scholarly journals PK11195, a peripheral benzodiazepine receptor (pBR) ligand, broadly blocks drug efflux to chemosensitize leukemia and myeloma cells by a pBR-independent, direct transporter-modulating mechanism

Blood ◽  
2005 ◽  
Vol 106 (10) ◽  
pp. 3584-3593 ◽  
Author(s):  
Roland B. Walter ◽  
Jason L. Pirga ◽  
Michelle R. Cronk ◽  
Sasha Mayer ◽  
Frederick R. Appelbaum ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Ectopic Expression ◽  
Leukemia Cell ◽  
Benzodiazepine Receptor ◽  
In Vitro Assays ◽  
Drug Efflux ◽  
Peripheral Benzodiazepine Receptor ◽  
Cancer Resistance ◽  
Resistance Protein

AbstractThe peripheral benzodiazepine receptor (pBR) ligand, PK11195, promotes mitochondrial apoptosis and blocks P-glycoprotein (Pgp)-mediated drug efflux to chemosensitize cancer cells at least as well or better than the Pgp modulator, cyclosporine A (CSA). We now show that PK11195 broadly inhibits adenosine triphosphate (ATP)-binding cassette (ABC) transporters in hematologic cancer cell lines and primary leukemia-cell samples, including multidrug resistance protein (MRP), breast cancer resistance protein (BCRP), and/or Pgp. Ectopic expression models confirmed that pBR can directly mediate chemosensitizing by PK11195, presumably via mitochondrial activities, but showed that pBR expression is unnecessary to PK11195-mediated efflux inhibition. PK11195 binds plasma-membrane sites in Pgp-expressing cells, stimulates Pgp-associated adenosine triphosphatase (ATPase) activity, and causes conformational changes in Pgp, suggesting that PK11195 modulates Pgp-mediated efflux by direct transporter interaction(s). PK11195 and CSA bind noncompetitively in Pgp-expressing cells, indicating that PK11195 interacts with Pgp at sites that are distinct from CSA-binding sites. Importantly, PK11195 concentrations that were effective in these in vitro assays can be safely achieved in patients. Because PK11195 promotes chemotherapy-induced apoptosis by a pBR-dependent mitochondrial mechanism and broadly blocks drug efflux by an apparently pBR-independent, ABC transporter-dependent mechanism, PK11195 may be a useful clinical chemosensitizer in cancer patients.

PK11195, a Peripheral Benzodiazepine Receptor (PBR) Ligand, Broadly Blocks Drug Efflux to Chemosensitize Leukemia and Myeloma Cells by a PBR-Independent, Direct Transporter-Modulating Mechanism.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1533-1533
Author(s):  
Roland B. Walter ◽  
Jason Pirga ◽  
Michelle R. Cronk ◽  
Sasha J. Mayer ◽  
Frederick R. Appelbaum ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Multidrug Resistance ◽  
Atpase Activity ◽  
Cell Lines ◽  
Abc Transporter ◽  
Ectopic Expression ◽  
Benzodiazepine Receptor ◽  
Drug Efflux ◽  
Peripheral Benzodiazepine Receptor ◽  
Resistance Protein

