51 research outputs found
Pharmacological interactions between phenylbenzothiazoles and aryl hydrocarbon receptor (AhR)
The aryl hydrocarbon receptor is a ligand-dependent transcription factor that induces expression of a number of genes encoding drug metabolizing enzymes, such as CYP1A1, CYP1A2 and CYP1B1. Recently, it was suggested that the AhR signaling pathway may be involved in mediating the anticancer activity of novel 2-(4-aminophenyl) benzothiazole drugs in MCF-7 breast cancer cells. There is no direct proof of direct binding between these drugs and AhR, and it is also unclear how AhR signaling per se plays a role in the activity of these drugs. This study investigates the role of AhR in the mechanism of action of the benzothiazole drugs by determining the ability of these drugs to bind to the rat hepatic AhR, to induce CYP1A1 mRNA and to inhibit cell growth in rat hepatoma H4-II-E cells.
The apparent binding kinetics of [3H]-TCDD to AhR in rat liver cytosol were, KD= 0.37nM and Bmax = 40 fmol/mg cytosolic protein. Using the standard assay conditions, 18 compounds competitively displaced [3H]-TCDD from specific sites, and are ligands for AhR. Induction of CYP1A1 mRNA by 5 compounds was determined in H4-II-E cells. The highest affinity ligand, IH445, was the most potent with an EC50 ~ 80-fold lower than that of TCDD (60 pM) with no detectable antagonistic activity in H4-II-E cells. The other high-affinity benzothiazoles tested were (30-100) x 103-fold less potent for inducing CYP1A1 mRNA than TCDD. The binding affinities of these compounds were 200-1000-fold higher than induction potency. For example, 5F 203 has a Ki value of 2.8 nM, induced CYP1A1 mRNA to similar maximal levels as seen with TCDD, and has an EC50 of 3 μM. The 1000-fold difference for 5F 203 between binding and CYP1A1 RNA induction was suggested to be a result of metabolism or that 5F 203 exhibits partial AhR antagonist activity. The time course effect on the CYP1A1/β-actin mRNA ratios by 5F 203 revealed that the response was increasing linearly in response to 5F 203 at 4 h treatment, indicating that the former possibilty is less likely to be a major factor. To address the second possibility, the antagonistic activity of 5F 203 on TCDD-induced CYP1A1 mRNA was investigated. H4-II-E cells were treated with increasing concentrations of TCDD ± 1μM 5F 203. The results demonstrated that 5F 203 shifted the EC50 of TCDD 100-fold to the right. Schild analysis on the antagonism of TCDD-induced CYP1A1 mRNA by different concentrations of 5F 203 provided a quantitative explanation for the 1000-fold difference between binding and induction for 5F 203. In contrast, the EC50 of 5F 203 in human MCF-7 cells was 2 nM, which is ~ 10-fold less potent than TCDD. Moreover, 5F 203 had no detectable antagonistic activity on TCDDinduced CYP1A1 mRNA. When 5F 203 was assessed for cell growth inhibition by MTT assay, it was found active in MCF-7 cells with a GI50 of 18 nM, but failed to elicit the same effect in H4-II-E cells.
