Gene Summary

Gene:ABCC1; ATP binding cassette subfamily C member 1
Aliases: MRP, ABCC, GS-X, MRP1, ABC29
Summary:The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra-and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This full transporter is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions as a multispecific organic anion transporter, with oxidized glutatione, cysteinyl leukotrienes, and activated aflatoxin B1 as substrates. This protein also transports glucuronides and sulfate conjugates of steroid hormones and bile salts. Alternatively spliced variants of this gene have been described but their full-length nature is unknown. [provided by RefSeq, Apr 2012]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:multidrug resistance-associated protein 1
Source:NCBIAccessed: 11 March, 2017

Cancer Overview

ABCC1 (MRP1 is associated with multidrug resistance in a wide range of cancers and a marker of tumor aggressiveness.

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (11)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ABCC1 (cancer-related)

Juang V, Lee HP, Lin AM, Lo YL
Cationic PEGylated liposomes incorporating an antimicrobial peptide tilapia hepcidin 2-3: an adjuvant of epirubicin to overcome multidrug resistance in cervical cancer cells.
Int J Nanomedicine. 2016; 11:6047-6064 [PubMed] Free Access to Full Article Related Publications
Antimicrobial peptides (AMPs) have been recently evaluated as a new generation of adjuvants in cancer chemotherapy. In this study, we designed PEGylated liposomes encapsulating epirubicin as an antineoplastic agent and tilapia hepcidin 2-3, an AMP, as a multidrug resistance (MDR) transporter suppressor and an apoptosis/autophagy modulator in human cervical cancer HeLa cells. Cotreatment of HeLa cells with PEGylated liposomal formulation of epirubicin and hepcidin 2-3 significantly increased the cytotoxicity of epirubicin. The liposomal formulations of epirubicin and/or hepcidin 2-3 were found to noticeably escalate the intracellular H2O2 and O2(-) levels of cancer cells. Furthermore, these treatments considerably reduced the mRNA expressions of MDR protein 1, MDR-associated protein (MRP) 1, and MRP2. The addition of hepcidin 2-3 in liposomes was shown to markedly enhance the intracellular epirubicin uptake and mainly localized into the nucleus. Moreover, this formulation was also found to trigger apoptosis and autophagy in HeLa cells, as validated by significant increases in the expressions of cleaved poly ADP ribose polymerase, caspase-3, caspase-9, and light chain 3 (LC3)-II, as well as a decrease in mitochondrial membrane potential. The apoptosis induction was also confirmed by the rise in sub-G1 phase of cell cycle assay and apoptosis percentage of annexin V/propidium iodide assay. We found that liposomal epirubicin and hepcidin 2-3 augmented the accumulation of GFP-LC3 puncta as amplified by chloroquine, implying the involvement of autophagy. Interestingly, the partial inhibition of necroptosis and the epithelial-mesenchymal transition by this combination was also verified. Altogether, our results provide evidence that coincubation with PEGylated liposomes of hepcidin 2-3 and epirubicin caused programmed cell death in cervical cancer cells through modulation of multiple signaling pathways, including MDR transporters, apoptosis, autophagy, and/or necroptosis. Thus, this formulation may provide a new platform for the combined treatment of traditional chemotherapy and hepcidin 2-3 as a new adjuvant for effective MDR reversal.

Dragoj M, Milosevic Z, Bankovic J, et al.
Targeting CXCR4 and FAK reverses doxorubicin resistance and suppresses invasion in non-small cell lung carcinoma.
Cell Oncol (Dordr). 2017; 40(1):47-62 [PubMed] Related Publications
BACKGROUND: Current high lung cancer mortality rates are mainly due to the occurrence of metastases and therapeutic resistance. Therefore, simultaneous targeting of these processes may be a valid approach for the treatment of this type of cancer. Here, we assessed relationships between CXC chemokine receptor type 4 (CXCR4) and focal adhesion kinase (FAK) gene expression levels and expression levels of the drug resistance-related genes ABCB1 and ABCC1, and tested the potential of CXCR4 and FAK inhibitors to reverse doxorubicin (DOX) resistance and to decrease the invasive capacity of non-small cell lung carcinoma (NSCLC) cells.
METHODS: qRT-PCR was used for gene expression analyses in primary lung tissue samples obtained from 30 NSCLC patients and the human NSCLC-derived cell lines NCI-H460, NCI-H460/R and COR-L23. MTT, flow cytometry, cell death and β-galactosidase activity assays were used to assess the in vitro impact of CXCR4 and FAK inhibitors on DOX sensitivity. In addition, invasion and gelatin degradation assays were used to assess the in vitro impact of the respective inhibitors on metastasis-related processes in combination with DOX treatment.
RESULTS: We found that ABCB1 over-expression was significantly associated with CXCR4 and FAK over-expression, whereas ABCC1 over-expression was associated with increased FAK expression. We also found that CXCR4 and FAK inhibitors strongly synergized with DOX in reducing cell viability, arresting the cell cycle in the S or G2/M phases and inducing senescence. Additionally, we found that DOX enhanced the anti-invasive potential of CXCR4 and FAK inhibitors by reducing gelatin degradation and invasion.
CONCLUSIONS: From our data we conclude that targeting of CXCR4 and FAK may overcome ABCB1 and ABCC1-dependent DOX resistance in NSCLC cells and that simultaneous treatment of these cells with DOX may potentiate the anti-invasive effects of CXCR4 and FAK inhibitors.

Drozd E, Krzysztoń-Russjan J, Marczewska J, et al.
Up-regulation of glutathione-related genes, enzyme activities and transport proteins in human cervical cancer cells treated with doxorubicin.
Biomed Pharmacother. 2016; 83:397-406 [PubMed] Related Publications
Doxorubicin (DOX), one of the most effective anticancer drugs, acts in a variety of ways including DNA damage, enzyme inhibition and generation of reactive oxygen species. Glutathione (GSH) and glutathione-related enzymes including: glutathione peroxidase (GPX), glutathione reductase (GSR) and glutathione S-transferases (GST) may play a role in adaptive detoxification processes in response to the oxidative stress, thus contributing to drug resistance phenotype. In this study, we investigated effects of DOX treatment on expression and activity of GSH-related enzymes and multidrug resistance-associated proteins in cultured human cervical cancer cells displaying different resistance against this drug (HeLa and KB-V1). Determination of expression level of genes encoding GST isoforms and MRP proteins (GCS, GPX, GSR, GSTA1-3, GSTM1, GSTP1, ABCC1-3, MGST1-3) was performed using StellARray™ Technology. Enzymatic activities of GPX and GSR were measured using biochemical methods. Expression of MRP1 was examined by immunofluorescence microscopy. This study showed that native expression levels of GSTM1 and GSTA3 were markedly higher in KB-V1 cells (2000-fold and 200-fold) compared to HeLa cells. Resistant cells have also shown significantly elevated expression of GSTA1 and GSTA2 genes (200-fold and 50-fold) as a result of DOX treatment. In HeLa cells, exposure to DOX increased expression of all genes: GSTM1 (7-fold) and GSTA1-3 (550-fold, 150-fold and 300-fold). Exposure to DOX led to the slight increase of GCS expression as well as GPX activity in KB-V1 cells, while in HeLa cells it did not. Expression of ABCC1 (MRP1) was not increased in any of the tested cell lines. Our results indicate that expression of GSTM1 and GSTA1-3 genes is up-regulated by DOX treatment and suggest that activity of these genes may be associated with drug resistance of the tested cells. At the same time, involvement of MRP1 in DOX resistance in the given experimental conditions is unlikely.

