RESUMO
Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. The 16S rRNA-based analysis showed the predominance of the Actinomycetales order, a well-known group of bioactive metabolite producers belonging to the Actinobacteria phylum. Cultivation techniques were applied, and 72 psychrotolerant Actinobacteria strains belonging to the genera Actinoplanes, Arthrobacter, Kribbella, Mycobacterium, Nocardia, Pilimelia, Pseudarthrobacter, Rhodococcus, Streptacidiphilus, Streptomyces and Tsukamurella were identified. The secondary metabolites were screened, and 17 isolates were identified as promising antitumour compound producers. However, the bio-guided assay showed a pronounced antiproliferative activity for the crude extracts of Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653. The TGI and LC50 values revealed the potential of these natural products to control the proliferation of breast (MCF-7), glioblastoma (U251), lung/non-small (NCI-H460) and kidney (786-0) human cancer cell lines. Cinerubin B and actinomycin V were the predominant compounds identified in Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653, respectively. Our results suggest that the rhizosphere of D. antarctica represents a prominent reservoir of bioactive actinobacteria strains and reveals it as an important environment for potential antitumour agents.
Assuntos
Actinobacteria , Técnicas de Cultura/métodos , Descoberta de Drogas , Neoplasias/patologia , Actinobacteria/metabolismo , Actinomycetales/metabolismo , Regiões Antárticas , Antraciclinas/isolamento & purificação , Antraciclinas/metabolismo , Antraciclinas/farmacologia , Antineoplásicos/isolamento & purificação , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Fatores Biológicos/biossíntese , Fatores Biológicos/isolamento & purificação , Fatores Biológicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Dactinomicina/biossíntese , Dactinomicina/isolamento & purificação , Dactinomicina/farmacologia , Humanos , Streptomyces/metabolismoRESUMO
INTRODUCTION: Acute myeloid leukaemia is the most common type of acute leukaemia in the world. Thus, the study of genetic alterations, such as single-nucleotide polymorphisms (SNPs), has contributed to a better understanding of the mechanisms underlying leukaemogenesis, to improve the prognosis and to increase the survival of these patients. However, there is no synthesis of evidence in the literature evaluating the quality of evidence and the risk of bias in the studies such that the results can be translated. Thus, this systematic review protocol aims to assess the impact of SNPs on genes involved in the metabolism of cytarabine and anthracyclines with respect to survival, treatment response and toxicity in patients with AML. METHODS: This systematic review protocol is based on PRISMA guidelines and includes searches in six electronic databases, contact with authors, repositories of clinical trials, and cancer research. Studies published in peer-reviewed journals will be included if they meet the eligibility criteria: (a) samples composed of individuals of any age, of both sexes, with a diagnosis of AML, regardless of the time of diagnosis of disease; (b) participants who have undergone or are undergoing cytarabine- and anthracycline-associated chemotherapy or cytarabine-only chemotherapy; and (c) in vivo studies. Studies that include patients with promyelocytic leukaemia (Fab type 3) will be excluded because this disease has different treatment. The process of study selection, data extraction, and evaluation/synthesis will be performed in duplicate. Assessment of methodological quality and risk of bias will be performed using the Cochrane Risk of Bias Tool for randomized clinical studies and the Downs-Black Checklist for cohort and case-control studies. The synthesis of evidence will include the level of evidence based on the GRADE protocol. A meta-analysis of the association between SNPs and outcomes may be performed based on Cochrane guidelines. DISCUSSION: It is expected that clinical decisions for AML patients will consider evidence-based practices to contribute to better patient management. In this way, we will be able to define how to treat patients with AML to improve their survival and quality of life. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42018100750.
