RESUMO
Treatment of p53-deficient PC-3 human prostate carcinoma cells with nanomolar concentrations of bis-anthracycline WP631 induced changes in gene expression, which resulted in G2/M cell cycle arrest, autophagy and cell death. The presence of 2-deoxy-D-glucose (2-DG), which induces metabolic stress and autophagy, enhanced the antiproliferative effects of WP631. Changes induced by WP631, 2-DG, or co-treatments with both compounds, in the expression of a variety of genes involved in autophagy and apoptosis were quantified by real-time PCR. They were consistent with a raise in autophagy followed by cell death. Some cells dying from G2/M phase showed features of necrosis like early changes in membrane permeability, while others were dying by apoptosis that occurred in presence of little caspase-3 activity. Our results indicate that WP631 is not only an antiproliferative agent acting on gene transcription, but it can also induce autophagy regardless of the presence of other pro-autophagy stimuli. The development of autophagy seemed to improve the cytotoxicity of WP631 in PC-3 cells. Our results indicate that autophagy would enhance the activity of DNA-binding drugs like WP631 that are potent inhibitors of gene transcription.
Assuntos
Autofagia/efeitos dos fármacos , Daunorrubicina/análogos & derivados , Proteína Supressora de Tumor p53/deficiência , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antibióticos Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Autofagia/genética , Proteína Beclina-1 , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Daunorrubicina/farmacologia , Desoxiglucose/farmacologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Citometria de Fluxo , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem da Fase G2 do Ciclo Celular/genética , Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Sequestossoma-1 , Fatores de TempoRESUMO
The occurrence of contaminants of emerging concern (CECs) or heavy metals in reclaimed water used for agricultural irrigation may affect crop morphology and physiology. Here, we analyzed lettuce (Lactuca sativa) grown in outdoor lysimeters and irrigated with either tap water, used as a control, or reclaimed water: CAS-reclaimed water, an effluent from a conventional activated sludge system (CAS) followed by chlorination and sand filtration, or MBR-reclaimed water, an effluent from a membrane biological reactor (MBR). Chemical analyses identified seven CECs in the reclaimed waters, but only two of them were detected in lettuce (carbamazepine and azithromycin). Metabolomic and transcriptomic analyses revealed that irrigation with reclaimed water increased the concentrations of several crop metabolites (5-oxoproline, leucine, isoleucine, and fumarate) and of transcripts codifying for the plant stress-related genes Heat-Shock Protein 70 (HSP70) and Manganese Superoxide Dismutase (MnSOD). In both cases, MBR-water elicited the strongest response in lettuce, perhaps related to its comparatively high sodium adsorption ratio (4.5), rather than to its content in CECs or heavy metals. Our study indicates that crop metabolomic and transcriptomic profiles depend on the composition of irrigating water and that they could be used for testing the impact of water quality in agriculture.
Assuntos
Metais Pesados , Qualidade da Água , Transcriptoma , Agricultura , Irrigação Agrícola , Lactuca/metabolismo , Metais Pesados/análise , Esgotos/análiseRESUMO
The regeneration of wastewater has been recognized as an effective strategy to counter water scarcity. Nonetheless, Wastewater Treatment Plant (WWTP) effluents still contain a wide range of contaminants of emerging concern (CECs) even after water depuration. Filtration through Soil Aquifer Treatment (SAT) systems has proven efficient for CECs removal although the attenuation of their associated biological effects still remains poorly understood. To evaluate this, three pilot SAT systems were monitored, two of them enhanced with different reactive barriers. SATs were fed with secondary effluents during two consecutive campaigns. Fifteen water samples were collected from the WWTP effluent, below the barriers and 15 m into the aquifer. The potential attenuation of effluent-associated biological effects by SATs was evaluated through toxicogenomic bioassays using zebrafish eleutheroembryos and human hepatic cells. Transcriptomic analyses revealed a wide range of toxic activities exerted by the WWTP effluents that were reduced by more than 70% by SAT. Similar results were observed when HepG2 hepatic cells were tested for cytotoxic and dioxin-like responses. Toxicity reduction appeared partially determined by the barrier composition and/or SAT managing and correlated with CECs removal. SAT appears as a promising approach to efficiently reduce effluent-associated toxicity contributing to environmental and human health preservation.
