Expression Of Multidrug Resistance Protein Research Articles

Study on the Chemotherapeutic Effect and Mechanism of Doxorubicin Hydrochloride on Drug-Resistant Gastric Cancer Cell Lines Using Metal-Organic Framework Fluorescent Nanoparticles as Carriers

Objective. To prepare a polyethylene glycol- (PEG-) modified rare earth metal-organic framework material drug delivery system, obtain DOX@Eu (BTC) fluorescent nanoparticles after loading doxorubicin (DOX), and explore the effect of DOX@Eu (BTC) fluorescent nanoparticles on the chemotherapy sensitivity of gastric cancer multidrug-resistant cells SGC7901/ADR. Methods. The rare earth metal-organic framework fluorescent nanoparticles EU (BTC) were prepared by the solvent method and modified with PEG, and DOX@Eu (BTC) fluorescent nanoparticles were obtained after loading DOX. The particle size distribution of the prepared nanoparticles was analyzed by TEM, the adsorption performance of the prepared nanoparticles was evaluated by BET, the effective drug loading of DOX in the nanoparticles was determined by TGA analysis, and the pH response release performance was evaluated by in vitro release experiments. The MTT method was used to test the toxicity of EU (BTC) to GES-1 and SGC7901/ADR cells and detect the proliferation of SGC7901/ADR cells in each group. A fluorescence confocal microscope was used to observe the positioning of DOX@Eu (BTC) in SGC7901/ADR cells. The expression level of miR-185 in each group of cells was detected by RT-qPCR. The Annexin V-FITC/PI method was used to determine the apoptosis rate of cells in each group. The expression of MRS2 and related drug resistance proteins in each group of cells was detected by Western blotting (WB). The dual-luciferase reporter gene experiment was used to verify the targeting relationship between miR-185 and MRS2. Results. Most of the prepared EU (BTC) fluorescent nanoparticles have a particle size between 50 and 200 nm and have good adsorption capacity. The effective drug loading of DOX is 29%, and it has pH-responsive release performance and can be used in acidic environments. DOX was immobilized in EU (BTC) fluorescent nanoparticles, and DOX@Eu (BTC) fluorescent nanoparticles were present in the cytoplasm or cell membrane of SGC7901/ADR cells. Compared with DOX, DOX@Eu (BTC) fluorescent nanoparticles have stronger cytotoxicity to SGC7901/ADR cells, which also effectively inhibited the expression of multidrug resistance proteins in cells. The expression level of miR-185 in SGC7901/ADR cells decreased, but the expression level of MRS2 protein in SGC7901/ADR cells increased. miR-185 and MRS2 proteins are closely related to the multidrug resistance of SGC7901/ADR cells, and MRS2 is the downstream target gene of miR-185. After the treating of SGC7901/ADR cells with DOX@Eu (BTC) fluorescent nanoparticles, the expression of miR-185 in the cells increased significantly, while the expression of MRS2 protein decreased significantly, and the magnitude of the change was more obvious than that of DOX treatment. Overexpression of miR-185 (miR-mimics) or inhibition of MRS2 (si-MRS2) enhanced the inhibitory effect of DOX@Eu (BTC) fluorescent nanoparticles on the proliferation of SGC7901/ADR cells, which significantly increased the induction of apoptosis by DOX@Eu (BTC) fluorescent nanoparticles, and simultaneous enhanced the inhibitory effect on the expression level of multidrug resistance protein. However, overexpression of miR-185 and MRS2 (pc-MRS2+miR-mimics) at the same time did not affect the chemotherapy sensitivity of SGC7901/ADR cells to DOX@Eu (BTC) fluorescent nanoparticles. However, simultaneous transfection of miR-185 mimics and pc-MRS2 did not affect the chemotherapy sensitivity of SGC7901/ADR cells to DOX@Eu (BTC) fluorescent nanoparticles. Conclusion. DOX@Eu (BTC) fluorescent nanoparticles can effectively enhance the chemotherapy sensitivity of SGC7901/ADR cells to DOX, which may be achieved by upregulating the expression of miR-185 in SGC7901/ADR cells and then inhibiting the expression of MRS2 protein.

Parthenolide increases the sensitivity of gastric cancer cells to chemotherapy.

