progress has been made, research with these and other agents is ongoing, and there is a need to identify makers of response to “tailor” the most suitable therapy, or sequence of therapies, to the individual patient, with the aim of improving outcomes and reducing unneeded toxicity.

Hsa-miR-631 resensitizes bortezomib-resistant multiple myeloma cell lines by inhibiting UbcH10.

Although bortezomib (BTZ) remains a first-line agent for multiple myeloma (MM) therapy, the development of BTZ resistance has become an indicator of poor prognosis in MM patients. It is thus urgent to develop strategies to restore the vulnerability of MM to BTZ. This study demonstrated, for the first time, that UbcH10 is highly expressed in BTZ-resistant myeloma cell lines U-266/BTZ, NCI-H929/BTZ and RPMI-8226/BTZ, which is attributed to the inactivation of post-transcriptional control. The in-depth study revealed that during the development of BTZ resistance in these cells, the hsa-miR-631 levels were decreased, which resulted in the increased expression of the target gene UbcH10. We also found that the multiple drug-resistant protein MDR1 exhibited a positive correlation with UbcH10 due to the reduced ubiquitination of MDR1, which was caused by high UbcH10 expression. Following overexpression of miR-631, both BTZ sensitivity and BTZ-induced apoptosis were enhanced in the resistant cells. Meanwhile, resensitization by miR-631 overexpression was blocked by exogenous expression of UbcH10, which was not regulated by intracellular miR-631. In conclusion, the miR-631/UbcH10/MDR1 pathway is closely associated with the development of BTZ resistance in myeloma cells, and the overexpression of miR-631 can significantly improve BTZ sensitivity in resistant myeloma cells.

Hinokitiol-Loaded Mesoporous Calcium Silicate Nanoparticles Induce Apoptotic Cell Death through Regulation of the Function of MDR1 in Lung Adenocarcinoma Cells.

Hinokitiol is a tropolone-related compound found in heartwood cupressaceous plants. Hinokitiol slows the growth of a variety of cancers through inhibition of cell proliferation. The low water solubility of hinokitiol leads to less bioavailability. This has been highlighted as a major limiting factor. In this study, mesoporous calcium silicate (MCS) nanoparticles, both pure and hinokitiol-loaded, were synthesized and their effects on A549 cells were analyzed. The results indicate that Hino-MCS nanoparticles induce apoptosis in higher concentration loads (>12.5 μg/mL) for A549 cells. Hino-MCS nanoparticles suppress gene and protein expression levels of multiple drug resistance protein 1 (MDR1). In addition, both the activity and the expression levels of caspase-3/-9 were measured in Hino-MCS nanoparticle-treated A549 cells. The Hino-MCS nanoparticles-triggered apoptosis was blocked by inhibitors of pan-caspase, caspase-3/-9, and antioxidant agents (N-acetylcysteine; NAC). The Hino-MCS nanoparticles enhance reactive oxygen species production and the protein expression levels of caspase-3/-9. Our data suggest that Hino-MCS nanoparticles trigger an intrinsic apoptotic pathway through regulating the function of MDR1 and the production of reactive oxygen species in A549 cells. Therefore, we believe that Hino-MCS nanoparticles may be efficacious in the treatment of drug-resistant human lung cancer in the future.

Pathogen-associated molecular patterns activate expression of genes involved in cell proliferation, immunity and detoxification in the amebocyte-producing organ of the snail Biomphalaria glabrata

