RESUMEN

The inhibitory glycine receptor (GlyR) is a key mediator of synaptic signalling in spinal cord, brain stem, and higher centres of the central nervous system. We examined the glycinergic activity of sarcophine (SN), a marine terpenoid known for its various biological activities, and its trans-diol derivative (7S, 8R)-dihydroxy-deepoxysarcophine (DSN). SN was isolated from the Red Sea soft coral Sacrophyton glaucum, DSN was semisynthesized by hydrolysis of the epoxide ring. In cytotoxicity tests against HEK293 cells, SN and DSN had LD50 values of 29.3 ± 3.0 mM and 123.5 ± 13.0 mM, respectively. Both compounds were tested against recombinant human α1 glycine receptors in HEK293 cells using whole-cell recording techniques. Both, SN and DSN were shown for the first time to be inhibitors of recombinant glycine receptors, with KIvalues of 2.1 ± 0.3 µM for SN, and 109 ± 9 µM for DSN. Receptor inhibition was also studied in vivo in a mouse model of strychnine toxicity. Surprisingly, in mouse experiments strychnine inhibition was not augmented by either terpenoid. While DSN had no significant effect on strychnine toxicity, SN even delayed strychnine effects. This could be accounted for by assuming that strychnine and sarcophine derivatives compete for the same binding site on the receptor, so the less toxic sarcophine can prevent strychnine from binding. The combination of modulatory activity and low level of toxicity makes sarcophines attractive structures for novel glycinergic drugs.

Asunto(s)

4-Butirolactona/análogos & derivados , Antozoos/metabolismo , Encéfalo/efectos de los fármacos , Antagonistas de Aminoácidos Excitadores/farmacología , Receptores de Glicina/antagonistas & inhibidores , Convulsiones/prevención & control , 4-Butirolactona/síntesis química , 4-Butirolactona/aislamiento & purificación , 4-Butirolactona/farmacología , 4-Butirolactona/toxicidad , Animales , Sitios de Unión , Unión Competitiva , Encéfalo/metabolismo , Encéfalo/fisiopatología , Modelos Animales de Enfermedad , Antagonistas de Aminoácidos Excitadores/síntesis química , Antagonistas de Aminoácidos Excitadores/aislamiento & purificación , Antagonistas de Aminoácidos Excitadores/toxicidad , Células HEK293 , Humanos , Masculino , Ratones , Unión Proteica , Receptores de Glicina/genética , Receptores de Glicina/metabolismo , Convulsiones/inducido químicamente , Convulsiones/metabolismo , Convulsiones/fisiopatología , Estricnina

RESUMEN

Five new isoprenoids, 3,4,8,16-tetra-epi-lobocrasol (1), 1,15ß-epoxy-deoxysarcophine (2), 3,4-dihydro-4α,7ß,8α-trihydroxy-Δ²-sarcophine (3), ent-sarcophyolide E (4), and 16-deacetyl- halicrasterol B (5) and ten known compounds 6‒15, were characterized from the marine soft coral Sarcophyton glaucum, collected off Taitung coastline. Their structures were defined by analyzing spectra data, especially 2D NMR and electronic circular dichroism (ECD). The structure of the known compound lobocrasol (7) was revised. Cytotoxicity potential of the isolated compounds was reported, too.

Asunto(s)

Antozoos/química , Antineoplásicos/aislamiento & purificación , Terpenos/aislamiento & purificación , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Línea Celular Tumoral , Dicroismo Circular , Humanos , Espectroscopía de Resonancia Magnética , Terpenos/química , Terpenos/farmacología

RESUMEN

Sarcophine-diol (SD) is a semi-synthetic derivative of sarcophine with a significant chemopreventive effect against non-melanoma skin cancer both in vitro and in vivo. Recently, we have studied the effect of SD on melanoma development using the mouse melanoma B16F10 cell line. In this study, our findings show that SD suppresses cell multiplication and diminishes membrane permeability for ethidium bromide (EB), a model marker used to measure cell permeability for Ca²âº ions. SD also decreases protein levels of COX-2, and increases degradation of phospholipases PLA2 and PLC(γ)1 and diminishes enzymatic activity of the Ca²âº-dependent cPLA2. This lower membrane permeability for Ca²âº-ions, associated with SD, is most likely due to the diminished content of lysophosphosphatidylcholine (lysoPC) within cell membranes caused by the effect of SD on PLA2. The decrease in diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3) due to inhibition of PLC(γ)1, leads to the downregulation of Ca²âº-dependent processes within the cell and also inhibits the formation of tumors. These findings support our previous data suggesting that SD may have significant potential in the treatment of melanoma.