To investigate the effect of parthenolide (PTL), a sesquiterpene lactone medicinal compound, on the sensitivity of the gastric cancer cell line SGC7901 and the DPP- and ADR-resistant sublines SGC7901/DDP and SGC7901/ADR to cisplatin [diamminedichloroplatinum (Ⅱ), DDP] and adriamycin (ADR) in vitro. SGC7901, SGC7901/DDP, and SGC7901/ADR were treated with various concentrations of PTL alone or in combination with DDP or ADR. The effects on cell proliferation, apoptosis, and expression/activity of several proliferation/apoptosis-related proteins [B-cell lymphoma-2 (Bcl-2), cyclin D1, nuclear factor-kappa B (NF-κB), and Caspase-8] and drug transporters (P-glycoprotein and multidrug resistance protein-1) were measured using flow cytometry, Western blotting, and in vitro activity assays. Treatment of SGC7901 cells with PTL inhibited cell growth, increased apoptosis, and sensitized the cells to DPP. Mechanistically, PTL treatment resulted in downregulation of NF-κB activity and Bcl-2 expression, and upregulation of Caspase-8 activity. Similarly, PTL co-treatment of SGC7901/DDP and SGC7901/ADR overcame their resistance to DDP and ADR, respectively, with concomitant inhibition of NF-κB, Bcl-2, Cyclin D1, P-glycoprotein, and multidrug resistance protein-1 expression and/or activity. PTL treatment decreases drug resistance in SGC7901, SGC7901/DDP, and SGC7901/ADR cells, as reflected by induction of apoptosis, inhibition of proliferation, downregulation of pro-survival and drug resistance pathways, and upregulation of pro-apoptotic pathways. Our results suggest that co-treatment with PTL may thus complement existing therapies for gastric cancer.

Enhanced gemcitabine cytotoxicity with knockdown of multidrug resistance protein genes in human cholangiocarcinoma cell lines.

Cholangiocarcinoma (CCA) is an often fatal primary cancer of the liver that tends to be resistant to chemotherapy. Multidrug resistance proteins (MRPs) contribute to the chemoresistance of these tumors. The objectives of the study were to document MRP expression profiles in two representative human intrahepatic and extrahepatic CCA cells lines (HuCCT1 and KMBC, respectively) and gemcitabine-induced cytotoxicity prior to and following MRP knockdown. Multidrug resistance protein mRNA and protein expression were documented by real-time reverse transcription-polymerase chain reaction and western blots, respectively. MRP knockdown was achieved with lentivirus small hairpin RNA constructs. Prior to gemcitabine exposure, MRP1, MRP2, MRP4, MRP5, and MRP6 mRNA were expressed in HuCCT1 cells and MRP1, MRP3, MRP4, and MRP5 in KMBC cells. Following gemcitabine exposure, MRP5 and MRP6 expressions were significantly upregulated in HuCCT1 cells and MRP5 in KMBC cells. In HuCCT1 cells, although MRP5 knockdown had no effect, MRP6 knockdown significantly increased gemcitabine-induced cytotoxicity. In KMBC cells, MRP5 knockdown significantly increased gemcitabine cytotoxicity. Inhibition of MRP6 expression in intra-hepatic and MRP5 in extra-hepatic should be explored as potential treatments for CCA in humans.

ANLN Directly Interacts with RhoA to Promote Doxorubicin Resistance in Breast Cancer Cells.

BackgroundChemotherapy resistance is the leading cause of cancer treatment failure. This research was conducted to explore a potential link between actin-binding protein anillin (ANLN) and doxorubicin resistance in breast cancer.Materials and MethodsWe compared ANLN expression and 50% inhibition concentration (IC50) of doxorubicin in human breast cancer cells (MDA-MB-231) and human breast cancer cells with doxorubicin resistance (MDA-MB-231/ADM). Co-immunoprecipitation was used to investigate the interaction between ANLN and RhoA. The cell viability, apoptosis, gene and protein expression were estimated by MTT, flow cytometry, quantitative real-time PCR and western blot.ResultsThe doxorubicin resistance in MDA-MB-231/ADM cells (IC50 = 19.40 ± 1.16 μg/mL) was significantly higher than that in MDA-MB-231 cells (IC50 = 1.65 ± 0.23 μg/mL). ANLN was up-regulated in MDA-MB-231/ADM cells compared to MDA-MB-231 cells. Furthermore, ANLN overexpression promoted cell viability and inhibited apoptosis of MDA-MB-231 cells. The gene and protein expression of multidrug resistance (MDR1) and cancer resistance protein (BCRP) were enhanced by ANLN overexpression in MDA-MB-231 cells. ANLN silencing suppressed cell viability and the expression of MDR1 and BCRP and facilitated apoptosis in MDA-MB-231/ADM cells. Moreover, ANLN promoted RhoA activation by interacting with RhoA. ANLN up-regulation enhanced cell viability and the expression of MDR1 and BCRP and decreased apoptosis of MDA-MB-231 cells. The influence conferred by ANLN overexpression was effectively abolished by C3 transferase.ConclusionThis work revealed that ANLN promoted doxorubicin resistance in breast cancer cells by activating RhoA. Thus, our study suggests a novel target for breast cancer treatment.

