Phytoestrogens modulate breast cancer resistance protein expression and function at the blood-cerebrospinal fluid barrier

PURPOSE: Breast cancer resistance protein (BCRP/ABCG2) is a drug efflux transporter expressed at the blood cerebrospinal fluid barrier (BCSFB), and influences distribution of drugs into the central nervous systems (CNS). Current inhibitors have failed clinically due to neurotoxicity. Novel approaches are needed to identify new modulators to enhance CNS delivery. This study examines 18 compounds (mainly phytoestrogens) as modulators of the expression/function of BCRP in an in vitro rat choroid plexus BCSFB model. METHODS: Modulators were initially subject to cytotoxicity (MTT) assessment to determine optimal non-toxic concentrations. Reverse-transcriptase PCR and confocal microscopy were used to identify the presence of BCRP in Z310 cells. Thereafter modulation of the intracellular accumulation of the fluorescent BCRP probe substrate Hoechst 33342 (H33342), changes in protein expression of BCRP (western blotting) and the functional activity of BCRP (membrane insert model) were assessed under modulator exposure. RESULTS: A 24 hour cytotoxicity assay (0.001 µM-1000 µM) demonstrated the majority of modulators possessed a cellular viability IC50 > 148 µM. Intracellular accumulation of H33342 was significantly increased in the presence of the known BCRP inhibitor Ko143 and, following a 24 hour pre-incubation, all modulators demonstrated statistically significant increases in H33342 accumulation (P < 0.001), when compared to control and Ko143. After a 24 hour pre-incubation with modulators alone, a 0.16-2.5-fold change in BCRP expression was observed for test compounds. The functional consequences of this were confirmed in a permeable insert model of the BCSFB which demonstrated that 17-β-estradiol, naringin and silymarin (down-regulators) and baicalin (up-regulator) can modulate BCRP-mediated transport function at the BCSFB. CONCLUSION: We have successfully confirmed the gene and protein expression of BCRP in Z310 cells and demonstrated the potential for phytoestrogen modulators to influence the functionality of BCRP at the BCSFB and thereby potentially allowing manipulation of CNS drug disposition.

Relación de largo plazo entre el precio de las viviendas y sus variables fundamentales para los distritos de La Molina, San Borja, San Isidro y Surco en Lima Metropolitana

El objetivo del presente trabajo es demostrar que, en el corto plazo, es probable que los precios de las viviendas en Lima Metropolitana (en los distritos de La Molina, San Borja, San Isidro y Surco) no tengan relación con sus variables fundamentales (precio de alquileres, índice de construcción, precio de terrenos, tipo de cambio, tasas de interés en soles y dólares y los ingresos). Esto indicaría un desalineamiento temporal del precio respecto de sus variables fundamentales; sin embargo, en el largo plazo sí lo harían. Esta demostración de que en el largo plazo las variables están cointegradas se realizará usando el test de cointegración de Johansen, y mediante el vector de corrección de errores se demostrará que en el corto plazo las variables no están cointegradas. El periodo muestral seleccionado abarca desde 2004Q1 hasta 2014Q3, dado que es el periodo en que se muestra un fuerte crecimiento y disminución del precio de las viviendas. La data ha sido obtenida del Banco Central de Reserva del Perú (BCRP), la Cámara Peruana de la Construcción (Capeco), el suplemento Urbania del diario El Comercio, la Superintendencia de Banca y Seguros (SBS) y el Instituto Nacional de Estadística e Informática (INEI). Se optó por analizar el precio de las viviendas de los distritos de La Molina, San Borja, San Isidro y Surco, debido a la disponibilidad de la data. El resultado del modelo de Johansen muestra que en el largo plazo las variables precio de alquileres, índice de construcción, precio de terrenos, tipo de cambio y los ingresos explican el comportamiento del precio de las viviendas; es decir, las variables están cointegradas. Por el contrario, las variables tasa de interés en soles y dólares no siguen el mismo comportamiento, por lo que no son consideradas para el test de Johansen. Para finalizar, el vector de corrección de errores muestra que, en el corto plazo, dichas variables no están cointegradas.

Phytochemical mediated-modulation of the expression and transporter function of breast cancer resistance protein at the blood-brain barrier:an in-vitro study

Clinical translation of BCRP inhibitors have failed due to neurotoxicity and novel approaches are required to identify suitable modulators of BCRP to enhance CNS drug delivery. In this study we examine 18 compounds, primarily phytochemicals, as potential novel modulators of AhR-mediated regulation of BCRP expression and function in immortalised and primary porcine brain microvascular endothelial cells as a mechanism to enhance CNS drug delivery. The majority of modulators possessed a cellular viability IC50 > 100 µM in both cell systems. BCRP activity, when exposed to modulators for 1 hour, was diminished for most modulators through significant increases in H33342 accumulation at < 10 µM with 2,6,4-trimethoflavone increasing H33342 intracellular accumulation by 3.7–6.6 fold over 1–100 µM. Western blotting and qPCR identified two inducers of BCRP (quercetin and naringin) and two down-regulators (17-β-estradiol and curcumin) with associated changes in BCRP efflux transport function further confirmed in both cell lines. siRNA downregulation of AhR resulted in a 1.75 ± 0.08 fold change in BCRP expression, confirming the role of AhR in the regulation of BCRP. These findings establish the regulatory role AhR of in controlling BCRP expression at the BBB and confirm quercetin, naringin, 17-β-estradiol, and curcumin as novel inducers and down-regulators of BCRP gene, protein expression and functional transporter activity and hence potential novel target sites and candidates for enhancing CNS drug delivery.