RESUMEN
Tanshinone IIA (Tan IIA), the primary bioactive compound derived from the traditional Chinese medicine (TCM) Salvia miltiorrhiza Bunge, has been reported to possess antitumor activity. However, its antitumor mechanisms are not fully understood. To resolve the potential antitumor mechanism(s) of Tan IIA, its gene expression profiles from our database was analyzed by connectivity map (CMAP) and the CMAP-based mechanistic predictions were confirmed/validated in further studies. Specifically, Tan IIA inhibited total protein kinase C (PKC) activity and selectively suppressed the expression of cytosolic and plasma membrane PKC isoforms ζ and ε. The Ras/MAPK pathway that is closely regulated by the PKC signaling is also inhibited by Tan IIA. While Tan IIA did not inhibit heat shock protein 90 (Hsp90), it synergistically enhanced the antitumor efficacy of the Hsp90 inhibitors 17-AAG and ganetespib in human breast cancer MCF-7 cells. In addition, Tan IIA significantly inhibited PI3K/Akt/mTOR signaling, and induced both cell cycle arrest and autophagy. Collectively, these studies provide new insights into the molecular mechanisms responsible for antitumor activity of Tan IIA.
Asunto(s)
Abietanos/farmacología , Antineoplásicos Fitogénicos/farmacología , Benzoquinonas/farmacología , Productos Biológicos/farmacología , Lactamas Macrocíclicas/farmacología , Proteína Quinasa C/antagonistas & inhibidores , Abietanos/química , Animales , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/uso terapéutico , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Productos Biológicos/química , Productos Biológicos/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Puntos de Control del Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Sinergismo Farmacológico , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Proteínas HSP90 de Choque Térmico/metabolismo , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Células MCF-7 , Ratones Desnudos , Fosfatidilinositol 3-Quinasas/metabolismo , Proteína Quinasa C/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Triazoles/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Certain botanical dietary supplements have been associated with idiosyncratic organ-specific toxicity. Similar toxicological events, caused by drug-induced mitochondrial dysfunction, have forced the withdrawal or U.S. FDA "black box" warnings of major pharmaceuticals. To assess the potential mitochondrial liability of botanical dietary supplements, extracts from 352 authenticated plant samples used in traditional Chinese, Ayurvedic, and Western herbal medicine were evaluated for the ability to disrupt cellular respiration. Blue cohosh (Caulophyllum thalictroides) methanol extract exhibited mitochondriotoxic activity. Used by some U.S. midwives to help induce labor, blue cohosh has been associated with perinatal stroke, acute myocardial infarction, congestive heart failure, multiple organ injury, and neonatal shock. The potential link between mitochondrial disruption and idiosyncratic herbal intoxication prompted further examination. The C. thalictroides methanol extract and three saponins, cauloside A (1), saponin PE (2), and cauloside C (3), exhibited concentration- and time-dependent mitochondriotoxic activities. Upon treatment, cell respiration rate rapidly increased and then dramatically decreased within minutes. Mechanistic studies revealed that C. thalictroides constituents impair mitochondrial function by disrupting membrane integrity. These studies provide a potential etiological link between this mitochondria-sensitive form of cytotoxicity and idiosyncratic organ damage.
Asunto(s)
Caulophyllum/química , Respiración de la Célula/efectos de los fármacos , Suplementos Dietéticos/toxicidad , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ácido Oleanólico/análogos & derivados , Saponinas/toxicidad , Relación Dosis-Respuesta a Droga , Humanos , Estructura Molecular , Ácido Oleanólico/química , Ácido Oleanólico/toxicidad , Fitoterapia , Saponinas/química , Estados UnidosRESUMEN
Natural product drug discovery programs often rely on the use of silica (Si) gel, reversed-phase media, or size-exclusion resins (e.g., RP-C18, Sephadex LH-20) for compound purification. The synthetic polymer-based sorbent Diaion HP20SS (cross-linked polystyrene matrix) is used as an alternative to prepare purified natural product libraries. To evaluate the impact of chromatographic media on the isolation of biologically active, yet chromatographically unstable natural products, Diaion HP20SS was evaluated side-by-side with normal-phase sorbents for irreversible binding of extract constituents and their effects on bioactivity. An array of chemically diverse natural product-rich extracts was selected as a test panel, and a cell-based reporter assay for hypoxia-inducible factor-1 (HIF-1) was employed to monitor potential change(s) in bioactivity. Silica gel caused significant irreversible binding of three out of 10 extracts. Curcuma longa, Saururus cernuus, and Citrus reticulata extracts showed decreased HIF-1 inhibitory activity after elution through Si gel. An additional nonpolar column wash of HP20SS with EtOAc retained considerable bioactivities of active extracts. In general, Si gel produced the greatest loss of bioactivity. However, HP20SS elution reduced significantly HIF-1 inhibitory activity of certain extracts (e.g., Asimina triloba).
