RESUMEN
Methyltrioxorhenium mediated oxidative addition/elimination nucleophilic substitution yielded alkylamino and arylamino cambinol derivatives characterized by anti-proliferative activity against wild-type and p53 mutated MGH-U1 and RT112 bladder cancer cell lines. Some of the novel compounds showed an activity higher than that of the lead compound. The reaction was highly regioselective, affording for the first time a panel of C-2 cambinol substitution products. Aliphatic primary and secondary amines, and primary aromatic amines, were used as nitrogen centered nucleophiles. Surprisingly, the antiproliferative activity of C-2 substituted cambinol derivatives was not correlated to the induction of p53 protein, as evaluated by the analysis of the cell viability on wild-type and p53 mutated cancer cell lines, and further confirmed by western blot analyses. These data suggest that they exert their antiproliferative activity by a mechanism completely different from cambinol.
Asunto(s)
Antineoplásicos/farmacología , Naftalenos/farmacología , Pirimidinonas/farmacología , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Antineoplásicos/síntesis química , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Estructura Molecular , Naftalenos/síntesis química , Naftalenos/química , Oxidación-Reducción , Pirimidinonas/síntesis química , Pirimidinonas/química , Relación Estructura-Actividad , Neoplasias de la Vejiga Urinaria/patologíaRESUMEN
Melatonin is considered a promising antitumor agent, promoting apoptosis in tumor cells and contrasting it in normal cells. The basis for this selectivity is presumed to be the ability of melatonin to stimulate reactive oxygen species (ROS) production in tumor cells. Here we investigate the effect of melatonin on three types of human lymphocytes: normal blood lymphocytes, BL41 Burkitt lymphoma, and the cognate Epstein-Barr virus (EBV)-converted E2r. We found that melatonin promotes ROS production in all these cells. Melatonin protects BL41 from apoptosis in the same manner as normal lymphocytes, whereas E2r are unaffected. These results show that ROS production is not limited to tumor lymphocytes nor it is involved in apoptosis promotion; that melatonin does not promote apoptosis in tumor lymphocytes, but EBV inhibits melatonin anti-apoptotic effects; and that the anti-apoptotic effect of melatonin does not depend on the well-known chemical antioxidant properties of melatonin.
Asunto(s)
Antioxidantes/farmacología , Apoptosis/efectos de los fármacos , Melatonina/farmacología , Linfocitos B/citología , Linfocitos B/metabolismo , Linfocitos B/virología , Linfoma de Burkitt/metabolismo , Linfoma de Burkitt/patología , Línea Celular Transformada , Línea Celular Tumoral , Transformación Celular Viral , Células Cultivadas , Citometría de Flujo , Herpesvirus Humano 4/fisiología , Interacciones Huésped-Patógeno , Humanos , Linfoma de Células B/metabolismo , Linfoma de Células B/patología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Highly oxidized lignans produced during the cytochrome P-450 metabolism in the cells show biological activities significantly different from those of their parent natural compounds. Lignans precursors of mammalian enterolignans were treated with a methyltrioxorhenium/hydrogen peroxide catalytic system to afford new compounds oxidized at benzylic as well as in arylic positions. The evaluation of the antioxidant and apoptogenic activity by in vivo protocols of these compounds showed some interesting structure-activity relationships related to the oxidation degree of the molecules.
Asunto(s)
Antioxidantes/síntesis química , Antioxidantes/farmacología , Apoptosis/efectos de los fármacos , Lignanos/síntesis química , Lignanos/farmacología , Compuestos Organometálicos , Antioxidantes/química , Catálisis , Línea Celular Tumoral , Humanos , Peróxido de Hidrógeno , Lignanos/química , Linfoma de Células B/tratamiento farmacológico , Oxidación-Reducción , Relación Estructura-ActividadRESUMEN
Polyphenols are a family of organic compounds characterized by a wide range of biological activities. Among natural polyphenols, the products derived from shikimic and polyketide biogenic pathways, such as lignans, neolignans, cardanols and flavonoids are of special interest owing to their powerful antioxidant, antitumoral, antimitotic, antiviral, cardiovascular and immunosuppressive activity. The biological activity of polyphenols can be finely tuned by the oxidation state of the molecule. Polyphenols are subject to oxidative metabolism in the cell by cytochrome p-450 dependent enzymes, mainly at reactive benzyl and aryl positions of the molecule, to yield highly oxidised derivatives, namely quinones, hydroquinones, semiquinones, catechols and others, whose biological activity can greatly differ from that of the parental compound. In fact, these derivatives are characterized by peculiar antitumoral, antioxidant and antiviral activities and show different chemical properties toward nucleophiles and electrophiles active sites in the cell. This behavior is dependent on the specific value of the redox potential in the cell. The low concentration of these metabolites in nature, and the difficulty to recover them from mammalian cells or fluids require novel procedures for their synthesis to collect adequate amounts of compounds for biological assays. On the other hand, only a few attentions has been devoted to design novel oxidative procedures for the synthesis of highly oxidised polyphenols characterized by higher biological activity. In this review, advances and challenges in the synthesis of natural and semi-synthetic highly oxidised polyphenols are reported focusing the attention in the recent years. Data on the antiviral, antioxidant and cytotoxic activities in vivo and in vitro systems for natural and semi-synthetic highly oxidised polyphenols are also reported, and the effect on the biological activity due to the introduction of one or more oxygen atoms in different reactive sites of the molecule, is discussed.