Asunto(s)

Permeabilidad de la Membrana Celular/efectos de los fármacos , Inhibidores de la Ciclooxigenasa 2/farmacología , Ciclooxigenasa 2/metabolismo , Diterpenos/farmacología , Fosfolipasa C gamma/metabolismo , Fosfolipasas A2 Citosólicas/antagonistas & inhibidores , Animales , Antozoos/química , Antozoos/metabolismo , Antineoplásicos/farmacología , Línea Celular Tumoral , Proliferación Celular , Ciclooxigenasa 2/genética , Diterpenos/química , Diterpenos/metabolismo , Regulación Enzimológica de la Expresión Génica , Melanoma/metabolismo , Ratones , Estructura Molecular , Fosfolipasa C gamma/genética , Fosfolipasas A2 Citosólicas/metabolismo

RESUMEN

Sarcophine-diol (SD) is a lactone ring-opened analogue of sarcophine. It has shown chemopreventive effects on chemically-induced skin tumor development in female CD-1 mice, as well as in a UVB-induced skin tumor development model in hairless SKH-1 mice at a dose of 30 µg SD applied topically and 180 mJ/cm(2) UVB. The objective of this study was to determine the dose-response on the chemopreventive effects of SD on SKH-1 hairless mice when exposed to a UVB radiation dose of 30 mJ/cm(2). This UVB dose better represents chronic human skin exposure to sunlight leading to skin cancer than previous studies applying much higher UVB doses. Carcinogenesis was initiated and promoted by UVB radiation. Female hairless SKH-1 mice were divided into five groups. The control group was topically treated with 200 µL of acetone (vehicle), and the SD treatment groups were topically treated with SD (30 µg, 45 µg, and 60 µg dissolved in 200 µL of acetone) 1 h before UVB radiation (30 mJ/cm(2)). The last group of animals received 60 µg SD/200 µL acetone without UVB exposure. These treatments were continued for 27 weeks. Tumor multiplicity and tumor volumes were recorded on a weekly basis for 27 weeks. Weight gain and any signs of toxicity were also closely monitored. Histological characteristics and the proliferating cell nuclear antigen (PCNA) were evaluated in the mice skin collected at the end of the experiment. The dose-response study proved a modest increase in chemopreventive effects with the increase in SD dose. SD reduced the number of cells positively stained with PCNA proliferation marker in mice skin. The study also showed that SD application without UVB exposure has no effect on the structure of skin. The results from this study suggest that broader range doses of SD are necessary to improve the chemopreventive effects.

Asunto(s)

Anticarcinógenos/farmacología , Carcinoma de Células Escamosas/prevención & control , Diterpenos/farmacología , Neoplasias Inducidas por Radiación/prevención & control , Neoplasias Cutáneas/prevención & control , Luz Solar/efectos adversos , Animales , Peso Corporal/efectos de la radiación , Carcinoma de Células Escamosas/etiología , Carcinoma de Células Escamosas/metabolismo , Femenino , Ratones , Ratones Pelados , Neoplasias Inducidas por Radiación/etiología , Neoplasias Inducidas por Radiación/metabolismo , Antígeno Nuclear de Célula en Proliferación/metabolismo , Piel/efectos de los fármacos , Piel/efectos de la radiación , Neoplasias Cutáneas/etiología , Neoplasias Cutáneas/metabolismo , Rayos Ultravioleta , Aumento de Peso/efectos de la radiación

RESUMEN

Sarcodiol (SD) is a semi-synthetic derivative of sarcophine, a marine natural product. In our previous work, we reported the significant chemopreventive effects of SD against non-melanoma skin cancer both in vitro and in vivo mouse models. In this investigation, we extended this work to study the effect of sarcodiol on melanoma development, the more deadly form of skin cancer, using the mouse melanoma B16F10 cell line. In this study we report that SD inhibits the de novo DNA synthesis and enhances fragmentation of DNA. We also evaluated the antitumor effect of SD on melanoma cell viability using several biomarkers for cell proliferation and apoptosis. SD inhibits the expression levels of signal transducers and activators of transcription protein (STAT-3) and cyclin D1, an activator of cyclin-dependent kinase 4 (Cdk4). SD treatment also enhances cellular level of tumor suppressor protein 53 (p53) and stimulates cleavage of the nuclear poly (ADP-ribose) polymerase (cleaved-PARP). SD also enhances cellular levels of cleaved Caspase-3, -8, -9 and stimulates enzymatic activities of Caspase-3, -8 and -9. These results, in addition to inhibition of cell viability, suggest that SD inhibits melanoma cell proliferation by arresting the cell-division cycle in a Go quiescent phase and activates programmed cell death (apoptosis) via extrinsic and intrinsic pathways. Finally, these studies demonstrate that SD shows a very promising chemopreventive effect in melanoma B16F10 tumor cells.