Assuntos
Água Subterrânea , Poluentes Químicos da Água , Purificação da Água , Animais , Humanos , Peixe-Zebra , Solo , Poluentes Químicos da Água/análise , Água/análise , Monitoramento Ambiental , Eliminação de Resíduos LíquidosRESUMO
C/G-rich DNA regions, which include those recognized by the Sp1 transcription factor in several gene promoters, also encompass potential binding sites for the DNA-intercalating anthracyclines doxorubicin and WP631. We explored the differences between changes in gene expression caused by the ability of these drugs to compete with Sp1 for binding to DNA and those produced by Sp1 knockdown. By quantitative RT-PCR of around 100 genes, most of them involved in control of cell cycle progression, we found that the treatment of human MDA-MB231 breast carcinoma cells with bis-anthracycline WP631 for 24 h produced a profile of gene down-regulation markedly different from the profile caused by doxorubicin treatment or by stable Sp1 knockdown. These observations are rationalized by considering a near-specific effect of WP631 on Sp1 interaction with several gene promoters, thus representing potential therapeutic targets for WP631, in contrast to a less specific effect of reducing the availability of Sp1 through RNA interference. Genes down-regulated upon each treatment were mapped to their molecular and biological functions, which documented the down-regulation, among other things, of genes involved in mRNA transcription regulation, granting us insights into the effects of challenging the transactivation of gene expression by Sp1.
Assuntos
RNA Mensageiro/biossíntese , Elementos de Resposta/fisiologia , Transcrição Gênica/fisiologia , Ativação Transcricional/fisiologia , Antibióticos Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Daunorrubicina/análogos & derivados , Daunorrubicina/farmacologia , Doxorrubicina/farmacologia , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , RNA Mensageiro/genética , Transcrição Gênica/efeitos dos fármacosRESUMO
Environmental toxicogenomics aims to collect, analyze and interpret data on changes in gene expression and protein activity resulting from exposure to toxic substances using high-performance omics technologies. Molecular profiling methods such as genomics, transcriptomics, proteomics, metabolomics, and bioinformatics techniques, permit the simultaneous analysis of a multitude of gene variants in an organism exposed to toxic agents to search for genes prone to damage, detect patterns and mechanisms of toxicity, and identify specific gene expression profiles that can provide biomarkers of exposure and risk. Compared to previous approaches to measuring molecular changes caused by toxicants, toxicogenomic technologies can improve environmental risk assessment while reducing animal studies. We discuss the prospects and limitations of converting omic datasets into valuable information, focusing on assessing the risks of mixed toxic substances to the environment and human health.
Assuntos
Genômica , Toxicogenética , Animais , Humanos , Toxicogenética/métodos , Genômica/métodos , Proteômica/métodos , Biologia Computacional , MetabolômicaRESUMO
Failure to eliminate cancer cells that have been exposed to cytotoxic agents may contribute to the development of resistance to antitumor drugs. A widespread model in present day oncology is that antitumor therapy involves the triggering of tumor cells to undergo apoptosis, and cells that can avoid apoptosis will be resistant to such therapy. Apoptosis is a defined program of cell death that is markedly influenced by the fact that many routes leading to it are mutated or deregulated in human cancer. Mutations in the tumor suppressor protein p53, a common feature of many cancers, may decrease the sensitivity of cells to some antitumor agents. Moreover, it has been increasingly reported that antitumor therapy not only causes apoptosis, but other forms of cell death as well, such as mitotic catastrophe, necrosis and autophagy, or a permanent cell arrest with phenotype characteristics of senescence. Mitotic catastrophe is a form of cell death that results from abnormal mitosis, which does not seem to depend on wild-type p53. Sometimes mitotic catastrophe is used restrictively for faulty mitosis leading to cell death, which may occur via apoptosis or necrosis. We critically review herein how antitumor therapy may elicit the response of human cancers through different cell pathways leading to cell death.