Asunto(s)
Antioxidantes/síntesis química , Antioxidantes/farmacología , Antivirales/síntesis química , Antivirales/farmacología , Productos Biológicos/farmacología , Fenoles/síntesis química , Fenoles/farmacología , Animales , Antioxidantes/química , Antivirales/química , Productos Biológicos/química , Proliferación Celular/efectos de los fármacos , Humanos , Oxidación-Reducción , Fenoles/químicaRESUMEN
Epstein-Barr Virus (EBV) is involved in the progression of lymphomas through still unknown mechanism involving increased resistance to induced apoptosis. We show here that in a set of apoptosis-resistant EBV-converted Burkitt's lymphoma clones, 5- and 12-lipoxygenases (LOXs) are over-expressed. Further investigations on 5-LOX showed that resistance to apoptosis increases parallely with the expression of 5-lipoxygenase (5-LOX). Inhibitors of 5-LOX: (a) decrease peroxides level, indicating that this enzyme promotes the generation of oxidative stress in EBV+ cells, and (b) potently induce apoptosis in the EBV resistant cell line E2R. 5- and 15-HETE, the products of the 5 and 15-LOXs, respectively, counteract 5-LOX inhibitor induced apoptosis, indicating that products of arachidonate metabolism, rather than peroxides, trigger a signal transduction that is required for survival of the EBV-converted cells. These findings suggest that 5- and, to a lesser extent, other LOXs, that are involved in tumor progression of several cell types, may also participate in lymphomagenesis, especially that EBV-mediated.
Asunto(s)
Araquidonato 5-Lipooxigenasa/genética , Araquidonato 5-Lipooxigenasa/metabolismo , Linfoma de Burkitt/enzimología , Linfoma de Burkitt/virología , Herpesvirus Humano 4/fisiología , Apoptosis , Araquidonato 12-Lipooxigenasa/metabolismo , Linfoma de Burkitt/genética , Linfoma de Burkitt/patología , Línea Celular Tumoral , Supervivencia Celular , Progresión de la Enfermedad , Humanos , Peroxidación de Lípido , ARN Neoplásico/genética , Especies Reactivas de Oxígeno/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Tumor cells often develop molecular strategies for survival to anoxia/reoxygenation stress as part of tumor progression. Here we describe that the B lymphoma Epstein-Barr-positive cells E2r survive reoxygenation in spite of a very high and long-lasting increase in cytosolic Ca2+ and the loss of about half of their mitochondria due to specific extrusion of the organelles from the cells. The extrusion typically occurs 3 days after reoxygenation, and a regular mitochondrial asset is regained after further 24 h.
Asunto(s)
Apoptosis , Calcio/metabolismo , Mitocondrias/metabolismo , Oxígeno/metabolismo , Línea Celular Tumoral , Proliferación Celular , HumanosRESUMEN
U937 monocytic cells show two main apoptotic nuclear morphologies, budding and cleavage, that are the result of two independent morphological routes, since they never interconvert one into the other, and are differently modulated by stressing or physiological apoptogenic agents [Exp Cell Res 1996; 223:340-347]. With the aim of understanding which biochemical alterations are at the basis of these alternative apoptotic morphologies, we performed an in situ analysis that showed that in U937 cells intracellular glutathione (GSH) is lost in cells undergoing apoptosis by cleavage, whereas it is maintained in apoptotic budding cells. Lymphoma cells BL41 lose GSH in apoptosis, and show the cleavage nuclear morphology; the same cells latently infected with Epstein Barr Virus (E2r line) undergo apoptosis without GSH depletion and show the budding nuclear morphology. GSH depletion is not only concomitant to, but is the determinant of the cleavage route, since the inhibition of apoptotic GSH efflux with cystathionine or methionine shifts the apoptotic morphology from cleavage to budding. Accordingly, cystathionine or methionine antagonizes apoptosis in the all-cleavage BL41, without affecting the all-budding E2r.