Expanding the Efflux In Vitro Assay Toolbox: A CRISPR-Cas9 Edited MDCK Cell Line with Human BCRP and Completely Lacking Canine MDR1

The Breast Cancer Resistance Protein (BCRP) is a key transporter in drug efflux and drug-drug interactions. However, endogenous expression of Multidrug Resistance Protein 1 (MDR1) confounds the interpretation of BCRP-mediated transport in in vitro models. Here we used a CRISPR-Cas9 edited Madin-Darby canine kidney (MDCK) II cell line (MDCKcMDR1-KO) for stable expression of human BCRP (hBCRP) with no endogenous canine MDR1 (cMDR1) expression (MDCK-hBCRPcMDR1-KO). Targeted quantitative proteomics verified expression of hBCRP, and global analysis of the entire proteome corroborated no or very low background expression of other drug transport proteins or metabolizing enzymes. This new cell line, had similar proteome like MDCKcMDR1-KO and a previously established, corresponding cell line overexpressing human MDR1 (hMDR1), MDCK-hMDR1cMDR1-KO. Functional studies with MDCK-hBCRPcMDR1-KO confirmed high hBCRP activity. The MDCK-hBCRPcMDR1-KO cell line together with the MDCK-hMDR1cMDR1-KO easily and accurately identified shared or specific substrates of the hBCRP and the hMDR1 transporters. These cell lines offer new, improved in vitro tools for the assessment of drug efflux and drug-drug interactions in drug development.

Acute and subchronic toxicity studies of rhein in immature and d-galactose-induced aged mice and its potential hepatotoxicity mechanisms

Rhein is a key ingredient in many herbal remedies and is widely used. However, herbs containing rhein are frequently associated with poisoning incidents, especially in elderly subjects. Acute and subchronic toxicity of rhein in Kunming mice (KM) was investigated in this experiment. Acute toxicity tests showed a 40% lethality at a given rhein dose of 4000 mg/kg, and the LD50 of rhein was calculated by the bliss method to be greater than 2185.6 mg/kg. In subchronic toxicity, d-gal-induced aged and immature animals were randomized into three groups that were exposed to rhein of 0, 175, and 375 mg/kg/d for 75 days, respectively. No mortality was observed in immature mice group, whereas 55.5% (5/9) subjects in aged mice groups died in the high dosage group. AST, ALT, IL-6, TNF-α levels and typical histopathological changes indicate that rhein causes liver injury. In addition, our investigation explored possible hepatotoxic mechanisms of rhein and experimental results showed increased ROS production, NRF-2 and MDA levels and decreased SOD levels, demonstrating that rhein causes oxidative stress. MMP and mitochondrial swelling levels were able to assess the impact of rhein on mitochondrial function. Furthermore, the effect of rhein on apoptosis can be detected by flow cytometry. Our studies suggested that rhein induces oxidative stress leading to mitochondria dysfunction and apoptotic activation. Multidrug resistance protein (MRP) is an efflux transporter protein and is capable of transporting cellular oxidative stress-related substances. To further clarify the role of MRP in rhein induced oxidative stress, we examined MRP expression in the liver. However, the expression of MRP has no statistical significance.

Drug Repositioning for P-Glycoprotein Mediated Co-Expression Networks in Colorectal Cancer.

