scholarly journals Dexamethasone increases expression and activity of multidrug resistance transporters at the rat blood-brain barrier

2008 ◽  
Vol 295 (2) ◽  
pp. C440-C450 ◽  
Author(s):  
Vishal S. Narang ◽  
Charles Fraga ◽  
Narendra Kumar ◽  
Jun Shen ◽  
Stacy Throm ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Mrna Levels ◽  
Cancer Resistance ◽  
Blood Brain ◽  
Multidrug Resistance Transporters ◽  
Dose Dependent ◽  
Expression And Activity

Brain edema is an important factor leading to morbidity and mortality associated with primary brain tumors. Dexamethasone, a synthetic glucocorticoid, is routinely prescribed with antineoplastic agents to alleviate pain associated with chemotherapy and reduce intracranial pressure. We investigated whether dexamethasone treatment increased the expression and activity of multidrug resistance (MDR) transporters at the blood-brain barrier. Treatment of primary rat brain microvascular endothelial cells with submicromolar concentrations of dexamethasone induced significantly higher levels of drug efflux transporters such as breast cancer resistance protein (abcg2), P-glycoprotein (P-gp; abcb1a/abcb1b), and MDR protein 2 (Mrp2; abcc2) as indicted by protein and mRNA levels as well as by functional activity. The effect of dexamethasone on transporter function was significant within 6 h of treatment, was dose dependent, and was reversible. Dexamethasone-induced upregulation of Bcrp and P-gp expression and function was partially abrogated by the glucocorticoid receptor (GR) antagonist RU486. In contrast, RU486 had no effect on the dexamethasone-induced upregulation of Mrp2, suggesting a GR-independent regulation of Mrp2, and a GR-dependent regulation of P-gp and Bcrp. In addition to the dexamethasone-induced upregulation of MDR transporters, we measured a dose-dependent and reversible increase in the expression of the nuclear transcription factor pregnane xenobiotic receptor (PXR). Administering dexamethasone to rats caused increased expression of PXR in brain microvessels within 24 h. These results suggest that adjuvant therapy with corticosteroids such as dexamethasone in the treatment of brain tumors may increase the expression of MDR transporters at the blood-brain barrier through pathways involving GR and PXR.

scholarly journals Effect of GenX on P-Glycoprotein, Breast Cancer Resistance Protein, and Multidrug Resistance–Associated Protein 2 at the Blood–Brain Barrier

2020 ◽  
Vol 128 (3) ◽  
pp. 037002 ◽  
Author(s):  
Ronald E. Cannon ◽  
Alicia C. Richards ◽  
Andrew W. Trexler ◽  
Christopher T. Juberg ◽  
Birandra Sinha ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Multidrug Resistance ◽  
Blood Brain Barrier ◽  
Breast Cancer Resistance Protein ◽  
Brain Barrier ◽  
Cancer Resistance ◽  
P Glycoprotein ◽  
Blood Brain ◽  
Resistance Protein

scholarly journals DDRE-32. ABC TRANSPORTERS RESTRICT THE BRAIN PENETRATION AND INTRACRANIAL EFFICACY OF ANTICANCER AGENTS EVEN WHEN BLOOD-BRAIN BARRIER INTEGRITY IS LOST

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii68-ii68
Author(s):  
Mark C de Gooijer ◽  
E Marleen Kemper ◽  
Levi C M Buil ◽  
Ceren H Çitirikkaya ◽  
Tessa Buckle ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Fluorescent Dyes ◽  
Tumor Vasculature ◽  
Brain Barrier ◽  
Normal Brain ◽  
Full Potential ◽  
Cancer Resistance ◽  
Blood Brain ◽  
The Impact

Abstract The impact of the blood-brain barrier (BBB) in brain tumors on the efficacy of anticancer drug therapy is controversial. In primary as well as metastatic brain tumors, the BBB is often disrupted. Yet, many intracranial cancers respond poorly to systemic therapies. We characterized the integrity of the BBB in a series of experimental intracranial tumor models using magnetic resonance imaging (MRI), fluorescent dyes and autoradiography. We also assessed the distribution and efficacy of docetaxel in healthy brain tissue and brain tumors that were grafted into P-glycoprotein (P-gp) proficient wild-type (WT) and deficient Abcb1a/b-/- recipient nude mice. Leakiness of the tumor vasculature varied from extensive to almost absent. Tumor blood vessels expressed P-gp and breast cancer resistance protein (BCRP). The leakiness of the vasculature resulted in higher docetaxel levels in tumors compared to normal brain. However, P-gp expression in tumor vessels reduced the drug distribution in tumors, which also translated into a reduced efficacy. Taken together, these studies demonstrate that leakiness of the BBB does not necessarily imply good accessibility to brain tumors of drugs that are substrates of P-gp and/or BCRP. Although therapeutic responses may be observed, the full potential of such therapeutics can still be attenuated by drug efflux pumps in the tumor vasculature. Therefore, only BBB-penetrable drugs with low to no affinity for efflux transporters should be considered for treatment of intracranial tumors.

scholarly journals Blood-Brain Barrier Disruption Increases Amyloid-Related Pathology in TgSwDI Mice

2021 ◽  
Vol 22 (3) ◽  
pp. 1231
Author(s):  
Ihab M. Abdallah ◽  
Kamal M. Al-Shami ◽  
Euitaek Yang ◽  
Amal Kaddoumi
Keyword(s):  
Mouse Model ◽  
Blood Brain Barrier ◽  
High Throughput Screening ◽  
Amyloid Β ◽  
Brain Barrier ◽  
Amyloid Angiopathy ◽  
Cancer Resistance ◽  
Screening Assay ◽  
Blood Brain ◽  
High Throughput Screening Assay