Assuntos
Antineoplásicos/farmacologia , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Neoplasias/tratamento farmacológico , Humanos , Transdução de Sinais/efeitos dos fármacosRESUMO
The analysis of how anthracyclines interfere with DNA-protein complexes, and the evaluation of their effects on gene transcription, can promote the development of new more specific anti-tumour agents. Daunorubicin and the bisintercalating anthracycline WP631 (which binds more tightly to DNA) have been compared for their ability to inhibit Sp1-DNA interactions and gene transcription. WP631 is more efficient at inhibiting transcription initiation from promoters containing an Sp1-binding site, and it is a potent inhibitor of Sp1-activated transcription both in vitro and in human cell lines. The analysis of gene expression profiles using arrays, which include several genes containing Sp1-putative binding sites, suggests that changes in the transcriptome induce cell cycle arrest and drive a time-dependent response of cells to death stimuli through distinct pathways, which rely on the anthracycline used and its concentration.
Assuntos
Antraciclinas/química , Sistemas de Liberação de Medicamentos , Fator de Transcrição Sp1/química , Transcrição Gênica/efeitos dos fármacos , Antraciclinas/farmacologia , Linhagem Celular Tumoral , Sistema Livre de Células , Daunorrubicina/análogos & derivados , Daunorrubicina/química , Daunorrubicina/farmacologia , Humanos , Estrutura Molecular , Fator de Transcrição Sp1/efeitos dos fármacosRESUMO
Multidrug-resistance protein 1 (MRP-1) confers resistance to a number of clinically important chemotherapeutic agents. The promoter of the mrp-1 gene contains an Sp1-binding site, which we targeted using the antitumor bis-anthracycline WP631. When MCF-7/VP breast cancer cells, which overexpress MRP-1 protein, were incubated with WP631 the expression of the multidrug-resistance protein gene decreased. Conversely, doxorubicin did not alter mrp-1 gene expression. The inhibition of gene expression was followed by a decrease in the activity of the MRP-1 protein. The IC(75) for WP631 (drug concentration required to inhibit cell growth by 75%) circumvented the drug-efflux pump, without addition of resistant modifiers. After treatment with WP631, MCF-7/VP cells were committed to die after entering mitosis (mitotic catastrophe), while treatment with doxorubicin did not affect cell growth. This is the first report on an antitumor drug molecule inhibiting the mrp-1 gene directly, rather than being simply a poor substrate for the transporter-mediated efflux. However, both situations appeared to coexist, thereby a superior cytotoxic effect was attained. Ours results suggest that WP631 offers great potential for the clinical treatment of tumors displaying a multidrug-resistance phenotype.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos/farmacologia , Neoplasias da Mama/patologia , Doxorrubicina/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Regulação para Baixo , Expressão Gênica/efeitos dos fármacos , Humanos , Células Tumorais CultivadasRESUMO
Exposure of Jurkat T lymphocytes containing functional p53 to nanomolar concentrations of bisanthracycline WP631 resulted in arrest at the G2/M checkpoint and transient senescence-like phenotype in the presence of DNA synthesis. The cells entered crisis, became polyploid, showed aberrant mitotic figures, and died through mitotic catastrophe. Cell death was accompanied by changes in the expression profile of various oncogenes and tumour suppressor genes including the down-regulation of p53. The changed expression was confirmed for some of these genes using semi-quantitative RT-PCR, and the decline in p53 protein levels was established. Our results suggest that WP631 induced changes in cell cycle control pathways leading to death of Jurkat T cells through mitotic catastrophe, which occurred in the absence of caspase-2 and caspase-3 activities, rather than apoptosis.