Colorectal cancer (CRC) is one of the most fatal types of cancers that is seen in both men and women. CRC is the third most common type of cancer worldwide. Over the years, several drugs are developed for the treatment of CRC; however, patients with advanced CRC can be resistant to some drugs. P-glycoprotein (P-gp) (also known as Multidrug Resistance 1, MDR1) is a well-identified membrane transporter protein expressed by ABCB1 gene. The high expression of MDR1 protein found in several cancer types causes chemotherapy failure owing to efflux drug molecules out of the cancer cell, decreases the drug concentration, and causes drug resistance. As same as other cancers, drug-resistant CRC is one of the major obstacles for effective therapy and novel therapeutic strategies are urgently needed. Network-based approaches can be used to determine specific biomarkers, potential drug targets, or repurposing approved drugs in drug-resistant cancers. Drug repositioning is the approach for using existing drugs for a new therapeutic purpose; it is a highly efficient and low-cost process. To improve current understanding of the MDR-1-related drug resistance in CRC, we explored gene co-expression networks around ABCB1 gene with different network sizes (50, 100, 150, 200 edges) and repurposed candidate drugs targeting the ABCB1 gene and its co-expression network by using drug repositioning approach for the treatment of CRC. The candidate drugs were also assessed by using molecular docking for determining the potential of physical interactions between the drug and MDR1 protein as a drug target. We also evaluated these four networks whether they are diagnostic or prognostic features in CRC besides biological function determined by functional enrichment analysis. Lastly, differentially expressed genes of drug-resistant (i.e., oxaliplatin, methotrexate, SN38) HT29 cell lines were found and used for repurposing drugs with reversal gene expressions. As a result, it is shown that all networks exhibited high diagnostic and prognostic performance besides the identification of various drug candidates for drug-resistant patients with CRC. All these results can shed light on the development of effective diagnosis, prognosis, and treatment strategies for drug resistance in CRC.

Drug Elimination Alteration in Acute Lymphoblastic Leukemia Mediated by Renal Transporters and Glomerular Filtration.

Drug elimination alteration has been well reported in acute lymphoblastic leukemia (ALL). Considering that transporters and glomerular filtration influence, to different extents, the drug disposition, and possible side effects, we evaluated the effects of ALL on major renal transporters and glomerular filtration mediated pharmacokinetic changes, as well as expression of renal drug transporters. ALL xenograft models were established and intravenously injected with substrates of renal transporters and glomerular filtration separately in NOD/SCID mice. The plasma concentrations of substrates, after single doses, were determined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). With the development of ALL, protein expression of MDR1, OAT3 and OCT2 were increased by 2.62-fold, 1.70-fold, and 1.45-fold, respectively, whereas expression of MRP2 and MRP4 were significantly decreased by 30.98% and 45.28% in the kidney of ALL groups compared with control groups. Clearance of MDR1-mediated digoxin, OAT3-mediated furosemide, and OCT2-mediated metformin increased by 3.04-fold, 1.47-fold, and 1.26-fold, respectively. However, clearance of MRPs-mediated methotrexate was reduced by 39.5%. These results are consistent with mRNA expression. Clearance of vancomycin and amikacin, as markers of glomerular filtration rate, had a 2.14 and 1.64-fold increase in ALL mice, respectively. The specific alteration of renal transporters and glomerular filtration in kidneys provide a rational explanation for changes in pharmacokinetics for ALL.

Crocin Increases Gastric Cancer Cells' Sensitivity to Doxorubicin.

Background:Crocin is one of the substantial constituents of saffron extract. It has multiple clinical effects including anti-cancer effects. The development of the multidrug resistance (MDR) phenotype is one of the principal causes of cancer chemotherapy failure. The multidrug resistance protein 1 (MDR1) is one of the MDR-related protein and is often overexpressed in different cancers. In the present study, we aimed to evaluate the influence of crocin on the expression and function of MDR1 protein in EPG85-257 and EPG85-257RDB gastric cancer cell lines. Methods:The cytotoxicity effect of crocin was evaluated by the MTT assay. The impacts of crocin on the expression and function of MDR1 were assessed by Real-time RT-PCR and MTT assay, respectively. Results:The results demonstrated that crocin decreased cell viability in a dose-dependent manner with higher intensity on the EPG85-257 than the EPG85-257RDB cells. Crocin did not make any significant changes in the MDR1 gene expression level in EPG85-257 and EPG85-257RDB cell lines. In contrast, crocin increased doxorubicin cytotoxicity in drug-resistant cells, which might be induced by reduced MDR1 activity. Conclusion:In summary, although crocin did not affect mRNA expression of MDR1, results of MTT assay suggest that it might inhibit the MDR1 function.