Asunto(s)
Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Extractos Vegetales/química , Podophyllum/química , Asimina/química , Aspalathus/química , Productos Biológicos , Cromatografía , Citrus/química , Curcuma/química , Cyclopia (Planta)/química , Dextranos , Femenino , Humanos , Lythraceae/química , Extractos Vegetales/análisis , Saururaceae/química , Gel de Sílice , Vaccinium macrocarpon/químicaRESUMEN
Bioassay-guided isolation and subsequent structure elucidation of a Bael tree Aegle marmelos lipid extract yielded two unstable acylated geranyloxycoumarin mixtures (1-2), six geranyloxycoumarins (3-8), (+)-9'-isovaleroxylariciresinol (9), and dehydromarmeline (10). In a T47D cell-based reporter assay, 1 and 2 potently inhibited hypoxia-induced HIF-1 activation (IC50 values 0.18 and 1.10 µgmL(-1), respectively). Insufficient material and chemical instability prevented full delineation of the fatty acyl side chain olefin substitution patterns in 1 and 2. Therefore, five fatty acyl geranyloxycoumarin ester derivatives (11-15) were prepared from marmin (3) and commercial fatty acyl chlorides by semisynthesis. The unsaturated C-6' linoleic acid ester derivative 14 that was structurally most similar to 1 and 2, inhibited HIF-1 activation with comparable potency (IC50 0.92 µM). The octanoyl (11) and undecanoyl (12) ester derivatives also suppressed HIF-1 activation (IC50 values 3.1 and 0.87 µM, respectively). Mechanistic studies revealed that these geranyloxycoumarin derivatives disrupt mitochondrial respiration, primarily at complex I. Thus, these compounds may inhibit HIF-1 activation by suppressing mitochondria-mediated hypoxic signaling. One surprising observation was that, while less potent, the purported cancer chemopreventive agent auraptene (8) was found to act as a mitochondrial poison that disrupts HIF-1 signaling in tumors.
Asunto(s)
Aegle/química , Cumarinas/química , Cumarinas/toxicidad , Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Mitocondrias/efectos de los fármacos , Extractos Vegetales/química , Extractos Vegetales/toxicidad , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Antineoplásicos Fitogénicos/farmacología , Antineoplásicos Fitogénicos/toxicidad , Mama/efectos de los fármacos , Mama/patología , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Línea Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cumarinas/aislamiento & purificación , Cumarinas/farmacología , Suplementos Dietéticos/efectos adversos , Suplementos Dietéticos/análisis , Femenino , Humanos , Factor 1 Inducible por Hipoxia/metabolismo , Mitocondrias/metabolismo , Mitocondrias/patología , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacologíaRESUMEN
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 compound (-)-epigallocatechin-3-gallate (EGCG) is the major catechin found in green tea [Camellia sinensis L. Ktze. (Theaceae)]. This polyphenolic compound and several related catechins are believed to be responsible for the health benefits associated with the consumption of green tea. The potential health benefits ascribed to green tea and EGCG include antioxidant effects, cancer chemoprevention, improving cardiovascular health, enhancing weight loss, protecting the skin from the damage caused by ionizing radiation, and others. The compound EGCG has been shown to regulate dozens of disease-specific molecular targets. Many of these molecular targets are only affected by concentrations of EGCG that are far above the levels achieved by either drinking green tea or consuming moderate doses of green tea extract-based dietary supplements. In spite of this, well-designed double-blinded controlled clinical studies have recently demonstrated the efficacy of green tea extracts and purified EGCG products in patients. Therefore, this review highlights results from what the authors believe to be some of the most clinically significant recent studies and describes current developments in the stereoselective total synthesis of EGCG.
