RESUMO
Background and Aim: One of the key components of the One Health approach to epidemic preparedness is raising awareness and increasing the knowledge of emerging infectious diseases, prevention, and risk reduction. However, related research can involve significant risks to biosafety and biosecurity. For this purpose, we organized a multidisciplinary biosafety hands-on workshop to inform and increase the knowledge of infectious diseases and risk mitigation. This study aimed to describe the process and outcome of a hands-on biosafety training program using a One Health approach across a multidisciplinary and multi-specialty group in Nigeria. Materials and Methods: A face-to-face hands-on training for 48 participants was organized by the West African Center for Emerging Infectious Diseases (WAC-EID) at the Jos University Teaching Hospital, serving as a lead institution for the Nigeria project site. Topics covered included (1) an overview of the WAC-EID research; (2) overview of infection prevention and control; (3) safety in animal handling and restraint, sample collection, and processing; (4) safety in field studies including rodent, bird and bat handling; (5) safety practices in the collection of mosquito and other arthropod vectors; (6) personal protective equipment training (disinfection, donning and doffing); and (7) safety in sample collection, labeling, and transportation. The program was executed using a mixed method of slide presentations, practical hands-on sessions, and video demonstrations. Pre- and post-course evaluation assessments and evaluation measures were used to assess training. Results: A total of 48 trainees participated in this training, with 12 (25%), 16 (33.3%), 14 (29.2%), 6 (12.5%) categorized as ornithology, entomology, mammalogy, and clinical interest groups, respectively. The pass rate for the pre-test was 29.4%, while for the post-test, it was 57.1%, or a 28% improvement. 88.6% of the trainees rated the training as relevant to them. Conclusion: Didactic and hands-on biosafety training is relevant in this era of zoonotic epidemics and pandemic preparedness. During this training program, there was a clear demonstration of knowledge transfer that can change the current practices of participants and improve the safety of infectious diseases research.
RESUMO
Understanding the dynamics of larval habitat utilization by mosquito communities is crucial for the design of efficient environmental control strategies. The authors investigated the structure of mosquito communities found at hotel compounds in Zanzibar, networks of mosquito interactions with larval habitats and robustness of mosquito communities to elimination of larval habitats. A total of 23 698 mosquitoes comprising 26 species in six genera were found. Aedes aegypti (n = 16 207), Aedes bromeliae/Aedes lillie (n = 1340), Culex quinquefasciatus (n = 1300) and Eretmapodites quinquevitattus (n = 659) were the most dominant species. Ecological network analyses revealed the presence of dominant, larval habitat generalist species (e.g., A. aegypti), exploiting virtually all types of water holding containers and few larval habitat specialist species (e.g., Aedes natalensis, Orthopodomyia spp). Simulations of mosquito community robustness to systematic elimination of larval habitats indicate that mosquito populations are highly sensitive to elimination of larval habitats sustaining higher mosquito species diversity. This study provides insights on potential foci of future mosquito-borne arboviral disease outbreaks in Zanzibar and underscores the need for detailed knowledge on the ecological function of larval habitats for effective mosquito control by larval sources management.
Assuntos
Aedes , Arbovírus , Animais , Ecossistema , Larva , Mosquitos Vetores , TanzâniaRESUMO
BACKGROUND: Spitzoid proliferations range from Spitz naevi to melanomas. There are few studies describing clinical features and outcomes in the paediatric population. OBJECTIVES: To determine the clinical features and outcomes of a large paediatric cohort with histopathologically confirmed Spitz tumours. METHODS: This was a retrospective cohort study of patients seen at Boston Children's Hospital who were aged < 20 years and had a histopathological diagnosis of spitzoid proliferation from 1 January 1994 to 23 October 2012. RESULTS: In total 595 patients with 622 spitzoid proliferations were identified (median age 7·4 years, interquartile range 4·6-11·7). Overall 512 proliferations (82·3%) were typical, 107 (17·2.%) were atypical and three (0·5%) were melanomas. The median ages at biopsy were 7·4, 7·2 and 17·2 years, respectively, and there was a significant difference in age at biopsy for patients with typical or atypical proliferations vs. melanoma (P < 0·01). Among samples with positive margins (n = 153), 55% (54 of 98) of typical proliferations, 77% (41 of 53) of atypical proliferations and 100% (two of two) of melanomas were re-excised. Six patients had sentinel lymph node biopsy performed, with three patients demonstrating nodes positive for melanocytic cells. Within a median follow-up of 4·1 years for the full cohort there were no related deaths. CONCLUSIONS: Spitz tumours have strikingly benign outcomes in the paediatric population, although this study is limited by the low number of melanomas and restriction to a single paediatric institution. Aggressive management recommendations should be reconsidered for children and adolescents with banal-appearing Spitz naevi, based on the clinically indolent behaviour in this cohort.