Assuntos
Antraciclinas/toxicidade , Antraciclinas/uso terapêutico , Antimetabólitos Antineoplásicos/toxicidade , Antimetabólitos Antineoplásicos/uso terapêutico , Citarabina/toxicidade , Citarabina/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Polimorfismo de Nucleotídeo Único , Prognóstico , Antraciclinas/metabolismo , Antimetabólitos Antineoplásicos/metabolismo , Citarabina/metabolismo , Humanos , Sobrevida , Revisões Sistemáticas como AssuntoRESUMO
The search for new compounds effective against Mycobacterium tuberculosis is still a priority in medicine. The evaluation of microorganisms isolated from non-conventional locations offers an alternative to look for new compounds with antimicrobial activity. Endophytes have been successfully explored as source of bioactive compounds. In the present work we studied the nature and antimycobacterial activity of a compound produced by Streptomyces scabrisporus, an endophyte isolated from the medicinal plant Amphipterygium adstringens. The active compound was detected as the main secondary metabolite present in organic extracts of the streptomycete and identified by NMR spectroscopic data as steffimycin B (StefB). This anthracycline displayed a good activity against M. tuberculosis H37Rv ATCC 27294 strain, with MIC100 and SI values of 7.8 µg/mL and 6.42, respectively. When tested against the rifampin mono resistant M. tuberculosis Mtb-209 pathogen strain, a better activity was observed (MIC100 of 3.9 µg/mL), suggesting a different action mechanism of StefB from that of rifampin. Our results supported the endophyte Streptomyces scabrisporus as a good source of StefB for tuberculosis treatment, as this anthracycline displayed a strong bactericidal effect against M. tuberculosis, one of the oldest and more dangerous human pathogens causing human mortality.
Assuntos
Antraciclinas/farmacologia , Sapindaceae/metabolismo , Anacardiaceae , Antraciclinas/isolamento & purificação , Antraciclinas/metabolismo , Anti-Infecciosos/farmacologia , Antituberculosos , Endófitos/isolamento & purificação , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/efeitos dos fármacos , Extratos Vegetais/isolamento & purificação , Plantas Medicinais/metabolismo , Sapindaceae/toxicidade , Streptomycetaceae/metabolismoRESUMO
Anthracyclines are cytostatic antibiotics discovered almost half a century ago exerting their action through inhibition of topoisomerase II. The two most representative drugs are doxorubicin and daunorubicin and they have been proven as useful antineoplastics and are widely prescribed in daily oncology practice; unfortunately, cardiotoxicity has been a limiting factor when it comes to their use. Diverse mechanisms have been involved in anthracycline cardiotoxicity, none of which are capable of causing the whole clinical picture by itself. Traditionally, reactive oxygen species (ROS) have received more attention, although recently basic research has proven other factors to be as important as ROS. These factors mainly involve sarcomeric structure disruption, toxic accumulation of metabolites, iron metabolism, energetic alterations and inflammation. The role of genetics has been studied by some groups, although a clear genotype-response relationship is yet to be elucidated. With the improved survival from different oncologic diseases we are witnessing more cases of chemotherapy-induced cardiotoxicity and the advent of new anticancer drugs poses several challenges for the cardiologist, highlighting the importance of a deep knowledge of the main mechanisms inducing this toxicity.
Hace casi medio siglo se descubrieron las antraciclinas; estas son antibióticos citostáticos inhibidores de la topoisomerasa II. Los 2 fármacos más representativos de este grupo son la doxorrubicina y la daunorrubicina. Estos fármacos han demostrado ser eficaces antineoplásicos y han sido ampliamente utilizados en la práctica oncológica. Desafortunadamente, la cardiotoxicidad sigue siendo un elemento limitante para su uso. Los mecanismos mediante los cuales estos fármacos ocasionan cardiotoxicidad son múltiples pero ninguno de ellos de forma individual es capaz de explicar el cuadro clínico por completo. Casi siempre se ha considerado que la formación de especies reactivas de oxígeno era responsable de gran parte de la toxicidad, sin embargo la experimentación básica reciente ha demostrado que hay otros factores, entre los que destacan las alteraciones en la estructura sarcomérica, la acumulación de metabolitos tóxicos, las alteraciones del metabolismo del hierro o de los mecanismos energéticos, y la liberación de mediadores de inflamación. Por otra parte, diversos grupos han investigado la intervención que la genética podría tener en el desarrollo de esta enfermedad, si bien no se puede definir aún una clara correlación genotipo-respuesta. Con el aumento de la supervivencia por el tratamiento de diversas enfermedades oncológicas, se están detectando más casos de cardiotoxicidad mediada por quimioterapia; y con la aparición de nuevos fármacos quimioterápicos se añaden nuevos retos, con lo que se demuestra la importancia del estudio profundo de los mecanismos causales.