Kobayashi M, Funayama R, Ohnuma S, et al.
Wnt-β-catenin signaling regulates ABCC3 (MRP3) transporter expression in colorectal cancer.
Cancer Sci. 2016; 107(12):1776-1784 [PubMed] Free Access to Full Article Related Publications
We determined the gene expression profiles for 48 ATP binding cassette (ABC) transporters in matched colon cancer and normal colon tissues in order to provide insight into the mechanisms underlying expression of transporters related to colon carcinogenesis. The expression of ABCB1, ABCC1, ABCC2, ABCC3, and ABCG2 was altered in association with colon carcinogenesis. Among these transporters, the expression of ABCC3 was repressed by Wnt signaling pathway in colon cancer cell lines. Knockdown of the pathway components transcription factor 7-like 2 (TCF7L2) or β-catenin thus increased ABCC3 expression, whereas activation of Wnt signaling with inhibitors of glycogen synthase kinase-3β (GSK-3β) reduced it. ChIP and luciferase reporter assays also showed that TCF7L2 binds to the ABCC3 locus and regulates its expression. Finally, overexpression of ABCC3 in colon cancer cells conferred resistance to anticancer drug-induced cytotoxicity. Our data thus suggest that Wnt signaling represses ABCC3 expression during colon carcinogenesis, and that subsequent upregulation of ABCC3 expression during drug treatment might contribute to acquired drug resistance.

Jiang YQ, Xu XP, Guo QM, et al.
Reversal of cisplatin resistance in non-small cell lung cancer stem cells by Taxus chinensis var.
Genet Mol Res. 2016; 15(3) [PubMed] Related Publications
Drug resistance in cells is a major impedance to successful treatment of lung cancer. Taxus chinensis var. inhibits the growth of tumor cells and promotes the synthesis of interleukins 1 and 2 and tumor necrosis factor, enhancing immune function. In this study, T. chinensis var.-induced cell death was analyzed in lung cancer cells (H460) enriched for stem cell growth in a defined serum-free medium. Taxus-treated stem cells were also analyzed for Rhodamine 123 (Rh-123) expression by flow cytometry, and used as a standard functional indicator of MDR. The molecular basis of T. chinensis var.-mediated drug resistance was established by real-time PCR analysis of ABCC1, ABCB1, and lung resistance-related protein (LRP) mRNA, and western blot analysis of MRP1, MDR1, and LRP. Our results revealed that stem cells treated with higher doses of T. chinensis var. showed significantly lower growth inhibition rates than did H460 cells (P < 0.05). The growth of stem and H460 cells treated with a combination of T. chinensis var. and cisplatin was also significantly inhibited (P < 0.05). Rh-123 was significantly accumulated in the intracellular region and showed delayed efflux in stem cells treated with T. chinensis var. (P < 0.05), compared to those treated with verapamil. T. chinensis var.-treated stem cells showed significant downregulation of the ABCC1, ABCB1, and LRP mRNA and MRP1, MDR1, and LRP (P < 0.05) compared to H460 cells. Thus, T. chinensis var.-mediated downregulation of MRP1, MDR1, and LRP might contribute to the reversal of drug resistance in non-small cell lung cancer stem cells.

Shahi MH, Farheen S, Mariyath MP, Castresana JS
Potential role of Shh-Gli1-BMI1 signaling pathway nexus in glioma chemoresistance.
Tumour Biol. 2016; 37(11):15107-15114 [PubMed] Related Publications
Chemoresistance is a common hurdle for the proper treatment of gliomas. The role of Shh-Gli1 signaling in glioma progression has been reported. However, its role in glioma chemoresistance has not been well studied yet. In this work, we found that Shh-Gli1 signaling regulates the expression of one stem cell marker, BMI1 (B cell-specific Moloney murine leukemia virus), in glioma. Interestingly, we also demonstrated high expression of MRP1 (multi-drug resistance protein 1) in glioma. MRP1 expression was decreased by BMI1 siRNA and Shh-Gli1 cell signaling specific inhibitor GANT61 in our experiments. GANT61 very efficiently inhibited cell colony growth in glioma cell lines, compared to temozolomide. Moreover, a synergic effect of GANT61 and temozolomide drastically decreased the LD50 of temozolomide in the cell colony experiments. Therefore, our results suggest that there is a potential nexus of Shh-Gli1-BMI1 cell signaling to regulate MRP1 and to promote chemoresistance in glioma. Henceforth, our study opens the possibility of facing new targets, Gli1 and BMI1, for the effective treatment of glioma suppression of chemoresistance with adjuvant therapy of GANT61 and temozolomide.

Arrigoni E, Galimberti S, Petrini M, et al.
ATP-binding cassette transmembrane transporters and their epigenetic control in cancer: an overview.
Expert Opin Drug Metab Toxicol. 2016; 12(12):1419-1432 [PubMed] Related Publications
INTRODUCTION: Members of the ATP-binding cassette (ABC) transmembrane transporters control the passage of several substrates across cell membranes, including drugs. This means that ABC transporters may exert a significant influence on the kinetics and dynamics of pharmacological agents, being responsible for the occurrence of multidrug-resistant (MDR) phenotype. Pharmacogenetic analyses have shed light on gene expression and polymorphisms as possible markers predictive of transporter activity. However, a non-negligible part of the variability in drug pharmacokinetics and pharmacodynamics still remains. Further research has demonstrated that different epigenetic mechanisms exert a coordinated control over ABC genes, and on the corresponding MDR phenotype. Areas covered: DNA methylation and histone modifications (namely acetylation, methylation, phosphorylation, etc.) significantly impact gene expression, as well as noncoding RNA molecules that are involved in the post-transcriptional control of the ABC transporters ABCB1, ABCC1 and ABCG2. We describe the epigenetic mechanisms of gene expression control for ABC transporters and their relevant association with the MDR phenotype in human cancer. Expert opinion: The clinical meaning of those observations is discussed in the review, highlighting the importance of the epigenetic control of the ABC transporters for the clinical therapeutic outcomes that despite their effects and applications, requires further investigation.

