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Guilherme L. Indig - One of the best experts on this subject based on the ideXlab platform.
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photophysical photochemical and tumor selectivity properties of bromine derivatives of Rhodamine 123
Photochemistry and Photobiology, 2005Co-Authors: Silvia H. D. Lacerda, Bindu Abraham, Thomas C. Stringfellow, Guilherme L. IndigAbstract:The conceptual basis for the development of mitochondrial targeting as a novel therapeutic strategy for both chemotherapy and photochemotherapy of neoplastic diseases rests on the observation that enhanced mitochondrial membrane potential is a common tumor cell phenotype. The potential of this strategy is highlighted by the fact that the toxic effects associated with a number of cationic dyes known to localize in energized cell mitochondria are much more pronounced in tumor cells than in normal cells. Here we evaluate the phototoxic properties of four bromine derivatives of Rhodamine-123 toward human uterine sarcoma (MES-SA) and green monkey kidney (CV-1) cells and compare the degrees of tumor cell selectivity associated with these dyes with those associated with two model mitochondrial triarylmethanes (crystal violet and ethyl violet). Selective phototoxicity toward tumor cells was found to be highly dependent upon the lipophilic/hydrophilic character of the cationic photosensitizer. Our experimental data have indicated that the probability of success of mitochondrial targeting in (photo)chemotherapy of neoplastic diseases is higher when the octan-1-ol/water partition coefficient of the drug candidate falls within approximately two orders of magnitude from that of the prototypical mitochondria-specific dye Rhodamine-123.
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Photophysical, Photochemical, and Tumor‐selectivity Properties of Bromine Derivatives of Rhodamine‐123
Photochemistry and photobiology, 2005Co-Authors: Silvia H. D. Lacerda, Bindu Abraham, Thomas C. Stringfellow, Guilherme L. IndigAbstract:The conceptual basis for the development of mitochondrial targeting as a novel therapeutic strategy for both chemotherapy and photochemotherapy of neoplastic diseases rests on the observation that enhanced mitochondrial membrane potential is a common tumor cell phenotype. The potential of this strategy is highlighted by the fact that the toxic effects associated with a number of cationic dyes known to localize in energized cell mitochondria are much more pronounced in tumor cells than in normal cells. Here we evaluate the phototoxic properties of four bromine derivatives of Rhodamine-123 toward human uterine sarcoma (MES-SA) and green monkey kidney (CV-1) cells and compare the degrees of tumor cell selectivity associated with these dyes with those associated with two model mitochondrial triarylmethanes (crystal violet and ethyl violet). Selective phototoxicity toward tumor cells was found to be highly dependent upon the lipophilic/hydrophilic character of the cationic photosensitizer. Our experimental data have indicated that the probability of success of mitochondrial targeting in (photo)chemotherapy of neoplastic diseases is higher when the octan-1-ol/water partition coefficient of the drug candidate falls within approximately two orders of magnitude from that of the prototypical mitochondria-specific dye Rhodamine-123.
Thomas C. Dowling - One of the best experts on this subject based on the ideXlab platform.
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Determination of Rhodamine 123 in cell lysate by HPLC with visible wavelength detection.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2005Co-Authors: Tahira Iqbal, Minori Kinjo, Thomas C. DowlingAbstract:Abstract Rhodamine 123 (R123) is widely used to quantify P-glycoprotein (P-GP) functional efflux activity in vitro. We developed a rapid and specific high-performance liquid chromatography (HPLC) method to quantify Rhodamine 123 for use in experimental cell culture studies. The R123 standards (2.5–250 ng/mL) and quality controls (QCs) (5, 75, 200 ng/mL) were prepared in cell lysis buffer consisting of 0.75% Triton 100X and 0.2% sodium chloride. The mobile phase consisted of acetonitrile, 1.5 mM tetrabutyl ammonium bromide in 20 mM sodium acetate buffer (pH 4.0) (50:20:30) delivered at a rate of 1.0 mL/min. Samples (50 μL) were injected onto a C18 reversed-phase HPLC column with detection at 500 nm. Analyte retention times were 1.4 and 4.3 min for R123 and internal standard (R6G), respectively. Intra- and inter-day coefficients of variation were ≤4.2%. Samples were stable for at least three freeze-thaw cycles at room temperature for 24 and 48 h. This method was used to evaluate the functional activity of P-glycoprotein in renal tubule cell models including human kidney (HK-2), Madin–Darby canine kidney (MDCK) and multi-drug resistance gene-transfected MDCK cells (MDR1-MDCK).
