Multidrug resistance (MDR) is one of the major obstacles in cancer chemotherapy. Our previous study has shown that icariin could reverse MDR in MG-63 doxorubicin-resistant (MG-63/DOX) cells. It is reported that icariin is usually metabolized to icariside II and icaritin. Herein, we investigated the effects of icariin, icariside II, and icaritin (ICT) on reversing MDR in MG-63/DOX cells. Among these compounds, ICT exhibited strongest effect and showed no obvious cytotoxicity effect on both MG-63 and MG-63/DOX cells ranging from 1 to 10 μmol·L. Furthermore, ICT increased accumulation of rhodamine 123 and 6-carboxyfluorescein diacetate and enhanced DOX-induced apoptosis in MG-63/DOX cells in a dose-dependent manner. Further studies demonstrated that ICT decreased the mRNA and protein levels of multidrug resistance protein 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1). We also verified that blockade of STAT3 phosphorylation was involved in the reversal effect of multidrug resistance in MG-63/DOX cells. Taken together, these results indicated that ICT may be a potential candidate in chemotherapy for osteosarcoma.
ATP Binding Cassette Transporter, Subfamily B ; drug effects ; genetics ; metabolism ; Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Survival ; drug effects ; Dose-Response Relationship, Drug ; Doxorubicin ; metabolism ; pharmacology ; toxicity ; Drug Resistance, Multiple ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; Flavonoids ; pharmacology ; Gene Expression Regulation, Neoplastic ; drug effects ; Humans ; Multidrug Resistance-Associated Proteins ; drug effects ; genetics ; metabolism ; Osteosarcoma ; drug therapy ; metabolism ; pathology ; Phosphorylation ; drug effects ; Rhodamine 123 ; metabolism ; STAT3 Transcription Factor ; antagonists & inhibitors ; metabolism ; Triterpenes ; pharmacology

Alectinib, an inhibitor of anaplastic lymphoma kinase (ALK), was approved by the Food and Drug Administration (FDA) for the treatment of patients with ALK-positive non-small cell lung cancer (NSCLC). Here we investigated the reversal effect of alectinib on multidrug resistance (MDR) induced by ATP-binding cassette (ABC) transporters, which is the primary cause of chemotherapy failure. We provide the first evidence that alectinib increases the sensitivity of ABCB1- and ABCG2-overexpressing cells to chemotherapeutic agents in vitro and in vivo. Mechanistically, alectinib increased the intracellular accumulation of ABCB1/ABCG2 substrates such as doxorubicin (DOX) and Rhodamine 123 (Rho 123) by inhibiting the efflux function of the transporters in ABCB1- or ABCG2-overexpressing cells but not in their parental sensitive cells. Furthermore, alectinib stimulated ATPase activity and competed with substrates of ABCB1 or ABCG2 and competed with [125I] iodoarylazidoprazosin (IAAP) photolabeling bound to ABCB1 or ABCG2 but neither altered the expression and localization of ABCB1 or ABCG2 nor the phosphorylation levels of AKT and ERK. Alectinib also enhanced the cytotoxicity of DOX and the intracellular accumulation of Rho 123 in ABCB1-overexpressing primary leukemia cells. These findings suggest that alectinib combined with traditional chemotherapy may be beneficial to patients with ABCB1- or ABCG2-mediated MDR.
Adenosine Triphosphatases ; Carcinoma, Non-Small-Cell Lung ; Doxorubicin ; Drug Resistance, Multiple* ; Drug Therapy ; Humans ; In Vitro Techniques* ; Leukemia ; Lymphoma ; Parents ; Phosphorylation ; Phosphotransferases ; Rhodamine 123 ; United States Food and Drug Administration

OBJECTIVETo investigate the role of capsaicin in regulating permeation of P-gp substrate rhodamine 123 (R123) across the jejunum, ileum and colon membranes of rats.