Aras Y, Erguven M, Aktas E, et al.
Antagonist activity of the antipsychotic drug lithium chloride and the antileukemic drug imatinib mesylate during glioblastoma treatment in vitro.
Neurol Res. 2016; 38(9):766-74 [PubMed] Related Publications
OBJECTIVES: Glioblastoma (GBM), the most common primary tumour of the central nervous system, is characterised by a high malignancy and poor prognosis. The aims of this study were to investigate whether the combination of imatinib mesylate (IM) and lithium chloride (LiCl) exhibited a synergistic effect in treatment and to determine whether midkine (MK) affected the fate of this treatment in vitro.
METHODS: Monolayer and spheroid cultures of the T98G human GBM cell line were treated with an IM and LiCl combination for 72 h. The cell proliferation index, apoptotic index, cell cycle distribution, apoptotic and anti-apoptotic protein levels, and cAMP level as well as the cellular morphology and ultrastructure were evaluated.
RESULTS: All applications inhibited cell proliferation and induced apoptosis. The most substantial decreases in cell proliferation and the caspase-3, epidermal growth factor receptor (EGFR), platelet derived growth factor receptor-alpha (PDGFR-α), multidrug resistance protein-1 (MRP-1), aquaporin-4 (AQP-4) and cAMP levels were induced by the LiCl treatment, which exhibited more pronounced effects compared with the combination treatment. LiCl was less effective in decreasing the MK and B cell lymphoma-2 (Bcl-2) levels compared with the combination treatment. The most substantial decrease in the p170 levels was identified following the combination treatment, whereas IM induced the second greatest decrease. LiCl alone had no effect on the p170 levels. IM induced the most substantial decrease in the phospho-glycogen synthase kinase 3-beta (p-GSK-3β)/glycogen synthase kinase 3-beta (GSK-3β) ratio, and LiCl induced the second most substantial decrease. Both LiCl and the combination treatment induced G2 + M arrest, whereas IM induced G0 + G1 arrest after 72 h of exposure. An apoptotic appearance and autophagic vacuoles were commonly identified in the LiCl, combination and IM groups, respectively.
CONCLUSIONS: The combination of IM and LiCl exhibited an antagonist effect, and MK had a role at this antagonism.

Mahdizadeh S, Karimi G, Behravan J, et al.
Crocin suppresses multidrug resistance in MRP overexpressing ovarian cancer cell line.
Daru. 2016; 24(1):17 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Crocin, one of the main constituents of saffron extract, has numerous biological effects such as anti-cancer effects. Multidrug resistance-associated proteins 1 and 2 (MRP1 and MRP2) are important elements in the failure of cancer chemotherapy. In this study we aimed to evaluate the effects of crocin on MRP1 and MRP2 expression and function in human ovarian cancer cell line A2780 and its cisplatin-resistant derivative A2780/RCIS cells.
METHODS: The cytotoxicity of crocin was assessed by the MTT assay. The effects of crocin on the MRP1 and MRP2 mRNA expression and function were assessed by real-time RT-PCR and MTT assays, respectively.
RESULTS: Our study indicated that crocin reduced cell proliferation in a dose-dependent manner in which the reduction in proliferation rate was more noticeable in the A2780 cell line compared to A2780/RCIS. Crocin reduced MRP1 and MRP2 gene expression at the mRNA level in A2780/RCIS cells. It increased doxorubicin cytotoxicity on the resistant A2780/RCIS cells in comparison with the drug-sensitive A2780 cells.
CONCLUSION: Totally, these results indicated that crocin could suppress drug resistance via down regulation of MRP transporters in the human ovarian cancer resistant cell line.

Chen YL, Yang TY, Chen KC, et al.
Hypoxia can impair doxorubicin resistance of non-small cell lung cancer cells by inhibiting MRP1 and P-gp expression and boosting the chemosensitizing effects of MRP1 and P-gp blockers.
Cell Oncol (Dordr). 2016; 39(5):411-433 [PubMed] Related Publications
BACKGROUND: Non-small cell lung cancers (NSCLCs) frequently exhibit resistance to therapeutic drugs, which seriously hampers their treatment. Here, we set out to assess the roles of the multidrug resistance protein 1 (MRP1) and P-glycoprotein (P-gp) in the doxorubicin (DOX) resistance of NSCLC cells, as well as the putative therapeutic efficacy of MRP1 and P-gp blockers on DOX-treated NSCLC cells.
METHODS: The impact of DOX on cell survival, DOX efflux and MRP1 and P-gp expression was assessed in 5 different NSCLC-derived cell lines (parental CH27, A549, H1299, H460, and DOX resistant CH27) in the absence or presence of MK571 (MRP1 inhibitor) or Verapamil (P-gp inhibitor), under both normoxic and hypoxic conditions.
RESULTS: We found that in response to DOX treatment, NSCLC cells that express high levels of MRP1 and P-gp (such as CH27) showed a better DOX efflux and a higher DOX resistance. MK571 and Verapamil were found to abolish DOX resistance and to act as chemosensitizers for DOX therapy in all cell lines tested. We also found that hypoxia could inhibit MRP1 and P-gp expression in a HIF-1α-dependent manner, abolish DOX resistance and boost the chemosensitizer effect of MK571 and Verapamil on DOX treatment of all the NSCLC cells tested, except the DOX-resistant CH27 cells.
CONCLUSIONS: From our data we conclude that MRP1 and P-gp play critical roles in the DOX resistance of the NSCLC cells tested. MRP1 and P-gp targeted therapy using MK571, Verapamil, CoCl2 or ambient hypoxia appeared to be promising in abolishing the DOX efflux and DOX resistance of the NSCLC cells. The putative therapeutic efficacies of MRP1 and/or P-gp blockers on NSCLC cells are worthy of note.

Kang HR, Choi HG, Jeon CK, et al.
Butyrate-mediated acquisition of chemoresistance by human colon cancer cells.
Oncol Rep. 2016; 36(2):1119-26 [PubMed] Related Publications
Butyrate is a short-chain fatty acid produced by the intestinal microflora and it not only induces apoptosis but also inhibits the proliferation of cancer cells. Recently, it has been reported that butyrate may cause resistance in colon cancer cells. Therefore, we investigated the effects of increased resistance to butyrate in HCT116 colon cancer cells. We established HCT116 cells resistant to butyrate (HCT116/BR) by treating HCT116 parental cells (HCT116/PT) with increasing concentrations of butyrate to a maximum of 1.6 mM for 3 months. The butyrate concentrations that inhibited cell growth by 50% (IC50) were 0.508 and 5.50 mM in HCT116/PT and HCT116/BR cells. The values after treatment with paclitaxel, 5-fluorouracil (5-FU), doxorubicin and trichostatin A (TSA) were 2.42, 2.36, 4.31 and 11.3-fold higher, respectively, in HCT116/BR cells compared with HCT116/PT cells. The protein expression of drug efflux pumps, such as P-glycoprotein (P-gp), breast cancer-resistant protein (BCRP) and the multidrug resistance associated protein 1 (MRP1), did not differ between HCT116/PT and HCT116/BR cells. The expression level of the anti-apoptotic Bcl-xL protein was increased while those of pro-apoptotic Bax and Bim proteins were reduced in HCT116/BR cells. There were no significant differences in cell motility and invasion. This study suggests that exposure of colon cancer cells to butyrate results in development of resistance to butyrate, which may play a role in the acquisition of chemoresistance in colon cancer.

