RESUMO
Sugarcane farmers can utilise a soil conservation technique called green cane trash blanketing, a form of mulching that can increase plant productivity through a number of channels, e.g., via altering soil physical, chemical and biological characteristics, and influence soil arthropod assemblages. Predatory mites (Mesostigmata) are important components of soil communities because they can control populations of other soil-dwelling pest species. Our aim was to characterise mulch-influenced predatory Mesostigmata community assemblages in sugarcane soils in Queensland, Australia. We found that application of a mulch layer significantly increased the abundance of Mesostigmata, and oribatid mites and collembolans, in soils. Furthermore, we observed that the assemblages of Mesostigmata in soil covered by mulch were significantly different to those in bare soil; and the assemblages of Mesostigmata changed over time. The assemblages of Mesostigmata, but not Oribatida or collembolans, were significantly different in soil under mulch depending on whether the mulch was freshly laid, or decomposing. Our results show that the use of mulch, specifically the green cane trash blanket, can increase overall microarthropod abundance including Mesostigmata. This is likely due to increased habitat complexity and changing resource availability.
Assuntos
Agricultura/métodos , Biodiversidade , Ácaros/fisiologia , Animais , Artrópodes/fisiologia , Densidade Demográfica , Queensland , Saccharum/crescimento & desenvolvimento , SoloRESUMO
Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts.
Assuntos
Antibacterianos/farmacologia , Abelhas/química , Flavonoides/farmacologia , Myrtaceae/química , Própole/química , Resinas Vegetais/farmacologia , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Produtos Biológicos , Flavonoides/química , Flavonoides/isolamento & purificação , Frutas/química , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Resinas Vegetais/química , Resinas Vegetais/isolamento & purificação , Staphylococcus aureus/efeitos dos fármacosRESUMO
The polyamines are growth factors in both normal and cancer cells. As the intracellular polyamine content correlates positively with the growth potential of that cell, the idea that depletion of polyamine content will result in inhibition of cell growth and, particularly tumour cell growth, has been developed over the last 15 years. The polyamine pathway is therefore a target for development of rationally designed, antiproliferative agents. Following the lessons from the single enzyme inhibitors (alpha-difluoromethylornithine DFMO), three generations of polyamine analogues have been synthesised and tested in vitro and in vivo. The analogues are multi-site inhibitors affecting multiple reactions in the pathway and thus prevent the up-regulation of compensatory reactions that have been the downfall of DFMO in anticancer chemotherapy. Although the initial concept was that the analogues may provide novel anticancer drugs, it now seems likely that the analogues will have wider applications in diseases involving hyperplasia.
Assuntos
Antineoplásicos/farmacologia , Poliaminas/farmacologia , Acetiltransferases/antagonistas & inibidores , Acetiltransferases/fisiologia , Animais , Antimetabólitos/farmacologia , Humanos , Inibidores da Ornitina Descarboxilase , Espermina/análogos & derivados , Espermina/farmacologiaRESUMO
The human diet contains significant amounts of amines and amine-related compounds that are present either naturally or as a result of food processing or storage. Some of these compounds are beneficial to health, while others are known to be hazardous or the dangers associated with them are poorly understood. Thus there is a need to bring together information from diverse scientific areas in order to evaluate the potential risks or benefits to human health of dietary amines.
Assuntos
Aminas , Aminas Biogênicas , Dieta , Poliaminas , Divisão Celular/fisiologia , Manipulação de Alimentos , HumanosRESUMO
Colorectal cancer is one of a number of cancers that may be amenable to prevention. The NSAIDs (non-steroidal anti-inflammatory drugs) have been shown to be effective chemopreventative agents in humans, but their mechanism of action is not clear. The polyamines are cellular polycations that are essential for cell growth and are overproduced in cancer cells. It is our hypothesis that inhibition of polyamine metabolism is an integral part of the mechanism of cancer prevention mediated by NSAIDs.
