RESUMEN
Peloruside A (peloruside), a compound isolated from the marine sponge Mycale hentscheli , inhibits growth of human (HL-60) and mouse (32D-ras) myeloid leukemic cells, as well as non-transformed 32D cells. Using the MTT cell proliferation assay and trypan blue dye exclusion tests, little difference was seen in growth inhibition between 32D and 32D- ras cells; however, peloruside was more cytotoxic to the oncogene-transformed cells. Peloruside also blocked 32D- ras cells more readily in G2/M of the cell cycle, leading to apoptosis. Annexin-V/propidium iodide staining of 32D and 32D- ras cells showed that 1.6 microM peloruside induced significant cell death by 36 hours in 32D cells (16% survival), but to comparable levels as early as 14 hours in 32D- ras cells (11% survival). There was no evidence for activation of either of the initiator caspases-8 or -9 by 0.1 microM peloruside following 12 hours of exposure. Peloruside inhibited T cell proliferation and IL-2 and IFN gamma production in both the mixed lymphocyte reaction and following CD3 cross-linking, and this effect was shown to be a non-specific cytotoxic effect. It is concluded that peloruside preferentially targets oncogene-transformed cells over non-transformed cells by inducing transformed cells to undergo apoptosis.
Asunto(s)
Apoptosis/efectos de los fármacos , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Proliferación Celular/efectos de los fármacos , Transformación Celular Neoplásica , Genes ras , Lactonas/farmacología , Linfocitos T/efectos de los fármacos , Animales , Anexina A5/metabolismo , Complejo CD3/efectos de los fármacos , Muerte Celular/efectos de los fármacos , Línea Celular , Reactivos de Enlaces Cruzados/farmacología , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Células HL-60 , Humanos , Interferón gamma/antagonistas & inhibidores , Interleucina-2/antagonistas & inhibidores , Prueba de Cultivo Mixto de Linfocitos , Ratones , Factores de TiempoRESUMEN
The marine sponge metabolites mycalamide A (mycalamide) and pateamine are extremely cytotoxic. While mycalamide has been shown to inhibit protein synthesis, the mechanism by which these compounds induce cell death is unknown. Using DNA laddering, Annexin-V staining, and morphological analysis, we demonstrate that both metabolites induce apoptosis in several different cell lines. Furthermore, both mycalamide and pateamine were more potent inducers of apoptosis in the 32D myeloid cell line after transformation with either the ras or bcr-abl oncogenes. This increased sensitivity was also observed in response to the protein synthesis inhibitors cycloheximide and puromycin, and cytosine-beta-D-arabinofuranoside (Ara-C), an inducer of DNA damage. We propose, therefore, that in 32D cells where Ras signalling has been altered either by constitutive expression of oncogenic ras or by Bcr/abl-mediated perturbation of upstream signalling events, increased susceptibility to apoptosis by a range of stimuli is conferred.