Abstract Background: Multidrug resistance (MDR) is frequently associated with expression of anti-apoptotic proteins of the Bcl-2 family and/or ATP-binding cassette (ABC) transporter proteins. We previously showed that the peripheral benzodiazepine receptor (pBR) ligand, PK11195, promotes mitochondrial apoptosis and blocks P-glycoprotein (Pgp)-mediated drug efflux, establishing PK11195 as a promising MDR reversal agent. We have now assessed its effect on other ABC transporters, namely multidrug resistance protein (MRP) and breast cancer resistance protein (BCRP), and have explored the mechanism by which PK11195 blocks drug efflux, focusing on Pgp as a paradigm. Methods: Flow cytometry was used to measure efflux of the cytotoxic drug, mitoxantrone (MIT), that was inhibited by cyclosporine A (CSA; to assess Pgp function), MK-571 (to assess MRP function), or Ko143 or GF120918 (to assess BCRP function). MIT-induced toxicity was determined after 24 hours by flow cytometry with DiOC6(3) plus propidium iodide staining, or by 3H-thymidine incorporation. Hematopoietic cell lines were virally transduced with human pBR to assess the effect of pBR expression on PK11195 action. Specific 3H-PK11195 binding was determined by competition with 1000-fold excess unlabeled PK11195. Microsome and plasma membranes were prepared using sucrose gradients. ATPase activity was measured as the liberation of inorganic phosphate detected by absorbance at 800nM. Conformation-specific and conformation-insensitive anti-Pgp monoclonal antibodies were used to analyze PK11195 effects on Pgp by flow cytometry. Results: Using a panel of human acute myeloid leukemia and multiple myeloma cell lines with endogenous or ectopic expression of one or more ABC transporter proteins, and using primary leukemia cell samples, we found that PK11195 broadly inhibits ABC transporter function, affecting not only Pgp but also MRP and BCRP. PK11195 blocked efflux often more effectively than CSA in Pgp+, MRP+ and BCRP+ cells, blocked efflux as well as the MRP modulator, MK-571, in MRP+ cells, and inhibited as well or better than the BCRP modulator, GF120918, in BCRP+ cells. Compared to parental cell lines, sublines over-expressing Pgp, MRP, or BCRP showed relative MIT-resistance in cytotoxicity assays. PK11195 co-treatments significantly increased MIT cytotoxicity in such cell lines expressing relatively high levels of one or more clinically relevant drug efflux protein even when anti-apoptotic proteins were also expressed. Ectopic expression models confirmed that pBR can directly mediate chemosensitizing by PK11195, presumably via mitochondrial activities, but that pBR expression is unnecessary for PK11195-mediated efflux inhibition. PK11195 bound plasma membrane sites in Pgp+ cells, stimulated Pgp-associated ATPase activity, and caused conformational changes of Pgp, suggesting that PK11195 modulates Pgp-mediated efflux by direct transporter interaction(s). PK11195 and CSA bound non-competitively in Pgp+ cells, indicating that PK11195 interacts with Pgp at sites that are distinct from CSA-binding sites. Discussion: PK11195 promotes chemotherapy-induced apoptosis by a pBR-dependent mitochondrial mechanism, and broadly blocks drug efflux by a pBR-independent, ABC transporter-dependent mechanism. Since PK11195 concentrations that are effective in vitro can be safely achieved in vivo, PK11195 may be a useful clinical chemosensitizer in patients with MDR+ malignancies.

scholarly journals Bisphenol A Inhibits the Transporter Function of the Blood-Brain Barrier by Directly Interacting with the ABC Transporter Breast Cancer Resistance Protein (BCRP)

2021 ◽  
Vol 22 (11) ◽  
pp. 5534
Author(s):  
Elin Engdahl ◽  
Maarten van Schijndel ◽  
Dimitrios Voulgaris ◽  
Michela Di Criscio ◽  
Kerry Ramsbottom ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Bisphenol A ◽  
Blood Brain Barrier ◽  
Breast Cancer Resistance Protein ◽  
Brain Barrier ◽  
Production Volume ◽  
Cancer Resistance ◽  
Blood Brain ◽  
Resistance Protein

The breast cancer resistance protein (BCRP) is an important efflux transporter in the blood-brain barrier (BBB), protecting the brain from a wide range of substances. In this study, we investigated if BCRP function is affected by bisphenol A (BPA), a high production volume chemical used in common consumer products, as well as by bisphenol F (BPF) and bisphenol S (BPS), which are used to substitute BPA. We employed a transwell-based in vitro cell model of iPSC-derived brain microvascular endothelial cells, where BCRP function was assessed by measuring the intracellular accumulation of its substrate Hoechst 33342. Additionally, we used in silico modelling to predict if the bisphenols could directly interact with BCRP. Our results showed that BPA significantly inhibits the transport function of BCRP. Additionally, BPA was predicted to bind to the cavity that is targeted by known BCRP inhibitors. Taken together, our findings demonstrate that BPA inhibits BCRP function in vitro, probably by direct interaction with the transporter. This effect might contribute to BPA’s known impact on neurodevelopment.

scholarly journals P-Glycoprotein and Breast Cancer Resistance Protein Restrict Apical-to-Basolateral Permeability of Human Brain Endothelium to Amyloid-β

2009 ◽  
Vol 29 (6) ◽  
pp. 1079-1083 ◽  
Author(s):  
Leon M Tai ◽  
A Jane Loughlin ◽  
David K Male ◽  
Ignacio A Romero
Keyword(s):  
Breast Cancer ◽  
Human Brain ◽  
Breast Cancer Resistance Protein ◽  
Amyloid Β ◽  
Cancer Resistance ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Resistance Protein ◽  
The Brain