Ren L, Huang C, Liu YH, et al.
[The effect and mechanism of microRNA-21 on cis-dichlorodiamineplatinum resistance in lung cancer cell strain].
Zhonghua Yi Xue Za Zhi. 2016; 96(18):1454-8 [PubMed] Related Publications
OBJECTIVE: To investigate the role of miR-21 on multidrug resistance (MDR) in non-small cell lung cancer(NSCLC)and to provide experimental and theoretical basis for MDR reversal.
METHODS: Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was used to determine the mRNA level of miR-21 both in the chemo-sensitivity cell strain A549 and the chemo-resistance cell strain A549/DDP (primary A549/DDP cells). The miR-21 interference sequence was synthesized and transfected into A549/DDP cells by liposome as the carrier. The miR-21 expression level was knocked down and the change of chemo-sensitivity of cells was detected. Effects of miR-21 on the cell apoptosis and cell cycle in miR-21-depleted A549/DDP cells were analyzed by flow cytometry to elucidate the involvement of miR-21 in MDR reversal in NSCLC. The expression of multidrug-resistant proteins Survivin, Cyclin D1, Epidermal growth factor receptor (EGFR), Multidrug resistance-associated protein1 (MRP1) and Lipoprotein receptor-related protein (LRP) were detected by Western blot.
RESULTS: MiR-21 level in multidrug-resistant NSCLC cell line A549/DDP was (5.223±0.316) folds higher than that in A549 cell line (t=48.318, P<0.01). Knockdown of miR-21 in A549/DDP cells significantly reversed their sensitivity to cis-DDP, meanwhile, the value of half maximal inhibitory concentration was significantly decreased compared with control group transfected with empty vector ((22.2±1.2) and (48.6±3.2) μmol/L, t=5.608, P<0.01). Cell apoptosis rate in A549/DDP cell with knockdown of miR-21 was significantly increased compared with primary A549/DDP cell line ((27.7±1.1) % and (16.8±1.1) %, t=10.183, P<0.01). Cell cycle G0/G1 phase in A549/DDP cell with knockdown of miR-21 was significantly decreased compared with primary A549/DDP cell line ((37.5±1.2) % and (43.4±2.3) %, t=8.202, P<0.01). Compared with primary A549/DDP cell line, the expression of Survivin, Cyclin D1, EGFR, MRP1 and LRP in A549/DDP cell with knockdown of miR-21 were significantly decreased ((71.7±4.3)%, t=8.325, P<0.01; (69.4±4.5)%, t=5.162, P<0.01; (52.3±3.2)%, t=8.042, P<0.01; (60.6±4.2)%, t=6.641, P<0.01; (72.9±3.8)%, t=4.566, P<0.01, respectively).
CONCLUSION: miR-21 silencing reverses the multidrug resistance in lung cancer cell via accelerating cell apoptosis and modulating multidrug resistance-related gene expression. miR-21 may be a potential therapeutic candidate in multidrug resistance patients with lung cancer.

Šemeláková M, Jendželovský R, Fedoročko P
Drug membrane transporters and CYP3A4 are affected by hypericin, hyperforin or aristoforin in colon adenocarcinoma cells.
Biomed Pharmacother. 2016; 81:38-47 [PubMed] Related Publications
Our previous results have shown that the combination of hypericin-mediated photodynamic therapy (HY-PDT) at sub-optimal dose with hyperforin (HP) (compounds of Hypericum sp.), or its stable derivative aristoforin (AR) stimulates generation of reactive oxygen species (ROS) leading to antitumour activity. This enhanced oxidative stress evoked the need for an explanation for HY accumulation in colon cancer cells pretreated with HP or AR. Generally, the therapeutic efficacy of chemotherapeutics is limited by drug resistance related to the overexpression of drug efflux transporters in tumour cells. Therefore, the impact of non-activated hypericin (HY), HY-PDT, HP and AR on cell membrane transporter systems (Multidrug resistance-associated protein 1-MRP1/ABCC1, Multidrug resistance-associated protein 2-MRP2/ABCC2, Breast cancer resistance protein - BCRP/ABCG2, P-glycoprotein-P-gp/ABCC1) and cytochrome P450 3A4 (CYP3A4) was evaluated. The different effects of the three compounds on their expression, protein level and activity was determined under specific PDT light (T0+, T6+) or dark conditions (T0- T6-). We found that HP or AR treatment affected the protein levels of MRP2 and P-gp, whereas HP decreased MRP2 and P-gp expression mostly in the T0+ and T6+ conditions, while AR decreased MRP2 in T0- and T6+. Moreover, HY-PDT treatment induced the expression of MRP1. Our data demonstrate that HP or AR treatment in light or dark PDT conditions had an inhibitory effect on the activity of individual membrane transport proteins and significantly decreased CYP3A4 activity in HT-29 cells. We found that HP or AR significantly affected intracellular accumulation of HY in HT-29 colon adenocarcinoma cells. These results suggest that HY, HP and AR might affect the efficiency of anti-cancer drugs, through interaction with membrane transporters and CYP3A4.

Yang H, Yao J, Yin J, Wei X
Decreased LRIG1 in Human Ovarian Cancer Cell SKOV3 Upregulates MRP-1 and Contributes to the Chemoresistance of VP16.
Cancer Biother Radiopharm. 2016; 31(4):125-32 [PubMed] Related Publications
The leucine-rich repeats and immunoglobulin-like domains (LRIG) are used as tumor suppressors in clinical applications. Although the LRIG has been identified to manipulate the cell proliferation via various oncogenic receptor tyrosine kinases in diverse cancers, its role in multidrug resistance needs to be further elucidated, especially in human ovarian cancer. We herein established that the etoposide (VP16)-resistant SKOV3 human ovarian cancer cell clones (SKOV3/VP16 cells) and mRNA expression of LRIG1 were significantly reduced by the treatment of VP16 in a concentration-dependent manner. Moreover, downregulated LRIG1 in SKOV3 could enhance the colony formation and resist the inhibition of proliferation by VP16, leading to the elevated expression of Bcl-2 and decreased apoptosis of SKOV3. Interestingly, our results uncovered that the multidrug resistance-associated protein 1 (MRP-1) was upregulated for the chemoresistance of VP16. To overcome the chemoresistance of SKOV3, SKOV3/VP16 was ectopically expressed of LRIG1. We found that the inhibition of VP16 on colony formation and proliferation was remarkably enhanced with increased apoptosis in SKOV3/VP16. Furthermore, the expression of MRP-1 and Bcl-2 was also inhibited, suggesting that the LRIG1could negatively control MRP-1 and the apoptosis to improve the sensitivity of VP16-related chemotherapy.

Lan WG, Xu DH, Xu C, et al.
Silencing of long non-coding RNA ANRIL inhibits the development of multidrug resistance in gastric cancer cells.
Oncol Rep. 2016; 36(1):263-70 [PubMed] Related Publications
The development of multidrug resistance (MDR) is a crucial cause of therapy failure in gastric cancer, which results in disease recurrence and metastasis. Long non-coding RNAs (lncRNAs) have been proven to be critical in carcinogenesis and metastasis of gastric cancer. However, little is known about the roles of ANRIL (antisense non-coding RNA in the INK4 locus) in gastric cancer MDR. The aim of our study is to identify the biological function of ANRIL in gastric cancer MDR. In our results, ANRIL was highly expressed in gastric cancer tissues of cisplatin-resistant and 5-fluorouracil (5-FU)-resistant patients, and the same upregulation trends were observed in cisplatin-resistant cells (BGC823/DDP) and 5-FU-resistant cells (BGC823/5-FU). In addition, BGC823/DDP and BGC823/5-FU cells transfected with ANRIL siRNA and treated with cisplatin or 5-FU, respectively, exhibited significant lower survival rate, decreased invasion capability, and high percentage of apoptotic tumor cells. The influence of ANRIL knockdown on MDR was assessed by measuring IC50 of BGC823/DDP and BGC823/5-FU cells to cisplatin and 5-FU, the result showed that silencing ANRIL decreased the IC50 values in gastric cancer cells. Moreover, qRT-PCR and western blotting revealed that ANRIL knockdown decreased the expression of MDR1 and MRP1, both of which are MDR related genes; regression analysis showed that the expression of ANRIL positively correlated with the expression of MDR1 and MRP1, resprectively In summary, knockdown of lncRNA ANRIL in gastric cancer cells inhibits the development of MDR, suggesting an efficacious target for reversing MDR in gastric cancer therapy.