Asunto(s)
Anticarcinógenos/uso terapéutico , Antioxidantes/uso terapéutico , Catequina/análogos & derivados , Animales , Anticarcinógenos/farmacología , Antioxidantes/farmacología , Catequina/farmacología , Catequina/uso terapéutico , Humanos , Estructura Molecular , Neoplasias/prevención & control , Piel/efectos de los fármacos , Té/químicaRESUMEN
Proteasome inhibitors have emerged as a clinically important therapy for neoplastic disease, with velcade, an organoboron compound used extensively in multiple myeloma. Recently, (-)-epigallocatechin gallate has been found to be a potent inhibitor of the proteasomal chymotrypsin-like activity. Other compounds that inhibit angiogenesis and are active as chemopreventive agents, such as curcumin, also inhibit proteasome activity. We have screened natural product extracts using ras-transformed endothelial cells (SVR cells) as a bioassay, and found that extracts of mate tea (Ilex paraguayensis) inhibit the growth of these endothelial cells. The extract was fractionated and found to have novel cinnamate esters that inhibit proteasome activity. Based upon the structures of the compounds isolated from mate tea, we examined synthetic analogs of these compounds for proteasome activity. Cinnamic acid amides had no inhibitory activity against proteasomes, whereas cinnamate esters displayed the activity. Based upon these findings, preclinical and clinical trials of topical cinnamate esters as proteasome inhibitors are warranted for psoriasis and other inflammatory disorders.
Asunto(s)
Cinamatos/química , Células Endoteliales/efectos de los fármacos , Ilex paraguariensis/química , Extractos Vegetales/química , Inhibidores de Proteasoma , División Celular/efectos de los fármacos , Línea Celular Transformada , Ácido Clorogénico/química , Ácido Clorogénico/farmacología , Cromatografía Líquida de Alta Presión , Cinamatos/farmacología , Células Endoteliales/citología , Ésteres/química , Ésteres/farmacología , Fase G2/efectos de los fármacos , Humanos , Células Jurkat , Resonancia Magnética Nuclear Biomolecular , Extractos Vegetales/farmacologíaRESUMEN
Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that induces oxygen-regulated genes in response to reduced oxygen conditions (hypoxia). Expression of the oxygen-regulated HIF-1alpha subunit correlates positively with advanced disease stages and poor prognosis in cancer patients. Green tea catechins are believed to be responsible for the cancer chemopreventive activities of green tea. We found that (-)-epicatechin-3-gallate (ECG, 1), one of the major green tea catechins, strongly activates HIF-1 in T47D human breast carcinoma cells. Among the green tea catechins tested, 1 demonstrated the strongest HIF-1-inducing activity, while (-)-epigallocatechin-3-gallate (EGCG, 2) was significantly less active. However, 2 is relatively unstable in the in vitro system studied. Compound 1 also increases the expression of HIF-1 target genes including GLUT-1, VEGF, and CDKN1A. In T47D cells, 1 induces nuclear HIF-1alpha protein without affecting HIF-1alpha mRNA. Both the induction of HIF-1alpha protein and activation of HIF-1 by 1 can be blocked by iron and ascorbate, indicating that 1 may activate HIF-1 through the chelation of iron. These results suggest that intended cancer chemoprevention with high-dose green tea extracts may be compromised, by the ability of tea catechins to promote tumor cell survival pathways associated with HIF-1 activation.