Assuntos
Melanoma/diagnóstico , Nevo de Células Epitelioides e Fusiformes/diagnóstico , Neoplasias Cutâneas/diagnóstico , Pele/patologia , Adolescente , Biópsia , Proliferação de Células , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Seguimentos , Humanos , Masculino , Melanoma/epidemiologia , Melanoma/patologia , Melanoma/terapia , Nevo de Células Epitelioides e Fusiformes/epidemiologia , Nevo de Células Epitelioides e Fusiformes/patologia , Nevo de Células Epitelioides e Fusiformes/terapia , Estudos Retrospectivos , Biópsia de Linfonodo Sentinela , Pele/diagnóstico por imagem , Neoplasias Cutâneas/epidemiologia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/terapia , Resultado do Tratamento , Adulto JovemRESUMO
The Infectious disease chytridiomycosis, which is caused by the fungal pathogen Batrachochytrium dendrobatidis, has been identified as one of the most important drivers of amphibian declines and extinction. In vitro B. dendrobatidis is susceptible to a range of disinfectants, but not all have been tested on animals and some that have been proven effective have harmful side effects on the surrounding environment or the animals being treated. We tested the efficacy of F10SC veterinary disinfectant to treat B. dendrobatidis in experimentally infected tadpole and juvenile Sclerophrys gutturalis and tadpoles of Sclerophrys poweri and Amietia hymenopus. The minimum inhibitory concentration for F10SC on in vitro B. dendrobatidis ranged between 1:7000 for 5-min contact time and 1:10000 for 10-min contact time. Based on the survival data of test animals the no observed effect concentration for 15-min contact time was estimated to be 1:2000 dilution for juveniles, and 1:10000 for tadpoles. In S. gutturalis juveniles an 86% infection clearance rate was achieved after five 15-min doses of 1:3000 dilution. A 100% clearance was achieved in A. hymenopus tadpoles after seven 15-min doses of 1:10000 dilution, and after nine doses of the same treatment in S. poweri tadpoles. F10SC has the benefit of being a concentrated compound that provides a treatment protocol which is nontoxic to tadpoles and post-metamorphic individuals, has a short half-life and is effective against B. dendrobatidis during short contact times, but further testing on different species of amphibians is advised.
Assuntos
Bufonidae , Quitridiomicetos/efeitos dos fármacos , Desinfetantes/administração & dosagem , Desinfetantes/farmacologia , Micoses/veterinária , Animais , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Micoses/tratamento farmacológico , Micoses/microbiologia , Fatores de Tempo , Resultado do TratamentoRESUMO
Seasonal, spatial, and habitat responses of carrion-associated Diptera assemblages can provide valuable information about the presence or absence of species and their relative abundance, and thereby enhance understanding of their responses to environmental variables and how this may have an impact on forensic investigations. Three different nature reserves (localities) within the Municipality of Tshwane, South Africa, were selected to determine whether species assemblages of carrion-feeding flies differ between seasons, localities, and habitat types. A total of 59,511 adult Diptera, identified to 35 species in eight different families, were collected using modified Redtop hanging traps, baited with liver and fish, during four seasons in three different habitat types. Species assemblages differed temporally, with season being the main factor determining species diversity and not locality or habitat. However, savanna and human-disturbed habitats supported a higher abundance and species richness than grassland habitats. Areas adjacent to the localities, such as large urban expanses in Dinokeng or agricultural holdings in Rietvlei, led to an increase in the abundance and mean species richness of carrion-associated Diptera, and in increased numbers of pest or invasive species such as Chrysomya megacephala (F.). Despite this, the overall species assemblages present in human-disturbed areas were very similar to those recorded in natural habitats.
