15 research outputs found
Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats
Safety and Efficacy of Combined Chelation Therapy with Deferasirox and Deferoxamine in a Gerbil Model of Iron Overload
In Vivo Testing of Luciferase Substrate Analogs in an Orthotopic Murine Model of Human Glioblastoma
In vivo bioluminescent imaging using cells expressing Renilla luciferase is becoming increasingly common. Hindrances to the more widespread use of Renilla luciferase are the high autoluminescence of its natural substrate, coelenterazine, in plasma; the relatively high absorbance by tissue of the light emitted by the enzyme–substrate reaction; rapid clearance of the substrate; and significant cost. These factors, save for the cost, which has its own limiting effect on use, can combine to reduce the sensitivity of in vivo assays utilizing this reporter system, and methods of increasing light output or decreasing autoluminescence could be of great benefit. A number of analogs of coelenterazine are being investigated that may accomplish one or both of these goals. In this study, we report on the testing of two new substrate analogs, EnduRen™ and ViviRen™, manufactured by Promega Corporation, in an orthotopic murine model of human glioblastoma expressing Renilla luciferase. We have tested these analogs in this cell line, both in vitro and in vivo, and find that the substrate ViviRen results in significantly greater light output than the natural substrate or the other analog EnduRen. This new substrate could be valuable for studies where greater sensitivity is important
The Effect of Supplemental Ascorbate on Defersirox Iron Chelation In the Iron-Loaded Gerbil
Ligand-Independent and Tissue-Selective Androgen Receptor Inhibition by Pyrvinium
Pyrvinium pamoate (PP) is a potent noncompetitive inhibitor of the androgen receptor (AR). Using a novel method of target identification, we demonstrate that AR is a direct target of PP in prostate cancer cells. We demonstrate that PP inhibits AR activity via the highly conserved DNA binding domain (DBD), the only AR inhibitor that functions via this domain. Furthermore, computational modeling predicts that pyrvinium binds at the interface of the DBD dimer and the minor groove of the AR response element. Because PP acts through the DBD, PP is able to inhibit the constitutive activity of AR splice variants, which are thought to contribute to the growth of castration resistant prostate cancer (CRPC). PP also inhibits androgen-independent AR activation by HER2 kinase. The antiandrogen activity of pyrvinium manifests in the ability to inhibit the in vivo growth of CRPC xenografts that express AR splice variants. Interestingly, PP was most potent in cells with endogenous AR expression derived from prostate or bone. PP was able to inhibit several other hormone nuclear receptors (NRs) but not structurally unrelated transcription factors. PP inhibition of other NRs was similarly cell-type selective. Using dual-energy X-ray absorptiometry, we demonstrate that the cell-type specificity of PP manifests in tissue-selective inhibition of AR activity in mice, as PP decreases prostate weight and bone mineral density but does not affect lean body mass. Our results suggest that the noncompetitive AR inhibitor pyrvinium has significant potential to treat CRPC, including cancers driven by ligand-independent AR signaling
In Vivo Testing of Renilla
In vivo bioluminescent imaging using cells expressing Renilla luciferase is becoming increasingly common. Hindrances to the more widespread use of Renilla luciferase are the high autoluminescence of its natural substrate, coelenterazine, in plasma; the relatively high absorbance by tissue of the light emitted by the enzyme–substrate reaction; rapid clearance of the substrate; and significant cost. These factors, save for the cost, which has its own limiting effect on use, can combine to reduce the sensitivity of in vivo assays utilizing this reporter system, and methods of increasing light output or decreasing autoluminescence could be of great benefit. A number of analogs of coelenterazine are being investigated that may accomplish one or both of these goals. In this study, we report on the testing of two new substrate analogs, EnduRen™ and ViviRen™, manufactured by Promega Corporation, in an orthotopic murine model of human glioblastoma expressing Renilla luciferase. We have tested these analogs in this cell line, both in vitro and in vivo, and find that the substrate ViviRen results in significantly greater light output than the natural substrate or the other analog EnduRen. This new substrate could be valuable for studies where greater sensitivity is important
Sex differences and steroid modulation of cardiac iron in a mouse model of iron overload
Ligand-Independent and Tissue-Selective Androgen Receptor Inhibition by Pyrvinium
Pyrvinium
pamoate (PP) is a potent noncompetitive inhibitor of
the androgen receptor (AR). Using a novel method of target identification,
we demonstrate that AR is a direct target of PP in prostate cancer
cells. We demonstrate that PP inhibits AR activity via the highly
conserved DNA binding domain (DBD), the only AR inhibitor that functions
via this domain. Furthermore, computational modeling predicts that
pyrvinium binds at the interface of the DBD dimer and the minor groove
of the AR response element. Because PP acts through the DBD, PP is
able to inhibit the constitutive activity of AR splice variants, which
are thought to contribute to the growth of castration resistant prostate
cancer (CRPC). PP also inhibits androgen-independent AR activation
by HER2 kinase. The antiandrogen activity of pyrvinium manifests in
the ability to inhibit the <i>in vivo</i> growth of CRPC
xenografts that express AR splice variants. Interestingly, PP was
most potent in cells with endogenous AR expression derived from prostate
or bone. PP was able to inhibit several other hormone nuclear receptors
(NRs) but not structurally unrelated transcription factors. PP inhibition
of other NRs was similarly cell-type selective. Using dual-energy
X-ray absorptiometry, we demonstrate that the cell-type specificity
of PP manifests in tissue-selective inhibition of AR activity in mice,
as PP decreases prostate weight and bone mineral density but does
not affect lean body mass. Our results suggest that the noncompetitive
AR inhibitor pyrvinium has significant potential to treat CRPC, including
cancers driven by ligand-independent AR signaling