Yuan Y, Cai T, Xia X, et al.
Nanoparticle delivery of anticancer drugs overcomes multidrug resistance in breast cancer.
Drug Deliv. 2016; 23(9):3350-3357 [PubMed] Related Publications
Breast cancer is a serious threat to women's health, because multidrug resistance (MDR) has hampered treatment and prognosis. Nanodelivery of anticancer agents is a new technology to be exploited in the treatment of patients, because it bypasses multispecific drug efflux transporters such as P-glycoprotein (ABCB1), multidrug resistance protein-1 (MRP1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). Drugs can be delivered to tumor tissue by passive and active tumor targeting strategies, which may reduce or reverse drug resistance. This review will mainly focus on MDR-associated proteins, as well as various nanoparticle formulations developed to overcome MDR in breast cancer.

Seo EJ, Saeed M, Law BY, et al.
Pharmacogenomics of Scopoletin in Tumor Cells.
Molecules. 2016; 21(4):496 [PubMed] Related Publications
Drug resistance and the severe side effects of chemotherapy necessitate the development of novel anticancer drugs. Natural products are a valuable source for drug development. Scopoletin is a coumarin compound, which can be found in several Artemisia species and other plant genera. Microarray-based RNA expression profiling of the NCI cell line panel showed that cellular response of scopoletin did not correlate to the expression of ATP-binding cassette (ABC) transporters as classical drug resistance mechanisms (ABCB1, ABCB5, ABCC1, ABCG2). This was also true for the expression of the oncogene EGFR and the mutational status of the tumor suppressor gene, TP53. However, mutations in the RAS oncogenes and the slow proliferative activity in terms of cell doubling times significantly correlated with scopoletin resistance. COMPARE and hierarchical cluster analyses of transcriptome-wide mRNA expression resulted in a set of 40 genes, which all harbored binding motifs in their promoter sequences for the transcription factor, NF-κB, which is known to be associated with drug resistance. RAS mutations, slow proliferative activity, and NF-κB may hamper its effectiveness. By in silico molecular docking studies, we found that scopoletin bound to NF-κB and its regulator IκB. Scopoletin activated NF-κB in a SEAP-driven NF-κB reporter cell line, indicating that NF-κB might be a resistance factor for scopoletin. In conclusion, scopoletin might serve as lead compound for drug development because of its favorable activity against tumor cells with ABC-transporter expression, although NF-κB activation may be considered as resistance factor for this compound. Further investigations are warranted to explore the full therapeutic potential of this natural product.

Saeed ME, Meyer M, Hussein A, Efferth T
Cytotoxicity of South-African medicinal plants towards sensitive and multidrug-resistant cancer cells.
J Ethnopharmacol. 2016; 186:209-23 [PubMed] Related Publications
ETHNOPHARMACOLOGICAL RELEVANCE: Traditional medicine plays a major role for primary health care worldwide. Cancer belongs to the leading disease burden in industrialized and developing countries. Successful cancer therapy is hampered by the development of resistance towards established anticancer drugs.
AIM: In the present study, we investigated the cytotoxicity of 29 extracts from 26 medicinal plants of South-Africa against leukemia cell lines, most of which are used traditionally to treat cancer and related symptoms.
MATERIAL AND METHODS: We have investigated the plant extracts for their cytotoxic activity towards drug-sensitive parental CCRF-CEM leukemia cells and their multidrug-resistant P-glycoprotein-overexpressing subline, CEM/ADR5000 by means of the resazurin assay. A panel of 60 NCI tumor cell lines have been investigated for correlations between selected phytochemicals from medicinal plants and the expression of resistance-conferring genes (ABC-transporters, oncogenes, tumor suppressor genes).
RESULTS: Seven extracts inhibited both cell lines (Acokanthera oppositifolia, Hypoestes aristata, Laurus nobilis, Leonotis leonurus, Plectranthus barbatus, Plectranthus ciliates, Salvia apiana). CEM/ADR5000 cells exhibited a low degree of cross-resistance (3.35-fold) towards the L. leonurus extract, while no cross-resistance was observed to other plant extracts, although CEM/ADR5000 cells were highly resistant to clinically established drugs. The log10IC50 values for two out of 14 selected phytochemicals from these plants (acovenoside A and ouabain) of 60 tumor cell lines were correlated to the expression of ABC-transporters (ABCB1, ABCB5, ABCC1, ABCG2), oncogenes (EGFR, RAS) and tumor suppressors (TP53). Sensitivity or resistance of the cell lines were not statistically associated with the expression of these genes, indicating that multidrug-resistant, refractory tumors expressing these genes may still respond to acovenoside A and ouabain.
CONCLUSION: The bioactivity of South African medicinal plants may represent a basis for the development of strategies to treat multidrug-resistant tumors either by phytotherapeutic approaches with whole plant preparations or by classical drug development with isolated compounds such as acovenoside A or ouabain.

Liu XY, Liu SP, Jiang J, et al.
Inhibition of the JNK signaling pathway increases sensitivity of hepatocellular carcinoma cells to cisplatin by down-regulating expression of P-glycoprotein.
Eur Rev Med Pharmacol Sci. 2016; 20(6):1098-108 [PubMed] Related Publications
OBJECTIVE: The resistance of hepatocellular carcinoma (HCC) to chemotherapy may be mediated by the c-Jun N-terminal kinase (JNK) pathway. We wished to verify the involvement of this pathway in resistance of HCC cells to cisplatin.
MATERIALS AND METHODS: We used HepG2 cell line and cisplatin-resistant clone (HepG2/DDP). Expressions of drug resistance and apoptosis-related genes were analyzed by qPCR. Protein expressions were assessed by Western blot. The JNK pathway was assessed as total JNK1/2 and JNK1/2 phosphorylation. Cell growth kinetics was quantified by the CCK-8 assay, and cell apoptosis (Annexin V / propidium iodide) by flow cytometry.
RESULTS: HepG2/DDP cells were more resistant and less apoptotic on cisplatin. Expression of drug-resistance genes MDR1, MRP1 and MPR2 was significantly up-regulated in HepG2/DDP cells (p < 0.05), with up-regulation of MDR1 being the highest. This was confirmed by Western blot analysis of P-glycoprotein (P-gp), MRP1 and MRP2 proteins, the proteins encoded by the above genes. Expression of anti-apoptotic genes Bcl-2 and Bcl-XL was significantly up-regulated, and expression of pro-apoptotic genes Bak and Bad was significantly reduced, in HepG2/DDP cells (p < 0.05). Cisplatin treatment of HepG2 led to increased phosphorylation of JNK1/2; the trend reversed by the inhibitor SP600125. Furthermore, cisplatin increased expression of P-gp, which was also attenuated by SP600125. Cell growth was inhibited more substantially, and cell apoptosis promoted, when HepG2 cells were exposed to both cisplatin and SP600125.
CONCLUSIONS: Inhibition of the JNK signaling pathway enhances the sensitivity of HCC cells to cisplatin by down-regulating the expression of P-gp.