Assuntos
Anticarcinógenos/uso terapêutico , Antineoplásicos/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/prevenção & controle , Poliaminas/metabolismo , Poliaminas/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Divisão Celular/efeitos dos fármacos , Neoplasias Colorretais/patologia , HumanosRESUMO
The identification of increased polyamine concentrations in a variety of diseases from cancer and psoriasis to parasitic infections has led to the hypothesis that manipulation of polyamine metabolism is a realistic target for therapeutic or preventative intervention in the treatment of certain diseases. The early development of polyamine biosynthetic single enzyme inhibitors such as alpha-difluoromethylornithine (DFMO) and methylglyoxal bis(guanylhydrazone) showed some interesting early promise as anticancer drugs, but ultimately failed in vivo. Despite this, DFMO is currently in use as an effective anti-parasitic agent and has recently also been shown to have further potential as a chemopreventative agent in colorectal cancer. The initial promise in vitro led to the development and testing of other potential inhibitors of the pathway namely the polyamine analogues. The analogues have met with greater success than the single enzyme inhibitors possibly due to their multiple targets. These include down regulation of polyamine biosynthesis through inhibition of ornithine decarboxylase and S-adenosylmethionine decarboxylase and decreased polyamine uptake. This coupled with increased activity of the catabolic enzymes, polyamine oxidase and spermidine/spermine N1-acetyltransferase, and increased polyamine export has made the analogues more effective in depleting polyamine pools. Recently, the identification of a new oxidase (PAO-h1/SMO) in polyamine catabolism and evidence of induction of both PAO and PAO-h1/SMO in response to polyamine analogue treatment, suggests the analogues may become an important part of future chemotherapeutic and/or chemopreventative regimens.
Assuntos
Doença , Inibidores Enzimáticos/metabolismo , Poliaminas/metabolismo , Animais , Eflornitina/metabolismo , Eflornitina/uso terapêutico , Inibidores Enzimáticos/uso terapêutico , Humanos , Mitoguazona/metabolismo , Mitoguazona/uso terapêutico , Ornitina Descarboxilase/metabolismo , Inibidores da Ornitina Descarboxilase , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Poliaminas/química , S-Adenosilmetionina/análogos & derivados , Poliamina OxidaseRESUMO
The naturally occurring polyamines are found in all living cells, where they fulfil a number of critical functions in relation to cell growth. The quest to identify these functions has been the subject of five independent colloquia hosted by the Biochemical Society and today still occupies several hundred scientists across Europe, the U.S.A. and Japan.
Assuntos
Poliaminas Biogênicas/fisiologia , Antineoplásicos , Poliaminas Biogênicas/antagonistas & inibidores , Humanos , TripanossomicidasRESUMO
Just over 30 years ago, the late Diane Russell published the first in a series of papers linking polyamines and cancer. These early studies led to a flurry of research activity in the polyamine field that continues to this day attempting to identify a role for the polyamines in cancer development, treatment and/or prevention. The recognition that polyamines are critical for the growth of cancer cells, and consequently the identification of their metabolic pathways as a target for therapeutic intervention, led to the development of a number of useful inhibitors of polyamine biosynthesis. Arguably the most significant addition to the polyamine field in the last 30 years was the synthesis of alpha-difluoromethylornithine (DFMO), which is being tested currently as a cancer chemopreventative agent in man and is used also as a highly effective trypanocidal agent. Although an extremely useful tool experimentally, DFMO has been disappointing in clinical trials with little therapeutic efficacy. Despite this setback, the polyamine pathway is still considered a viable target for chemotherapeutic intervention. This has led to the development of the polyamine analogues as multifunctional inhibitors that will produce inhibition of tumour cell growth, polyamine depletion and optimum therapeutic efficacy.
Assuntos
Antineoplásicos/farmacologia , Poliaminas Biogênicas/antagonistas & inibidores , Poliaminas Biogênicas/biossíntese , Inibidores Enzimáticos/farmacologia , Humanos , Poliaminas/farmacologiaRESUMO
Colorectal cancer is a major health problem in the western world and is associated with significant morbidity and mortality. Diet makes a significant contribution to the disease, with high fat, low fibre diets correlating positively with a high incidence of colorectal cancer. Intracellular polyamine concentrations and ornithine decarboxylase activity are both increased in colorectal cancer tissue and in premalignant polyps. Measurement of the polyamine content of serum and urine of individuals has been proposed as a diagnostic marker of malignancy but a number of false positives make this idea untenable. There may, however, still be a role for the measurement of urinary polyamine content as a means of monitoring the efficacy of therapy. Inhibition of polyamine metabolism by polyamine analogues or by non-steroidal anti-inflammatory drugs may be useful in the chemotherapy and/or chemoprevention of colorectal cancer. Preliminary results suggest that a low polyamine diet might be helpful as part of a health care plan for cancer patients.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/prevenção & controle , Dieta , Poliaminas/metabolismo , Neoplasias Colorretais/terapia , Feminino , Humanos , Masculino , Poliaminas/análise , Prognóstico , Medição de Risco , Sensibilidade e EspecificidadeRESUMO
Metallothioneins (MTs) have a major role to play in metal metabolism, and may also protect DNA against oxidative damage. MT protein has been found localized in the nucleus during S-phase. The mRNA encoding the MT-1 isoform has a perinuclear localization, and is associated with the cytoskeleton; this targeting, due to signals within the 3'-untranslated region (3'-UTR), facilitates nuclear localization of MT-1 during S-phase [Levadoux, Mahon, Beattie, Wallace and Hesketh (1999) J. Biol. Chem. 274, 34961-34966]. Using cells transfected with MT gene constructs differing in their 3'-UTRs, the role of MT protein in the nucleus has been studied. Chinese hamster ovary cells were transfected with either the full MT gene (MTMT cells) or with the MT 5'-UTR and coding region linked to the 3'-UTR of glutathione peroxidase (MTGSH cells). Cell survival following exposure to oxidative stress and chemical agents was higher in cells expressing the native MT gene than in cells where MT localization was disrupted, or in untransfected cells. Also, MTMT cells showed less DNA damage than MTGSH cells in response to either hydrogen peroxide or mutagen. After exposure to UV light or mutagen, MTMT cells showed less apoptosis than MTGSH cells, as assessed by DNA fragmentation and flow cytometry. The data indicate that the perinuclear localization of MT mRNA is important for the function of MT in a protective role against DNA damage and apoptosis induced by external stress.