These results prove that 5F 203 is a potent agonist in MCF-7 cells, but a partial agonist in H4-II-E cells. The partial agonism observed with 5F 203 is a compound-specific property given that another analogue, IH 445, was found potent inducer of CYP1A1 mRNA with no antagonistic activity. The results of this study reveal species-specific partial agonism of the AhR. The potency of the cytostatic effect of 5F 203 parallel potency for inducing CYP1A1 mRNA in both cells. Moreover, both, the cytostatic effect of 5F 203 and partial agonism of AhR for inducing CYP1A1 mRNA is species-specific. Whether agonism/antagonism for the induction of CYP1A1 mRNA is related to the anticancer activity of 5F 203 remains to be elucidated
Preclincial evaluation of Gold-DTDTPA Nanoparticles As Theranostic Agents In Prostate Cancer Radiotherapy
International audienceAim: Gold nanoparticles have attracted significant interest in cancer diagnosis and treatment. Herein, we evaluated the theranostic potential of dithiolated diethylenetriamine pentaacetic acid (DTDTPA) conjugated AuNPs (Au@DTDTPA) for CT-contrast enhancement and radiosensitization in prostate cancer. Materials & methods: In vitro assays determined Au@DTDTPA uptake, cytotoxicity, radiosensitizing potential and DNA damage profiles. Human PC3 xenograft tumor models were used to determine CT enhancement and radiation modulating effects in vivo. Results: Cells exposed to nanoparticles and radiation observed significant additional reduction in survival compared with radiation only. Au@DTDTPA produced a CT enhancement of 10% and a significant extension in tumor growth delay from 16.9 days to 38.3 compared with radiation only. Conclusion: This study demonstrates the potential of Au@DTDTPA to enhance CT-image contrast and simultaneously increases the radiosensitivity of prostate tumors
Pharmacological interactions between phenylbenzothiazoles and aryl hydrocarbon receptor (AhR)
The aryl hydrocarbon receptor is a ligand-dependent transcription factor that induces expression of a number of genes encoding drug metabolizing enzymes, such as CYP1A1, CYP1A2 and CYP1B1. Recently, it was suggested that the AhR signaling pathway may be involved in mediating the anticancer activity of novel 2-(4-aminophenyl) benzothiazole drugs in MCF-7 breast cancer cells. There is no direct proof of direct binding between these drugs and AhR, and it is also unclear how AhR signaling per se plays a role in the activity of these drugs. This study investigates the role of AhR in the mechanism of action of the benzothiazole drugs by determining the ability of these drugs to bind to the rat hepatic AhR, to induce CYP1A1 mRNA and to inhibit cell growth in rat hepatoma H4-II-E cells. The apparent binding kinetics of [3H]-TCDD to AhR in rat liver cytosol were, KD= 0.37nM and Bmax = 40 fmol/mg cytosolic protein. Using the standard assay conditions, 18 compounds competitively displaced [3H]-TCDD from specific sites, and are ligands for AhR. Induction of CYP1A1 mRNA by 5 compounds was determined in H4-II-E cells. The highest affinity ligand, IH445, was the most potent with an EC50 ~ 80-fold lower than that of TCDD (60 pM) with no detectable antagonistic activity in H4-II-E cells. The other high-affinity benzothiazoles tested were (30-100) x 103-fold less potent for inducing CYP1A1 mRNA than TCDD. The binding affinities of these compounds were 200-1000-fold higher than induction potency. For example, 5F 203 has a Ki value of 2.8 nM, induced CYP1A1 mRNA to similar maximal levels as seen with TCDD, and has an EC50 of 3 μM. The 1000-fold difference for 5F 203 between binding and CYP1A1 RNA induction was suggested to be a result of metabolism or that 5F 203 exhibits partial AhR antagonist activity. The time course effect on the CYP1A1/β-actin mRNA ratios by 5F 203 revealed that the response was increasing linearly in response to 5F 203 at 4 h treatment, indicating that the former possibilty is less likely to be a major factor. To address the second possibility, the antagonistic activity of 5F 203 on TCDD-induced CYP1A1 mRNA was investigated. H4-II-E cells were treated with increasing concentrations of TCDD ± 1μM 5F 203. The results demonstrated that 5F 203 shifted the EC50 of TCDD 100-fold to the right. Schild analysis on the antagonism of TCDD-induced CYP1A1 mRNA by different concentrations of 5F 203 provided a quantitative explanation for the 1000-fold difference between binding and induction for 5F 203. In contrast, the EC50 of 5F 203 in human MCF-7 cells was 2 nM, which is ~ 10-fold less potent than TCDD. Moreover, 5F 203 had no detectable antagonistic activity on TCDDinduced CYP1A1 mRNA. When 5F 203 was assessed for cell growth inhibition by MTT assay, it was found active in MCF-7 cells with a GI50 of 18 nM, but failed to elicit the same effect in H4-II-E cells. These results prove that 5F 203 is a potent agonist in MCF-7 cells, but a partial agonist in H4-II-E cells. The partial agonism observed with 5F 203 is a compound-specific property given that another analogue, IH 445, was found potent inducer of CYP1A1 mRNA with no antagonistic activity. The results of this study reveal species-specific partial agonism of the AhR. The potency of the cytostatic effect of 5F 203 parallel potency for inducing CYP1A1 mRNA in both cells. Moreover, both, the cytostatic effect of 5F 203 and partial agonism of AhR for inducing CYP1A1 mRNA is species-specific. Whether agonism/antagonism for the induction of CYP1A1 mRNA is related to the anticancer activity of 5F 203 remains to be elucidated.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Pharmacological interactions between phenylbenzothiazoles and aryl hydrocarbon receptor (AhR)
The aryl hydrocarbon receptor is a ligand-dependent transcription factor that induces expression of a number of genes encoding drug metabolizing enzymes, such as CYP1A1, CYP1A2 and CYP1B1. Recently, it was suggested that the AhR signaling pathway may be involved in mediating the anticancer activity of novel 2-(4-aminophenyl) benzothiazole drugs in MCF-7 breast cancer cells. There is no direct proof of direct binding between these drugs and AhR, and it is also unclear how AhR signaling per se plays a role in the activity of these drugs. This study investigates the role of AhR in the mechanism of action of the benzothiazole drugs by determining the ability of these drugs to bind to the rat hepatic AhR, to induce CYP1A1 mRNA and to inhibit cell growth in rat hepatoma H4-II-E cells.