ACLY: A biomarker of recurrence in breast cancer

ObjectiveACLY is a cytoplasmic metabolic enzyme involved in lipid synthesis. It also affects proliferation and metastasis of breast cancer. However, the correlation of ACLY expression with breast cancer recurrence is unclear. MethodsThe Oncomine and TCGA databases were used to investigate the mRNA expression of ACLY in breast cancer. Immunohistochemistry (IHC) was used to evaluate ACLY expression level in tumor tissues and normal tissues from 127 breast cancer patients. Next, the prognostic role of ACLY was explored by analyzing the clinicopathological features and prognosis during follow-up. The role of ACLY in breast cancer cells drug resistance was further detected by CCK-8 assays and quantitative real-time polymerase chain reaction (qRT-PCR). ResultsACLY mRNA and protein expression was significantly increased in the breast cancer tissues compared to normal tissues. Clinically, high ACLY levels were associated with ER status, PR status, tumor size, TNM stage, and lymph node invasion. Upregulated ACLY predicted worse tumor relapse-free survival (RFS) of breast cancer patients in univariate analyses and in multivariate models. In subgroup analysis, patients with high ACLY expression showed worse RFS in the TNM III or ER positive subgroups. Moreover, ACLY over-expression induced the resistance of breast cancer cells to docetaxel and promoted the expression of multi-drug resistant protein ABCB1/ABCG2. ConclusionsOur study highlights the possibility of ACLY as a potential and independent biomarker for the recurrence prediction in breast cancer patients. It may be related to ACLY promoting drug resistance in breast cancer cells.

LncRNA NORAD targets miR-410-3p to regulate drug resistance sensitivity of osteosarcoma

The current experiment was performed to investigate the effect of LncRNA NORAD on the sensitivity of miR-410-3p to drug resistance of osteosarcoma cells. The cisplatin-resistant cell line HOS/DDP was induced; si-NC, si-NORAD, miR-NC, miR-410-3p, pcDNA-NC, and pcDNA-NORAD were transfected into HOS/DDP cells, respectively; record as a si-NC group, si-NORAD group, miR-NC group, miR-410-3p group, pcDNA-NC group, pcDNA-NORAD group; si-NORAD was co-transfected into HOS/DDP cells with anti-miR-NC, anti-miR-410-3p, recorded as an anti-miR-NC+si-NORAD group and anti-miR-410-3p+si-NORAD group. Real-time quantitative PCR (RT-qPCR) was used to detect LncRNA NORAD, miR-410-3p and multidrug resistance protein 1 (MRP1) mRNA expression levels; Western blot was used to detect cyclin D1 (CyclinD1), MRP1, phosphorylated (p-p65), phosphorylated IкBα (p-IкBα) protein expression; cell counting kit 8 (CCK-8) was used to detect cell viability; dual luciferase report assay to detect targeting relationship between LncRNA NORAD and miR-410-3p. Compared with osteosarcoma cells HOS, the expression levels of LncRNA NORAD, MRP1 mRNA and protein in osteosarcoma resistant cells HOS/DDP were significantly increased, and miR-410-3p expression levels were significantly reduced (P<0.05). Low expression of NORAD or high expression of miR-410-3p, CyclinD1, MRP1 expression levels were significantly reduced, the cell survival rate was significantly reduced, and the half inhibitory concentration of cisplatin was significantly reduced (P<0.05). LncRNA NORAD targets and regulates miR-410-3p, and low expression of miR-410-3p can reverse the effects of low NORAD expression on HOS/DDP cell proliferation and cisplatin resistance. Low expressions of NORAD, p-p65, p-IкBα protein expression levels were significantly reduced; low expression of miR-410-3p could reverse the inhibitory effect of low NORAD expression on p-p65, p-IкBα protein expression. Inhibition of LncRNA NORAD expression can inhibit the proliferation of osteosarcoma HOS/DDP cells through targeted regulation of miR-410-3p, increasing its sensitivity to cisplatin, and it may be related to the NF-κB signaling pathway.

M2 Macrophages Infiltrating Epithelial Ovarian Cancer Express MDR1: A Feature That May Account for the Poor Prognosis.