In Alzheimer’s disease (AD), several studies have reported blood-brain barrier (BBB) breakdown with compromised function. P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are transport proteins localized at the BBB luminal membrane and play an important role in the clearance of amyloid-β (Aβ). The purpose of this study was to investigate the effect of pharmacological inhibition of Aβ efflux transporters on BBB function and Aβ accumulation and related pathology. Recently, we have developed an in vitro high-throughput screening assay to screen for compounds that modulate the integrity of a cell-based BBB model, which identified elacridar as a disruptor of the monolayer integrity. Elacridar, an investigational compound known for its P-gp and BCRP inhibitory effect and widely used in cancer research. Therefore, it was used as a model compound for further evaluation in a mouse model of AD, namely TgSwDI. TgSwDI mouse is also used as a model for cerebral amyloid angiopathy (CAA). Results showed that P-gp and BCRP inhibition by elacridar disrupted the BBB integrity as measured by increased IgG extravasation and reduced expression of tight junction proteins, increased amyloid deposition due to P-gp, and BCRP downregulation and receptor for advanced glycation end products (RAGE) upregulation, increased CAA and astrogliosis. Further studies revealed the effect was mediated by activation of NF-κB pathway. In conclusion, results suggest that BBB disruption by inhibiting P-gp and BCRP exacerbates AD pathology in a mouse model of AD, and indicate that therapeutic drugs that inhibit P-gp and BCRP could increase the risk for AD.

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 17-β-Estradiol: A Powerful Modulator of Blood–Brain Barrier BCRP Activity

2010 ◽  
Vol 30 (10) ◽  
pp. 1742-1755 ◽  
Author(s):  
Anika MS Hartz ◽  
Anne Mahringer ◽  
David S Miller ◽  
Björn Bauer
Keyword(s):  
Blood Brain Barrier ◽  
Ex Vivo ◽  
Brain Barrier ◽  
Cancer Resistance ◽  
Transport Activity ◽  
Brain Capillaries ◽  
Therapeutic Drugs ◽  
Blood Brain ◽  
Capillary Membranes ◽  
Blood Brain Barrier Model

The ATP-driven efflux transporter, breast cancer resistance protein (BCRP), handles many therapeutic drugs, including chemotherapeutics, limiting their ability to cross the blood–brain barrier. This study provides new insight into rapid, nongenomic regulation of BCRP transport activity at the blood–brain barrier. Using isolated brain capillaries from rats and mice as an ex vivo blood–brain barrier model, we show that BCRP protein is highly expressed in brain capillary membranes and functionally active in intact capillaries. We show that nanomolar concentrations of 17-β-estradiol (E2) rapidly reduced BCRP transport activity in the brain capillaries. This E2-mediated effect occurred within minutes and did not involve transcription, translation, or proteasomal degradation, indicating a nongenomic mechanism. Removing E2 after 1 h fully reversed the loss of BCRP activity. Experiments using agonists and antagonists for estrogen receptor (ER)α and ERβ and brain capillaries from ERα and ERβ knockout mice demonstrated that E2 could signal through either receptor to reduce BCRP transport function. We speculate that this nongenomic E2-signaling pathway could potentially be used for targeting BCRP at the blood–brain barrier, in brain tumors, and in brain tumor stem cells to improve chemotherapy of the central nervous system.

Hyperosmolar blood-brain barrier disruption in baboons: an in vivo study using positron emission tomography and rubidium-82

1996 ◽  
Vol 84 (3) ◽  
pp. 494-502 ◽  
Author(s):  
Bernhard Zünkeler ◽  
Richard E. Carson ◽  
Jeffrey Olson ◽  
Ronald G. Blasberg ◽  
Mary Girton ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Emission Tomography ◽  
Brain Barrier ◽  
Blood Brain ◽  
Positron Emission ◽  
The Mean ◽  
Rubidium 82

✓ Hyperosmolar blood-brain barrier (BBB) disruption remains controversial as an adjuvant therapy to increase delivery of water-soluble compounds to extracellular space in the brain in patients with malignant brain tumors. To understand the physiological effects of BBB disruption more clearly, the authors used positron emission tomography (PET) to study the time course of BBB permeability in response to the potassium analog rubidium-82 (82Rb, halflife 75 seconds) following BBB disruption in anesthetized adult baboons. Mannitol (25%) was injected into the carotid artery and PET scans were performed before and serially at 8- to 15-minute intervals after BBB disruption. The mean influx constant (K1), a measure of permeability-surface area product, in ipsilateral, mannitol-perfused mixed gray- and white-matter brain regions was 4.9 ± 2.4 µl/min/ml (± standard deviation) at baseline and increased more than 100% (ΔK1 = 9.4 ± 5.1 µl/min/ml, 18 baboons) in brain perfused by mannitol. The effect of BBB disruption on K1 correlated directly with the total amount of mannitol administered (p < 0.005). Vascular permeability returned to baseline with a halftime of 24.0 ± 14.3 minutes. The mean brain plasma volume rose by 0.57 ± 0.34 ml/100 ml in ipsilateral perfused brain following BBB disruption. This work provides a basis for the in vivo study of permeability changes induced by BBB disruption in human brain and brain tumors.

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