Priscilla S. Dannies - One of the best experts on this subject based on the ideXlab platform.
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Rapid stimulation of Rhodamine 123 efflux from multidrug-resistant KB cells by progesterone
Biochemical pharmacology, 1993Co-Authors: Erik M. Jancis, Rocco Carbone, Chen Hong-xing, Richard B. Hochberg, Priscilla S. DanniesAbstract:Rhodamine 123 is a mitochondrial dye that is retained for prolonged periods by carcinoma cells. While investigating causes of retention of this dye, we found that 10 microM progesterone caused a rapid stimulation of efflux of Rhodamine 123 within 15 min from KB V20C cells, which overexpress the multidrug resistance pump. Progesterone did not stimulate efflux from KB cells that do not overexpress the pump, and verapamil blocked Rhodamine 123 efflux in the presence or absence of progesterone, indicating that Rhodamine 123 is removed from KB V20C cells by the multidrug resistance pump. Progesterone, however, is unlikely to stimulate Rhodamine 123 efflux by simply increasing pump activity for two reasons: (1) progesterone inhibited the efflux of daunomycin from KB V20C cells, so it did not stimulate efflux of all drugs, and (2) progesterone inhibited efflux of Rhodamine 123 from L1210/VMDRC cells and had little effect on Adr MCF7 cells; both overexpress the multidrug resistance pump. In the experiments with KB V20C cells, progesterone was the most active steroid tested. At 10 microM, progesterone caused a 70-fold stimulation, desoxycorticosterone, testosterone, promegestone and estradiol about 20-fold, and others had little or no effect. Progesterone may act by a non-genomic mechanism to decrease intracellular binding of Rhodamine 123, making the dye accessible to the multidrug resistance pump.
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Estradiol induction of Rhodamine 123 efflux and the multidrug resistance pump in rat pituitary tumor cells.
Molecular pharmacology, 1993Co-Authors: E M Jancis, Rocco Carbone, K J Loechner, Priscilla S. DanniesAbstract:Rhodamine 123 is a fluorescent dye that localizes in mitochondria, is a substrate for the multidrug resistance pump, and is retained for long periods of time by carcinoma cells. 17 beta-Estradiol causes GH4C1 cells (rat pituitary tumor cells) to lose Rhodamine 123 fluorescence faster than untreated cells. We found that estradiol induces accumulation of the mRNA for the multidrug resistance pump 3-5-fold, with maximum induction occurring within 1 day at 10(-9) M estradiol. Immunoblot analysis demonstrated that estradiol induces a protein of 150 kDa that reacts with an antibody to P-glycoprotein, the multidrug resistance pump. The reduced retention of Rhodamine 123 caused by estradiol is prevented by verapamil and cyclosporin, inhibitors of the pump. A clone resistant to the effects of estradiol on Rhodamine 123 has greatly reduced levels of mRNA for the pump. The effect of estradiol is more marked on Rhodamine 123 retention than it is on that of Rhodamine 110 or tetramethylRhodamine methyl ester. We conclude that estradiol enhances Rhodamine 123 efflux by inducing the multidrug resistance gene. The specificity for Rhodamine 123, compared with other analogs, may be caused by differences in accessibility to the pump.
Silvia H. D. Lacerda - One of the best experts on this subject based on the ideXlab platform.