Assuntos
Biodiversidade , Dípteros/classificação , Ecossistema , Animais , Cadáver , Dípteros/fisiologia , Entomologia , Ciências Forenses , Estações do Ano , África do SulRESUMO
In pest management programmes that incorporate the sterile insect technique (SIT), the ability of mass-reared insects to tolerate dry conditions may influence their survival after release in the field. In the present study, desiccation resistance of adult mass-reared Queensland fruit flies, Bactrocera tryoni (Frogatt) (Diptera: Tephritidae), that are routinely released in SIT programmes was compared with that of wild flies at 1, 10 and 20 days after adult eclosion. Under dry conditions without access to food or water, longevity of mass-reared B. tryoni was significantly less than that of their wild counterparts. Desiccation resistance of mass-reared flies declined monotonically with age, but this was not the case for wild flies. The sharp decline in desiccation resistance of mass-reared flies as they aged was likely explained by decreased dehydration tolerance. As in an earlier study, desiccation resistance of females was significantly lower than that of males but this was particularly pronounced in mass-reared females. Female susceptibility to dry conditions corresponded with declining dehydration tolerance with age and associated patterns of reproductive development, which suggests that water content of their oocyte load is not available for survival during periods of water stress.
Assuntos
Tephritidae/fisiologia , Água/fisiologia , Adaptação Fisiológica , Animais , Peso Corporal , Dessecação , Feminino , MasculinoRESUMO
Amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has been hypothesised to be an indigenous parasite of African amphibians. In Cameroon, however, previous surveys in one region (in the northwest) failed to detect this pathogen, despite the earliest African Bd having been recorded from a frog in eastern Cameroon, plus one recent record in the far southeast. To reconcile these contrasting results, we present survey data from 12 localities across 6 regions of Cameroon from anurans (n = 1052) and caecilians (n = 85) of ca. 108 species. Bd was detected in 124 amphibian hosts at 7 localities, including Mt. Oku, Mt. Cameroon, Mt. Manengouba and lowland localities in the centre and west of the country. None of the hosts were observed dead or dying. Infected amphibian hosts were not detected in other localities in the south and eastern rainforest belt. Infection occurred in both anurans and caecilians, making this the first reported case of infection in the latter order (Gymnophiona) of amphibians. There was no significant difference between prevalence and infection intensity in frogs and caecilians. We highlight the importance of taking into account the inhibition of diagnostic qPCR in studies on Bd, based on all Bd-positive hosts being undetected when screened without bovine serum albumin in the qPCR mix. The status of Bd as an indigenous, cosmopolitan amphibian parasite in Africa, including Cameroon, is supported by this work. Isolating and sequencing strains of Bd from Cameroon should now be a priority. Longitudinal host population monitoring will be required to determine the effects, if any, of the infection on amphibians in Cameroon.
Assuntos
Anfíbios , Quitridiomicetos/isolamento & purificação , Micoses/veterinária , Animais , Camarões/epidemiologia , Micoses/epidemiologia , Micoses/microbiologia , Vigilância da PopulaçãoRESUMO
The current study is an important step toward calibrating, validating, and improving irradiation methods used for Bactrocera tryoni (Froggatt) sterile insect technique (SIT). We used routine International Atomic Energy Agency/U.S. Department of Agriculture/Food and Agriculture Organization quality control tests assessing percentage of emergence, flight ability, sex ratio, mortality under stress, reproductive sterility, and sexual competitiveness, as well as a nonstandard test of longevity under nutritional stress to assess the impact of a range of target irradiation doses (60, 65, 70, 75, and 80 Gy) on the product quality of mass reared B. tryoni used in SIT. Sterility induction remained adequate (>99.5%) for sterile male-fertile female crosses, and 100% sterility was achieved in fertile male-sterile female crosses and sterile male-sterile female crosses for each irradiation doses tested. There was significant increase in mortality under stress as irradiation dose increased, and reduced participation in mating by males irradiated at higher doses. The current target-sterilizing dose for SIT of 70-75 Gy is associated with significant reduction in fly product "quality". Our data suggest that adequate sterility and improved fly quality could be achieved through a small reduction in target sterilizing dose.