METHODSThe permeability of R123 or fluorescein sodium (CF) across the jejunum, ileum and colon membranes of male SD rats was evaluated using a Ussing chamber. The concentration of R123 or CF in the receptor was determined using fluorospectrophotometry to calculate the apparent permeability coefficient (Papp).

RESULTSCompared with the blank control group, capsaicin increased the permeability of R123 across jejunal membranes in the mucosal-to-serosal (M-S) direction and decreased its permeability in the serosal-to-mucosal (S-M) direction, but produced no obvious effect on R123 transport across the ileum or colon membranes. Capsaicin caused a regional increase in the permeability of CF across the jejunal membranes compared with the control group, but CF transport across the ileum and colon membranes was not affected.

CONCLUSIONCapsaicin can affect the transport of R123 and CF across rat jejunal membranes, and this effect is shows an obvious intestine segment-related difference probably because of the different distribution of P-gp or tight junction in the intestines. This finding suggests that capsaicin is a weak P-gp inhibitor and an improver of mucous membrane channels.

ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Animals ; Capsaicin ; pharmacology ; Colon ; metabolism ; Fluorescein ; pharmacokinetics ; Ileum ; metabolism ; Intestinal Absorption ; Jejunum ; metabolism ; Male ; Permeability ; Rats ; Rats, Sprague-Dawley ; Rhodamine 123 ; pharmacokinetics

The tumor multidrug resistance reversal effect of NPB304, a novel taxane, was studied. MTT assay was used to determine the IC50 of chemotherapy drugs. Western blotting assay was applied to analyze the expression of P-glycoprotein (P-gp). The effect of compounds on the P-gp function and P-gp ATPase activity was determined by rhodamine 123 (Rh123) accumulation assay and analysis kit, respectively. Molecular docking was employed to predict the binding force between compounds and P-gp. Transmembrane transport of NPB304 was analyzed using MDCK II and MDR1-MDCK II cell model. NPB304 displayed multidrug resistance reversal effect on KBV cells and MCF-7/paclitaxel cells, NPB304 collaborative with P-glycoprotein (P-gp) inhibitors verapamil enhanced the reversal activity, specifically, 10 μmol x L(-1) verapamil in combination with paclitaxel reversed resistance by 56.5-fold, while combined with NPB304 increased the reversal fold; NPB304 synergistically increased Rh123 accumulation in the resistant cells when combined with verapamil, and NPB304 at 0-1 μmol x L(-1) enhanced the ATPase activity activated by verapamil was observed. NPB304 existed the hydrophobic interactions with the TM regions of P-gp, and the binding force between NPB304 and the A chain of the TM region was stronger. P-gp ATPase activity assay demonstrated NPB304 at lower concentrations (0-1.5 μmol x L(-1)) could activate the P-gp ATPase, playing a role on inhibition of P-gp function. However, NPB304 did not have an obvious feature of P-gp substrate. NPB304 exerted itself and synergy with verapamil activity on reversing tumor resistance via inhibiting the P-gp function.
ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Antineoplastic Agents ; pharmacology ; Biological Transport ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Drug Synergism ; Humans ; MCF-7 Cells ; Rhodamine 123 ; Taxoids ; pharmacology ; Verapamil ; pharmacology