Asunto(s)
Apoptosis , Compuestos Epoxi/farmacología , Piranos/farmacología , Tiazoles/farmacología , Animales , Anexina A5/farmacología , Supervivencia Celular , Colorantes/farmacología , Cicloheximida/farmacología , Citarabina/farmacología , ADN/efectos de los fármacos , Daño del ADN , Electroforesis en Gel de Agar , Inhibidores Enzimáticos/farmacología , Citometría de Flujo , Concentración 50 Inhibidora , Macrólidos , Modelos Químicos , Poríferos , Inhibidores de la Síntesis de la Proteína/farmacología , Puromicina/farmacología , Sales de Tetrazolio/farmacología , Azul de Tripano/farmacologíaRESUMEN
A novel secondary sponge metabolite, peloruside A (peloruside), isolated from the marine sponge Mycale sp. (New Zealand), was tested for its cytotoxic effects on mammalian cells in culture. The macrolide structure of peloruside is similar to that of the protein kinase C (PKC) activator, bryostatin-1 (bryostatin), both containing a pyranose ring adjacent to a gemdimethyl moiety. Peloruside is a potent inhibitor of cell proliferation. Treatment of different mammalian cell lines with peloruside for 48-96 h gave IC50 values ranging from 4 to 15 nM, using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium (MTT) cell proliferation assay. Peloruside was shown to be both cytostatic and cytotoxic by trypan blue dye exclusion tests. Peloruside induced apoptosis in a dose-dependent manner in murine (32D) and human (HL-60) myeloid cell lines, revealed by DNA laddering in agarose gels and flow cytometric analysis of annexin-V- and propidium iodide-stained cells. Treatment of HL-60 cells caused vacuolisation, partial substrate adherence, and the appearance of multi-lobed nuclei, suggesting the induction of a differentiation pathway. Vacuolisation was also observed in a human lung cancer cell line (H441). Opening of the pyranose ring of peloruside by sodium borohydride reduction increased the 48 h IC50 value by 26-fold in 32D cells, suggesting a similar active site to that proposed for bryostatin. However, unlike bryostatin, peloruside failed to bind to PKC in HL-60 cells and was unable to synergize with the calcium ionophore, ionomycin, or with interleukin-2, to activate T-lymphocytes in culture. In summary, although structurally similar to bryostatin, peloruside is a potent inhibitor of cell proliferation, has apoptosis-inducing properties and has a unique mode of action independent of PKC.
Asunto(s)
Antineoplásicos/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Lactonas/farmacología , Poríferos/química , Proteína Quinasa C/química , Animales , Anexina A5/metabolismo , Antineoplásicos/química , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Brioestatinas , División Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , ADN/genética , ADN/aislamiento & purificación , Electroforesis en Gel de Agar , Ensayo de Inmunoadsorción Enzimática , Células HL-60 , Humanos , Interleucina-2/metabolismo , Interleucina-2/farmacología , Ionóforos , Lactonas/química , Macrólidos , Oxidación-Reducción , Bazo/citología , Bazo/efectos de los fármacos , Relación Estructura-Actividad , Linfocitos T/efectos de los fármacos , Sales de Tetrazolio , TiazolesRESUMEN
A new mycalamide, mycalamide D (3), has been isolated from the New Zealand marine sponge Mycale sp. This new metabolite, in which the C13-O-methyl group of mycalamide A (1) is replaced by a hydrogen atom, was found to be cytotoxic to a range of mammalian cell lines, with a potency approximately 20-fold less than that of 1.
Asunto(s)
Antineoplásicos/aislamiento & purificación , Poríferos/química , Piranos/aislamiento & purificación , Animales , Antineoplásicos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Células LLC-PK1 , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Conformación Molecular , Nueva Zelanda , Piranos/farmacología , Espectrofotometría Ultravioleta , Estereoisomerismo , Porcinos , Células Tumorales CultivadasRESUMEN
The mechanism of action, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of mycophenolate mofetil are reviewed. Mycophenolate mofetil is used to prevent or treat allograft rejection after solid-organ transplantation. A prodrug, mycophenolate mofetil is rapidly hydrolyzed to mycophenolic acid after oral administration. Mycophenolic acid inhibits de novo purine synthesis, resulting in antiproliferative effects on T and B lymphocytes. The absolute bioavailability of mycophenolic acid is 94% for oral administration; the maximum plasma concentration occurs after two hours. Mycophenolic acid undergoes hepatic glucuronidation to an inactive salt that is renally excreted. Clinical trials of mycophenolate mofetil in renal transplant patients suggest that the drug is effective for the prevention of acute rejection and as rescue therapy. Clinical data on mycophenolate mofetil therapy in liver transplant patients are too limited to permit conclusions. Clinical trials of the drug for primary immunosuppression in heart transplant patients have not been conducted, but studies of this agent as rescue therapy suggest efficacy. Mycophenolic acid has proved useful for long-term management of psoriasis. The most common adverse effects of mycophenolate mofetil are gastrointestinal. Nephrotoxicity and overt hepatotoxicity have not been reported, but the drug may be linked to bone marrow suppression and certain malignancies. Mycophenolate mofetil is available as a 250-mg capsule for oral use. The recommended initial dosage is 1 g twice daily. Mycophenolate mofetil appears to be a useful addition to the armamentarium of immunosuppressive drugs, particularly for kidney transplant patients, but more study is needed to clarify its role.
