RESUMEN
The cananga tree alkaloid sampangine (1) has been extensively investigated for its antimicrobial and antitumor potential. Mechanistic studies have linked its biological activities to the reduction of cellular oxygen, the induction of reactive oxygen species (ROS), and alterations in heme biosynthesis. Based on the yeast gene deletion library screening results that indicated mitochondrial gene deletions enhanced the sensitivity to 1, the effects of 1 on cellular respiration were examined. Sampangine increased oxygen consumption rates in both yeast and human tumor cells. Mechanistic investigation indicated that 1 may have a modest uncoupling effect, but predominately acts by increasing oxygen consumption independent of mitochondrial complex IV. Sampangine thus appears to undergo redox cycling that may involve respiratory chain-dependent reduction to a semi-iminoquinone followed by oxidation and consequent superoxide production. Relatively high concentrations of 1 showed significant neurotoxicity in studies conducted with rat cerebellar granule neurons, indicating that sampangine use may be associated with potential neurotoxicity.
Asunto(s)
Alcaloides/farmacología , Antiinfecciosos/farmacología , Antineoplásicos Fitogénicos/farmacología , Quinonas/farmacología , Animales , Benzoquinonas , Ciclo Celular/efectos de los fármacos , División Celular , Respiración de la Célula/efectos de los fármacos , Transporte de Electrón , Compuestos Heterocíclicos de 4 o más Anillos/farmacología , Humanos , Mitocondrias/metabolismo , Estructura Molecular , Naftiridinas , Oxidación-Reducción , Oxígeno , Ratas , Especies Reactivas de Oxígeno/metabolismo , Saccharomyces cerevisiae , Superóxidos/metabolismoRESUMEN
The biologically active lipopeptide kalkitoxin was previously isolated from the marine cyanobacterium Moorea producens (Lyngbya majuscula). Kalkitoxin exhibited N-methyl-D-aspartate (NMDA)-mediated neurotoxicity and acted as an inhibitory ligand for voltage-sensitive sodium channels in cultured rat cerebellar granule neurons. Subsequent studies revealed that kalkitoxin generated a delayed form of colon tumor cell cytotoxicity in 7-day clonogenic cell survival assays. Cell line- and exposure time-dependent cytostatic/cytotoxic effects were previously observed with mitochondria-targeted inhibitors of hypoxia-inducible factor-1 (HIF-1). The transcription factor HIF-1 functions as a key regulator of oxygen homeostasis. Therefore, we investigated the ability of kalkitoxin to inhibit hypoxic signaling in human tumor cell lines. Kalkitoxin potently and selectively inhibited hypoxia-induced activation of HIF-1 in T47D breast tumor cells (IC50 5.6 nM). Mechanistic studies revealed that kalkitoxin inhibits HIF-1 activation by suppressing mitochondrial oxygen consumption at electron transport chain (ETC) complex I (NADH-ubiquinone oxidoreductase). Further studies indicate that kalkitoxin targets tumor angiogenesis by blocking the induction of angiogenic factors (i.e., VEGF) in tumor cells.
Asunto(s)
Inhibidores de la Angiogénesis/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Lípidos/farmacología , Neovascularización Patológica/tratamiento farmacológico , Tiazoles/farmacología , Inhibidores de la Angiogénesis/administración & dosificación , Neoplasias de la Mama/patología , Hipoxia de la Célula/efectos de los fármacos , Línea Celular Tumoral , Complejo I de Transporte de Electrón/efectos de los fármacos , Complejo I de Transporte de Electrón/metabolismo , Femenino , Humanos , Factor 1 Inducible por Hipoxia/metabolismo , Concentración 50 Inhibidora , Lípidos/administración & dosificación , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Transducción de Señal/efectos de los fármacos , Tiazoles/administración & dosificación , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
Active immunization is being explored as a potential therapeutic to combat accidental overdose and to mitigate the abuse potential of opioids. Hapten design is one of the crucial factors that determines the efficacy of a candidate vaccine to substance abuse and remains one of the most active areas of research in vaccine development. Herein we report for the first time the synthesis of three novel opiate surrogates with the linker attachment site at C14, 1 (6,14-AmidoHap), 2 (14-AmidoMorHap), and 3 (14-AmidoHerHap) as novel heroin haptens. The compounds 1, 2, and 3 are analogues with different substituents at C6: an acetamide, a hydroxyl moiety, and an acetate, respectively. All three haptens had a phenolic hydroxyl group at C3. The haptens were conjugated to the tetanus toxoid carrier protein, adjuvanted with liposomal monophosphoryl lipid A/aluminum hydroxide and were tested in mice in terms of immunogenicity and efficacy. Immunization of mice resulted in antibody endpoint titers of >105 against all the haptens. Neither of the conjugates of 1, 2, and 3 had induced antibodies with selectivity broad enough to recognize and bind heroin, 6-AM, and morphine resulting in little to no protection against the antinociceptive effects of heroin in vivo. Only the mice immunized with conjugate 3 were partially protected against heroin-induced antinociception. These results contribute to the growing body of knowledge that the linker position and the subtle structural differences in the hapten scaffold impact the selectivity of the induced antibodies. Together, these highlight the importance of rational hapten design for heroin vaccine development.