PURPOSE: To investigate the chemotherapeutic effect of quercetin against cancer cells, signaling pathway of apoptosis was explored in human pancreatic cells. METHODS: Various anticancer drugs including adriamycin, cisplatin, 5-fluorouracil (5-FU) and gemcitabine were used. Cell viability was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphe-nyltetra zolium bromide assay. Apoptosis was determined by 4'-6-diamidino-2-phenylindole nuclei staining and flow cytometry in PANC-1 cells treated with 50 microg/mL quercetin for 24 hours. Expression of endoplas mic reticulum (ER) stress mediators including, Grp78/Bip, p-PERK, PERK, ATF4, ATF6 and GADD153/CHOP proteins were measured by Western blot analysis. Mitochondrial membrane potential was measured by fluorescence staining with JC-1, rhodamine 123. Quercetin induced the apoptosis of PANC-1, which was characterized as nucleic acid and genomic DNA fragmentation, chromatin condensation, and sub-G0/G1 fraction of cell cycle increase. But not adriamycin, cisplatin, gemcitabine, and 5-FU. PANC-1 cells were markedly sensitive to quercetin. RESULTS: Treatment with quercetin resulted in the increased accumulation of intracellular Ca2+ ion. Treatment with quercetin also increased the expression of Grp78/Bip and GADD153/CHOP protein and induced mitochondrial dysfunction. Quercetin exerted cytotoxicity against human pancreatic cancer cells via ER stress-mediated apoptotic signaling including reactive oxygen species production and mitochondrial dysfunction. CONCLUSION: These data suggest that quercetin may be an important modulator of chemosensitivity of cancer cells against anticancer chemotherapeutic agents.
Apoptosis* ; Benzimidazoles ; Blotting, Western ; Carbocyanines ; Cell Cycle ; Cell Survival ; Chromatin ; Cisplatin ; Deoxycytidine ; DNA Fragmentation ; Doxorubicin ; Drug Therapy ; Flow Cytometry ; Fluorescence ; Fluorouracil ; Humans ; Membrane Potential, Mitochondrial ; Pancreatic Neoplasms ; Quercetin* ; Reactive Oxygen Species ; Reticulum ; Rhodamine 123

In this study, cepharanthine hydrochloride (CH) was tested for its potential ability to modulate the expression and function of P-glycoprotein (P-gp) in the multidrug-resistant human chronic myelogenous leukemia cell line K562/ADR. Cytotoxicity of adriamycin (ADR) alone or in combination with CH or verapamil (VER) in K562 and K562/ADR cells was determined by MTT assay. Based on flow cytometric technology, the effect of CH or VER on the uptake and efflux of rhodamine123 (Rho123) and the accumulation of ADR in these cells was detected by measuring Rho123 or ADR-associated mean fluorescence intensity (MFI). The effects of CH and VER on P-glycoprotein (P-gp) expression in K562 and K562/ADR cells were also measured using a flow cytometry with PE-conjugated P-glycoprotein antibody. The results show that CH significantly enhanced the sensitivity of K562/ADR cells to ADR, 4 micromol x L(-1) of CH enhanced the sensitivity of K562/ADR cells to ADR by 7.43 folds, the reversal activity was 3.19 times higher than that of verapamil. However, CH had no effect on drug-sensitive K562 cells (P < 0.05). CH increased Rho123 and ADR accumulation in a concentration-dependent manner (2-8 micromol x L(-1)) and inhibited the efflux of Rho123 from these cells, but did not affect the accumulation and efflux of Rho123 from the wild-type drug-sensitive K562 cells. The inhibition effect of CH on P-gp expression in K562/ADR cells is in a time- and concentration-dependent manner. The reversal activity of CH is possibility related to inhibition of P-gp function and expression, which lead to an increased intracellular accumulation of anticancer drugs.
ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Antibiotics, Antineoplastic ; metabolism ; pharmacology ; Antineoplastic Agents, Phytogenic ; administration & dosage ; pharmacology ; Benzylisoquinolines ; administration & dosage ; pharmacology ; Dose-Response Relationship, Drug ; Doxorubicin ; metabolism ; pharmacology ; Drug Resistance, Multiple ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; Humans ; K562 Cells ; Rhodamine 123 ; metabolism