Assuntos
Fertilidade/efeitos da radiação , Infertilidade , Tephritidae/efeitos da radiação , Animais , Morte , Relação Dose-Resposta à Radiação , Feminino , Voo Animal/efeitos da radiação , Luz , Longevidade/efeitos da radiação , Masculino , Pupa/efeitos da radiação , Reprodução/efeitos da radiação , Caracteres SexuaisRESUMO
Patients on cardiac assist devices are often considered to be high-risk solid organ donors. We report the first case of a reduced size liver transplant performed using the left lateral segment of a pediatric donor whose cardiac function was supported by a Berlin Heart. The recipient was a 22-day-old boy with neonatal hemochromatosis who developed fulminant liver failure shortly after birth. The transplant was complicated by mild delayed graft function, which required delayed biliary reconstruction and abdominal wall closure, as well as a bile leak. However, the graft function improved quickly over the first week and the patient was discharged home with normal liver function 8 weeks after transplant. The presence of a cardiac assist device should not be considered an absolute contraindication for abdominal organ donation. Normal organ procurement procedures may require alteration due to the unusual technical obstacles that are encountered when the donor has a cardiac assist device.
Assuntos
Coração Auxiliar , Falência Hepática Aguda/cirurgia , Transplante de Fígado , Doadores de Tecidos , Pré-Escolar , Função Retardada do Enxerto , Feminino , Hemocromatose/complicações , Humanos , Recém-Nascido , Falência Hepática Aguda/etiologia , Masculino , Tamanho do Órgão , Obtenção de Tecidos e ÓrgãosRESUMO
PURPOSE: Pleuropulmonary blastoma (PPB) is a rare intrathoracic neoplasm of early childhood arising in the lung or visceral pleura. Approximately 150 cases have been reported in the literature, with only one previously documented case of PPB in siblings. PATIENTS AND METHODS: We present the case of two brothers diagnosed with PPB. RESULTS: A two month-old boy with an abnormal breathing pattern was referred for evaluation of a cystic mass discovered on chest radiograph. Computed tomography (CT) of the chest was performed at our institution which revealed findings compatible with congenital cystic adenomatoid malformation (CCAM) of the right middle and lower lobes. The patient underwent urgent thoracic exploration one week later after developing severe respiratory distress. Histological examination revealed PPB type I (cystic). The patient's 15-month-old brother was presumed to have a CCAM noted radiographically months earlier during an asthma exacerbation. He underwent elective cyst resection and was also found to have type I PPB. The index patient was treated with adjuvant chemotherapy due to the large size of the PPB and intraoperative spillage of cystic fluid during the emergent surgery. In contrast, the brother is being followed without adjuvant chemotherapy, given the much smaller size of the PPB, wide margins of resection, and lack of spillage. Family history included an uncle diagnosed at age 11 with an unusual form of T cell acute lymphoblastic leukemia. CONCLUSION: Although PPB is known to have a familial association with other neoplasms, this case represents only the second report of PPB occurring in siblings. The importance of thoroughly investigating and resecting pulmonary cystic masses in the pediatric population is highlighted by these cases.
Assuntos
Neoplasias Pulmonares/diagnóstico , Neoplasias Pleurais/diagnóstico , Blastoma Pulmonar/diagnóstico , Predisposição Genética para Doença , Humanos , Lactente , Neoplasias Pulmonares/cirurgia , Masculino , Neoplasias Pleurais/cirurgia , Pneumonectomia , Blastoma Pulmonar/cirurgiaRESUMO
The 1st recorded histological evidence of chytridiomycete fungal infection in a free-ranging ranid amphibian in South Africa is presented. Literature on causes of a worldwide decline in amphibian populations is briefly reviewed.