Asunto(s)

4-Butirolactona/análogos & derivados , Anticarcinógenos/farmacología , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Fragmentación del ADN , Diterpenos/farmacología , Melanoma Experimental/tratamiento farmacológico , Neoplasias Cutáneas/prevención & control , 4-Butirolactona/farmacología , Animales , Caspasas/fisiología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Quinasa 4 Dependiente de la Ciclina/análisis , ADN/biosíntesis , Fragmentación del ADN/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Melanoma Experimental/patología , Ratones , Proteínas de Neoplasias/análisis , Poli(ADP-Ribosa) Polimerasas/metabolismo , Factor de Transcripción STAT3/metabolismo

RESUMEN

Sarcophine-diol (SD), one of the structural modifications of sarcophine, has shown chemopreventive effects on 12-dimethylbenz(a)anthracene-initiated and 12-O-tetradecanoylphorbol-13-acetate-promoted skin tumor development in female CD-1 mice. The objective of this study was to determine the chemopreventive effects of SD on UVB-induced skin tumor development in hairless SKH-1 mice, a model more relevant to human skin cancer, and to determine the possible mechanisms of action. Carcinogenesis was initiated and promoted by UVB radiation. Female hairless SKH-1 mice were divided into two groups having 27 mice in each group: control and SD treatment. The control group was topically treated with 100 microL acetone and SD treatment group was topically treated with SD (30 microg/100 microL in acetone) 1 hour before each UVB radiation for 32 weeks. Tumor counts were recorded on a weekly basis for 30 weeks. Effects of SD on the expression of caspases were investigated to elucidate the possible mechanism of action. The proteins from epidermal homogenates of experimental mice were used for SDS-PAGE and Western blotting using specific antibodies against caspase-3, caspase-8 and caspase-9 respectively. TUNEL assay was used for determining DNA fragmented apoptotic cells in situ. Results showed that at the end of experiment, tumor multiplicity in control and SD treatment groups was 25.8 and 16.5 tumors per mouse respectively. Furthermore, Topical treatment of SD induced DNA fragmented apoptotic cells by upgrading the expressions of cleaved caspase-3 and caspase-8. This study clearly suggested that SD could be an effective chemopreventive agent for UVB-induced skin cancer by inducing caspase dependent apoptosis.

Asunto(s)

4-Butirolactona/análogos & derivados , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Carcinoma de Células Escamosas/prevención & control , Neoplasias Inducidas por Radiación/prevención & control , Neoplasias Cutáneas/prevención & control , Rayos Ultravioleta , 4-Butirolactona/farmacología , Animales , Peso Corporal/efectos de los fármacos , Carcinoma de Células Escamosas/patología , Caspasa 3/metabolismo , Caspasa 8/metabolismo , Fragmentación del ADN/efectos de los fármacos , Femenino , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Ratones , Ratones Pelados , Modelos Animales , Neoplasias Cutáneas/patología

RESUMEN

Sarcotriol (ST) has been shown to be chemopreventive on 7,12-dimethyl-benz(a)anthracene (DMBA) initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor development in CD-1 mice in recent studies from our laboratory. The objective of this study was to determine the chemopreventive effects of ST on ultraviolet B (UVB)-induced skin tumor development in female SKH-1 hairless mice, an experimental model relevant to human skin cancer development, and its possible mechanisms of action. Female SKH-1 mice were divided into two groups: Control and ST treated. Control was topically treated with 100 microliter acetone and ST treated group administered with 30 microgram ST in 100 microliter acetone one hour before UVB exposure. For UVB-induced tumorigenesis, carcinogenesis was initiated and promoted by UVB (180 mJ/cm(2)). Group weights and tumor counts were taken once every week. After 30 weeks, mice were sacrificed and dorsal skin samples were collected. The proteins from the skin sample were further used for SDS-PAGE and Western blotting using specific antibodies against caspase-3, caspase-8, caspase-9 and p53. Tumor multiplicity was found 19.6, 5.2 in the control and ST treated groups respectively. Caspase-3, -8, -9 and p53 were significantly (P < 0.05) upregulated in ST treated group compared to Control group. Together, this study for the first time identifies the chemopreventive effects of ST in UVB-induced carcinogenesis possibly by inducing apoptosis and upregulating p53.