S1-M1-80 cells, derived from human colon carcinoma S1 cells, are mitoxantrone-selected ABCG2-overexpressing cells and are widely used in in vitro studies of multidrug resistance(MDR). In this study, S1-M1-80 cell xenografts were established to investigate whether the MDR phenotype and cell biological properties were maintained in vivo. Our results showed that the proliferation, cell cycle, and ABCG2 expression level in S1-M1-80 cells were similar to those in cells isolated from S1-M1-80 cell xenografts (named xS1-M1-80 cells). Consistently, xS1-M1-80 cells exhibited high levels of resistance to ABCG2 substrates such as mitoxantrone and topotecan, but remained sensitive to the non-ABCG2 substrate cisplatin. Furthermore, the specific ABCG2 inhibitor Ko143 potently sensitized xS1-M1-80 cells to mitoxantrone and topotecan. These results suggest that S1-M1-80 cell xenografts in nude mice retain their original cytological characteristics at 9 weeks. Thus, this model could serve as a good system for further investigation of ABCG2-mediated MDR.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; antagonists & inhibitors ; metabolism ; Adenosine ; analogs & derivatives ; pharmacology ; Animals ; Antineoplastic Agents ; pharmacology ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; Cell Survival ; drug effects ; Cisplatin ; pharmacology ; Colonic Neoplasms ; metabolism ; pathology ; Diketopiperazines ; Doxorubicin ; metabolism ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Female ; Heterocyclic Compounds, 4 or More Rings ; Humans ; Inhibitory Concentration 50 ; KB Cells ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Mitoxantrone ; pharmacology ; Neoplasm Proteins ; antagonists & inhibitors ; metabolism ; Neoplasm Transplantation ; Rhodamine 123 ; metabolism ; Topotecan ; pharmacology

An in vitro P-glycoprotein mediated drug biliary excretion model (B-Clear model) was developed and validated using sandwich-cultured rat hepatocytes (SCRH) and a model substrate rhodamine 123 (Rh123). SCRH formed functional bile canalicular networks after 5 days of culture. Rh123 (10 micromol x L(-1)) was then incubated with the SCRH in standard Ca+ Hanks buffer or Ca(2+)-free buffer. The cumulative cell uptake and canalicular efflux of Rh123 under Ca2+ and Ca(2+)-free conditions were measured with a LC-MS/MS method. The biliary excretion index (BEI) and instinct biliary clearance (CL(bile, int)) were calculated. To assess the effect of known P-gp inhibitors on the efflux of Rh123, cyclosporine A (CyA), tariquidar (TQD) or quinidine (QND) (10, 50 and 100 micromol x L(-1)) was pre-incubated separately with SCRH for 30 min, then co-incubated with Rh123. The BEI and CL(bile, int) of Rh123 obtained from the SCRH model were (17.8 +/- 1.3) % and (10.7 +/- 0.9) mL x min(-1) x kg(-1), respectively. All the three P-gp inhibitors showed a dose-dependent inhibition on the bile clearance of Rh123, indicating that the B-Clear model with SCRH was functional properly. The biliary excretion of loperamide (LPAD) and the role of P-gp were further investigated with this validated model. The BEI and CL(bile, int) for LPAD (20 micromol x L(-1)) were obtained after it was incubated with SCRH for 30 min, and found to be (12.9 +/- 1.2)% and (6.1 +/- 0.3) mL x min(-1) x kg(-1) respectively. The dose-dependent inhibition on LPAD biliary excretion by CyA, TQD or QND confirmed the major role of P-gp in LPAD canalicular efflux. The results suggested that the B-Clear model with SCRH would be a useful tool for evaluation of P-gp mediated efflux and drug-drug interaction.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Animals ; Biliary Tract ; metabolism ; Cells, Cultured ; Chromatography, High Pressure Liquid ; Cyclosporine ; pharmacology ; Hepatocytes ; cytology ; metabolism ; Loperamide ; metabolism ; Male ; Quinidine ; pharmacology ; Quinolines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Rhodamine 123 ; metabolism ; Tandem Mass Spectrometry