Assuntos
Humanos , Antraciclinas/efeitos adversos , Cardiomiopatias/induzido quimicamente , Antraciclinas/metabolismo , CardiologiaRESUMO
Anthracyclines are cytostatic antibiotics discovered almost half a century ago exerting their action through inhibition of topoisomerase II. The two most representative drugs are doxorubicin and daunorubicin and they have been proven as useful antineoplastics and are widely prescribed in daily oncology practice; unfortunately, cardiotoxicity has been a limiting factor when it comes to their use. Diverse mechanisms have been involved in anthracycline cardiotoxicity, none of which are capable of causing the whole clinical picture by itself. Traditionally, reactive oxygen species (ROS) have received more attention, although recently basic research has proven other factors to be as important as ROS. These factors mainly involve sarcomeric structure disruption, toxic accumulation of metabolites, iron metabolism, energetic alterations and inflammation. The role of genetics has been studied by some groups, although a clear genotype-response relationship is yet to be elucidated. With the improved survival from different oncologic diseases we are witnessing more cases of chemotherapy-induced cardiotoxicity and the advent of new anticancer drugs poses several challenges for the cardiologist, highlighting the importance of a deep knowledge of the main mechanisms inducing this toxicity.
Assuntos
Antraciclinas/efeitos adversos , Cardiomiopatias/induzido quimicamente , Antraciclinas/metabolismo , Cardiologia , HumanosRESUMO
Doxorubicin, one of the most widely used anticancer drugs, is composed of a tetracyclic polyketide aglycone and l-daunosamine as a deoxysugar moiety, which acts as an important determinant of its biological activity. This is exemplified by the fewer side effects of semisynthetic epirubicin (4'-epi-doxorubicin). An efficient combinatorial biosynthetic system that can convert the exogenous aglycone ε-rhodomycinone into diverse glycosylated derivatives of doxorubicin or its biosynthetic intermediates, rhodomycin D and daunorubicin, was developed through the use of Streptomyces venezuelae mutants carrying plasmids that direct the biosynthesis of different nucleotide deoxysugars and their transfer onto aglycone, as well as the postglycosylation modifications. This system improved epirubicin production from ε-rhodomycinone by selecting a substrate flexible glycosyltransferase, AknS, which was able to transfer the unnatural sugar donors and a TDP-4-ketohexose reductase, AvrE, which efficiently supported the biosynthesis of TDP-4-epi-l-daunosamine. Furthermore, a range of doxorubicin analogs containing diverse deoxysugar moieties, seven of which are novel rhodomycin D derivatives, were generated. This provides new insights into the functions of deoxysugar biosynthetic enzymes and demonstrates the potential of the S. venezuelae-based combinatorial biosynthetic system as a simple biological tool for modifying structurally complex sugar moieties attached to anthracyclines as an alternative to chemical syntheses for improving anticancer agents.
Assuntos
Doxorrubicina/metabolismo , Streptomyces/genética , Streptomyces/metabolismo , Antraciclinas/metabolismo , Daunorrubicina/metabolismo , Doxorrubicina/química , Epirubicina , Engenharia Genética , Glicosilação , Glicosiltransferases/metabolismo , Família Multigênica , Plasmídeos/genéticaRESUMO
Glycosylation pattern in cosmomycins is a distinctive feature among anthracyclines. These antitumor compounds possess two trisaccharide chains attached at C-7 and C-10, each of them with structural variability, mainly at the distal deoxysugar moieties. We have characterized a 14-kb chromosomal region from Streptomyces olindensis containing 13 genes involved in cosmomycin biosynthesis. Two of the genes, cosG and cosK, coding for glycosyltransferase were inactivated with the generation of five new derivatives. Structural elucidation of these compounds showed altered glycosylation patterns indicating the capability of both glycosyltransferases of transferring deoxysugars to both sides of the aglycone and the flexibility of CosK with respect to the deoxysugar donor. A model is proposed for the glycosylation steps during cosmomycins biosynthesis.