Assuntos
Mitose/genética , Linfócitos T/metabolismo , Transcrição Gênica/genética , Proteína Supressora de Tumor p53/genética , Apoptose/efeitos dos fármacos , Western Blotting , Caspase 2/metabolismo , Caspase 3/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Senescência Celular/efeitos dos fármacos , Senescência Celular/genética , Daunorrubicina/análogos & derivados , Daunorrubicina/farmacologia , Relação Dose-Resposta a Droga , Expressão Gênica/efeitos dos fármacos , Perfilação da Expressão Gênica , Humanos , Células Jurkat , Mitose/efeitos dos fármacos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Poliploidia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Linfócitos T/efeitos dos fármacos , Linfócitos T/patologia , Telomerase/genética , Telomerase/metabolismo , Fatores de Tempo , Transcrição Gênica/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismoRESUMO
Sp1 (specificity protein 1) is a well-known member of a family of transcription factors that also includes Sp2, Sp3 and Sp4, which are implicated in an ample variety of essential biological processes and have been proven important in cell growth, differentiation, apoptosis and carcinogenesis. Sp1 activates the transcription of many cellular genes that contain putative CG-rich Sp-binding sites in their promoters. Sp1 and Sp3 proteins bind to similar, if not the same, DNA tracts and compete for binding, thus they can enhance or repress gene expression. Evidences exist that the Sp-family of proteins regulates the expression of genes that play pivotal roles in cell proliferation and metastasis of various tumors. In patients with a variety of cancers, high levels of Sp1 protein are considered a negative prognostic factor. A plethora of compounds can interfere with the trans-activating activities of Sp1 and other Sp proteins on gene expression. Several pathways are involved in the down-regulation of Sp proteins by compounds with different mechanisms of action, which include not only the direct interference with the binding of Sp proteins to their putative DNA binding sites, but also promoting the degradation of Sp protein factors. Down-regulation of Sp transcription factors and Sp1-regulated genes is drug-dependent and it is determined by the cell context. The acknowledgment that several of those compounds are safe enough might accelerate their introduction into clinical usage in patients with tumors that over-express Sp1.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Marcação de Genes/métodos , Neoplasias/metabolismo , Neoplasias/terapia , Fator de Transcrição Sp1/metabolismo , Animais , Antineoplásicos/administração & dosagem , Sítios de Ligação/fisiologia , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias/genética , Regiões Promotoras Genéticas , Fator de Transcrição Sp1/genéticaRESUMO
WP631, a new DNA-binding drug that bisintercalates into DNA with high affinity, seems to be highly cytotoxic against Jurkat T lymphocytes. The purpose of this study was to gain new insights into the mechanisms by which WP631 halts proliferation in this cell type. Treating Jurkat cells with nanomolar concentrations of WP631 produced G(2)/M arrest, inhibited the transcription of c-myc and p53 genes, and induced limited apoptosis during the duration of treatment. Suppression of c-myc and p53 expression, and time-dependent decline in c-Myc and p53 protein levels, was associated with growth arrest. A weak interdependence was also found between the potent antiproliferative activity and the apoptotic response; treatment with WP631 for 24-36hr produced arrest in G(2)/M and allowed for partial DNA repair. Longer treatments with WP631 allowed some repaired cells to re-enter the cell cycle, but produced aneuploidy or apoptosis in others.
Assuntos
Daunorrubicina/análogos & derivados , Daunorrubicina/farmacologia , Fase G2/efeitos dos fármacos , Substâncias Intercalantes/farmacologia , Mitose/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-myc/metabolismo , Transcrição Gênica/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismo , Humanos , Células Jurkat , Proteínas Proto-Oncogênicas c-myc/genética , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/patologia , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genéticaRESUMO
Several DNA-binding drugs are being developed to create tailored molecules which can discriminate among the different sequences of the whole genome. By discriminating among specific sites in DNA, these molecules may provide optimal drug therapy. The complete sequencing of the human genome offers a wealth of DNA targets to be analyzed as potential drug-binding sites. To increase our understanding of DNA-drug interactions and their selectivity, we have studied the relative and absolute occurrence of CG-rich sequences, of various lengths, in human gene promoters. In several promoters, including those of oncogenes, cell cycle regulation factors, tumor suppressors and housekeeping genes, the presence of potential binding sites containing CpG steps (in which many drugs are known to intercalate) is variable, but in many cases these sites are not randomly distributed. Sequences 6-7 base pairs in length, like CGCCCG or CGCCCCG, occur only once in some promoters, thus they may be potentially specific therapeutic targets.