Multi drug resistance protein 1 (MDR1) expression on tumor cells has been widely investigated in context of drug resistance. However, the role of MDR1 on the immune cell infiltrate of solid tumors remains unknown. The aim of this study was to analyze the prognostic significance of a MDR1+ immune cell infiltrate in epithelial ovarian cancer (EOC) and to identify the MDR1+ leucocyte subpopulation. MDR1 expression was analyzed by immunohistochemistry in 156 EOC samples. In addition to MDR1+ cancer cells, we detected a MDR1+ leucocyte infiltrate (high infiltrate >4 leucocytes per field of view). Correlations and survival analyses were calculated. To identify immune cell subpopulations immunofluorescence double staining was performed. The MDR1+ leucocyte infiltrate was associated with human epidermal growth factor receptor 2 (HER2) (cc = 0.258, p = 0.005) and tumor-associated mucin 1 (TA-MUC1) (cc = 0.202, p = 0.022) expression on cancer cells. A high MDR1+ leucocyte infiltrate was associated with impaired survival, especially in patients whose carcinoma showed either serous histology (median OS 28.80 vs. 50.64 months, p = 0.027, n = 91) or TA-MUC1 expression (median OS 30.60 vs. 63.36 months, p = 0.015, n = 110). Similar findings for PFS suggest an influence of MDR1+ immune cells on the development of chemoresistance. A Cox regression analysis confirmed the independency of a high MDR1+ leucocyte infiltrate as prognostic factor. M2 macrophages were identified as main part of the MDR1+ leucocyte infiltrate expressing MDR1 as well as the M2 marker CD163 and the pan-macrophage marker CD68. Infiltration of MDR1+ leucocytes, mostly M2 macrophages, is associated with poor prognosis of EOC patients. Further understanding of the interaction of M2 macrophages, MDR1 and TA-MUC1 appears to be a key aspect to overcome chemoresistance in ovarian cancer.

Pterostilbene Enhances Cytotoxicity and Chemosensitivity in Human Pancreatic Cancer Cells.

Gemcitabine (GEM) drug resistance causes high mortality rates and poor outcomes in pancreatic ductal adenocarcinoma (PDAC) patients. Receptor for advanced glycation end products (RAGE) involvement in the GEM resistance process has been demonstrated. Therefore, finding a safe and effective way to inhibit receptors for RAGE-initiated GEM resistance is urgent. Pterostilbene (PTE), a natural methoxylated analogue derived from resveratrol and found in grapes and blueberries, has diverse bioactivities, such as antioxidative, anti-inflammatory, and anticancer qualities. The overall research objective was to determine the potential of PTE to enhance tumor cytotoxicity and chemosensitivity in PDAC cells. Our results have demonstrated that PTE induced S-phase cell cycle arrest, apoptosis, and autophagic cell death and inhibited multidrug resistance protein 1 (MDR1) expression by downregulating RAGE/PI3K/Akt signaling in both MIA PaCa-2 and MIA PaCa-2 GEMR cells (GEM-resistant cells). Remarkably, convincing evidence was established by RAGE small interfering RNA transfection. Taken together, our study demonstrated that PTE promoted chemosensitivity by inhibiting cell proliferation and MDR1 expression via the RAGE/PI3K/Akt axis in PDAC cells. The observations in these experiments indicate that PTE may play a crucial role in MDR1 modulation for PDAC treatment.

Reversal Effect of Dihydromyricetin on Multiple Drug Resistance in SGC7901/5-FU Cells.

Background:One of the most common treatment for gastric cancer is chemotherapy, however, multiple drug resistance (MDR) induce the therapeutic effect which result in the failure of anticancer therapy. Dihydromyricetin (DMY) was reported to have antitumor activities on various human cancer cells in vitro, our previous studies demonstrated that DMY combined with mitomycin has inhibitory effect on proliferation of gastric carcinoma cells. However, the underlying role of DMY reversing the MDR of gastric carcinoma is poor understood. The aim of this study was to evaluate the reversal effect of DMY on MDR and investigate the molecular mechanisms in vitro. Methods:Using MTT assay, we identified the toxicity of DMY on SGC7901 and SGC7901/5-FU cells. The effect of DMY on 5-FU induced apoptosis was evaluated by flow cytometry analysis. Using RT-PCR and Western blot, we determined the MDR1 mRNA and protein expression. Results:DMY induced growth inhibition in both SGC7901 and SGC7901/5-FU cells, the IC50 value was 13.64±1.15 µg/mL, 20.69±1.82 µg/mL respectively. DMY treatment sensitized SGC7901/5-FU cells to cytotoxicity of 5-FU. The combination of DMY with 5-FU increased the apoptosis rate (9.91%, 16.67%) comparing with 5-FU alone (5.25%). Comparing with the control group, the MDR1 mRNA and protein expression in SGC7901/5-FU cells after treatment of DMY decreased significantly (P< 0.05). Conclusion:In brief, our study demonstrated that DMY effectively reversed multi-drug resistance occurring in SGC7901/5-FU cells cultured in vitro, and the potential mechanism was involved in the downregulation of the MDR1 expression.