Assuntos
Quitridiomicetos/isolamento & purificação , Dermatomicoses/veterinária , Ranidae/microbiologia , Animais , Dermatomicoses/patologia , Dinâmica Populacional , África do SulRESUMO
In oestrogen receptor (ER)-positive breast carcinoma cells, 17beta-oestradiol suppresses a dose-dependent induction of cell death by tumour necrosis factor alpha (TNF). The ability of oestrogens to promote cell survival in ER-positive breast carcinoma cells is linked to a coordinate increase in Bcl-2 expression, an effect that is blocked with the pure anti-oestrogen ICI 182,780. The role of Bcl-2 in MCF-7 cell survival was confirmed by stable overexpression of Bcl-2 which resulted in suppression of apoptosis induced by doxorubicin (DOX), paclitaxel (TAX) and TNF as compared to vector-control cells. The pure anti-oestrogen ICI 182,780 in combination with TNF, DOX or TAX potentiated apoptosis in vector-transfected cells. Interestingly, pre-treatment with ICI 182,780 markedly enhanced chemotherapeutic drug- or TNF-induced apoptosis in Bcl-2 expressing cells, an effect that was correlated with ICI 182,780 induced activation of c-Jun N-terminal kinase. Our results suggest that the effects of oestrogens/anti-oestrogens on the regulation of apoptosis may involve coordinate activation of signalling events and Bcl-2 expression.
Assuntos
Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Estradiol/análogos & derivados , Estradiol/farmacologia , Neoplasias Hormônio-Dependentes/tratamento farmacológico , Neoplasias Hormônio-Dependentes/patologia , Fator de Necrose Tumoral alfa/farmacologia , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/farmacologia , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/administração & dosagem , Doxorrubicina/farmacologia , Interações Medicamentosas , Estradiol/administração & dosagem , Moduladores de Receptor Estrogênico/administração & dosagem , Moduladores de Receptor Estrogênico/farmacologia , Feminino , Fulvestranto , Genes bcl-2 , Humanos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neoplasias Hormônio-Dependentes/genética , Neoplasias Hormônio-Dependentes/metabolismo , Paclitaxel/administração & dosagem , Paclitaxel/farmacologia , Transdução de Sinais , Transfecção , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/administração & dosagemRESUMO
BACKGROUND: Nuclear factor-kappa B (NF-kappa B) is a known survival pathway, and it may explain differential sensitivity to tumor necrosis factor-alpha (TNF-alpha) and chemotherapeutic-induced apoptosis in apoptotically sensitive (APO+) and apoptotically resistant (APO-) Michigan Cancer Foundation-7 breast cancer cells. METHODS: Crystal violet viability and luciferase reporter gene assays were used to determine the inhibitory concentration of viability at 50% (IC(50)) and the inhibitory concentration of activity at 50% (EC(50)) values in APO- and APO+ cells with the selective NF-kappa B inhibitor, BAY 11-7082 (BAY). The apoptotic reporter assay was used to determine the effects of the transfection of the inhibitory kappa B-dominant negative (I kappa B-DN) construct in conjunction with TNF, paclitaxel, or doxorubicin treatments in these cells. RESULTS: The concentrations at which 50% of cell viability is inhibited (IC(50)) and at which 50% of NF-kappa B activity is inhibited (EC(50)) for BAY in APO- and APO+ cells were 95.24 micromol/L and 1.53 micromol/L, respectively, and 7.62 micromol/L and 2.64 micromol/L, respectively. The IC(50) and the EC(50) values were equivalent for the APO+ cells (P =.665), but not for the APO- cells (P =.025). I kappa B-DN--transfection alone, or with TNF, doxorubicin, or paclitaxel treatments resulted in cell death of both APO- and APO+ cells as compared with vector-control; however, greater cytotoxicity was seen in the APO+ cells. Direct comparison of the APO+ cells versus the APO- cells revealed that these differences were significant (P =.05). CONCLUSIONS: Pharmacologic or molecular inhibition of the NF-kappa B pathway blocked cell survival in MCF-7 APO+ cells, while only molecular inhibition induced cytotoxicity in the APO- cells. Selective manipulation of the NF-kappa B pathway in combination with standard chemotherapeutic agents may lead to an increased potency and efficacy of these agents.