Yi YJ, Jia XH, Wang JY, et al.
Knockdown of HOXA10 reverses the multidrug resistance of human chronic mylogenous leukemia K562/ADM cells by downregulating P-gp and MRP-1.
Int J Mol Med. 2016; 37(5):1405-11 [PubMed] Related Publications
Multidrug resistance (MDR) of leukemia cells is a major obstacle in chemotherapeutic treatment. The high expression and constitutive activation of P-glycoprotein (P-gp) and multidrug resistance protein-1 (MRP-1) have been reported to play a vital role in enhancing cell resistance to anticancer drugs in many tumors. The present study aimed to investigate the reversal of MDR by silencing homeobox A10 (HOXA10) in adriamycin (ADR)-resistant human chronic myelogenous leukemia (CML) K562/ADM cells by modulating the expression of P-gp and MRP-1. K562/ADM cells were stably transfected with HOXA10-targeted short hairpin RNA (shRNA). The results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis showed that the mRNA and protein expression of HOXA10 was markedly suppressed following transfection with a shRNA-containing vector. The sensitivity of the K562/ADM cells to ADR was enhanced by the silencing of HOXA10, due to the increased intracellular accumulation of ADR. The accumulation of ADR induced by the silencing of HOXA10 may be due to the downregulation of P-gp and MRP-1. Western blot analysis revealed that downregulating HOXA10 inhibited the protein expression of P-gp and MRP-1. Taken together, these results suggest that knockdown of HOXA10 combats resistance and that HOXA10 is a potential target for resistant human CML.

Rigalli JP, Tocchetti GN, Arana MR, et al.
The phytoestrogen genistein enhances multidrug resistance in breast cancer cell lines by translational regulation of ABC transporters.
Cancer Lett. 2016; 376(1):165-72 [PubMed] Related Publications
Breast cancer is the most frequent malignancy in women. Multidrug resistance due to overexpression of ABC drug transporters is a common cause of chemotherapy failure and disease recurrence. Genistein (GNT) is a phytoestrogen present in soybeans and hormone supplements. We investigated the effect of GNT on the expression and function of ABC transporters in MCF-7 and MDA-MB-231 breast cancer cell lines. Results demonstrated an induction at the protein level of ABCC1 and ABCG2 and of ABCC1 in MCF-7 and MDA-MB-231, respectively. MCF-7 cells showed a concomitant increase in doxorubicin and mitoxantrone efflux and resistance, dependent on ABCG2 activity. ABCC1 induction by GNT in MDA-MB-231 cells modified neither drug efflux nor chemoresistance due to simultaneous acute inhibition of the transporter activity by GNT. All inductions took place at the translational level, as no increment in mRNA was observed and protein increase was prevented by cycloheximide. miR-181a, already demonstrated to inhibit ABCG2 translation, was down-regulated by GNT, explaining translational induction. Effects were independent of classical estrogen receptors. Results suggest potential nutrient-drug interactions that could threaten chemotherapy efficacy, especially in ABCG2-expressing tumors treated with substrates of this transporter.

Kataoka J, Shiraha H, Horiguchi S, et al.
Loss of Runt-related transcription factor 3 induces resistance to 5-fluorouracil and cisplatin in hepatocellular carcinoma.
Oncol Rep. 2016; 35(5):2576-82 [PubMed] Free Access to Full Article Related Publications
Runt-related transcription factor 3 (RUNX3) is known to function as a tumor suppressor in gastric cancer and other types of cancers, including hepatocellular carcinoma (HCC). However, its role has not been fully elucidated. In the present study, we aimed to evaluate the role of RUNX3 in HCC. We used the human HCC cell lines Hep3B, Huh7 and HLF; RUNX3 cDNA was introduced into Hep3B and Huh7 cells, which were negative for endogenous RUNX3 expression, and RUNX3 siRNA was transfected into HLF cells, which were positive for endogenous RUNX3. We analyzed the expression of RUNX3 and multidrug resistance-associated protein (MRP) by immunoblotting. MTT assays were used to determine the effects of RUNX3 expression on 5-fluorouracil (5-FU) and cisplatin (CDDP) sensitivity. Finally, 23 HCC specimens resected from patients with HCC at Okayama University Hospital were analyzed, and correlations among immunohistochemical expression of RUNX3 protein and MRP protein were evaluated in these specimens. Exogenous RUNX3 expression reduced the expression of MRP1, MRP2, MRP3 and MRP5 in the RUNX3-negative cells, whereas knockdown of RUNX3 in the HLF cells stimulated the expression of these MRPs. An inverse correlation between RUNX3 and MRP expression was observed in the HCC tissues. Importantly, loss of RUNX3 expression contributed to 5-FU and CDDP resistance by inducing MRP expression. These data have important implications in the study of chemotherapy resistance in HCC.

Chen JR, Jia XH, Wang H, et al.
Timosaponin A-III reverses multi-drug resistance in human chronic myelogenous leukemia K562/ADM cells via downregulation of MDR1 and MRP1 expression by inhibiting PI3K/Akt signaling pathway.
Int J Oncol. 2016; 48(5):2063-70 [PubMed] Related Publications
One of the major causes of failure in chemotherapy for patients with human chronic myelogenous leukemia (CML) is the acquisition of multidrug resistance (MDR). MDR is often associated with the overexpression of drug efflux transporters of the ATP-binding cassette (ABC) protein family. Timosaponin A-III (TAIII), a saponin isolated from the rhizome of Anemarrhena asphodeloides, has previously demonstrated the ability to suppress certain human tumor processes and the potential to be developed as an anticancer agent. Nevertheless, the ability of TAIII to reverse MDR has not yet been explored. In this study, the adriamycin (ADM) resistance reversal effect of TAIII in human CML K562/ADM cells and the underlying mechanism was investigated. The Cell Counting Kit-8 (CCK-8) assay showed that TAIII had a reversal effect on the drug resistance of K562/ADM cells. Flow cytometry assay showed increased intracellular accumulation of ADM after cells were pretreated with TAIII, and the changes in the accumulation of rhodamine-123 (Rho-123) and 5(6)-carboxyfluorescein diacetate (CFDA) dye in K562/ADM cells were determined to be similar to the changes of intracellular accumulation of ADM. After pretreatment of cells with TAIII, the decreasing expression of P-gp and MRP1 mRNA was examined by reverse transcription polymerase chain reaction (RT-PCR). Western blotting showed TAIII inhibiting P-gp and MRP1 expression depended on the PI3K/Akt signaling pathway by decreasing the activity of p-Akt. Moreover, wortmannin an inhibitor of PI3K/Akt signaling pathway has a strong inhibitory effect on the expression of p-Akt, P-gp and MRP1. Besides, the combined treatment with TAIII did not have an affect on wortmannin downregulation of p-Akt, P-gp and MRP1. Taken together, our findings demonstrate, for the first time, that TAIII induced MDR reversal through inhibition of P-gp and MRP1 expression and function with regained adriamycin sensitivity which might mainly correlate to the regulation of PI3K/Akt signaling pathway.