The apparent binding kinetics of [3H]-TCDD to AhR in rat liver cytosol were, KD= 0.37nM and Bmax = 40 fmol/mg cytosolic protein. Using the standard assay conditions, 18 compounds competitively displaced [3H]-TCDD from specific sites, and are ligands for AhR. Induction of CYP1A1 mRNA by 5 compounds was determined in H4-II-E cells. The highest affinity ligand, IH445, was the most potent with an EC50 ~ 80-fold lower than that of TCDD (60 pM) with no detectable antagonistic activity in H4-II-E cells. The other high-affinity benzothiazoles tested were (30-100) x 103-fold less potent for inducing CYP1A1 mRNA than TCDD. The binding affinities of these compounds were 200-1000-fold higher than induction potency. For example, 5F 203 has a Ki value of 2.8 nM, induced CYP1A1 mRNA to similar maximal levels as seen with TCDD, and has an EC50 of 3 μM. The 1000-fold difference for 5F 203 between binding and CYP1A1 RNA induction was suggested to be a result of metabolism or that 5F 203 exhibits partial AhR antagonist activity. The time course effect on the CYP1A1/β-actin mRNA ratios by 5F 203 revealed that the response was increasing linearly in response to 5F 203 at 4 h treatment, indicating that the former possibilty is less likely to be a major factor. To address the second possibility, the antagonistic activity of 5F 203 on TCDD-induced CYP1A1 mRNA was investigated. H4-II-E cells were treated with increasing concentrations of TCDD ± 1μM 5F 203. The results demonstrated that 5F 203 shifted the EC50 of TCDD 100-fold to the right. Schild analysis on the antagonism of TCDD-induced CYP1A1 mRNA by different concentrations of 5F 203 provided a quantitative explanation for the 1000-fold difference between binding and induction for 5F 203. In contrast, the EC50 of 5F 203 in human MCF-7 cells was 2 nM, which is ~ 10-fold less potent than TCDD. Moreover, 5F 203 had no detectable antagonistic activity on TCDDinduced CYP1A1 mRNA. When 5F 203 was assessed for cell growth inhibition by MTT assay, it was found active in MCF-7 cells with a GI50 of 18 nM, but failed to elicit the same effect in H4-II-E cells.