RESUMEN
A natural product chemistry-based approach was applied to discover small-molecule inhibitors of hypoxia-inducible factor-1 (HIF-1). A Petrosaspongia mycofijiensis marine sponge extract yielded mycothiazole (1), a solid tumor selective compound with no known mechanism for its cell line-dependent cytotoxic activity. Compound 1 inhibited hypoxic HIF-1 signaling in tumor cells (IC(50) 1nM) that correlated with the suppression of hypoxia-stimulated tumor angiogenesis in vitro. However, 1 exhibited pronounced neurotoxicity in vitro. Mechanistic studies revealed that 1 selectively suppresses mitochondrial respiration at complex I (NADH-ubiquinone oxidoreductase). Unlike rotenone, MPP(+), annonaceous acetogenins, piericidin A, and other complex I inhibitors, mycothiazole is a mixed polyketide/peptide-derived compound with a central thiazole moiety. The exquisite potency and structural novelty of 1 suggest that it may serve as a valuable molecular probe for mitochondrial biology and HIF-mediated hypoxic signaling.
Asunto(s)
Complejo I de Transporte de Electrón/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Poríferos/química , Tiazoles/farmacología , Animales , Línea Celular , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Complejo I de Transporte de Electrón/metabolismo , Inhibidores Enzimáticos/aislamiento & purificación , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Factor 1 Inducible por Hipoxia/genética , Factor 1 Inducible por Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Neovascularización Patológica/tratamiento farmacológico , Neuronas/efectos de los fármacos , Ratas , Tiazoles/aislamiento & purificaciónRESUMEN
Products that contain twig extracts of pawpaw (Asimina triloba) are widely consumed anticancer alternative medicines. Pawpaw crude extract (CE) and purified acetogenins inhibited hypoxia-inducible factor-1 (HIF-1)-mediated hypoxic signaling pathways in tumor cells. In T47D cells, pawpaw CE and the acetogenins 10-hydroxyglaucanetin (1), annonacin (2), and annonacin A (3) inhibited hypoxia-induced HIF-1 activation with IC(50) values of 0.02 microg/mL, 12 nM, 13 nM, and 31 nM, respectively. This inhibition correlates with the suppression of the hypoxic induction of HIF-1 target genes VEGF and GLUT-1. The induction of secreted VEGF protein represents a key event in hypoxia-induced tumor angiogenesis. Both the extract and the purified acetogenins blocked the angiogenesis-stimulating activity of hypoxic T47D cells in vitro. Pawpaw extract and acetogenins inhibited HIF-1 activation by blocking the hypoxic induction of nuclear HIF-1alpha protein. The inhibition of HIF-1 activation was associated with the suppression of mitochondrial respiration at complex I. Thus, the inhibition of HIF-1 activation and hypoxic tumor angiogenesis constitutes a novel mechanism of action for these anticancer alternative medicines.
Asunto(s)
Acetogeninas/aislamiento & purificación , Acetogeninas/farmacología , Antineoplásicos Fitogénicos/aislamiento & purificación , Antineoplásicos Fitogénicos/farmacología , Asimina/química , Transportador de Glucosa de Tipo 1/efectos de los fármacos , Factor 1 Inducible por Hipoxia/efectos de los fármacos , Neovascularización Fisiológica/efectos de los fármacos , Plantas Medicinales/química , Factores de Crecimiento Endotelial Vascular/efectos de los fármacos , Acetogeninas/química , Antineoplásicos Fitogénicos/química , Terapias Complementarias , Ensayos de Selección de Medicamentos Antitumorales , Transportador de Glucosa de Tipo 1/análisis , Transportador de Glucosa de Tipo 1/genética , Humanos , Concentración 50 Inhibidora , Estructura Molecular , Factores de Crecimiento Endotelial Vascular/análisis , Factores de Crecimiento Endotelial Vascular/genéticaRESUMEN
The transcription factor hypoxia-inducible factor-1 (HIF-1) represents an important molecular target for anticancer drug discovery. In a T47D cell-based reporter assay, the Caulerpa spp. algal pigment caulerpin (1) inhibited hypoxia-induced as well as 1,10-phenanthroline-induced HIF-1 activation. The angiogenic factor vascular endothelial growth factor (VEGF) is regulated by HIF-1. Caulerpin (10 microM) suppressed hypoxic induction of secreted VEGF protein and the ability of hypoxic T47D cell-conditioned media to promote tumor angiogenesis in vitro. Under hypoxic conditions, 1 (10 microM) blocked the induction of HIF-1alpha protein, the oxygen-regulated subunit that controls HIF-1 activity. Reactive oxygen species produced by mitochondrial complex III are believed to act as a signal of cellular hypoxia that leads to HIF-1alpha protein induction and activation. Further mechanistic studies revealed that 1 inhibits mitochondrial respiration at electron transport chain (ETC) complex I (NADH-ubiquinone oxidoreductase). Under hypoxic conditions, it is proposed that 1 may disrupt mitochondrial ROS-regulated HIF-1 activation and HIF-1 downstream target gene expression by inhibiting the transport or delivery of electrons to complex III.