Assuntos
Neoplasias da Mama , Resistencia a Medicamentos Antineoplásicos , NF-kappa B/genética , NF-kappa B/metabolismo , Nitrilas , Compostos Orgânicos , Sulfonas , Antineoplásicos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Doxorrubicina/farmacologia , Feminino , Expressão Gênica/efeitos dos fármacos , Genes Reporter , Humanos , Concentração Inibidora 50 , Luciferases/genética , NF-kappa B/antagonistas & inibidores , Paclitaxel/farmacologia , Células Tumorais Cultivadas/citologia , Células Tumorais Cultivadas/efeitos dos fármacosRESUMO
The molecular details of hypoxia-induced cellular responses have been difficult to identify since there is as yet no known oxygen receptor. We used cDNA microarray technology to extend our studies pertaining to these molecular details in human hepatocellular carcinoma (Hep3B) cells that produce erythropoietin (Epo) in response to hypoxia. Of approximately 1200 genes in the array, those associated with integrin-linked kinase (ILK), fibronectin precursor and glycogen synthase kinase-3beta (GSK-3beta) were markedly stimulated after exposure of Hep3B cells to low oxygen (1%) for 6 h. Epo, HIF-1, and von Hippel-Lindau cDNAs were measured in parallel as markers of low oxygen responses in Hep3B cells. ILK is a serine, threonine protein kinase that interacts with the cytoplasmic domains of integrin beta1 and beta3. This interaction localizes ILK to focal adhesion plaques. ILK is stimulated by cell-fibronectin interaction as well as insulin. It is regulated in a phosphatidylinositol 3-kinase dependent manner and can phosphorylate protein kinase B (PKB/AKT) and GSK-3beta. As a result of these and other activities ILK has been shown to affect anchorage-independent cell survival, cell cycle progression and tumorigenesis in nude mice. ILK has also been implicated in the Wnt pathway and as a critical target in PTEN-dependent tumor therapies. To our knowledge this is the first report implicating the ILK pathway in low oxygen responses. Other genes identified as a result of the microarray analysis not previously known to change as a result of low oxygen treatment were elongation factor-1alpha, glycyl-tRNA synthetase, and laminin receptor protein-1. These findings were all corroborated by RT-PCR assays and in some instances Western blot analysis.
Assuntos
Carcinoma Hepatocelular/metabolismo , Perfilação da Expressão Gênica/métodos , Hipóxia/metabolismo , Neoplasias Hepáticas/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Transdução de Sinais , Western Blotting , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Carcinoma Hepatocelular/genética , Primers do DNA/química , Fibronectinas/genética , Fibronectinas/metabolismo , Glicina-tRNA Ligase/genética , Glicina-tRNA Ligase/metabolismo , Quinase 3 da Glicogênio Sintase , Quinases da Glicogênio Sintase , Humanos , Neoplasias Hepáticas/genética , Fator 1 de Elongação de Peptídeos/genética , Fator 1 de Elongação de Peptídeos/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Receptores de Laminina/genética , Receptores de Laminina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Carcinosarcoma is an uncommon malignancy of the esophagus that presents as a bulky intraluminal polypoid lesion of the esophagus. Histologically, both carcinomatous and sarcomatous components are seen. Because of accelerated intraluminal growth, esophageal carcinosarcoma often presents relatively early. This report describes a 64-year-old man with carcinosarcoma who was successfully treated with an esophagectomy. As in typical squamous cell carcinoma, early detection and treatment by surgical resection are needed to produce significant long-term survival.
Assuntos
Carcinossarcoma , Neoplasias Esofágicas , Carcinossarcoma/epidemiologia , Carcinossarcoma/patologia , Carcinossarcoma/cirurgia , Neoplasias Esofágicas/epidemiologia , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/cirurgia , Esofagectomia , Esôfago/patologia , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
We found that in MCF-7 breast carcinoma cells, PI3K and Akt suppressed a dose-dependent induction of apoptosis by tumor necrosis factor alpha (TNF). PI3K and Akt stimulated NF-kappaB activation in a dose-dependent manner, suggesting a common link between these two pathways. TNF has been shown to activate both an apoptotic cascade, as well as a cell survival signal through NF-kappaB. PI3K and AKT cell survival signaling were correlated with increased TNF-stimulated NF-kappaB activity in MCF-7 cells. We demonstrate that while both TNFR1 and NIK are partially involved in Akt-induced NF-kappaB stimulation, a dominant negative IkappaBalpha completely blocked Akt-NF-kappaB cross-talk. PI3K-Akt signaling activated NF-kappaB through both TNFR signaling-dependent and -independent mechanisms, potentially representing a mechanism by which Akt functions to suppress apoptosis in cancer.