The clearance of amyloid beta (Aβ) from the brain represents a novel therapeutic target for Alzheimer's disease. Conflicting data exist regarding the contribution of adenosine triphosphatebinding cassette transporters to the clearance of Aβ through the blood-brain barrier. Therefore, we investigated whether Aβ could be a substrate for P-glycoprotein (P-gp) and/or for breast cancer resistance protein (BCRP) using a human brain endothelial cell line, hCMEC/D3. Inhibition of P-gp and BCRP increased apical-to-basolateral, but not basolateral-to-apical, permeability of hCMEC/D3 cells to 125l Aβ 1–40. Our in vitro data suggest that P-gp and BCRP might act to prevent the blood-borne Aβ 1–40 from entering the brain.

Oleic acid increases uptake and decreases the P-gp-mediated efflux of the veterinary anthelmintic Ivermectin

Drug Research ◽  
2018 ◽  
Vol 69 (03) ◽  
pp. 173-180 ◽  
Author(s):  
Bilal Houshaymi ◽  
Nadine Nasreddine ◽  
Mamdouh Kedees ◽  
Zeina Soayfane
Keyword(s):  
Oleic Acid ◽  
Intestinal Mucosa ◽  
Drug Formulation ◽  
Dependent Manner ◽  
Cancer Resistance ◽  
P Glycoprotein ◽  
Resistance Protein ◽  
Complex Micelles

AbstractThe bioavailability of ivermectin is modulated by lipid-based formulations and membrane efflux transporters such as Breast Cancer Resistance Protein and P-glycoprotein (BCRP and P-gp). We have investigated the effect of oleic acid on the uptake of ivermectin in vitro using Caco-2 cells and in vivo in the intestines of wild-type mice. Complex micelles (M) with oleic acid induced a significant increase (e. g. for M3 was 7-fold, p≤0.001) in the uptake of the drug in a time-dependent manner with no involvement of cholesterol in the mechanism. In vivo results showed a significant increase in the concentration of plasma and intestinal mucosa ivermectin (p≤0.01) in mice receiving oleic acid-based drug formulation. We also examined the expression of the drug efflux transporter, BCRP and P-gp in Caco-2 cells and found a significant decrease (p≤0.001) in their level in the presence of 5 mM oleic acid. Treatment of mice with oleic acid-based formulation showed a significant decrease in the activity of P-gp in the intestinal mucosa (p≤0.01). This study highlighted the effect of oleic acid in decreasing the expression and the activity of P-gp-mediated ivermectin efflux and in limiting the drug absorption by increasing its uptake and bioavailability in Caco-2 cells and intestine, respectively.

scholarly journals Modulation of Placental Breast Cancer Resistance Protein by HDAC1 in Mice: Implications for Optimization of Pharmacotherapy During Pregnancy

2021 ◽  
Author(s):  
Chuan Wang ◽  
Dan Ma ◽  
Yimin Hua ◽  
Hongyu Duan
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Resistance Protein ◽  
Negative Control ◽  
Great Promise ◽  
Cancer Resistance ◽  
Gene Expressions ◽  
Time Curve ◽  
Resistance Protein

AbstractBreast cancer resistance protein (BCRP/ABCG2) is a critical drug efflux transporters by limiting drugs’ transplacental transfer rates. More investigations on the regulation of placental BCRP offer great promise for enabling pronounced progress in individualized and safe pharmacotherapy during pregnancy. Histone deacetylases (HDACs) play an important role in epigenetic regulation of placental genes. It was reported recently by us that HDAC1 was involved in placental BCRP regulation in vitro. The aim of this study was to further explore the effect of HDAC1 on placental BCRP expression and functionality in animals. Randomly assigned C57BL pregnant dams received intraperitoneal injections of a negative control siRNA or Hdac1 siRNA from embryonic day 7.5 (E7.5) to E15.5, respectively. At E16.5, glyburide (GLB), a probe for evaluating placental BCRP efflux functionality, was injected via the tail vein. Animals were sacrificed through cervical dislocation at various times (5–180 min) after drug administration. The maternal blood, placentas, and fetal-units were collected. GLB concentrations were determined by a validated high-performance liquid chromatography/mass spectrometry (HPLC-MS) assay. Real-time quantitative PCR (qRT-PCR), Western blot, and immunohistochemical (IHC) analysis were employed to identify mRNA/protein levels and localization of gene expressions, respectively. It was noted that Hdac1 inhibition significantly decreased placental Bcrp expression, with markedly increases of GLB concentrations and area under the concentration-time curve (AUC) in fetal-units. Particularly, the ratios of fetal-unit/maternal plasma GLB concentrations were also significantly elevated following Hdac1 repression. Taken together, these findings suggested that HDAC1 was involved in positive regulation of placental BCRP expression and functionality in vivo.

