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1.
Br J Cancer ; 128(11): 2025-2035, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36966235

RESUMO

BACKGROUND: Histopathologic regression following neoadjuvant treatment (NT) of oesophageal cancer is a prognostic factor of survival, but the nodal status is not considered. Here, a score combining both to improve prediction of survival after neoadjuvant therapy is developed. METHODS: Seven hundred and fifteen patients with oesophageal squamous cell (SCC) or adenocarcinoma (AC) undergoing NT and esophagectomy were analysed. Histopathologic response was classified according to percentage of vital residual tumour cells (VRTC): complete response (CR) without VRTC, major response with <10% VRTC, minor response with >10% VRTC. Nodal stage was classified as ypN0 and ypN+. Kaplan-Meier and Cox regression were used for survival analysis. RESULTS: Survival analysis identified three groups with significantly different mortality risks: (1) low-risk group for CR (ypT0N0) with 72% 5-year overall survival (5y-OS), (2) intermediate-risk group for minor/major responders and ypN0 with 59% 5y-OS, and (3) high-risk group for minor/major responders and ypN+ with 20% 5y-OS (p < 0.001). Median survival in AC and SCC cohorts were comparable (3.8 (CI 95%: 3.1, 5.3) vs. 4.6 years (CI 95%: 3.3, not reached), p = 0.3). CONCLUSIONS: Histopathologic regression and nodal status should be combined for estimating AC and SCC prognosis. Poor survival in the high-risk group highlights need for adjuvant therapy.


Assuntos
Adenocarcinoma , Neoplasias Esofágicas , Humanos , Terapia Neoadjuvante , Estadiamento de Neoplasias , Neoplasias Esofágicas/patologia , Prognóstico , Terapia Combinada , Adenocarcinoma/patologia , Esofagectomia , Resultado do Tratamento , Estudos Retrospectivos
2.
Clin. transl. oncol. (Print) ; 23(8): 1601-1610, ago. 2021. ilus, tab, graf
Artigo em Inglês | IBECS | ID: ibc-222159

RESUMO

Introduction The inflammatory microenvironment has emerged as one of the focuses of cancer research. Little is known about the immune environment in esophageal adenocarcinoma (EAC) and possible tumor-escape mechanisms to avoid immune cell attack. Patients and methods We measured T cell inflammation (CD3, CD8) in the microenvironment using a standardized software-based evaluation algorithm considering different predefined tumor areas as well as expression of MHC class 1 and PD-L1 on 75 analyzable primarily resected and locally advanced (≥ pT2) EACs. We correlated these findings statistically with clinical data. Results Patients with high amounts of T cell infiltration in their tumor center showed a significant survival benefit of 41.4 months compared to 16.3 months in T cell poor tumors (p = 0.025), although CD3 fails to serve as an independent prognostic marker in multivariate analysis. For the invasion zone, a correlation between number of T-cells and overall survival was not detectable. Loss of MHC1 protein expression on tumor cells was seen in 32% and PD-L1 expression using the combined positive score (CPS) in 21.2%. Most likely due to small numbers of cases, both markers are not prognostically relevant, even though PD-L1 expression correlates with advanced tumor stages. Discussion Our analyses reveal an outstanding, though not statistically independent, prognostic relevance of T-cell-rich inflammation in our group of EACs, in particular driven by the tumor center. For the first time, we describe that the inner part of the invasion zone in EACs shows significantly fewer T-cells than other tumor segments and is prognostically irrelevant. We also demonstrate that the loss of antigen presenting ability via MHC1 downregulation by the carcinoma cells is a common escape mechanism in EACs. Future work will need to show whether tumors with MHC class 1 loss respond less well to immunotherapy (AU)


Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Microambiente Tumoral/imunologia , Evasão Tumoral/imunologia , Linfócitos do Interstício Tumoral , Neoplasias Esofágicas/imunologia , Adenocarcinoma/imunologia , Invasividade Neoplásica/imunologia , Neoplasias Esofágicas/mortalidade , Neoplasias Esofágicas/patologia , Regulação para Baixo , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Fatores de Tempo , Prognóstico
3.
Clin Transl Oncol ; 23(8): 1601-1610, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33566304