FNDC5 promotes paclitaxel sensitivity of non-small cell lung cancers via inhibiting MDR1

Therapeutic benefits and clinical application of paclitaxel for treating non-small cell lung cancers (NSCLCs) are extremely hampered due to the chemoresistance. A recent study found that fibronectin type III domain-containing protein 5 (FNDC5) was downregulated in NSCLCs cells and negatively correlated with the clinicopathological characteristics in patients with NSCLCs. However, the role and potential molecular basis for FNDC5 in paclitaxel sensitivity of NSCLCs remain unclear. Paclitaxel-sensitive or resistant NSCLCs cell lines were exposed to small interfering RNA against FNDC5 (siFndc5) or recombinant irisin in the presence or absence of paclitaxel. NSCLCs cell lines have decreased FNDC5 expression compared with the normal human lung epithelial cells, which was further downregulated in paclitaxel-resistant cells. Irisin treatment suppressed, whereas Fndc5 silence promoted NSCLCs cells proliferation under basal conditions. Besides, we found that FNDC5 increased paclitaxel chemosensitivity in paclitaxel-sensitive or resistant NSCLCs cell lines via downregulating multidrug resistance protein 1 (MDR1). Further studies revealed that FNDC5 inhibited MDR1 expression via blocking nuclear factor-κB (NF-κB) activation. FNDC5 promotes paclitaxel sensitivity of NSCLCs cells via inhibiting NF-κB/MDR1 signaling, and FNDC5 might be a novel therapeutic target for the treatment of NSCLCs.

Identification of cofilin-1 as a novel mediator for the metastatic potentials and chemoresistance of the prostate cancer cells

Prostate cancer (PCa) is the most common malignancy among men. Tumor metastasis and chemoresistance contribute to the major cause of the mortality. In this study, we compared the protein profiles of two prostate cancer cell lines with different metastatic potentials, and identified cofilin-1 (CFL1) was one of the most differentially expressed proteins between two cell lines. Further results suggested that cofilin-1 promoted the remodeling of F-actin cytoskeleton, and enhanced the proliferation, migration and invasion of the prostate cancer cells via activation of P38 MAPK signaling pathway. In addition, cofilin-1 elevated the expression and drug efflux activity of multidrug resistance protein 1 (MDR1) by P38 MAPK signaling pathway, resulting in decrease of the adriamycin-induced apoptosis as well as the lytic cell death, and the subsequent resistance against adriamycin. Collectively, cofilin-1 might serve as a novel target candidate for both inhibiting the metastasis and reversing the chemoresistance of PCa.

Epigenetic Regulation of Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein Transporters by Histone Deacetylase Inhibition.

Multidrug resistance protein 1 (MDR1, ABCB1, P-glycoprotein) and breast cancer resistance protein (BCRP, ABCG2) are key efflux transporters that mediate the extrusion of drugs and toxicants in cancer cells and healthy tissues, including the liver, kidneys, and the brain. Altering the expression and activity of MDR1 and BCRP influences the disposition, pharmacodynamics, and toxicity of chemicals, including a number of commonly prescribed medications. Histone acetylation is an epigenetic modification that can regulate gene expression by changing the accessibility of the genome to transcriptional regulators and transcriptional machinery. Recently, studies have suggested that pharmacological inhibition of histone deacetylases (HDACs) modulates the expression and function of MDR1 and BCRP transporters as a result of enhanced histone acetylation. This review addresses the ability of HDAC inhibitors to modulate the expression and the function of MDR1 and BCRP transporters and explores the molecular mechanisms by which HDAC inhibition regulates these transporters. While the majority of studies have focused on histone regulation of MDR1 and BCRP in drug-resistant and drug-sensitive cancer cells, emerging data point to similar responses in nonmalignant cells and tissues. Elucidating epigenetic mechanisms regulating MDR1 and BCRP is important to expand our understanding of the basic biology of these two key transporters and subsequent consequences on chemoresistance as well as tissue exposure and responses to drugs and toxicants. SIGNIFICANCE STATEMENT: Histone deacetylase inhibitors alter the expression of key efflux transporters multidrug resistance protein 1 and breast cancer resistance protein in healthy and malignant cells.