Asunto(s)
Inmunosupresores/farmacología , Ácido Micofenólico/análogos & derivados , Rechazo de Injerto/prevención & control , Trasplante de Corazón , Humanos , Inmunosupresores/administración & dosificación , Inmunosupresores/efectos adversos , Inmunosupresores/metabolismo , Trasplante de Riñón , Trasplante de Hígado , Ácido Micofenólico/administración & dosificación , Ácido Micofenólico/efectos adversos , Ácido Micofenólico/metabolismo , Ácido Micofenólico/farmacología , ProfármacosRESUMEN
The British/Belgian Gall Stone Study Group (BBGSG) post-dissolution trial was a prospective, multicentre, randomised, double blind trial of: (i) low dose ursodeoxycholic acid, (ii) placebo, and (iii) a high fibre, low refined carbohydrate diet in the prevention of gall stone recurrence in patients with complete gall stone dissolution. Further aims included establishing the timing and frequency of recurrence and its association with biliary symptoms, a comparison of the sensitivity of ultrasonography v oral cholecystectography in detecting recurrent stones, and a search for risk factors predicting recurrence. Ninety three patients entered the study, and 82 were followed up for up to five years (mean (SEM) 28 (1.5) months) with six monthly ultrasonography and yearly oral cholecystectography. There were 21 recurrences (26 by oral cholecystectography or ultrasonography, or both), only two of which were symptomatic, which were detected between 12 and 42 months after trial entry. This corresponded to an actuarial recurrence rate of 33.9 (7.0%) by lifetable analysis at 42 months and subsequently. There were four recurrences in the ursodeoxycholic acid, six in the placebo, and 11 in the diet groups, corresponding to 21.9 (9.9)%, 27.4 (10.1)%, and 45.8 (12.4)% respectively at 42 months by lifetable analysis (NS). Variables including age, obesity, menopausal state, pregnancy, and oestrogen containing drugs were not shown to affect recurrence rate. Men had more frequent recurrence than women (NS). Patients who had had multiple stones experienced more recurrences than did those with single stones (NS). Recurrence did not occur in patients who took non-steroidal anti-inflammatory drugs (NSAIDs) (p < 0.02). The stone free interval between stone dissolution and trial entry proved to be important--those stone free > nine months had a recurrence rate of only 12.7 (6.0)% at 42 months compared with 55.4 (12.5)% in those stone free < nine months (p < 0.01). There was imbalance between the ursodeoxycholic acid and placebo groups for this factor, and after applying a statistical correction, the adjusted recurrence rate in the ursodeoxycholic acid group was 15% compared with 30% in both placebo and diet groups (NS). These data suggest that after medical dissolution, the risk of gall stone recurrence is not reduced by a high fibre, low refined carbohydrate diet: it may be lowered, but not abolished, by low dose ursodeoxycholic acid.