RESUMO

INTRODUCTION: The inflammatory microenvironment has emerged as one of the focuses of cancer research. Little is known about the immune environment in esophageal adenocarcinoma (EAC) and possible tumor-escape mechanisms to avoid immune cell attack. PATIENTS AND METHODS: We measured T cell inflammation (CD3, CD8) in the microenvironment using a standardized software-based evaluation algorithm considering different predefined tumor areas as well as expression of MHC class 1 and PD-L1 on 75 analyzable primarily resected and locally advanced (≥ pT2) EACs. We correlated these findings statistically with clinical data. RESULTS: Patients with high amounts of T cell infiltration in their tumor center showed a significant survival benefit of 41.4 months compared to 16.3 months in T cell poor tumors (p = 0.025), although CD3 fails to serve as an independent prognostic marker in multivariate analysis. For the invasion zone, a correlation between number of T-cells and overall survival was not detectable. Loss of MHC1 protein expression on tumor cells was seen in 32% and PD-L1 expression using the combined positive score (CPS) in 21.2%. Most likely due to small numbers of cases, both markers are not prognostically relevant, even though PD-L1 expression correlates with advanced tumor stages. DISCUSSION: Our analyses reveal an outstanding, though not statistically independent, prognostic relevance of T-cell-rich inflammation in our group of EACs, in particular driven by the tumor center. For the first time, we describe that the inner part of the invasion zone in EACs shows significantly fewer T-cells than other tumor segments and is prognostically irrelevant. We also demonstrate that the loss of antigen presenting ability via MHC1 downregulation by the carcinoma cells is a common escape mechanism in EACs. Future work will need to show whether tumors with MHC class 1 loss respond less well to immunotherapy.


Assuntos
Adenocarcinoma/imunologia , Neoplasias Esofágicas/imunologia , Linfócitos do Interstício Tumoral/citologia , Evasão Tumoral/imunologia , Microambiente Tumoral/imunologia , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Idoso , Antígeno B7-H1/análise , Antígeno B7-H1/metabolismo , Regulação para Baixo , Neoplasias Esofágicas/mortalidade , Neoplasias Esofágicas/patologia , Feminino , Antígenos HLA-A/análise , Antígenos HLA-A/metabolismo , Antígenos HLA-B/análise , Antígenos HLA-B/metabolismo , Humanos , Imunidade Celular , Inflamação/imunologia , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica/imunologia , Prognóstico , Fatores de Tempo
4.
Chirurg ; 91(8): 642-649, 2020 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-32405728

RESUMO

The understanding of the development of pancreatic cancer has undergone considerable development over the last two decades. This is mainly due to the progress and use of methods for molecular biological analysis of pancreatic carcinomas. There is now a fundamental understanding with respect to the genetic drivers for the development of pancreatic cancer and the correlation with clinical data as well as the classification of different genetic characteristics of individual tumors even enables an estimation of the prognosis in some cases. The most common mutation in ductal adenocarcinoma, which if found in >90% of tumors, is the mutation of the KRAS oncogene. The other three, CDKN2A, p53 and SMAD4, are all tumor suppressor genes and are mutated in approximately 90%, 70% and 50% of carcinomas, respectively. In addition, genetic mutations predisposing to pancreatic cancer have been identified. Among the most important are BRCA2, p16/CDKN2A, STK11, PRSS1, PALP2, FANCC, FANCG and ATM. The classification of different subtypes and the knowledge of individual mutations (especially BRCA) can also be used to assess the response to treatment in individual cases. This applies to "conventional" combination chemotherapies (especially FOLFIRINOX) and also to targeted treatment approaches with tyrosine kinase inhibitors, PARP inhibitors and PD­1 inhibitors. If knowledge about the course of the disease and decisions on individual therapies become established in everyday clinical practice in the future, this may also have a decisive impact on surgery as the most important pillar of curative treatment. This ranges from the increased achievement of secondary operability to the expansion of indications with respect to resection even in patients with metastases.