scholarly journals Quercetin Is a Flavonoid Breast Cancer Resistance Protein Inhibitor with an Impact on the Oral Pharmacokinetics of Sulfasalazine in Rats

Pharmaceutics ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 397
Author(s):  
Yoo-Kyung Song ◽  
Jin-Ha Yoon ◽  
Jong Kyu Woo ◽  
Ju-Hee Kang ◽  
Kyeong-Ryoon Lee ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Resistance Protein ◽  
Fold Increase ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Cancer Resistance ◽  
Concentration Dependent Manner ◽  
Resistance Protein

The potential inhibitory effect of quercetin, a major plant flavonol, on breast cancer resistance protein (BCRP) activity was investigated in this study. The presence of quercetin significantly increased the cellular accumulation and associated cytotoxicity of the BCRP substrate mitoxantrone in human cervical cancer cells (HeLa cells) in a concentration-dependent manner. The transcellular efflux of prazosin, a stereotypical BCRP substrate, was also significantly reduced in the presence of quercetin in a bidirectional transport assay using human BCRP-overexpressing cells; further kinetic analysis revealed IC50 and Ki values of 4.22 and 3.91 μM, respectively. Moreover, pretreatment with 10 mg/kg quercetin in rats led to a 1.8-fold and 1.5-fold increase in the AUC8h (i.e., 44.5 ± 11.8 min∙μg/mL vs. 25.7 ± 9.98 min∙μg/mL, p < 0.05) and Cmax (i.e., 179 ± 23.0 ng/mL vs. 122 ± 23.2 ng/mL, p < 0.05) of orally administered sulfasalazine, respectively. Collectively, these results provide evidence that quercetin acts as an in vivo as well as in vitro inhibitor of BCRP. Considering the high dietary intake of quercetin as well as its consumption as a dietary supplement, issuing a caution regarding its food–drug interactions should be considered.

scholarly journals Organoarsenic Compounds with In Vitro Activity against the Malaria Parasite Plasmodium falciparum

Biomedicines ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 260
Author(s):  
Sofia Basova ◽  
Nathalie Wilke ◽  
Jan Christoph Koch ◽  
Aram Prokop ◽  
Albrecht Berkessel ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Rapid Development ◽  
Sexual Transmission ◽  
Leukemia Cell ◽  
Leukemia Cell Line ◽  
In Vitro Assays ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

The rapid development of parasite drug resistance as well as the lack of medications targeting both the asexual and the sexual blood stages of the malaria parasite necessitate the search for novel antimalarial compounds. Eleven organoarsenic compounds were synthesized and tested for their effect on the asexual blood stages and sexual transmission stages of the malaria parasite Plasmodium falciparum using in vitro assays. The inhibitory potential of the compounds on blood stage viability was tested on the chloroquine (CQ)-sensitive 3D7 and the CQ-resistant Dd2 strain using the Malstat assay. The most effective compounds were subsequently investigated for their effect on impairing gametocyte development and gametogenesis, using the gametocyte-producing NF54 strain in respective cell-based assays. Their potential toxicity was investigated on leukemia cell line Nalm-6 and non-infected erythrocytes. Five out of the 11 compounds showed antiplasmodial activities against 3D7, with half-maximal inhibitory concentration (IC50) values ranging between 1.52 and 8.64 µM. Three of the compounds also acted against Dd2, with the most active compound As-8 exhibiting an IC50 of 0.35 µM. The five compounds also showed significant inhibitory effects on the parasite sexual stages at both IC50 and IC90 concentrations with As-8 displaying the best gametocytocidal activity. No hemolytic and cytotoxic effect was observed for any of the compounds. The organoarsenic compound As-8 may represent a good lead for the design of novel organoarsenic drugs with combined antimalarial and transmission blocking activities.

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