RESUMO
Prognostic and predictive factors are indispensable tools in the treatment of patients with neoplastic disease. For the most part, such factors rely on a few specific cell surface, histological, or gross pathologic features. Gene expression assays have the potential to supplement what were previously a few distinct features with many thousands of features. We have developed Bayesian regression models that provide predictive capability based on gene expression data derived from DNA microarray analysis of a series of primary breast cancer samples. These patterns have the capacity to discriminate breast tumors on the basis of estrogen receptor status and also on the categorized lymph node status. Importantly, we assess the utility and validity of such models in predicting the status of tumors in crossvalidation determinations. The practical value of such approaches relies on the ability not only to assess relative probabilities of clinical outcomes for future samples but also to provide an honest assessment of the uncertainties associated with such predictive classifications on the basis of the selection of gene subsets for each validation analysis. This latter point is of critical importance in the ability to apply these methodologies to clinical assessment of tumor phenotype.
Assuntos
Neoplasias da Mama/genética , Bacillus anthracis , Neoplasias da Mama/enzimologia , Neoplasias da Mama/patologia , Neoplasias da Mama/cirurgia , Enzimas/genética , Feminino , Humanos , Excisão de Linfonodo , Linfonodos/patologia , Família Multigênica , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Valor Preditivo dos Testes , Probabilidade , Receptores de Estrogênio/análise , Reprodutibilidade dos TestesRESUMO
We have used high-density DNA microarrays to provide an analysis of gene regulation during the mammalian cell cycle and the role of E2F in this process. Cell cycle analysis was facilitated by a combined examination of gene control in serum-stimulated fibroblasts and cells synchronized at G(1)/S by hydroxyurea block that were then released to proceed through the cell cycle. The latter approach (G(1)/S synchronization) is critical for rigorously maintaining cell synchrony for unambiguous analysis of gene regulation in later stages of the cell cycle. Analysis of these samples identified seven distinct clusters of genes that exhibit unique patterns of expression. Genes tend to cluster within these groups based on common function and the time during the cell cycle that the activity is required. Placed in this context, the analysis of genes induced by E2F proteins identified genes or expressed sequence tags not previously described as regulated by E2F proteins; surprisingly, many of these encode proteins known to function during mitosis. A comparison of the E2F-induced genes with the patterns of cell growth-regulated gene expression revealed that virtually all of the E2F-induced genes are found in only two of the cell cycle clusters; one group was regulated at G(1)/S, and the second group, which included the mitotic activities, was regulated at G(2). The activation of the G(2) genes suggests a broader role for E2F in the control of both DNA replication and mitotic activities.
Assuntos
Proteínas de Transporte , Proteínas de Ciclo Celular , Replicação do DNA , Proteínas de Ligação a DNA , Perfilação da Expressão Gênica , Mitose/fisiologia , Fatores de Transcrição/fisiologia , Animais , Ciclo Celular , Linhagem Celular , Fatores de Transcrição E2F , Camundongos , Análise de Sequência com Séries de Oligonucleotídeos , Proteína 1 de Ligação ao Retinoblastoma , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The large ribosomal subunit of the thermophilic fungus Thermomyces lanuginosus was reconstructed in three dimensions from electron micrographs. This is the first reported reconstruction of the eukaryotic complex and demonstrates specific structural features such as an intersubunit canyon and a potential channel for the nascent peptide chain.
Assuntos
Fungos Mitospóricos/ultraestrutura , Ribossomos/ultraestrutura , Algoritmos , Temperatura Alta , Microscopia Eletrônica/métodos , Modelos EstruturaisRESUMO
The large ribosomal subunit of the thermophilic fungus Thermomyces lanuginosus was treated with 2.96 M NH4Cl to remove specific complements of ribosomal proteins, and the core particles thereby derived were imaged by bright field transmission electron microscopy, and recurring views computed by single particle electron image analysis. A new characteristic projection was elucidated which showed a large depression or channel passing through the subunit. Such a channel has been perceived in the prokaryotic large ribosomal subunit under certain conditions and has been postulated to be the exit pathway for the nascent polypeptide chain, but its existence has not hitherto been demonstrated in eukaryotes.