Assuntos
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica , Inibidor p16 de Quinase Dependente de Ciclina/genética , Humanos , Mutação , Prognóstico , Proteína Supressora de Tumor p53/genética
5.
Chirurg ; 89(7): 510-515, 2018 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-29557488

RESUMO

BACKGROUND: Several case series reported results of surgical resection in patients with pancreatic ductal adenocarcinoma in a metastasized stage. AIM: A summarized overview of the current state of knowledge and a summary of the results of currently available studies. MATERIAL AND METHODS: A systematic search was carried out in MEDLINE and PubMed with respect to metastasized pancreatic cancer and surgical resection. RESULTS: The evidence level for surgical resection in the metastasized stage is weak and so far no prospective trials are available. The largest single-arm trial included 85 patients with hepatic metastasis. In cases of hepatic oligometastasis an overall survival of 11-14 months was observed. In the presence of pulmonary metastasis, overall survival seems to be prolonged compared to intra-abdominal metastasis, although the evidence level is relatively weak. CONCLUSION: According to the available results, a general recommendation for surgical resection in a metastasized stage cannot be given; however, the results show a possible benefit for some well-selected patient subgroups. Prospective trials must validate these data and investigate the use of combined surgical and systemic treatments in the case of resectable metastatic pancreatic cancer.


Assuntos
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Carcinoma Ductal Pancreático/patologia , Carcinoma Ductal Pancreático/cirurgia , Hepatectomia , Humanos , Metástase Neoplásica , Pancreatectomia , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/cirurgia , Estudos Prospectivos
6.
Oncogene ; 36(17): 2394-2404, 2017 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-27941874

RESUMO

Colorectal cancer (CRC) is a complex disease with still unsatisfactory prognosis even in western societies, although substantial progress has been made in pre-screening programs, surgical techniques and targeted therapy options. Mediator of motility-1 (Memo-1) was previously recognized as an important effector of cell migration downstream of receptor tyrosine kinase signaling in breast cancer. This study identified Memo-1 as frequently overexpressed in CRC and established a close link between extracellular HER2 activation, AhR/ARNT transcriptional activity and Memo-1 expression. Dissection of the hMemo-1 gene promoter using reporter assays and chromatin IP techniques revealed recruitment of Aryl hydrocarbon receptor (AhR)/Aryl hydrocarbon receptor nuclear-translocator (ARNT) complex, which positively influenced Memo-1 expression in cancer cells. We found that Memo-1 depletion negatively influenced the cellular actin network and that its expression is required for HER2-mediated cell migration and invasion. Moreover, analyses of Memo-1 expression in primary CRC revealed correlation with clinical parameters that point to Memo-1 as a new prognostic factor of aggressive disease in CRC patients. Altogether, these observations demonstrate that Memo-1 is an important downstream regulator of HER2-driven CRC cell migration and invasion through connecting extracellular signals from membrane to the cytoskeletal actin network.


Assuntos
Neoplasias Colorretais/patologia , Regulação Neoplásica da Expressão Gênica , Ferroproteínas não Heme/genética , Proteínas/metabolismo , Receptor ErbB-2/metabolismo , Receptor ErbB-3/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Progressão da Doença , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Invasividade Neoplásica , Regiões Promotoras Genéticas/genética , Transdução de Sinais
7.
Clin Genet ; 90(4): 343-50, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-26916598

RESUMO

The basal transcription of heme oxygenase-1 (HO-1) regulation is dependent upon a GT repeat germ line polymorphism (GTn) in the promoter of the HO-1 gene. We determined the prognostic value of HO-1 promoter polymorphism on the natural postoperative course of complete resected oesophageal cancer. Genomic DNA from 297 patients was amplified by polymerase chain reaction and sequenced. The results were correlated with clinicopathological parameters, disseminated tumour cells in bone marrow (DTC) and clinical outcome. Depending on short allele with <25 and long allele with ≥25, GTn repeats three genotypes (SS, SL and LL) were defined. A diverse role of GTn was evident in squamous cell carcinoma (SCC) and adenocarcinoma (AC). In SCC, the SS genotype presented less advanced tumours with lower rate DTC in bone marrow and relapse compared with L-allele carriers. In contrast, AC patients with the SS genotype displayed a complete opposing tumour characteristic. The disease-free (DFS) and overall survival (OS) in SCC patients was markedly reduced in LL genotypes (p < 0.001). In AC contrarily the SS genotype patients displayed the worst DFS and OS (p < 0.001). GTn is a strong prognostic factor with diverse prognostic value for recurrence and survival in AC and SCC.