The anterior pericardial wall of the snail Biomphalaria glabrata has been identified as a site of hemocyte production, hence has been named the amebocyte-producing organ (APO). A number of studies have shown that exogenous abiotic and biotic substances, including pathogen associated molecular patterns (PAMPs), are able to stimulate APO mitotic activity and/or enlarge its size, implying a role for the APO in innate immunity. The molecular mechanisms underlying such responses have not yet been explored, in part due to the difficulty in obtaining sufficient APO tissue for gene expression studies. By using a modified RNA extraction technique and microarray technology, we investigated transcriptomic responses of APOs dissected from snails at 24 h post-injection with two bacterial PAMPs, lipopolysaccharide (LPS) and peptidoglycan (PGN), or with fucoidan (FCN), which may mimic fucosyl-rich glycan PAMPs on sporocysts of Schistosoma mansoni. Based upon the number of genes differentially expressed, LPS exhibited the strongest activity, relative to saline-injected controls. A concurrent activation of genes involved in cell proliferation, immune response and detoxification metabolism was observed. A gene encoding checkpoint 1 kinase, a key regulator of mitosis, was highly expressed after stimulation by LPS. Also, seven different aminoacyl-tRNA synthetases that play an essential role in protein synthesis were found to be highly expressed. In addition to stimulating genes involved in cell proliferation, the injected substances, especially LPS, also induced expression of a number of immune-related genes including arginase, peptidoglycan recognition protein short form, tumor necrosis factor receptor, ficolin, calmodulin, bacterial permeability increasing proteins and E3 ubiquitin-protein ligase. Importantly, significant up-regulation was observed in four GiMAP (GTPase of immunity-associated protein) genes, a result which provides the first evidence suggesting an immune role of GiMAP in protostome animals. Moreover, altered expression of genes encoding cytochrome P450, glutathione-S-transferase, multiple drug resistance protein as well as a large number of genes encoding enzymes associated with degradation and detoxification metabolism was elicited in response to the injected substances.

High Expression of Lung Resistance Protein mRNA at Diagnosis Predicts Poor Early Response to Induction Chemotherapy in Childhood Acute Lymphoblastic Leukemia.

Treatment failure in leukemia is due to either pharmacokinetic resistance or cell resistance to drugs. Gene expression of multiple drug resistance protein (MDR-1), multidrug resistance-related protein (MRP) and low resistance protein (LRP) was assessed in 45 pediatric ALL cases and 7 healthy controls by real time PCR. The expression was scored as negative, weak, moderate and strong. The male female ratio of cases was 2.75:1 and the mean age was 5.2 years. Some 26/45 (58%) were in standard risk, 17/45(38%) intermediate and 2/45 (4%) in high risk categorie, 42/45 (93%) being B-ALL and recurrent translocations being noted in 5/45 (11.0%). Rapid early response (RER) at day 14 was seen in 37/45 (82.3%) and slow early response (SER) in 8/45 (17.7%) cases. Positive expression of MDR-1, LRP and MRP was noted in 14/45 (31%), 15/45 (33%) and 27/45 (60%) cases and strong expression in 3/14 (21%), 11/27 (40.7%) and 8/15 (53.3%) cases respectively. Dual or more gene positivity was noted in 17/45 (38%) cases. 46.5 % (7/15) of LRP positive cases at day 14 were in RER as compared to 100% (30/30) of LRP negative cases (p<0.05). All 8 (100%) LRP positive cases in SER had strong LRP expression (p=<0.05). Moreover, only 53.3% of LRP positive cases were in haematological remission at day 30 as compared to 100% of LRP negative cases (p=<0.05). Our study indicated that increased LRP expression at diagnosis in pediatric ALL predicts poor response to early treatment and hence can be used as a prognostic marker. However, larger prospective studies with longer follow up are needed, to understand the clinical relevance of drug resistance proteins.

Anterior gradient 2 is a binding stabilizer of hypoxia inducible factor-1α that enhances CoCl2 -induced doxorubicin resistance in breast cancer cells.

Hypoxia inducible factor-1α (HIF-1α) is associated with human breast cancer chemoresistance. Various reports have suggested that multiple pathways are involved in HIF-1α induction and that the molecular mechanisms regulating HIF-1α-induced chemoresistance are still not fully understood. Here, we report that anterior gradient 2 (AGR2), a proposed breast cancer biomarker, is an essential regulator in hypoxia-induced doxorubicin resistance through the binding and stabilization of HIF-1α. Our results show that knockdown of AGR2 in MCF-7 cells leads to the suppression of HIF-1α-induced doxorubicin resistance, whereas elevated levels of AGR2 in MDA-MB-231 cells enhance HIF-1α-induced doxorubicin resistance. AGR2 expression, in turn, is upregulated by the hypoxic induction of HIF-1α at both translational and transcriptional levels via a hypoxia-responsive region from −937 to −912 bp on the AGR2 promoter sequence. By specific binding to HIF-1α, the increased level of intracellular AGR2 stabilizes HIF-1α and delays its proteasomal degradation. Finally, we found that AGR2-stabilized HIF-1α escalates multiple drug resistance protein 1 (MDR1) mRNA levels and limits doxorubicin intake of MCF-7 cells, whereas MCF-7/ADR, a doxorubicin resistant cell line with deficient AGR2 and HIF-1α, acquires wild-type MDR1 overexpression. Our findings, for the first time, describe AGR2 as an important regulator in chemical hypoxia-induced doxorubicin resistance in breast cancer cells, providing a possible explanation for the variable levels of chemoresistance in breast cancers and further validating AGR2 as a potential anti-breast cancer therapeutic target.