Assuntos
DNA/química , DNA/genética , Gliceraldeído-3-Fosfato Desidrogenases/genética , Preparações Farmacêuticas/metabolismo , Regiões Promotoras Genéticas , Proteína BRCA2/genética , Sequência de Bases , Sítios de Ligação , Ciclina D1/genética , Humanos , Dados de Sequência MolecularRESUMO
DIG-MSK (demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK) is a recently isolated compound of the mithramycin family of antitumor antibiotics, which includes mithramycin A (MTA) and mithramycin SK (MSK). Here, we present evidence that the binding of DIG-MSK to DNA shares the general features of other mithramycins such as the preference for C/G-rich tracts, but there are some differences in the strength of binding and the DNA sequence preferentially recognized by DIG-MSK. We aimed at gaining further insights into the DIG-MSK mechanism of action by direct comparison with the effects of the parental MTA. Similar to MTA, MSK and DIG-MSK accumulated rapidly in A2780, IGROV1 and OVCAR3 human ovarian cancer cell lines, and DIG-MSK was a potent inhibitor of both basal and induced expression of an Sp1-driven luciferase vector. This inhibitory activity was confirmed for the endogenous Sp1 gene and a set of Sp-responsive genes, and compared to that of MTA and MSK. Furthermore, DIG-MSK was stronger than MTA as inhibitor of Sp3-driven transcription and endogenous Sp3 gene expression. Differences in the effects of MTA, MSK and DIG-MSK on gene expression may have a large influence on their biological activities.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Neoplasias Ovarianas/tratamento farmacológico , Plicamicina/análogos & derivados , Fator de Transcrição Sp1/fisiologia , Transcrição Gênica/fisiologia , Antibióticos Antineoplásicos/uso terapêutico , Sítios de Ligação/fisiologia , Linhagem Celular Tumoral , Feminino , Proteínas Ligadas por GPI/genética , Proteínas Ligadas por GPI/fisiologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Cinética , Plicamicina/farmacologia , Plicamicina/uso terapêutico , RNA/química , RNA/genética , Reação em Cadeia da Polimerase em Tempo Real , Fator de Transcrição Sp1/genética , Espectrometria de FluorescênciaRESUMO
Cell death plays an important role in cancer growth and progression, as well as in the efficiency of chemotherapy. Although apoptosis is commonly regarded as the principal mechanism of programmed cell death, it has been increasingly reported that several anticancer agents do not only induce apoptosis but other forms of cell death such as necrosis, autophagy and mitotic catastrophe, as well as the state of permanent loss of proliferative capacity known as senescence. A deeper understanding of what we know about chemotherapy-induced death is rather relevant considering the emerging knowledge of non-apoptotic cell death signaling pathways, and the fact that many tumors have the apoptosis pathway seriously compromised. In this review we examine the effects that various anti-cancer agents have on pathways involved in the different cell death outcomes. Novel and specific anti-cancer agents directed toward members of the cell death signaling pathways are being developed and currently being tested in clinical trials. If we precisely activate or inhibit molecules that mediate the diversity of cell death outcomes, we might succeed in more effective and less toxic chemotherapy.