Assuntos
Adenocarcinoma/genética , Carcinoma de Células Escamosas/genética , Neoplasias Esofágicas/genética , Heme Oxigenase-1/genética , Polimorfismo Genético , Regiões Promotoras Genéticas , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/cirurgia , Análise Mutacional de DNA , Intervalo Livre de Doença , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/cirurgia , Feminino , Heme Oxigenase-1/química , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Recidiva , Sequências Repetitivas de Ácido Nucleico , Resultado do Tratamento
9.
Chirurg ; 86(9): 881-8, 2015 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-25616746

RESUMO

BACKGROUND: Appendectomy is the most frequently performed non-elective surgical procedure in general surgery. Despite the questionable benefit, inflammatory markers, such as leukocyte count and C-related protein (CRP) are often determined before and after the surgical procedure. Clinicians are not infrequently confronted with the question whether a patient can be discharged despite an increase in inflammatory laboratory parameters. OBJECTIVES: The aim of the current study was to retrospectively evaluate the clinical course of patients after appendectomy and the correlation with inflammatory laboratory findings. MATERIAL AND METHODS: A total of 969 patients underwent a surgical procedure due to clinically suspected acute appendicitis. All clinical, laboratory and histopathological data were obtained from the patient records and a quality control database. Laboratory results were correlated with clinical and histopathological data (e.g. t-test, χ (2)-test, regression analysis and ROC curves). RESULTS: In patients without acute appendicitis operative trauma caused an increase in CRP up to a median of 31 mg/dl on the first postoperative day and up to 47 mg/dl on postoperative day 2. The overall morbidity was 6.2%. The strongest predictive parameter for complications was a CRP of more than 108 mg/l on the first postoperative day with an odds ratio of 16.6 (96% CI 6.4/42.8, p < 0.001, specificity 88% and sensitivity 69%). Patients with CRP values below the threshold suffered from complications in 1.1 % of cases in contrast to patients above the threshold in 16.8% of cases (p < 0.001). CONCLUSION: A moderate postoperative elevation of CRP values is not a general contraindication for discharge; however, postoperative determination of CRP serum values after appendectomy might be an effective predictor for complications and should therefore be measured in the clinical routine.


Assuntos
Apendicectomia , Apendicite/sangue , Apendicite/cirurgia , Proteína C-Reativa/análise , Complicações Pós-Operatórias/sangue , Complicações Pós-Operatórias/diagnóstico , Doença Aguda , Adulto , Apendicite/diagnóstico , Feminino , Humanos , Laparoscopia , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Retrospectivos , Estatística como Assunto , Adulto Jovem
10.
Chirurg ; 79(9): 874-6, 2008 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-18209992
11.
Mol Cell ; 8(2): 247-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11545727

RESUMO

In the August issue of Developmental Cell, Tay and Richter examine the consequences of eliminating CPEB function in mice. Their studies reveal an important role for this translational regulator at the pachytene stage of germ cell differentiation.


Assuntos
Células Germinativas/fisiologia , Meiose/fisiologia , Biossíntese de Proteínas , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Poliadenilação e Clivagem de mRNA , Animais , Ciclina B/genética , Ciclina B/metabolismo , Ciclina B1 , Feminino , Masculino , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas c-mos/genética , Proteínas Proto-Oncogênicas c-mos/metabolismo , RNA Mensageiro/metabolismo
12.
Arzneimittelforschung ; 51(8): 690-7, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11556131