Asunto(s)
Apoptosis/fisiología , Linfoma de Burkitt/patología , Núcleo Celular/patología , Glutatión/metabolismo , Células U937/patología , Apoptosis/efectos de los fármacos , Linfoma de Burkitt/metabolismo , Linfoma de Burkitt/virología , Cistationina/farmacología , Citometría de Flujo , Glutatión/antagonistas & inhibidores , Herpesvirus Humano 4/fisiología , Humanos , Metionina/farmacología , Células U937/metabolismo , Células U937/virologíaRESUMEN
A novel and efficient procedure to prepare highly oxidised aryltetralin lignans, such as isopodophyllotoxone and (-)-aristologone derivatives, by oxidation of podophyllotoxin and galbulin with methylrhenium trioxide (MTO) and novel MTO heterogeneous catalysts is reported. It is noteworthy that in the case of isopodophyllotoxone derivatives the functionalisation of the C-4 position of the C-ring and the ring-opening of the D-lactone moiety increased the activity against topoisomerase II while causing the undesired inhibition of tubulin polymerisation to disappear. The novel (-)-aristologone derivatives showed apoptogenic activity against resistant human lymphoma cell lines.
Asunto(s)
Apoptosis/efectos de los fármacos , Lignanos/química , Lignanos/farmacología , Compuestos Organometálicos/química , Tetrahidronaftalenos/química , Inhibidores de Topoisomerasa II , Animales , Catálisis , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , ADN-Topoisomerasas de Tipo II/metabolismo , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Humanos , Lignanos/síntesis química , Estructura Molecular , Oxidación-Reducción , Podofilotoxina/química , Podofilotoxina/farmacologíaRESUMEN
Glutathione depletion by inhibition of its synthesis with buthionine sulfoximine (BSO) is a focus of the current research in antitumor therapy, BSO being used as chemosensitizer. We had previously shown that two human tumor cell lines (U937 and HepG2) survive to treatment with BSO: BSO can elicit an apoptotic response, but the apoptotic process is aborted after cytochrome c release and before caspase activation, suggesting the development of an adaptive response (FASEB J., 1999, 13, 2031-2036). Here, we investigate the mechanisms of such an adaptation. We found that following BSO, U937 up-regulate Bcl-2 mRNA and protein levels, by a mechanism possibly involving NF-kappaB transcription factor; the increase in protein level is limited by a rapid decay of Bcl-2 in BSO-treated cells, suggesting that redox imbalance speeds up Bcl-2 turnover. BSO-dependent Bcl-2 up-regulation is associated with the ability to survive to BSO. Indeed, 1) its abrogation by CAPE or protein synthesis inhibition sensitizes U937 to BSO; 2) in a panel of four tumor lines, BSO-resistant (U937, HepG2, and HGB1) but not BSO-sensitive (BL41) cells can up-regulate Bcl-2 following GSH depletion; remarkably, only the latter are chemosensitized by BSO.
Asunto(s)
Butionina Sulfoximina/farmacología , Resistencia a Antineoplásicos , Glutatión/deficiencia , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Glutatión/metabolismo , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Células U937RESUMEN
It has been suggested that an atypical course of primary infection by EBV and the reactivation of EBV infection in transplanted patients may induce hepatitis. We explored the possibility to dissect the infectious activity from the ability to promote B lymphocyte proliferation in vivo by injecting in nu/nu mice a low number (2 x 10(6)-0.05 x 10(6)) of cells from CE a normal human bone marrow-derived B cell line. This line carries an endogenous EBV in episomal and linear forms. Twenty nu/nu mice were inoculated subcutaneously with the B cell line CE and a matched group with the cell line RAG obtained by EBV in vitro infection of normal human peripheral blood. The mice injected with the CE line did not develop a lymphoproliferative disease, but 5 of them displayed typical histopathological lesions of chronic hepatitis without involvement of other organs. Similar results were obtained in 2 out of 20 animals in the RAG group. A close association between liver lesions and a previous EBV infection, by putative circulating B lymphoblastoid cells releasing their EBV, was established by PCR and by in situ hybridization with BamHI "W" DNA probe. This latter probe detected the presence of about 15% of positive cells only in affected livers. In addition, the rare detection in some hepatocytes of "A" type Cowdry bodies would suggest the occurrence of continuous EBV replication although at a very low level. These data show that we succeeded in dissecting the infectious from the proliferative activity of the endogenous EBV carrier CE cell line. This provides in addition a promising model for chronic EBV-associated hepatitis.