These results prove that 5F 203 is a potent agonist in MCF-7 cells, but a partial agonist in H4-II-E cells. The partial agonism observed with 5F 203 is a compound-specific property given that another analogue, IH 445, was found potent inducer of CYP1A1 mRNA with no antagonistic activity. The results of this study reveal species-specific partial agonism of the AhR. The potency of the cytostatic effect of 5F 203 parallel potency for inducing CYP1A1 mRNA in both cells. Moreover, both, the cytostatic effect of 5F 203 and partial agonism of AhR for inducing CYP1A1 mRNA is species-specific. Whether agonism/antagonism for the induction of CYP1A1 mRNA is related to the anticancer activity of 5F 203 remains to be elucidated
The contribution of hydrogen peroxide to the radiosensitizing effect of gold nanoparticles
International audiencePlasmid DNA in aerated aqueous solution is used as a probe to determine whose of the reactive oxygen species (ROS) generated after absorption of ultra-soft X-rays (USX) take part in biomolecule damage in the presence and in absence of Gold Nano-Particles (GNP) and specific scavengers. Citrate-coated GNPs with core sizes of 6, 10 and 25 nm are synthetized and characterized, especially in terms of plasmon band shift, ζ-potential and hydrodynamic radii (respectively 9, 21 and 30 nm). We confirm the radiosensitizing effect of GNP and show that the SSB number per plasmid increases when, for a same mass of gold element, the core size of the gold nanoparticles decreases. Hydroxyl radicals (radical dotOH) are scavenged using the positively-charged 2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) and the neutral dimethyl sulfoxide (DMSO) molecules. Due to both negatively-charged environments of DNA and GNP, at identical scavenging capacity, TRIS is more effective at quenching radical dotOH than DMSO. The strong radiosensitizing effect of hydroxyl radicals is confirmed. Methanoate anions are then used to transform radical dotOH into hydrogen peroxide; the latter being known to be non-aggressive regarding DNA in the absence of easily oxidable metallic ions (Fenton reactions). Surprisingly, in the presence of GNP, high DNA damage yields are observed even though hydrogen peroxide might not be hold as responsible. Conversely, the radiosensitizing effect of GNP is not observed anymore when H2O2 is scavenged using pyruvate ions. We demonstrate that hydrogen peroxide constitutes quite unexpectedly a hidden stock of radical dotOH which are activated at the surface of the GNP by decomposition of H2O2 molecules
Two step promotion of a hot tumor immune environment by gold decorated iron oxide nanoflowers and light-triggered mild hyperthermia
International audiencePhotoactivated Gold decorated iron oxide nanoflowers induce a hot tumor immune microenvironnment in triple negative breast cancer model
Increase of OH radical yields due to the decomposition of hydrogen peroxide by gold nanoparticles under X-ray irradiation
International audienceWe elucidate the decomposition mechanism of hydrogen peroxide, which is formed by water radiolysis, by gold nanoparticles (GNPs) under X-ray irradiation. The variations in yields of hydrogen peroxide generated in the presence of GNPs are evaluated using the Ghormley technique. The increase of yields of OH radicals has been quantified using Ampliflu® Red solutions. Almost all hydrogen peroxide generated by irradiation of <25 Gy is decomposed by GNPs, while the yield of OH radicals increases by 1.6 times. The amount of OH radicals thus obtained is almost equivalent to that of the decomposed hydrogen peroxide. The decomposition of hydrogen peroxide is an essential reaction to produce additional OH radicals efficiently in the vicinity of GNPs
Optimization of the synthesis of nanostructured Tb3+-doped Gd2O3 by in-situ luminescence following up
International audienc
2-(4-Amino-3-methylphenyl)-5-fluorobenzothiazole is a ligand and shows species-specific partial agonism of the Aryl Hydrocarbon Receptor
2-(4-Amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) and related compounds are a series
of anti-cancer candidate pharmaceuticals (Table 1.), that have been shown to activate the
AhR. We show that these compounds are high affinity ligands for the rat AhR, but a quantitative
assay for their ability to induce CYP1A1 RNA in H4IIEC3 cells, a measure of activation of the
AhR, showed a poor relationship between affinity for the AhR and ability to induce CYP1A1
RNA. 5F 203, an agonist with low potency, was able to antagonise the induction of CYP1A1
RNA by TCDD, while IH 445, a potent agonist, did not antagonise the induction of CYP1A1
RNA by TCDD, and Schild analysis confirmed 5F 203 to be a potent antagonist of the induction
of CYP1A1 RNA by TCDD in H4IIEC3 cells. In contrast, several benzothiazoles show potent
induction of CYP1A1 RNA in human MCF-7 cells, and 5F 203 is unable to detectably antagonise
the induction of CYP1A1 RNA in MCF-7 cells, showing a species difference in antagonism.
Evaluation of the antiproliferative activity of benzothiazoles showed that the ability to
agonise the AhR correlated with growth inhibition both in H4IIEC3 cells for a variety of benzothiazoles,
and between H4IIEC3 and MCF-7 cells for 5F 203, suggesting an important role
of agonism of the AhR in the anti-proliferative activity of benzothiazoles
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