RESUMO

Autovaccines are prepared from autologous, human, non-pathogenic, "rough" variants of E. coli derived from the stool flora of individuals according to a highly standardized procedure. As a fundamental concept within microbiological therapy, these autovaccines are mainly used to treat chronic inflammatory disorders associated with impaired immune reactions resistant to standard therapeutic treatments. Generally, immunomodulatory effects of outer membrane components or cell wall fragments of gram-negative bacteria on innate or adaptive immunity are widely accepted but nevertheless mechanisms of actions of these autovaccines remained obscure, despite some recent publication about other autovaccine preparations of different origin. Hence, immunomodulating properties of autovaccine were investigated in a pilot study with 78 outpatients with variable disorders ranging from recurrent respiratory infections to diffuse gastrointestinal complaints. Patients received their autologous bacteria parenterally in increasing doses. Before application and 4 to 6 weeks after application of autovaccine, blood samples of the patients were taken to investigate a range of immunological parameters such as acute phase proteins, serum antibodies and cytokines. The results revealed that autovaccines were able to modulate significantly the release of three potent immunoregulatory cytokines e.g. interferon-gamma, granulocyte-macrophage-colony stimulating factor and interleukin-1 beta, whereas specific humoral immunity remained largely unaffected. From these results it may be concluded that the autovaccine mainly act antigen non-specifically on the cytokine level rather than inducing a specific vaccination. Further studies with more detailed kinetic measurements of cytokines will have to verify these results.


Assuntos
Adjuvantes Imunológicos/farmacologia , Vacinas Bacterianas/farmacologia , Escherichia coli/imunologia , Reação de Fase Aguda/imunologia , Adolescente , Adulto , Idoso , Anticorpos Antibacterianos/biossíntese , Citocinas/biossíntese , Ensaio de Imunoadsorção Enzimática , Fezes/microbiologia , Feminino , Humanos , Imunoglobulinas/biossíntese , Imunoglobulinas/imunologia , Leucócitos/imunologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto
13.
Arzneimittelforschung ; 51(2): 180-7, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11258049

RESUMO

Pharmaceuticals of biological origin consisting of bacterial culture suspensions (BCS) as active ingredients have long been used for the treatment of hemorrhoidal diseases and chronic anal pruritogenic eczemas. However, some of these pharmaceuticals often contain glucocorticoids such as hydrocortisone as an anti-inflammatory supplement. Therefore, the question arises whether the claimed immunostimulatory capacity of the bacterial culture suspension might be altered by the steroid. Up to now, numerous reports support the evidence that the stimulation of the different Fc-receptor subtypes on leucocytes result in profound immunoregulatory activities influencing phagocytosis and antigen processing, antibody-dependent cytotoxicity or secretory functions thereby enhancing the overall activities of the immune system towards foreign antigens/pathogens. With these findings in mind it was investigated whether the immunomodulatory capacity(s) of the BCS in the presence of hydrocortisone will be modified by solid-phase bound immunoglobulins (Igs). For this purpose freshly prepared human peripheral blood leucocytes (PBLs) were incubated with different concentrations of the BCS (0.1, 1, 10 micrograms/ml), either with or without fixed human immunoglobulins in the presence of increasing concentrations of hydrocortisone. As a parameter of PBL activation the secretion of different cytokines was measured, e.g. tumor necrosis factor alpha (TNF-alpha), interleukin-10 (IL-10) and granulocyte-macrophage colony stimulating factor (GM-CSF). Cytokines were determined with specific sandwich ELISAs. With this modified cell culture system it was demonstrated that the immunosuppressive activities, normally caused by hydrocortisone, were partially antagonized by the combination of BCS plus fixed Igs. TNF-alpha and GM-CSF were significantly more produced, even in the presence of hydrocortisone, whereas the synthesis of IL-10 was diminished by fixed Igs. However, this effect could be reversed with increasing concentrations of hydrocortisone. These results raise the possibility that in the natural environment, e.g. the rectal mucosa, antigens derived from the BCS are bound by specific Igs, thereby modifying secretory and effector functions of locally present leucocytes in another way as free antigens. The biological relevance of these in vitro data with respect to the therapeutic benefit of the BCS preparations with hydrocortisone will be discussed considering recent findings in the literature.