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photophysical photochemical and tumor selectivity properties of bromine derivatives of Rhodamine 123
Photochemistry and Photobiology, 2005Co-Authors: Silvia H. D. Lacerda, Bindu Abraham, Thomas C. Stringfellow, Guilherme L. IndigAbstract:The conceptual basis for the development of mitochondrial targeting as a novel therapeutic strategy for both chemotherapy and photochemotherapy of neoplastic diseases rests on the observation that enhanced mitochondrial membrane potential is a common tumor cell phenotype. The potential of this strategy is highlighted by the fact that the toxic effects associated with a number of cationic dyes known to localize in energized cell mitochondria are much more pronounced in tumor cells than in normal cells. Here we evaluate the phototoxic properties of four bromine derivatives of Rhodamine-123 toward human uterine sarcoma (MES-SA) and green monkey kidney (CV-1) cells and compare the degrees of tumor cell selectivity associated with these dyes with those associated with two model mitochondrial triarylmethanes (crystal violet and ethyl violet). Selective phototoxicity toward tumor cells was found to be highly dependent upon the lipophilic/hydrophilic character of the cationic photosensitizer. Our experimental data have indicated that the probability of success of mitochondrial targeting in (photo)chemotherapy of neoplastic diseases is higher when the octan-1-ol/water partition coefficient of the drug candidate falls within approximately two orders of magnitude from that of the prototypical mitochondria-specific dye Rhodamine-123.
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Photophysical, Photochemical, and Tumor‐selectivity Properties of Bromine Derivatives of Rhodamine‐123
Photochemistry and photobiology, 2005Co-Authors: Silvia H. D. Lacerda, Bindu Abraham, Thomas C. Stringfellow, Guilherme L. IndigAbstract:The conceptual basis for the development of mitochondrial targeting as a novel therapeutic strategy for both chemotherapy and photochemotherapy of neoplastic diseases rests on the observation that enhanced mitochondrial membrane potential is a common tumor cell phenotype. The potential of this strategy is highlighted by the fact that the toxic effects associated with a number of cationic dyes known to localize in energized cell mitochondria are much more pronounced in tumor cells than in normal cells. Here we evaluate the phototoxic properties of four bromine derivatives of Rhodamine-123 toward human uterine sarcoma (MES-SA) and green monkey kidney (CV-1) cells and compare the degrees of tumor cell selectivity associated with these dyes with those associated with two model mitochondrial triarylmethanes (crystal violet and ethyl violet). Selective phototoxicity toward tumor cells was found to be highly dependent upon the lipophilic/hydrophilic character of the cationic photosensitizer. Our experimental data have indicated that the probability of success of mitochondrial targeting in (photo)chemotherapy of neoplastic diseases is higher when the octan-1-ol/water partition coefficient of the drug candidate falls within approximately two orders of magnitude from that of the prototypical mitochondria-specific dye Rhodamine-123.
Tahira Iqbal - One of the best experts on this subject based on the ideXlab platform.
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Determination of Rhodamine 123 in cell lysate by HPLC with visible wavelength detection.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2005Co-Authors: Tahira Iqbal, Minori Kinjo, Thomas C. DowlingAbstract:Abstract Rhodamine 123 (R123) is widely used to quantify P-glycoprotein (P-GP) functional efflux activity in vitro. We developed a rapid and specific high-performance liquid chromatography (HPLC) method to quantify Rhodamine 123 for use in experimental cell culture studies. The R123 standards (2.5–250 ng/mL) and quality controls (QCs) (5, 75, 200 ng/mL) were prepared in cell lysis buffer consisting of 0.75% Triton 100X and 0.2% sodium chloride. The mobile phase consisted of acetonitrile, 1.5 mM tetrabutyl ammonium bromide in 20 mM sodium acetate buffer (pH 4.0) (50:20:30) delivered at a rate of 1.0 mL/min. Samples (50 μL) were injected onto a C18 reversed-phase HPLC column with detection at 500 nm. Analyte retention times were 1.4 and 4.3 min for R123 and internal standard (R6G), respectively. Intra- and inter-day coefficients of variation were ≤4.2%. Samples were stable for at least three freeze-thaw cycles at room temperature for 24 and 48 h. This method was used to evaluate the functional activity of P-glycoprotein in renal tubule cell models including human kidney (HK-2), Madin–Darby canine kidney (MDCK) and multi-drug resistance gene-transfected MDCK cells (MDR1-MDCK).