Dasatinib reverses drug resistance by downregulating MDR1 and Survivin in Burkitt lymphoma cells

BackgroundCurrent chemotherapies for Burkitt lymphoma (BL) have dramatically improved its clinical outcome. However, chemoresistance can lead to chemotherapy failure and very poor prognosis; thus, novel strategies are urgently required for patients with drug-resistant BL. To investigate the mechanisms underlying drug resistance in BL, we established drug-resistant BL cell lines: HS-Sultan/ADM (adriamycin-resistant), HS-Sultan/VCR (vincristine-resistant), HS-Sultan/DEX (dexamethasone-resistant), and HS-Sultan/L-PAM (melphalan-resistant).MethodsDrug transporter and survival factor expression were investigated the using western blotting and real time polymerase chain reaction. Cell survival was analyzed by trypan blue dye exclusion method.ResultsThe established cell lines acquired cross-resistance to adriamycin, vincristine, dexamethasone, and melphalan and exhibited 50% inhibitory concentration values 106-, 40-, 81-, and 45-fold higher than the parental cell lines, respectively. We found that protein and mRNA expression of MDR1 and Survivin were higher in drug-resistant BL cells than in the parent cells. Treatment with verapamil, an MDR1 inhibitor, or Survivin siRNA alongside each anti-cancer drug suppressed the proliferation of all drug-resistant BL cells. Src kinase activity was higher in all resistant cell lines than the parental cells; suppressing Src with dasatinib restored drug sensitivity by reducing MDR1 and Survivin expression.ConclusionsMDR1 and Survivin upregulation are responsible for resistance to conventional drugs and dasatinib can restore drug sensitivity by reducing MDR1 and Survivin expression in drug-resistant BL cells. Src inhibitors could therefore be a novel treatment strategy for patients with drug resistant BL.

Z-guggulsterone regulates MDR1 expression mainly through the pregnane X receptor-dependent manner in human brain microvessel endothelial cells

Recently studies showed that pregnane X receptor (PXR) was expressed in human brain microvessel endothelial cells and coordinately induced multidrug resistance protein 1 (MDR1) expression. The present study aimed to investigate the regulatory effect of Z-guggulsterone on MDR1 in human brain microvessel endothelial cells, and explored whether it involved modulation of PXR. The results showed that Z-guggulsterone (30 μM) simultaneously inhibited the expression of PXR and MDR1 at 24 h in human brain-derived microvessel endothelial cells (hBDMECs). Meanwhile, the levels of PXR and MDR1 expression were simultaneously reduced in PXR siRNA-transfected hBDMECs; MDR-1 siRNA-transfected hBDMECs showed significant decrease in MDR1 expression, but no change in PXR expression. Furthermore, Z-guggulsterone inhibited the activation of PXR in hBDMECs through decreasing the release of cAMP/PKA. Z-guggulsterone reduced the co-activator SRC-1 expression in hBDMECs, as to prevent the activation of MDR1 gene transcription. In addition, Z-guggulsterone (30 μM) at 24 h significantly inhibited the expression of human constitutive androstane receptor (CAR) protein in hBDMECs. However, after treatment with Z-guggulsterone (≤30 μM), the level of MDR1 reporter gene activity was lower in human PXR-transfected cells than that in human CAR-transfected cells. The inhibition effect of Z-guggulsterones on MDR1 reporter gene activation was gradually enhanced with the increase of human PXR to CAR ratio, which was greater extent than that with the increase of human CAR to hPXR ratio. The present study suggested that Z-guggulsterone down-regulating the efflux function and expression of MDR1 in hBDMECs might be mainly through the PXR-dependent manner.

Talazoparib nanoparticles for overcoming multidrug resistance in triple-negative breast cancer.

Herein, we investigated efflux pumps-mediated talazoparib-resistance in the treatment of triple-negative breast cancer (TNBC). Furthermore, we produced a novel talazoparib-solid lipid nanoparticles (SLNs) and then explored in vitro therapeutic efficacy of talazoparib-SLNs to overcome talazoparib-resistance in TNBC cells. Talazoparib-SLNs formulation was produced and then characterized. Calcein and Rho-123 were used to analyze the functional activity of drug efflux pumps in these cells. Additionally, RT-PCR, western blot and immunofluorescence analysis were used to detect the messenger RNA, and protein expression level, and cellular localization of the multidrug resistance (MDR1), breast cancer resistance protein (BCRP), and MRP1. We found that talazoparib efflux was mediated by BCRP and MRP1 pumps in TNBC cells. Talazoparib-SLNs could significantly enhance therapeutic efficacy of talazoparib. Furthermore, talazoparib-SLNs were more effective in the suppression of MDR1, BCRP, and MRP1 gene and protein expression levels than talazoparib. Consequently, this study suggests that talazoparib-SLNs formulation represents a promising therapeutic carrier to reverse MDR-mediated resistance in TNBC.