Asunto(s)
Caulerpa/química , Factor 1 Inducible por Hipoxia/efectos de los fármacos , Indoles/farmacología , Colorantes/química , Colorantes/farmacología , Complejo I de Transporte de Electrón/antagonistas & inhibidores , Femenino , Humanos , Indoles/química , Indoles/aislamiento & purificación , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Estructura Molecular , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
The lipid extract of the marine sponge Mycale sp. inhibited the activation of hypoxia-inducible factor-1 (HIF-1) in a human breast tumor T47D cell-based reporter assay. Bioassay-guided isolation and structure elucidation yielded 18 new lipophilic 2,5-disubstituted pyrroles and eight structurally related known compounds. The active compounds inhibited hypoxia-induced HIF activation with moderate potency (IC50 values <10 microM). Mechanistic studies revealed that the active compounds suppressed mitochondrial respiration by blocking NADH-ubiquinone oxidoreductase (complex I) at concentrations that inhibited HIF-1 activation. Under hypoxic conditions, reactive oxygen species produced by mitochondrial complex III are believed to act as a signal of cellular hypoxia that leads to HIF-1alpha protein induction and activation. By inhibiting electron transport (or delivery) to complex III under hypoxic conditions, lipophilic Mycale pyrroles appear to disrupt mitochondrial ROS-regulated HIF-1 signaling.
Asunto(s)
Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Factor 1 Inducible por Hipoxia/metabolismo , Mitocondrias/metabolismo , Poríferos/química , Pirroles/aislamiento & purificación , Pirroles/farmacología , Animales , Respiración de la Célula/efectos de los fármacos , Femenino , Humanos , Biología Marina , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Palau , Pirroles/químicaRESUMEN
A natural product chemistry-based approach was employed to discover small-molecule inhibitors of the important tumor-selective molecular target hypoxia-inducible factor-1 (HIF-1). Bioassay-guided isolation of an active lipid extract of a Saipan collection of the marine sponge Lendenfeldia sp. afforded the terpene-derived furanolipid furospongolide as the primary inhibitor of hypoxia-induced HIF-1 activation (IC(50) 2.9 µM, T47D breast tumor cells). The active component of the extract also contained one new cytotoxic scalarane sesterterpene and two previously reported scalaranes. Furospongolide blocked the induction of the downstream HIF-1 target secreted vascular endothelial growth factor (VEGF) and was shown to suppress HIF-1 activation by inhibiting the hypoxic induction of HIF-1α protein. Mechanistic studies indicate that furospongolide inhibits HIF-1 activity primarily by suppressing tumor cell respiration via the blockade of NADH-ubiquinone oxidoreductase (complex I)-mediated mitochondrial electron transfer.
Asunto(s)
Antineoplásicos/aislamiento & purificación , Antineoplásicos/farmacología , Furanos/aislamiento & purificación , Furanos/farmacología , Subunidad alfa del Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Poríferos/química , Animales , Antineoplásicos/química , Neoplasias de la Mama/metabolismo , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Furanos/química , Humanos , Biología Marina , Estructura Molecular , Factor A de Crecimiento Endotelial Vascular/efectos de los fármacosRESUMEN
Hypoxia is a common feature of solid tumors, and the extent of tumor hypoxia correlates with advanced disease stages and treatment resistance. The transcription factor hypoxia-inducible factor-1 (HIF-1) represents an important tumor-selective molecular target for anticancer drug discovery directed at tumor hypoxia. A natural product chemistry-based approach was employed to discover small molecule inhibitors of HIF-1. Bioassay-guided isolation of an active lipid extract of the tropical legumaceous plant Lonchocarpus glabrescens and structure elucidation afforded two new HIF-1 inhibitors: alpinumisoflavone (compound 1) and 4'-O-methylalpinumisoflavone (compound 2). In human breast tumor T47D cells, compounds 1 and 2 inhibited hypoxia-induced HIF-1 activation with IC(50) values of 5 and 0.6 mum, respectively. At the concentrations that in hibited HIF-1 activation, compound 2 inhibited hypoxic induction of HIF-1 target genes (CDKN1A, GLUT-1, and VEGF), tumor angiogenesis in vitro, cell migration, and chemotaxis. Compound 2 inhibits HIF-1 activation by blocking the induction of nuclear HIF-1alpha protein, the oxygen-regulated subunit that controls HIF-1 activity. Mechanistic studies indicate that, unlike rotenone and other mitochondrial inhibitors, compound 2 represents the first small molecule that inhibits HIF-1 activation by simultaneously suppressing mitochondrial respiration and disrupting protein translation in vitro. This unique mechanism distinguishes compound 2 from other small molecule HIF-1 inhibitors that are simple mitochondrial inhibitors or flavanoid-based protein kinase inhibitors.