Asunto(s)
Catequina/análogos & derivados , Catequina/farmacología , Proteínas de Unión al ADN , Proteínas Nucleares , Té , Factores de Transcripción , Hipoxia de la Célula/efectos de los fármacos , Hipoxia de la Célula/genética , Proteínas de Unión al ADN/efectos de los fármacos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Humanos , Factor 1 Inducible por Hipoxia , Subunidad alfa del Factor 1 Inducible por Hipoxia , Estructura Molecular , Proteínas Nucleares/efectos de los fármacos , Proteínas Nucleares/genética , Proteínas Nucleares/fisiología , Estereoisomerismo , Relación Estructura-Actividad , Factores de Transcripción/efectos de los fármacos , Factores de Transcripción/genética , Factores de Transcripción/fisiología , Factor A de Crecimiento Endotelial Vascular/efectos de los fármacosRESUMEN
The transcription factor hypoxia-inducible factor-1 (HIF-1) is a key regulator of tumor cell adaptation and survival under hypoxic conditions. Selective HIF-1 inhibitors represent an important new class of potential molecular-targeted antitumor therapeutic agents. Extracts of plants and marine organisms were evaluated using a T47D human breast tumor cell-based reporter assay for HIF-1 inhibitors. Bioassay-guided fractionation of the lipid extract of Saururus cernuus resulted in the isolation of manassantin B (1) and a new compound, 4-O-demethylmanassantin B (2). The structure of 2 was determined spectroscopically. The absolute configurations of manassantin-type dineolignans have not been previously reported. Therefore, the absolute configurations of the chiral centers in each side chain were deduced from spectroscopic analysis of the Mosher MTPA ester derivatives of 1. Both 1 and 2 are among the most potent small molecule HIF-1 inhibitors discovered, to date, with IC(50) values of 3 and 30 nM, respectively. Compounds 1 and 2 selectively inhibited hypoxia-activated HIF-1 in contrast to iron chelator-activated HIF-1. Compounds 1 and 2 also inhibited hypoxic induction of the angiogenic factor VEGF. Further study revealed that 1 selectively blocked the induction of HIF-1alpha protein, the oxygen regulated HIF-1 subunit that determines HIF-1 activity.
Asunto(s)
Antineoplásicos Fitogénicos/aislamiento & purificación , Antineoplásicos Fitogénicos/farmacología , Proteínas de Unión al ADN/antagonistas & inhibidores , Furanos/aislamiento & purificación , Furanos/farmacología , Hipoxia , Lignanos/aislamiento & purificación , Lignanos/farmacología , Proteínas Nucleares/antagonistas & inhibidores , Plantas Medicinales/química , Saururaceae/química , Antineoplásicos Fitogénicos/química , Relación Dosis-Respuesta a Droga , Ensayo de Inmunoadsorción Enzimática , Furanos/química , Factor 1 Inducible por Hipoxia , Concentración 50 Inhibidora , Lignanos/química , Estereoisomerismo , Relación Estructura-Actividad , Factores de Transcripción/antagonistas & inhibidores , Factor A de Crecimiento Endotelial Vascular/análisisRESUMEN
An assay for inhibitors of LFA-1/ICAM-1 mediated cell-cell adhesion has been employed to identify new pharmacologically active compounds from marine cyanobacteria and algae. From a panel of sixty unusual marine natural products, seventeen compounds inhibited LFA-1/ICAM-1-based cell aggregation without showing significant cytotoxicity in the primary assay. Six compounds inhibited the cell-cell adhesion of HL-60 cells to CHO-ICAM-1 cells. The unusual oxylipin Cymathere aldehyde methyl ester (IC (50) 3.5 microM), cyanobacterial lipopeptides microcolins B (IC (50) 0.15 microM) and D (IC (50) 0.9 microM), bromophenol avrainvilleol (IC (50) 2.2 microM), sesquiterpene cymopol (IC (50) 2.7 microM), and cryptophyte derived compound styrylchromone hormothamnione diacetate (IC (50) 1.5 microM) significantly inhibited LFA-1/ICAM-1 mediated cell adhesion. The pharmacological activity and structure-activity relationships of selected marine algal metabolites are described. Abbreviations. LFA-1:Lymphocyte function-associated molecule-1 ICAM-1:Intercellular cell adhesion molecule-1 PMA:Phorbol 12-myristate 13-acetate HL-60:Promyelocytic human leukemia-60 CHO:Chinese hamster ovary