Manifestation of cystic fibrosis transmembrane regulator (CFTR) in hepatic ductal structures and renal tubules of female rats with experimental cholestasis of pregnancy.

Studies by the immunohistochemical method with semiquantitative analysis of images showed that hyperprolactinemia stimulated CFTR protein manifestation in the bile ducts of female rats, which was clearly expressed in experimental cholestasis of pregnancy. The expression of CFTR in the renal tubules was reduced in hyperprolactinemia under conditions of normal liver function and in cholestasis of pregnancy. Significant positive correlations between CFTR, prolactin receptor, and multiple drug resistance protein 3 were detected in the bile ducts, but not in the renal tubules. Presumably, prolactin has a direct effect on CFTR expression in the bile ducts and indirect effect in the renal tubules. Changes in CFTR protein manifestation in the hepatic ductal structures and renal tubules in experimental pregnancy cholestasis could aggravate the disease.

Protection of a Ceramide Synthase 2 Null Mouse from Drug-induced Liver Injury: ROLE OF GAP JUNCTION DYSFUNCTION AND CONNEXIN 32 MISLOCALIZATION

Very long chain (C22-C24) ceramides are synthesized by ceramide synthase 2 (CerS2). A CerS2 null mouse displays hepatopathy because of depletion of C22-C24 ceramides, elevation of C16-ceramide, and/or elevation of sphinganine. Unexpectedly, CerS2 null mice were resistant to acetaminophen-induced hepatotoxicity. Although there were a number of biochemical changes in the liver, such as increased levels of glutathione and multiple drug-resistant protein 4, these effects are unlikely to account for the lack of acetaminophen toxicity. A number of other hepatotoxic agents, such as d-galactosamine, CCl4, and thioacetamide, were also ineffective in inducing liver damage. All of these drugs and chemicals require connexin (Cx) 32, a key gap junction protein, to induce hepatotoxicity. Cx32 was mislocalized to an intracellular location in hepatocytes from CerS2 null mice, which resulted in accelerated rates of its lysosomal degradation. This mislocalization resulted from the altered membrane properties of the CerS2 null mice, which was exemplified by the disruption of detergent-resistant membranes. The lack of acetaminophen toxicity and Cx32 mislocalization were reversed upon infection with recombinant adeno-associated virus expressing CerS2. We establish that Gap junction function is compromised upon altering the sphingolipid acyl chain length composition, which is of relevance for understanding the regulation of drug-induced liver injury.

A simple method for isolating and culturing the rat brain microvascular endothelial cells

Brain microvascular endothelial cells (BMECs), a main component of the blood–brain barrier, play a critical role in the pathogenesis of many brain diseases. The primary culture of BMECs has been used in various models for studying cerebrovascular diseases in vitro. However, there are still several problems existing in the isolation and cultivation of primary rat BMECs, such as low yield, contamination with other cell types, and requirement of a large number of animals and expensive growth factor. In this study, we describe a simple, economical (without any growth factor) and repeatable method to obtain endothelial cells with high purity (>99%) and yield (about 2.2×107 per rat) from cerebral cortexes of neonatal rat, mainly from gray matter. In vitro examinations determined that the isolated cells expressed typical phenotypic markers of differentiated brain endothelium such as multiple drug resistant protein, von Willebrand factor, platelet endothelial cell adhesion molecule 1 (PECAM-1/CD31), and intercellular adhesion molecule (ICAM). These cells also possessed morphological and ultra-structural characteristics that were observed by phase contrast microscope and electric microscope. Then GFAP and α-SMA were used, respectively, to identify astrocyte and pericyte which were potential to contaminate primary culturing of BMECs. And specific reaction of endothelial cells to external stimulation was tested by culture with TNF-α for 24h. All these results of our experiments supply that our protocol provides an effective and reliable method to obtain high purity and yield of rat BMECs and offers a useful tool for studying cellular physiology, cerebrovascular diseases, brain tumors, blood–brain barrier and neurovascular units, etc.