Assuntos
Antineoplásicos/farmacologia , Morte Celular/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Antineoplásicos/uso terapêutico , Ensaios Clínicos como Assunto , Avaliação Pré-Clínica de Medicamentos , Humanos , Neoplasias/patologiaRESUMO
We have examined the relationship between chemotherapy-induced mitotic catastrophe and cell death by apoptosis in both wild-type and p53(-/-) HCT116 human colon carcinoma cells treated with nanomolar concentrations of paclitaxel (PTX), a drug that acts on tubulin altering the normal development of mitosis. After treatment, HCT116 cells entered mitosis regardless of the presence of functional p53, which resulted in changes in the distribution of cells in the different phases of the cell cycle, and in cell death. In the presence of PTX, the percentage of polyploid cells observed was higher in p53-deficient cells, indicating that mitotic slippage was favored compared to wild-type cells, with the presence of large multinucleate cells. PTX caused mitotic catastrophe and about 50-60% cells that were entering an aberrant mitosis died through an apoptotic-like pathway characterized by the presence of phosphatidylserine in the outer cell membrane, which occurred in the absence of significant activation of caspases. Lack of p53 facilitated endoreduplication and polyploidy in PTX-treated cells, but cells were still killed with similar efficacy through the same apoptotic-like mechanism in the absence of caspase activity.
Assuntos
Apoptose/genética , Caspases/metabolismo , Neoplasias do Colo/genética , Mitose , Paclitaxel/farmacologia , Moduladores de Tubulina/farmacologia , Ciclo Celular/genética , Morte Celular/genética , Neoplasias do Colo/tratamento farmacológico , Endorreduplicação , Células HCT116 , Humanos , Paclitaxel/uso terapêutico , Poliploidia , Proteína Supressora de Tumor p53/genéticaRESUMO
The effects of mithramycin SK (MSK) and demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK (DIG-MSK; EC-8042), two novel analogs of the antitumor antibiotic mithramycin A, on gene transcription were examined in human HCT116 colon carcinoma cells by quantitative real-time PCR of 89 genes mainly involved in cell cycle control. Each one of the analogs down-regulated a different set of genes, while only five genes were down-regulated by both compounds. Moreover, other genes were significantly up-regulated, among them p21(WAF1)/CDKN1A which is involved in halting cells at the G1 and G2/M checkpoints. These results are rationalized in terms of MSK or DIG-MSK competition with various transcription factors for binding to consensus C/G-rich tracts encompassed in gene promoters. Changes in cell cycle distribution and protein levels after treatment with every analog were consistent with changes observed in gene expression.
Assuntos
Antineoplásicos/farmacologia , Genes cdc , Plicamicina/análogos & derivados , Apoptose , Sítios de Ligação , Pontos de Checagem da Fase G1 do Ciclo Celular , Pontos de Checagem da Fase G2 do Ciclo Celular , Células HCT116 , Humanos , Necrose , Plicamicina/farmacologia , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacosRESUMO
Mitotic catastrophe is a mechanism of cell death characterized by the occurrence of aberrant mitosis with the formation of large cells that contain multiple nuclei, which are morphologically distinguishable from apoptotic cells. Sometimes, mitotic catastrophe is used restrictively to indicate a type of cell death that occurs during or after a faulty mitosis leading to cell death, which takes place via necrosis or apoptosis, rather than a cell death itself. Several antitumor drugs and ionizing radiation are known to induce mitotic catastrophe, but precisely how the ensuring lethality is regulated or what signals are involved is barely characterized. The type of cell death resulting from antitumor therapy can be determined by the mechanism of action of the antitumor agent, dosing regimen of the therapy, and the genetic background in the cells being treated. Wild-type p53 promotes apoptosis or senescence, while mitotic catastrophe is independent of p53. Mitotic catastrophe can be regarded as a delayed response of p53-mutant tumors that are resistant to some damage. In this context, the elucidation of the mechanisms of treatment-induced mitotic catastrophe should contribute to an improvement of the antitumor therapy, because most of the solid tumors bear an inactive p53 protein.