BACKGROUND AND PURPOSE: Recent studies have demonstrated that resveratrol (RSV) reduces the incidence of age-related macular degeneration, Alzheimer's disease (AD), and stroke, while melatonin (MEL) supplementation reduces the progression of the cognitive impairment in AD patients. The purpose of this investigation was to assess whether the co-administration of MEL and RSV exerts synergistic effects on their neuroprotective properties against beta-amyloid (Abeta)-induced neuronal death. METHODS: The neuroprotective effects of co-treatment with MEL and RSV on Abeta1-42 -induced cell death, was measured by MTT reduction assay. Abeta1-42 caused an increase in intracellular levels of reactive oxygen species (ROS), as assessed by H2-DCF-DA dye, and a reduction of total glutathione (GSH) levels and mitochondrial membrane potential, as assessed using monochlorobimane and rhodamine 123 fluorescence, respectively. Western blotting was used to investigate the intracellular signaling mechanism involved in these synergic effects. RESULTS: We treated a murine HT22 hippocampal cell line with MEL or RSV alone or with both simultaneously. MEL and RSV alone significantly attenuated ROS production, mitochondrial membrane-potential disruption and the neurotoxicity induced by Abeta1-42. They also restored the Abeta1-42-induced depletion of GSH, back to within its normal range and prevented the Abeta1-42-induced activation of glycogen synthase kinase 3beta (GSK3beta). However, co-treatment with MEL and RSV did not exert any significant synergistic effects on either the recovery of the Abeta1-42-induced depletion of GSH or on the inhibition of Abeta1-42-induced GSK3beta activation. Abeta1-42 treatment increased AMP-activated protein kinase (AMPK) activity, which is associated with subsequent neuronal death. We demonstrated that MEL and RSV treatment inhibited the phosphorylation of AMPK. CONCLUSIONS: Together, our results suggest that co-administration of MEL and RSV acts as an ef-fective treatment for AD by attenuating Abeta1-42-induced oxidative stress and the AMPK-dependent pathway.
Alzheimer Disease ; AMP-Activated Protein Kinases ; Blotting, Western ; Cell Death ; Cell Line ; Fluorescence ; Glutathione ; Glycogen Synthase Kinase 3 ; Glycogen Synthase Kinases ; Humans ; Incidence ; Macular Degeneration ; Melatonin ; Membrane Potential, Mitochondrial ; Neurons ; Neuroprotective Agents ; Oxidative Stress ; Phosphorylation ; Pyrazoles ; Reactive Oxygen Species ; Reference Values ; Rhodamine 123 ; Stilbenes ; Stroke

Gastrodin (GAS) is the major bioactive component of the extracts from the rhizome of Gastrodia elata Blume. The aim of this study is to investigate the transport of GAS in Caco-2 cells and the interaction of P-glycoprotein and GAS. The apparent permeability coefficients (Papp) of GAS were measured as a function of directions and concentrations. It was demonstrated that the efflux ratio was < 2.0 over the range of 50-500 micromol x L(-1) of GAS from bi-directional transport studies. The transport rate of GAS was dependent on the concentrations. Papp of GAS was not affected by transport directions, GAS concentration or the classical inhibitors of P-glycoprotein (verapamil and GF 120918). The cellular accumulation of GAS in Bcap37/MDR1 cells transected with hMDR1 gene, was similar to that in Bcap37 cells. The accumulation in both cell lines was concentration dependent. GAS did not affect the accumulation of Rhodamine 123 in Bcap37/MDR1 cells over the range of 50-500 micromol x L(-1). It indicated that the transport of GAS in Caco-2 cell monolayers mainly is by passive paracellular transport pathway. P-glycoprotein did not participate in the absorption of GAS in the intestine or the transport across the blood-brain barrier.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; metabolism ; Acridines ; pharmacology ; Benzyl Alcohols ; isolation & purification ; pharmacokinetics ; Biological Transport ; Blood-Brain Barrier ; Breast Neoplasms ; pathology ; Caco-2 Cells ; Cell Line, Tumor ; Drug Resistance, Multiple ; Gastrodia ; chemistry ; Glucosides ; isolation & purification ; pharmacokinetics ; Humans ; Plants, Medicinal ; chemistry ; Rhodamine 123 ; pharmacokinetics ; Tetrahydroisoquinolines ; pharmacology ; Verapamil ; pharmacology