Asunto(s)
Colelitiasis/prevención & control , Carbohidratos de la Dieta/uso terapéutico , Fibras de la Dieta/uso terapéutico , Ácido Ursodesoxicólico/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Bélgica/epidemiología , Colelitiasis/epidemiología , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Recurrencia , Factores de Riesgo , Factores de Tiempo , Reino Unido/epidemiologíaRESUMEN
Calcium carbonate is a major component of gallstones, but there are few data on calcium and carbonate (CO3(2-)) concentrations in human bile. Therefore, in patients undergoing cholecystectomy for gallstones, total [CaTOT] and free ionized [Ca2+] calcium concentrations, pH, PCO2, and total [CO2] were measured and [CO3(2-)] was derived in gallbladder and hepatic bile (aspirated anaerobically at surgery or from T tubes). Gallbladder bile had lower pH (6.96 vs. 7.30) and total [CO2] (14.1 vs. 21.6 mmol/L), higher PCO2 (53.8 vs. 40.2 mm Hg), lower [CO3(2-)] (2.52 vs. 6.11 x 10(5) mol/L) and lower [Ca2+] x [CO3(2-)] ion product (1.88 vs. 4.74 x 10(-8) mol/L) than did hepatic bile. Gallbladder bile pH correlated positively with total [CO2], [CO3(2-)], and [Ca2+] x [CO3(2-)] but negatively with PCO2. Patients with surface gallstone calcification had similar gallbladder bile [CaTOT] and [Ca2+] but higher gallbladder bile pH (7.30 vs. 6.90), lower PCO2 (42.9 vs. 57.2 mm Hg), higher [CO3(2-)] (7.29 vs. 1.84 x 10(-5) mol/L), and higher [Ca2+] x [CO3(2-)] ion product [4.73 vs. 1.45 x 10(-8) (mol/L)2] than those with radiolucent gallstones. There were no differences in these parameters between patients with cholesterol stones and those with pigment stones. These data suggest that the human gallbladder acidifies bile by secreting hydrogen ion and that impairment of this secretion is one cause of calcified gallstone formation in humans.
Asunto(s)
Bilis/química , Calcio/análisis , Carbonatos/análisis , Colelitiasis/metabolismo , Vesícula Biliar/química , Hígado/química , Adulto , Anciano , Dióxido de Carbono/sangre , Femenino , Humanos , Concentración de Iones de Hidrógeno , Masculino , Persona de Mediana EdadRESUMEN
In a five year study, 55 patients with radiolucent gall stones were treated with the combination of 7.5 mg chenodeoxycholic acid (CDCA) and 5.0 mg ursodeoxycholic acid (UDCA)/kg/day--that is, half the monotherapeutic doses. Side effects were few but four patients could not tolerate the prescribed bile acids because of diarrhoea or nausea. Analysis of fasting duodenal bile confirmed that CDCA+UDCA converted supersaturated into unsaturated bile but the saturation indices did not predict the dissolution response. By actuarial analysis, the confirmed (by ultrasound x2) complete gall stone dissolution rates in all 55 patients were mean (SEM) 29 (7)% at 12 and 44 (8)% at 24 months. The advent of routine computed tomography before treatment enabled comparison of dissolution efficacy in those screened by computed tomography (n = 24), whose maximum gall stone attenuation was less than 100 Hounsfield units, with that in those not screened (n = 29). Although stone size and number were comparable, patients screened by computed tomography had significantly better dissolution rates (p less than 0.025) than those not screened in this way. At 12 months, partial or complete gall stone dissolution rates were 93 (7)% in the screened and 55 (11)% in the non-screened patients. At 18 months, complete dissolution rates were 64 (12%) and 20 (9)% respectively. Computed tomography before treatment is cost effective in selecting those patients likely to achieve gall stone dissolution on treatment with UDCA+CDCA.
Asunto(s)
Ácido Quenodesoxicólico/uso terapéutico , Colelitiasis/terapia , Ácido Ursodesoxicólico/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Calcinosis/diagnóstico por imagen , Colelitiasis/química , Colelitiasis/diagnóstico por imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Tiempo , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
The efficacy, safety, and side-effects of a piezo-ceramic system for extracorporeal shock-wave lithotripsy of gallbladder stones were assessed in the first 38 patients treated. Gallstone fragmentation was achieved in 34 patients; 25 required more than 1 treatment session (range 1-5). Extracorporeal shock-wave lithotripsy, conducted without sedation, analgesia, or anaesthesia, was well tolerated by all patients; no patient reported pain or discomfort either during or after the procedure. Side-effects were negligible: transient microscopic haematuria in 2 patients, transiently abnormal liver function tests in 1, and short-lived cutaneous petechiae in 4. Initial experience shows that lithotripsy with this system is effective, safe, and well tolerated.