Curcumin-loaded nanoparticles induce apoptotic cell death through regulation of the function of MDR1 and reactive oxygen species in cisplatin-resistant CAR human oral cancer cells

Curcumin is a polyphenolic compound which possesses anticancer potential. It has been shown to induce cell death in a variety of cancer cells, however, its effect on CAL27‑cisplatin-resistant human oral cancer cells (CAR cells) has not been elucidated to date. The low water solubility of curcumin which leads to poor bioavailability, however, has been highlighted as a major limiting factor. In this study, we utilized water-soluble PLGA curcumin nanoparticles (Cur-NPs), and investigated the effects of Cur-NPs on CAR cells. The results showed Cur-NPs induced apoptosis in CAR cells but exhibited low cytotoxicity to normal human gingival fibroblasts (HGFs) and normal human oral keratinocytes (OKs). Cur-NPs triggered DNA concentration, fragmentation and subsequent apoptosis. Compared to untreated CAR cells, a more detectable amount of Calcein-AM accumulation was found inside the treated CAR cells. Cur-NPs suppressed the protein and mRNA expression levels of MDR1. Both the activity and the expression levels of caspase-3 and caspase-9 were elevated in the treated CAR cells. The Cur-NP-triggered apoptosis was blocked by specific inhibitors of pan-caspase (z-VAD-fmk), caspase-3 (z-DEVD-fmk), caspase-9 (z-LEHD-fmk) and antioxidant agent (N-acetylcysteine; NAC). Cur-NPs increased reactive oxygen species (ROS) production, upregulated the protein expression levels of cleaved caspase-3/caspase-9, cytochrome c, Apaf-1, AIF, Bax and downregulated the protein levels of Bcl-2. Our results suggest that Cur-NPs triggered the intrinsic apoptotic pathway through regulating the function of multiple drug resistance protein 1 (MDR1) and the production of reactive oxygen species (ROS) in CAR cells. Cur-NPs could be potentially efficacious in the treatment of cisplatin-resistant human oral cancer.

N-Benzyloxycarbonyl-S-(2,4-dinitrophenyl)glutathione dibutyl diester is inhibitory to melarsoprol resistant cell lines overexpressing the T. bruceiMRPA transporter

A series of glutathione derivatives 1–4, modified at the N,S and/or COOH sites, with in vitro antitrypanosomal activity were tested against bloodstream form Trypanosoma brucei 247 wild type and a T. b. brucei 247 strain over-expressing the multiple drug resistance protein (MRPA) by 50–100x to assess the susceptibility of these compounds to resistance by the TbMRP protein. Of the compounds tested, only compound 1 inhibited both bloodstream form T. brucei and T. bruceiMRPA, with a resistance factor of 1.4, indicating it to be an inhibitor of this protein and proteins acting in synergy with the transporter, whilst 2 &3 and its derivatives showed reduced inhibitory activity against T. bruceiMRPA, indicating them to be substrates and susceptible to resistance.

Characterization of Human Colorectal Cancer MDR1/P-gp Fab Antibody

In this study, the peptide sized 21 kDa covering P-gp transmembrane region was first prepared for generating a novel mouse monoclonal antibody Fab fragment with biological activity against multiple drug resistance protein P-gp21 by phage display technology. Phage-displayed antibody library prepared from mice spleen tissues was selected against the recombinant protein P-gp21 with five rounds of panning. A number of clones expressing Fab bound to P-gp21, showing neutralized activity in vitro, were isolated and screened by enzyme-linked immunosorbent assay based on its recognition properties to P-gp21 and human colorectal cancer tissue homogenate, resulting in identification of an optimal recombinant Fab clone (Number 29). Further characterization by recloning number 29 into an expression vector showed significant induction of the Fab antibody in the clone number 29 by Isopropyl β-D-1-thiogalactopyranoside (IPTG). After purified by HiTrap Protein L, the specificity of the Fab antibody to P-gp21 was also confirmed. Not only was the targeted region of this monoclonal Fab antibody identified as a 16-peptide epitope (ALKDKKELEGSGKIAT) comprising residues 883–898 within the transmembrane (TM) domain of human P-gp, but also the binding ability with it was verified. The clinical implication of our results for development of personalized therapy of colorectal cancer will be further studied.