Assuntos
Anti-Inflamatórios/farmacologia , Citocinas/metabolismo , Escherichia coli/química , Hidrocortisona/farmacologia , Imunoglobulinas/farmacologia , Leucócitos/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Meios de Cultura/química , Ensaio de Imunoadsorção Enzimática , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Humanos , Imunoglobulina G/imunologia , Técnicas In Vitro , Interleucina-10/biossíntese , Leucócitos/metabolismo , Estimulação Química , Fator de Necrose Tumoral alfa/metabolismo
15.
Neuroimmunomodulation ; 9(4): 203-8, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11847482

RESUMO

OBJECTIVE: Recently, therapy with nicotinamide adenine dinucleotide (NADH) revealed positive effects on neurodegenerative disorders associated with inflammation of the CNS, such as Parkinson's disease or Alzheimer's disease. Pathophysiologically, focal CNS inflammation seems to be accompanied by an unbalanced cytokine production, pointing to an involvement of the immune system. Therefore, the aim of our study was to investigate whether NADH could influence cytokine release of peripheral blood leukocytes (PBLs) with special reference to interleukin-6 (IL-6). METHODS: PBLs from 18 healthy donors were incubated in vitro with different concentrations of NADH to generate dose-response curves. As a control, mitogen-treated cells and unstimulated cells were included. RESULTS: In PBLs from the 18 healthy donors, NADH significantly stimulated the dose-dependent release of IL-6, ranging from 6.25 to 400 microg/ml, compared to medium-treated cells (p < 0.001). An amount of 1,000 pg/ml IL-6 was induced by NADH concentrations ranging from 3.1 to >25 microg/ml. CONCLUSIONS: It is concluded that NADH possesses cytokine-modulating effects on peripheral blood cells. The biological relevance of these data is discussed in the context of the recent use of NADH for the treatment of several neurodegenerative disorders.


Assuntos
Interleucina-6/biossíntese , Leucócitos/efeitos dos fármacos , NAD/farmacologia , Adulto , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Interferon gama/farmacologia , Interleucina-6/metabolismo , Interleucinas/farmacologia , Leucócitos/metabolismo , Ativação Linfocitária/efeitos dos fármacos , NAD/administração & dosagem , NAD/uso terapêutico , Estimulação Química , Fator de Necrose Tumoral alfa/farmacologia
16.
Development ; 127(5): 1063-8, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10662645

RESUMO

The coupled regulation of oskar mRNA localization and translation in time and space is critical for correct anteroposterior patterning of the Drosophila embryo. Localization-dependent translation of oskar mRNA, a mechanism whereby oskar RNA localized at the posterior of the oocyte is selectively translated and the unlocalized RNA remains in a translationally repressed state, ensures that Oskar activity is present exclusively at the posterior pole. Genetic experiments indicate that translational repression involves the binding of Bruno protein to multiple sites, the Bruno Response Elements (BRE), in the 3' untranslated region (UTR) of oskar mRNA. We have established a cell-free translation system derived from Drosophila ovaries, which faithfully reproduces critical features of mRNA translation in vivo, namely cap structure and poly(A) tail dependence. We show that this ovary extract, containing endogenous Bruno, is able to recapitulate oskar mRNA regulation in a BRE-dependent way. Thus, the assembly of a ribonucleoprotein (RNP) complex leading to the translationally repressed state occurs in vitro. Moreover, we show that a Drosophila embryo extract lacking Bruno efficiently translates oskar mRNA. Addition of recombinant Bruno to this extract establishes the repressed state in a BRE-dependent manner, providing a direct biochemical demonstration of the critical role of Bruno in oskar mRNA translation. The approach that we describe opens new avenues to investigate translational regulation in Drosophila oogenesis at a biochemical level.


Assuntos
Proteínas de Drosophila , Drosophila/embriologia , Proteínas de Insetos/genética , Oócitos/fisiologia , Ovário/fisiologia , Biossíntese de Proteínas , Proteínas de Ligação a RNA/metabolismo , Animais , Sistema Livre de Células , Feminino , RNA Mensageiro/genética , Proteínas Recombinantes/metabolismo , Transcrição Gênica
17.
EMBO J ; 18(21): 6146-54, 1999 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-10545124

RESUMO

Translational repression of male-specific-lethal 2 (msl-2) mRNA by Sex-lethal (SXL) controls dosage compensation in Drosophila. In vivo regulation involves cooperativity between SXL-binding sites in the 5' and 3' untranslated regions (UTRs). To investigate the mechanism of msl-2 translational control, we have developed a novel cell-free translation system from Drosophila embryos that recapitulates the critical features of mRNA translation in eukaryotes: cap and poly(A) tail dependence. Importantly, tight regulation of msl-2 translation in this system requires cooperation between the SXL-binding sites in both the 5' and 3' UTRs, as seen in vivo. However, in contrast to numerous other developmentally regulated mRNAs, the regulation of msl-2 mRNA occurs by a poly(A) tail-independent mechanism. The approach described here allows mechanistic analysis of translational control in early Drosophila development and has revealed insights into the regulation of dosage compensation by SXL.