Assuntos
Apoptose , NF-kappa B/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas , Fator de Necrose Tumoral alfa/farmacologia , Linhagem Celular , Relação Dose-Resposta a Droga , Humanos , Luciferases/metabolismo , Plasmídeos/metabolismo , Proteínas Proto-Oncogênicas c-akt , Proteínas Recombinantes/metabolismo , Transdução de Sinais , Transfecção , Células Tumorais CultivadasRESUMO
Widespread use of MCF-7 human breast cancer cells as a model system for breast cancer has lead to variations in these cells between different laboratories. Although several reports have addressed these differences in terms of proliferation and estrogenic response, differences in sensitivity to apoptosis have just begun to be described. Based on the possible differences in apoptotic sensitivity that may arise due to the existence of MCF-7 cell variants, we determined the relative sensitivity of MCF-7 cell variants from three established laboratories (designated M, L and N) to known inducers of apoptosis. Consistent with our previous studies we demonstrate that differences exist among these variants in regards to tumor necrosis factor alpha (TNF)-induced cell death and inhibition of proliferation in a dose-dependent manner. To establish if the difference in apoptotic susceptibility was specific to TNF, the three MCF-7 cell variants were tested for their response to other known inducers of apoptosis: okadaic acid, staurosporine and 4-hydroxy-tamoxifen. Viability and DNA fragmentation analysis revealed a similar pattern of resistance to apoptosis by all agents in the MCF-7 M variant. The MCF-7 L variant was resistant to okadaic acid and 4-hydroxy-tamoxifen but not staurosporine. In contrast, MCF-7 N cells were sensitive to induction of apoptosis by all agents. The role of both protein kinase C (PKC) and estrogen signaling in the regulation of cell survival prompted investigation of these pathways as a mechanism for differential sensitivity of MCF-7 cell variants to apoptosis. While both estrogen receptor alpha (ERalpha) and ERbeta were expressed in MCF-7 M and N cells, the absence of ERbeta in MCF-7 L cells correlated with decreased estrogen responsiveness of the L variant. Variations in estrogenic responsiveness and PKC isoform expression may account for the enhanced susceptibility of both the L and N variants to staurosporine.
Assuntos
Neoplasias da Mama/metabolismo , Proteína Quinase C/metabolismo , Receptores de Estrogênio/metabolismo , Células Tumorais Cultivadas/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Neoplasias da Mama/fisiopatologia , Estradiol/farmacologia , Receptor alfa de Estrogênio , Receptor beta de Estrogênio , Feminino , Humanos , Isoformas de Proteínas/farmacologia , Receptores de Estrogênio/efeitos dos fármacos , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/fisiologiaRESUMO
Peptide hormones act to regulate apoptosis through activation of multiple pro- and anti-apoptotic signaling cascades of which lipid signaling events represent an important facet of the cellular rheostat that determines survival and death decisions. Activation of sphingomyelinase, which generates ceramide, is an intermediate in cellular stress responses and induction of apoptosis in many systems. Conversely, phosphatidylinositol 3-kinase (PI3K) is a critical signaling molecule involved in regulating cell survival and proliferation pathways. In the present study, we investigate cross-talk between the PI3K and sphingomyelinase pathways as a mechanism for regulation of cell survival/death decisions. We show that phorbol ester, insulin-like growth factor 1, and a constitutively active PI3K suppress both tumor necrosis factor-induced apoptosis and ceramide generation. Conversely, inhibition of the PI3K pathway with expression of a kinase-dead PI3K both prevented survival signaling and enhanced tumor necrosis factor-induced ceramide generation. The ability of exogenous sphingomyelinase to induce ceramide generation was partially suppressed by expression of constitutively active PI3K and enhanced by inhibition of PI3K suggesting that cross-talk between PI3K and ceramide generation within cells is regulated subsequent to activation of sphingomyelinase.