BPR1K653, a Novel Aurora Kinase Inhibitor, Exhibits Potent Anti-Proliferative Activity in MDR1 (P-gp170)-Mediated Multidrug-Resistant Cancer Cells

BackgroundOver-expression of Aurora kinases promotes the tumorigenesis of cells. The aim of this study was to determine the preclinical profile of a novel pan-Aurora kinase inhibitor, BPR1K653, as a candidate for anti-cancer therapy. Since expression of the drug efflux pump, MDR1, reduces the effectiveness of various chemotherapeutic compounds in human cancers, this study also aimed to determine whether the potency of BPR1K653 could be affected by the expression of MDR1 in cancer cells.Principal FindingsBPR1K653 specifically inhibited the activity of Aurora-A and Aurora-B kinase at low nano-molar concentrations in vitro. Anti-proliferative activity of BPR1K653 was evaluated in various human cancer cell lines. Results of the clonogenic assay showed that BPR1K653 was potent in targeting a variety of cancer cell lines regardless of the tissue origin, p53 status, or expression of MDR1. At the cellular level, BPR1K653 induced endo-replication and subsequent apoptosis in both MDR1-negative and MDR1-positive cancer cells. Importantly, it showed potent activity against the growth of xenograft tumors of the human cervical carcinoma KB and KB-derived MDR1-positive KB-VIN10 cells in nude mice. Finally, BPR1K653 also exhibited favorable pharmacokinetic properties in rats.Conclusions and SignificanceBPR1K653 is a novel potent anti-cancer compound, and its potency is not affected by the expression of the multiple drug resistant protein, MDR1, in cancer cells. Therefore, BPR1K653 is a promising anti-cancer compound that has potential for the management of various malignancies, particularly for patients with MDR1-related drug resistance after prolonged chemotherapeutic treatments.

The expression and significance of MRP1, LRP, TOPOIIβ, and BCL2 in tongue squamous cell carcinoma

Multiple drug resistance protein 1 (MRP1), lung resistance protein (LRP), topoisomerase IIβ (TOPOIIβ) and B-cell lymphoma 2 (BCL2) are well known in the development of drug resistance in cancer cells. The aim of this study was to evaluate the relationship between them and the clinicopathological features, their expression differences between tumor tissue and experimental drug-resistant model in tongue carcinoma. Multiple drug resistance protein 1, LRP, TOPOIIβ, and BCL2 expression was examined by immunohistochemistry in specimens from radical surgeries of 65 patients with tongue carcinoma. A cisplatin-resistance cell line, SCC-15/cisplatin, was established from a cisplatin-sensitive cell line, SCC-15. A MTT-based method was used to analyze drug potencies. Immunofluorescence was used to detect protein expression in both cell lines. Western blot was used to compare the protein expressions in specimens and SCC-15/cisplatin cells. We found higher expression of MRP1, LRP, and BCL2 and lower expression of TOPOIIβ in tongue carcinoma compared with adjacent non-neoplastic tongue tissues (P < 0.05). In addition, MRP1 and TopoIIβ expression were significantly associated with clinical stage, lymph node metastasis and histologic grade, and LRP was significantly associated with histologic grade in the samples (P < 0.05). Finally, Western blot showed that higher expressions of MRP1, LRP, and BCL2 and lower expression of TopoIIβ were observed in SCC-15/cisplatin cells than in clinical samples. Our results suggest that the high expressions of MRP1, LRP, and BCL2 and low expression of TOPOIIβ in patients with tongue carcinoma indicates that intrinsic drug resistance may exist in tongue carcinoma, and is associated with tumor differentiation and cisplatin resistance in tongue carcinoma.