Assuntos
Antraciclinas/química , Antraciclinas/metabolismo , Glicosiltransferases/genética , Streptomyces/metabolismo , Proteínas de Bactérias/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Deleção de Genes , Ordem dos Genes , Teste de Complementação Genética , Glicosilação , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Estrutura Molecular , Análise de Sequência de DNA , Streptomyces/enzimologia , Streptomyces/genéticaRESUMO
One cause of multidrug resistance is the overexpression of P-glycoprotein, a 170 kDa plasma membrane ABC transporter, which functions as an ATP-driven efflux pump with broad specificity for hydrophobic drugs, peptides, and natural products. The protein appears to interact with its substrates within the membrane environment. Previous reports suggested the existence of at least two binding sites, possibly overlapping and displaying positively cooperative interactions, termed the H and R sites for their preference for Hoechst 33342 and rhodamine 123, respectively. In this work, we have used several fluorescence approaches to characterize the molecular interaction of purified P-glycoprotein (Pgp) with the dye LDS-751, which is proposed to bind to the R site. A 50-fold enhancement of LDS-751 fluorescence indicated that the protein binding site was located in a hydrophobic environment, with a polarity lower than that of chloroform. LDS-751 bound with sub-micromolar affinity (K(d) = 0.75 microM) and quenched P-glycoprotein intrinsic Trp fluorescence by 40%, suggesting that Trp emitters are probably located close to the drub-binding regions of the transporter and may interact directly with the dye. Using a FRET approach, we mapped the possible locations of the LDS-751 binding site relative to the NB domain active sites. The R site appeared to be positioned close to the membrane boundary of the cytoplasmic leaflet. The location of both H and R drug binding sites is in agreement with the idea that Pgp may operate as a drug flippase, moving substrates from the inner leaflet to the outer leaflet of the plasma membrane.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antraciclinas/metabolismo , Corantes Fluorescentes/metabolismo , Mapeamento de Peptídeos , Rodamina 123/metabolismo , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/química , Sítios de Ligação , Domínio Catalítico , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Lipossomos , Modelos Químicos , Nucleotídeos/metabolismo , Compostos Orgânicos , Mapeamento de Peptídeos/métodos , Fosfatidilcolinas/química , Ligação Proteica , Estrutura Terciária de Proteína , Espectrometria de FluorescênciaRESUMO
The effect of pH on cell growth and retamycin production in batch bioreactor cultures of Streptomyces olindensis ICB20 was investigated. In fermentations pH-controlled over the range 6.0-8.0, the highest retamycin production was achieved at pH 7.0, and the maximum concentration of retamycin, about 1.36 A (absorbance) units, was about 43, 58 and 232% higher than the values obtained at pH 7.5, 6.0 and 8.0 respectively.
Assuntos
Antraciclinas/metabolismo , Antibióticos Antineoplásicos/biossíntese , Reatores Biológicos/microbiologia , Técnicas de Cultura de Células/métodos , Concentração de Íons de Hidrogênio , Streptomyces/crescimento & desenvolvimento , Streptomyces/metabolismo , Proliferação de Células , Streptomyces/químicaRESUMO
A morphologically structured model is proposed to describe trends in biomass growth, substrate consumption, and antitumoral retamycin production during batch and fed-batch cultivations of Streptomyces olindensis. Filamentous biomass is structured into three morphological compartments (apical, subapical, and hyphal), and the production of retamycin, a secondary metabolite, is assumed to take place in the subapical cell compartment. Model accounts for the effect of glucose as well as complex nitrogen source on both the biomass growth and retamycin production. Laboratory data from bench-scale batch and fed-batch fermentations were used to estimate some model parameters by nonlinear regression. The predictive capability of the model was then tested for additional fed-batch and continuous experiments not used in the previous fitting procedure. The model predictions show fair agreement to the experimental data. The proposed model can be useful for further studies on process optimization and control.