Teng YN, Sheu MJ, Hsieh YW, et al.
β-carotene reverses multidrug resistant cancer cells by selectively modulating human P-glycoprotein function.
Phytomedicine. 2016; 23(3):316-23 [PubMed] Related Publications
BACKGROUND: The issue of multidrug resistance (MDR) cancer is one of the major barriers to successful chemotherapy treatment. The ATP-binding cassette (ABC) efflux transporters play an important role in the chemotherapeutic failure. Several generations of ABC efflux transporter inhibitors have been developed, however, none of them could provide better clinical outcome due to systemic toxicities and significant drug-drug interactions. Therefore, the present study focused on identifying the effect of the natural carotenoid on ABC transporters and may provide a safer choice to defeat MDR cancer.
PURPOSE: The aim of the present study was to evaluate the inhibitory potency of β-carotene on the ABC efflux transporters, as well as the reversal effect of β-carotene toward MDR cancers. The underlying molecular mechanisms and inhibitory kinetics of β-carotene on the major ABC efflux transporter, P-glycoprotein, were further investigated.
METHODS: The human P-gp (ABCB1/Flp-In(TM)-293), MRP1 (ABCC1/Flp-In(TM)-293) and BCRP (ABCG2/Flp-In(TM)-293) stable expression cells were established by using the Flp-In(TM) system. The cytotoxicity of β-carotene was evaluated by MTT assay in the established cell lines, sensitive cancer cell lines (HeLaS3 and NCI-H460) and resistant cancer cell lines (KB-vin and NCI-H460/MX20). Surface protein detection assay and eFluxx-ID Green Dye assay were applied for confirmation of surface expression and function of the transporters. The transporter inhibition potency of β-carotene was evaluated by calcein-AM uptake assay and mitoxantrone accumulation assay. Further interaction kinetics between β-carotene and P-gp were analyzed by rhodamine123 and doxorubicin efflux assay. The influence of β-carotene on ATPase activity was evaluated by Pgp-Glo(TM) Assay System.
RESULTS: Among the tested ABC efflux transporters, β-carotene significantly inhibited human P-gp efflux function without altering ABCB1 mRNA expression. Furthermore, β-carotene stimulated both P-gp basal ATPase activity and the verapamil-stimulated P-gp ATPase activity. In addition, β-carotene exerted partially inhibitory effect on BCRP efflux function. The combination of β-carotene and chemotherapeutic agents significantly potentiated their cytotoxicity in both cell stably expressed human P-gp (ABCB1/Flp-In(TM)-293) and MDR cancer cells (KB-vin and NCI-H460/MX20).
CONCLUSION: The present study indicated that β-carotene may be considered as a chemo-sensitizer and regarded as an adjuvant therapy in MDR cancer treatment.

Gordillo GM, Biswas A, Khanna S, et al.
Multidrug Resistance-associated Protein-1 (MRP-1)-dependent Glutathione Disulfide (GSSG) Efflux as a Critical Survival Factor for Oxidant-enriched Tumorigenic Endothelial Cells.
J Biol Chem. 2016; 291(19):10089-103 [PubMed] Article available free on PMC after 06/05/2017 Related Publications
Endothelial cell tumors are the most common soft tissue tumors in infants. Tumor-forming endothelial (EOMA) cells are able to escape cell death fate despite excessive nuclear oxidant burden. Our previous work recognized perinuclear Nox-4 as a key contributor to EOMA growth. The objective of this work was to characterize the mechanisms by which EOMA cells evade oxidant toxicity and thrive. In EOMA cells, compared with in the cytosol, the nuclear GSSG/GSH ratio was 5-fold higher. Compared to the ratio observed in healthy murine aortic endothelial (MAE) cells, GSSG/GSH was over twice as high in EOMA cells. Multidrug resistance-associated protein-1 (MRP-1), an active GSSG efflux mechanism, showed 2-fold increased activity in EOMA compared with MAE cells. Hyperactive YB-1 and Ape/Ref-1 were responsible for high MRP-1 expression in EOMA. Proximity ligand assay demonstrated MRP-1 and YB-1 binding. Such binding enabled the nuclear targeting of MRP-1 in EOMA in a leptomycin-B-sensitive manner. MRP-1 inhibition as well as knockdown trapped nuclear GSSG, causing cell death of EOMA. Disulfide loading of cells by inhibition of GSSG reductase (bischoloronitrosourea) or thioredoxin reductase (auranofin) was effective in causing EOMA death as well. In sum, EOMA cells survive a heavy oxidant burden by rapid efflux of GSSG, which is lethal if trapped within the cell. A hyperactive MRP-1 system for GSSG efflux acts as a critical survival factor for these cells, making it a potential target for EOMA therapeutics.

Bekele RT, Venkatraman G, Liu RZ, et al.
Oxidative stress contributes to the tamoxifen-induced killing of breast cancer cells: implications for tamoxifen therapy and resistance.
Sci Rep. 2016; 6:21164 [PubMed] Article available free on PMC after 06/05/2017 Related Publications
Tamoxifen is the accepted therapy for patients with estrogen receptor-α (ERα)-positive breast cancer. However, clinical resistance to tamoxifen, as demonstrated by recurrence or progression on therapy, is frequent and precedes death from metastases. To improve breast cancer treatment it is vital to understand the mechanisms that result in tamoxifen resistance. This study shows that concentrations of tamoxifen and its metabolites, which accumulate in tumors of patients, killed both ERα-positive and ERα-negative breast cancer cells. This depended on oxidative damage and anti-oxidants rescued the cancer cells from tamoxifen-induced apoptosis. Breast cancer cells responded to tamoxifen-induced oxidation by increasing Nrf2 expression and subsequent activation of the anti-oxidant response element (ARE). This increased the transcription of anti-oxidant genes and multidrug resistance transporters. As a result, breast cancer cells are able to destroy or export toxic oxidation products leading to increased survival from tamoxifen-induced oxidative damage. These responses in cancer cells also occur in breast tumors of tamoxifen-treated mice. Additionally, high levels of expression of Nrf2, ABCC1, ABCC3 plus NAD(P)H dehydrogenase quinone-1 in breast tumors of patients at the time of diagnosis were prognostic of poor survival after tamoxifen therapy. Therefore, overcoming tamoxifen-induced activation of the ARE could increase the efficacy of tamoxifen in treating breast cancer.