Assuntos
Antineoplásicos/uso terapêutico , Ciclo Celular/efeitos dos fármacos , Mitose/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Ciclo Celular/genética , Dano ao DNA , Regulação Neoplásica da Expressão Gênica , Genes p53 , Humanos , Mitose/genética , Mutação , Necrose , Neoplasias/genética , Neoplasias/patologiaRESUMO
Differential cleavage at three restriction enzyme sites was used to determine the specific binding to DNA of the antitumour antibiotics mithramycin A (MTA), chromomycin A(3) (CRO) and six chromophore-modified analogues bearing shorter side chains attached at C-3, instead of the pentyl chain. All these antibiotics were obtained through combinatorial biosynthesis in the producer organisms. MTA, CRO and their six analogues showed differences in their capacity for inhibiting the rate of cleavage by restriction enzymes that recognize C/G-rich tracts. Changes in DNA melting temperature produced by these molecules were also analyzed, as well as their antiproliferative activities against a panel of colon, ovarian and prostate human carcinoma cell lines. Moreover, the cellular uptake of several analogues was examined to identify whether intracellular retention was related to cytotoxicity. These experimental approaches provided mutually consistent evidence of a seeming correlation between the strength of binding to DNA and the antiproliferative activity of the chromophore-modified molecules. Four of the analogues (mithramycin SK, mithramycin SDK, chromomycin SK and chromomycin SDK) showed promising biological profiles.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Cromomicinas/farmacologia , Enzimas de Restrição do DNA/antagonistas & inibidores , Plicamicina/análogos & derivados , Linhagem Celular Tumoral , Cromomicina A3/farmacologia , Neoplasias do Colo/tratamento farmacológico , Desoxirribonucleases de Sítio Específico do Tipo II/antagonistas & inibidores , Feminino , Citometria de Fluxo , Humanos , Masculino , Neoplasias Ovarianas/tratamento farmacológico , Plicamicina/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Relação Estrutura-AtividadeRESUMO
HCT116 (p53(+/+)) human colon carcinoma cells treated with nanomolar concentrations of doxorubicin underwent transient senescence, synthesized DNA, showed endopolyploidization, increased their size and became multinucleated without a significant increase in mitosis. Nuclei underwent a budding process that involved the release of buds outside the nuclear membrane, and some of the buds seemed to escape from the polyploid cells. A clonogenic assay showed that some cells proliferated following the initial treatment. In general, cells ensuing after budding were not resistant to a variety of drugs, although some of them turned out to be resistant, indicating a potential selective advantage. Nuclear budding was accompanied by changes in protein levels in the giant cells, including inhibition of p53 and enhanced expression of p21(WAF1) and the meiosis-related Mos. The buds might be a mechanism for the segregation and elimination of redundant DNA, or for generating viable aneuploid cells with a potentially extended life span.
Assuntos
Divisão do Núcleo Celular/fisiologia , Núcleo Celular/fisiologia , Resistencia a Medicamentos Antineoplásicos/fisiologia , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/fisiologia , Núcleo Celular/efeitos dos fármacos , Divisão do Núcleo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Senescência Celular/efeitos dos fármacos , Senescência Celular/fisiologia , Doxorrubicina/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistência a Múltiplos Medicamentos/fisiologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Células HCT116 , HumanosRESUMO
Exposure of MDA-MB-231 and MCF-7/VP human breast carcinoma cells to the anthracyclines doxorubicin and WP631 induced polyploidy, formation of multinucleated cells and cell death by mitotic catastrophe through caspase-dependent and caspase-independent mechanisms. In both cell lines, the antiproliferative effect of WP631 was higher than that of doxorubicin and a transient halt in G(2)/M was observed without cell senescence, while p53-dependent apoptosis did not occur in these cells. Mitotic catastrophe was linked to necrosis, but also to apoptosis-like death, estimated by differential cell staining with annexin-V-fluorescein and propidium iodide. Drug-induced changes in the expression of c-myc and p21(WAF1), and in their respective protein levels, were observed. They depended on the cell line, the anthracycline used and its concentration, and they were consistent with the cell cycle progression through G(2) to mitosis. Significant activation of caspase-2 and caspase-3 was only observed in MDA-MB-231 cells treated with doxorubicin but not with WP631, indicating that caspases may be not mandatory for the occurrence of cell death through mitotic catastrophe. In MCF-7/VP cells, which do not express functional caspase-3, mitotic catastrophe was also induced.