Assuntos
Metalotioneína/genética , Metalotioneína/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Células CHO , Ensaio Cometa , Cricetinae , Dano ao DNA , Peróxido de Hidrogênio/farmacologia , Metilnitronitrosoguanidina/farmacologia , Estresse Oxidativo , Transfecção , Raios UltravioletaRESUMO
High concentrations of acetyl polyamines have been observed in human breast cancer compared with the equivalent normal tissue, however, no explanation as to the reason for the increases has been proposed. In this study, we show that changes in the enzymes responsible for the breakdown of acetyl polyamines occur in breast cancer tissue. Spermidine/spermine N1-acetyltransferase, the first and rate-limiting enzyme in polyamine catabolism, is increased in the tumor tissue whereas polyamine oxidase (PAO) is decreased. The changes in PAO correlate with prognostic factors, and activity decreases as the size and histological grade of tumors increase. The metabolism of polyamines by PAO generates locally high concentrations of hydrogen peroxide, a known inducer of apoptosis; thus, low PAO activity may contribute to the low level of apoptosis seen in tumor cells. Therefore, drugs that induce PAO activity may be a novel means of attacking tumor cells.
Assuntos
Acetiltransferases/metabolismo , Neoplasias da Mama/enzimologia , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Acetilação , Poliaminas Biogênicas/metabolismo , Neoplasias da Mama/patologia , Catálise , Feminino , Humanos , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Poliamina OxidaseRESUMO
The mechanisms of the response of ornithine decarboxylase(ODC), the rate-limiting enzyme in polyamine biosynthesis, to amino acid supplementation were studied in the human colon adenocarcinoma cell line, Caco-2. Supplementation of serum-deprived, subconfluent Caco-2 cells with any one of a series of amino acids (10 mM) resultedin increased ODC activity, reaching a maximum of approx. 12.5-fold after approx. 4 h, over control cells either not supplemented or supplemented with iso-osmolar D-mannitol. Glycine, L-asparagine and L-serine, as well as their D-enantiomers, were the strongest effectors and acted in a concentration-dependent manner; millimolar concentrations of most of these amino acids being sufficient to significantly increase ODC activity. In contrast, supplementation with D-methionine, L-lysine, L-aspartate or L-glutamate had little or no effect on ODC activity, whereas supplemental L-methionine, L-arginine, L-ornithine or L-cysteine was inhibitory. Polyamine assays showed that the putrescine content of cells varied in accordance with the changes in ODC activity. Western-blot and Northern-blot analyses revealed specifically increased levels of ODC protein but not mRNA,respectively, in response to supplementation with an ODC-inducing amino acid. Suppression of the increase in cycloheximide-treated cellsconfirmed a requirement for protein synthesis. Pulse-labelling of cellswith [(35)S]methionine showed a 3-fold increase in thesynthesis of ODC protein after 4 h of supplementation with glycineor L-serine. Supplemental glycine also augmented, reversibly, the half-life of ODC by almost 4-fold and simultaneously decreased the activity of putrescine-induced free antizyme. These results suggest that translational, but not transcriptional, regulation of ODC takes part in ODC induction by amino acids in Caco-2 cells. However, it also appears to occur in concert with decreased enzyme in activation and/or degradation.