Assuntos
Mecanismo Genético de Compensação de Dose , Proteínas de Drosophila , Drosophila/embriologia , Proteínas Nucleares/genética , Biossíntese de Proteínas , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Fatores de Transcrição/genética , Regiões 3' não Traduzidas/genética , Regiões 5' não Traduzidas/genética , Animais , Sítios de Ligação/genética , Proteínas de Ligação a DNA , Regulação da Expressão Gênica , Poli A/genética , Capuzes de RNA/genética
18.
RNA ; 4(2): 142-50, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9570314

RESUMO

Male-specific expression of the protein male-specific-lethal 2 (MSL-2) controls dosage compensation in Drosophila. msl-2 gene expression is inhibited in females by Sex-lethal (SXL), an RNA binding protein known to regulate pre-mRNA splicing. An intron present at the 5' untranslated region (UTR) of msl-2 mRNA contains putative SXL binding sites and is retained in female flies. Here we show that SXL plays a dual role in the inhibition of msl-2 expression. Cotransfection of Drosophila Schneider cells with an SXL expression vector and a reporter containing the 5' UTR of msl-2 mRNA resulted in retention of the 5' UTR intron and efficient accumulation of the unspliced mRNA in the cytoplasm, where its translation was blocked by SXL, but not by the intron per se. Both splicing and translation inhibition by SXL were recapitulated in vitro and found to be dependent upon SXL binding to high-affinity sites within the intron, showing that SXL directly regulates these events. Our data reveal a coordinated mechanism for the regulation of msl-2 expression by the same regulatory factor: SXL enforces intron retention in the nucleus and subsequent translation inhibition in the cytoplasm.


Assuntos
Proteínas de Drosophila , Drosophila melanogaster/genética , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Animais , Sequência de Bases , Sítios de Ligação/genética , DNA/genética , Drosophila melanogaster/metabolismo , Feminino , Expressão Gênica , Genes Reporter , Íntrons , Masculino , Biossíntese de Proteínas , Splicing de RNA/genética , RNA Mensageiro/metabolismo , Diferenciação Sexual/genética
19.
Bioessays ; 19(1): 23-8, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9008414

RESUMO

One distinguishing feature of vertebrate oocyte meiosis is its discontinuity; oocytes are released from their prophase I arrest, usually by hormonal stimulation, only to again halt at metaphase II, where they await fertilization. The product of the c-mos proto-oncogene, Mos, is a key regulator of this maturation process. Mos is a serine-threonine kinase that activates and/or stabilizes maturation-promoting factor (MPF), the master cell cycle switch, through a pathway that involves the mitogen-activated protein kinase (MAPK) cascade. Oocytes arrested at prophase I lack detectable levels of Mos, which must be synthesized from a pool of maternal mRNAs for proper maturation. While Mos is necessary throughout maturation in Xenopus, it seems to be required only for meiosis II in the mouse. The translational activation of c-mos mRNA at specific times during meiosis requires cytoplasmic polyadenylation. Cis- and trans-acting factors for polyadenylation are, therefore, essential elements of maturation.


Assuntos
Meiose/fisiologia , Oócitos/fisiologia , Proteínas Proto-Oncogênicas c-mos/fisiologia , Animais , Sequência de Bases , Proteínas Quinases Dependentes de Cálcio-Calmodulina/fisiologia , Feminino , Mesotelina , Camundongos , Oócitos/citologia , Oócitos/crescimento & desenvolvimento , Oogênese/fisiologia , Biossíntese de Proteínas , Proteínas Proto-Oncogênicas c-mos/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Xenopus
20.
Curr Biol ; 7(11): R705-8, 1997 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-9382788
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