Ma M, Zhao L, Sun G, et al.
Mda-7/IL-24 enhances sensitivity of B cell lymphoma to chemotherapy drugs.
Oncol Rep. 2016; 35(5):3122-30 [PubMed] Related Publications
Interleukin-24 (IL-24) is a cytokine encoded by a tumor suppressor gene of the IL-10 family, also known as the melanoma differentiation associated gene-7 (Mda-7) and first discovered in human melanoma cells. Mda-7/IL-24 has been shown to inhibit the proliferation of various human tumor cell lines, but its effect on the sensitivity of B cell lymphoma to chemotherapy agents is not yet clear. The present study investigated the effects of Mda-7/IL-24 overexpression on the sensitivity of human B cell lymphoma cells to chemotherapy, as well as its mechanism of action. The sensitivity of stable Mda-7/IL-24 overexpressing Raji and Daudi cells to cis-diamminedichloroplatinum (CDDP), epirubicin and vinblastine (VCR) were assessed by the MTS method, and the IC50 value calculated. Cell apoptosis and the intracellular accumulation of Rhodamine-123 were assayed by flow cytometry. The expression of multidrug resistance gene 1 (MDR1), B-cell-specific Moloney murine leukemia virus insertion site 1 (BMI1), topoisomerase II (Topo II) and multidrug resistance-related protein 1 (MRP1) mRNA and protein were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. In addition, western blot analysis was also used to investigate the effect of Mda-7/IL-24 on activity of GTP-RhoA-ERK signaling pathway in Raji and Daudi cells. Growth inhibition and apoptosis rates of Mda-7/IL-24 overexpressing Raji and Daudi cells were higher than those of non-transfected cells and cells transfected with vector alone when treated with CDDP, epirubicin and VCR. The IC50 values of CDDP, epirubicin and VCR were lower for Mda-7/IL-24-overexpressing Raji and Daudi cells than for non-transfected cells and cells transfected with empty vector. Intracellular accumulation of Rhodamine-123 and the expression of Topo II were higher, while the levels of MDR1, BMI and MRP1 mRNA and protein were lower, in Mda-7/IL-24 overexpressing Raji and Daudi cells. Furthermore, the activities of GTP-RhoA-ERK signaling pathway in Raji and Daudi cells were suppressed. These results indicated that Mda-7/IL-24 enhanced the sensitivity of B lymphoma cells to chemotherapy agents by altering the expression of multidrug-resistance genes via downregulating GTP-RhoA-ERK signaling pathway, suggesting that treatment of B cell lymphomas with Mda-7/IL-24 could avoid MDR.

Katayama R, Sakashita T, Yanagitani N, et al.
P-glycoprotein Mediates Ceritinib Resistance in Anaplastic Lymphoma Kinase-rearranged Non-small Cell Lung Cancer.
EBioMedicine. 2016; 3:54-66 [PubMed] Article available free on PMC after 06/05/2017 Related Publications
The anaplastic lymphoma kinase (ALK) fusion oncogene is observed in 3%-5% of non-small cell lung cancer (NSCLC). Crizotinib and ceritinib, a next-generation ALK tyrosine kinase inhibitor (TKI) active against crizotinib-refractory patients, are clinically available for the treatment of ALK-rearranged NSCLC patients, and multiple next-generation ALK-TKIs are currently under clinical evaluation. These ALK-TKIs exhibit robust clinical activity in ALK-rearranged NSCLC patients; however, the emergence of ALK-TKI resistance restricts the therapeutic effect. To date, various secondary mutations or bypass pathway activation-mediated resistance have been identified, but large parts of the resistance mechanism are yet to be identified. Here, we report the discovery of p-glycoprotein (P-gp/ABCB1) overexpression as a ceritinib resistance mechanism in ALK-rearranged NSCLC patients. P-gp exported ceritinib and its overexpression conferred ceritinib and crizotinib resistance, but not to PF-06463922 or alectinib, which are next-generation ALK inhibitors. Knockdown of ABCB1 or P-gp inhibitors sensitizes the patient-derived cancer cells to ceritinib, in vitro and in vivo. P-gp overexpression was identified in three out of 11 cases with in ALK-rearranged crizotinib or ceritinib resistant NSCLC patients. Our study suggests that alectinib, PF-06463922, or P-gp inhibitor with ceritinib could overcome the ceritinib or crizotinib resistance mediated by P-gp overexpression.

Zhan M, Zhao X, Wang H, et al.
miR-145 sensitizes gallbladder cancer to cisplatin by regulating multidrug resistance associated protein 1.
Tumour Biol. 2016; 37(8):10553-62 [PubMed] Related Publications
Gallbladder cancer (GBC) is the most common malignancy in biliary tract with poor prognosis. Due to its high chemoresistance, systemic chemotherapies have had limited success in treating GBC patients. MicroRNAs (miRNAs) are emerging novel regulators of chemoresistance, which modulate the expression of drug resistance-related genes. In this study, we investigated the association between miR-145 expression and cisplatin sensitivity by both in vivo and in vitro analysis. Quantitative PCR (q-PCR) analysis indicated an increased miR-145 expression in GBC tissues. In addition, studies on GBC cell lines suggested an increased cisplatin efficacy with miR-145 overexpression, whereas decreasing miR-145 expression reduced cisplatin sensitivity. Further, we found that miR-145 accelerated MRP1 mRNA degradation by directly targeting its 3'-UTR and therefore caused increased cisplatin toxicity in GBC cells. Moreover, lower miR-145 and higher MRP1 expression levels predicted poor prognosis in GBC patients who received chemotherapy. Collectively, our findings established a rationale for using miR-145 expression as a biomarker to identify cisplatin-resistant GBC patients and propose that treatment strategies increasing the expression of miR-145 could be a new therapeutic approach for GBC patients.

Ye P, Xing H, Lou F, et al.
Histone deacetylase 2 regulates doxorubicin (Dox) sensitivity of colorectal cancer cells by targeting ABCB1 transcription.
Cancer Chemother Pharmacol. 2016; 77(3):613-21 [PubMed] Related Publications
PURPOSE: Histone deacetylases (HDACs) have been shown to regulate cell cycle, differentiation, and apoptosis of colorectal cancer (CRC) cells, while their roles in drug sensitivity remain unclear. The objectives of the present study were to investigate the effects of HDAC2 on drug resistance of CRC cells.
METHODS: We measured the expression of class I HDACs (HDAC1, 2, 3, 8) in CRC and human normal colonic epithelial cells. Additionally, we inhibited HDAC2 via siRNA or overexpressed it via pcDNA/HDAC2 transfection to evaluate its roles in doxorubicin (Dox) sensitivity.
RESULTS: Our present study showed HDAC2 was significantly increased in CRC cell lines as compared to human normal colonic epithelial cells. Silencing of HDAC2 can obviously enhance the sensitivity of HCT-116 and SW480 cells to dDox. Further, knockdown of HDAC2 can significantly (p < 0.05) downregulate the expression of ABCB1, while not ABCG2, ABCC1, ABCA1, or ABCC2. Inhibition of HDAC2 decreased ABCB1 promoter activities and the phosphorylation of c-fos and c-Jun, which can directly interact with the ABCB1 promoter and then promote its transcription. Overexpression of HDAC2 by pcDNA/HDAC2 transfection significantly increased the sensitivity of CRC cells to Dox and upregulated the levels of P-gp, p-c-fos, and p-c-Jun.
CONCLUSIONS: Our data revealed that HDAC2 can regulate Dox sensitivity of CRC cells by targeting ABCB1 transcription. It suggested that HDAC2 might be an important target for CRC therapy. Further, the combination of HDAC2-specific inhibitor and anticancer drugs including Dox might be an efficiency approach to elevate the treatment outcome of CRC.

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