Assuntos
Aminoácidos/metabolismo , Inibidores Enzimáticos/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Ornitina Descarboxilase/genética , Biossíntese de Proteínas , Proteínas/metabolismo , Aminoácidos/farmacologia , Células CACO-2 , Meios de Cultura Livres de Soro , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Cinética , Metionina/metabolismo , Ornitina Descarboxilase/biossíntese , Ornitina Descarboxilase/metabolismoRESUMO
The cytotoxicity of two novel polyamine analogues was compared with that of a known cytotoxic drug, etoposide, in a human promyelogenous leukemic cell line. CHEN-spm showed significant acute cytotoxicity in these cells and was comparable to etoposide in terms of IC(50) value. The cell death observed from both CHEN-spm and etoposide was typically apoptotic with increased DNA fragmentation, altered cell morphology, and cell cycle distribution. CPEN-spm, on the other hand, exhibited no toxic effects over the short-term (24 h) exposure period. Intracellular polyamine content decreased in the presence of all inhibitors but only CPEN-spm produced significant induction of spermidine/spermine N(1)-acetyltransferase in 24 h. Thus, increased polyamine catabolism appears not to be essential for the initiation of apoptotic cell death in these human leukemic cells.
Assuntos
Antineoplásicos/farmacologia , Poliaminas/antagonistas & inibidores , Poliaminas/química , Poliaminas/farmacologia , Acetiltransferases/metabolismo , Antineoplásicos Fitogênicos/farmacologia , Apoptose , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , DNA de Neoplasias/antagonistas & inibidores , Indução Enzimática/efeitos dos fármacos , Etoposídeo/análogos & derivados , Humanos , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/metabolismo , Células Tumorais Cultivadas/patologia , Células Tumorais Cultivadas/fisiologiaRESUMO
The influence of mRNA localization on metallothionein-1 protein distribution was studied by immunocytochemistry. We used Chinese hamster ovary cells that had been transfected with either a native metallothionein-1 gene construct or metallothionein-1 5'-untranslated region and coding sequences linked to the 3'-untranslated region from glutathione peroxidase. The change in the 3'-untranslated region caused the delocalization of the mRNA with a loss of the perinuclear localization and association with the cytoskeleton. Clones were selected which expressed similar levels of metallothionein-1 protein, as assessed by radioimmunoassay. The results showed that loss of metallothionein-1 mRNA localization was associated with a loss of metallothionein-1 protein localization, most notably with a lack of metallothionein-1 protein in the nucleus of synchronized cells which were beginning to synthesize DNA. This indicates that the association of metallothionein-1 mRNA with the cytoskeleton around the nucleus is essential for efficient shuttling of the protein into the nucleus during the G(1) to S phase transition. This is the first demonstration of a physiological role for perinuclear mRNA localization and we propose that such localization may be important for a wide range of nuclear proteins, including those that shuttle between nucleus and cytoplasm in a cell cycle dependent manner.
Assuntos
Núcleo Celular/metabolismo , Citoesqueleto/metabolismo , Metalotioneína/metabolismo , RNA Mensageiro/metabolismo , Regiões 3' não Traduzidas/genética , Animais , Transporte Biológico , Células CHO , Ciclo Celular , Núcleo Celular/genética , Cricetinae , Citoplasma/metabolismo , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Imuno-Histoquímica , Metalotioneína/genética , Microscopia Confocal , Fase S , Timidina/metabolismo , Fatores de Tempo , TransfecçãoRESUMO
Plant mitochondria from both potato and mung bean incorporated radioactivity into acid insoluble material when incubated with labelled polyamines (spermine, spermidine and putrescine). Extensive washing of mitochondrial precipitates with trichloroacetic acid and the excess of cold polyamine failed to remove bound radioactivity. Addition of nonradioactive polyamine stopped further incorporation of radioactivity but did not release radioactivity already bound. The radioactivity is incorporated into the membrane fraction. The labelling process has all the features of an enzymatic reaction: it is long lasting with distinctive kinetics peculiar to each polyamine, it is temperature dependent and is affected by N-ethylmaleimide. The latter inhibits the incorporation of putrescine but stimulates the incorporation of spermine and spermidine. Treatment of prelabelled mitochondria with pepsin releases bound radioactivity thus indicating protein to be the ligand for the attachment of polyamines. HPLC of mitochondrial hydrolysates revealed that the radioactivity bound to mitochondria is polyamines; traces of acetyl polyamines were also found in some samples. On autoradiograms of SDS/PAGE gels several radioactive bands of proteins were detected. Protein sequencing of labelled spots from a 2D gel gave a sequence which was 60% identical to catalase. We suggest that the attachment of polyamines to mitochondrial proteins occurs cotranslationally possibly via transglutaminases.
Assuntos
Mitocôndrias/química , Proteínas de Plantas/química , Poliaminas/química , Sequência de Aminoácidos , Membrana Celular/química , Cromatografia Líquida de Alta Pressão , Eletroforese em Gel de Poliacrilamida , Endopeptidases/química , Etilmaleimida , Fabaceae/química , Cinética , Plantas Medicinais , Inibidores da Síntese de Proteínas/farmacologia , Putrescina/farmacologia , Solanum tuberosum/química , Reagentes de Sulfidrila , TemperaturaRESUMO
The topoisomerase II inhibitor etoposide induced apoptosis in HL-60 cells within 4 h of exposure to the drug, as measured by changes in morphology, DNA fragmentation and cytotoxicity assays. Etoposide-induced apoptosis was accompanied by an increase in polyamine efflux from the cells and a decrease in total polyamine content during the first 24 h of exposure to the drug. Although both enzyme activities increased slightly, there were no significant changes in spermidine/spermine N1-acetyltransferase activity or polyamine oxidase activity. After longer exposures (48-72 h), significant induction of spermidine/spermine N1-acetyltransferase activity and loss of polyamine content occurred. These results suggest that polyamine oxidation and the resultant hydrogen peroxide produced may be associated with the initiation of apoptosis, while induction of the acetyltransferase and overall loss of intracellular polyamines may be involved in the final, possibly necrotic, stages of cell death.
Assuntos
Apoptose/efeitos dos fármacos , Etoposídeo/farmacologia , Leucemia Promielocítica Aguda/metabolismo , Poliaminas/metabolismo , Acetiltransferases/metabolismo , Divisão Celular/efeitos dos fármacos , Células HL-60 , Humanos , Leucemia Promielocítica Aguda/enzimologia , Leucemia Promielocítica Aguda/patologia , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Poliamina OxidaseRESUMO
Reactive oxygen species (ROS) are involved in a number of disease states where they are believed to be responsible for cellular damage. In this study we examined the effect of ROS generation on polyamine catabolism. Treatment of human breast cancer cells with either H2O2 or hyperoxia increased the activity of spermidine/spermine N1-acetyltransferase (SSAT). These increases occurred before any significant signs of cellular injury. Agents known to decrease the production of reactive oxygen species such as dimethylthiourea and o-phenanthroline prevented the increase in SSAT activity indicating ROS involvement in the induction process. These results suggest that induction of SSAT may be a protective response to oxidative stress in mammalian cells facilitating removal of polyamines from the cell to prevent their toxic accumulation.
Assuntos
Acetiltransferases/biossíntese , Espécies Reativas de Oxigênio/metabolismo , Neoplasias da Mama/metabolismo , Sequestradores de Radicais Livres/farmacologia , Radicais Livres/metabolismo , Humanos , Hiperóxia/metabolismo , Quelantes de Ferro/farmacologia , Fenantrolinas/farmacologia , Tioureia/análogos & derivados , Tioureia/farmacologia , Células Tumorais CultivadasRESUMO
High concentrations of oxygen, indispensable for the treatment of severe hypoxemia from neonatal as well as adult respiratory distress syndrome, increase the risk of oxygen toxicity. Biochemical mechanisms are lipid peroxidation, protein sulfhydryl oxidation, enzyme inactivation, and DNA damage. Recent reports suggest that cytokines might be involved in free radical injury as well as in adaptive response to hyperoxic injury. However, actual signal transduction pathways involving cytokines have not yet been clarified. In this study we exposed cultured human umbilical vein endothelial cells (HUVECs) to either ambient air or 100% oxygen, and compared for the rate of DNA synthesis ([3H]thymidine uptake) at different time points up to 72 h. After exposing the cells to each treatment condition, we extracted RNA, constructed complementary DNA using reverse transcriptase, amplified the specific DNA segments of cytokines by polymerase chain reaction (PCR), and used the PCR products for gel electrophoresis to examine the bands which signified mRNA levels of corresponding cytokines. There was a significant decrease in the rate of DNA synthesis as early as 24 h. The mRNA expression of IL-1 beta and TNFa seemed less influenced by hyperoxia, while IL-8 and TGF beta showed marked increase in mRNA levels at 6 h of 100% oxygen exposure.