Memorial Sloan Kettering Cancer Center

About: Memorial Sloan Kettering Cancer Center is a healthcare organization based out in New York, New York, United States. It is known for research contribution in the topics: Cancer & Population. The organization has 30293 authors who have published 65381 publications receiving 4462534 citations. The organization is also known as: MSKCC & New York Cancer Hospital.

Stat proteins and oncogenesis.

Abstract: The discovery of Stat proteins’ key role in IFN signaling, initially described over ten years ago, provided the first molecular link of growth factor receptor stimulation to the direct activation of a transcription factor (1). Since that time a large number of growth factor receptors and some nonreceptor tyrosine kinases have been found to lead to the activation of these transcription factors (2). The contributions of individual Stat proteins to normal cytokine signaling and development have been studied in various cell culture systems and in vivo in mice made deficient for one or more of these proteins (3). This approach has identified some related roles, as well as many unique, nonoverlapping physiological roles, for the various members of the Stat family. In summary, Stat1-deficient mice are unable to respond to IFNs and are subsequently susceptible to bacterial and viral pathogens. Likewise, disruption of Stat2 gives rise to animals unable to respond to type 1 IFNs, with increased susceptibility to viral infections (see Candotti et al., this Perspective series, ref. 4). Stat4- and Stat6-deficient animals reveal a requirement for IL-12– or IL-4–mediated proliferation of T cells, respectively (see Decker et al., this series, ref. 5). The phenotypes of Stat5A and Stat5B individual knockouts reveal the importance of Stat5A in breast development and lactation and the importance of Stat5B in the development of sexually dimorphic patterns of gene expression within the liver. In addition to these phenotypes, Stat5A/5B double knockouts are abnormal in their T cell and B cell development. Because Stat3-deficient animals die early in embryogenesis, the role of this protein in a number of biological functions had to be determined in conditional knockouts. As discussed by Levy and Lee in this series (6), Stat3 is implicated in keratinocyte migration, T cell apoptosis, IL-10–mediated signaling in macrophages, and the induction of apoptosis in the involuting breast. Beyond these various roles in normal cellular and physiological processes, the Stat proteins are now known to participate in cellular transformation and oncogenesis. Here, I consider the evidence implicating these molecules, particularly Stats 1, 3, and 5, in tumor formation and progression.

Immobilized Gallium(III) Affinity Chromatography of Phosphopeptides

Abstract: A novel procedure for micropurification of phosphorylated peptides, as a front end to mass spectrometric analysis, is described. As a result of a systematic study, we propose the use of an immobilized metal affinity chromatography (IMAC) in a microtip (Erdjument-Bromage, H.; et al. J. Chromatogr., A 1998, 826, 167−181) format, more specifically in combination with Ga(III) ions. Manual Ga(III) IMAC is easy to perform; phosphopeptides are retrieved in a near-quantitative and highly selective manner, to yield a concentrated sample for direct analysis by matrix-assisted laser desorption/ionization time-of-flight and nanoelectrospray ionization mass spectrometry. Ga(III) ions offer distinct advantages over the use of other metals, such as Fe(III) and Al(III), in terms of both selectivity and versatility, including facile base elution. Selectivity is best illustrated by effective enrichment of phosphopeptides that were present in a molar ratio of ∼2% on a background of unphosphorylated protein, a situation very...

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds.

Abstract: Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds. BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds, and then identified four years later by a positional cloning strategy. BRCA2 was mapped to chromosomal 13q at about the same time. Just fifteen months later, Wooster et al. reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DMA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

Quantitative flux analysis reveals folate-dependent NADPH production

Abstract: ATP is the dominant energy source in animals for mechanical and electrical work (for example, muscle contraction or neuronal firing). For chemical work, there is an equally important role for NADPH, which powers redox defence and reductive biosynthesis1. The most direct route to produce NADPH from glucose is the oxidative pentose phosphate pathway, with malic enzyme sometimes also important2, 3. Although the relative contribution of glycolysis and oxidative phosphorylation to ATP production has been extensively analysed, similar analysis of NADPH metabolism has been lacking. Here we demonstrate the ability to directly track, by liquid chromatography–mass spectrometry, the passage of deuterium from labelled substrates into NADPH, and combine this approach with carbon labelling and mathematical modelling to measure NADPH fluxes. In proliferating cells, the largest contributor to cytosolic NADPH is the oxidative pentose phosphate pathway. Surprisingly, a nearly comparable contribution comes from serine-driven one-carbon metabolism, in which oxidation of methylene tetrahydrofolate to 10-formyl-tetrahydrofolate is coupled to reduction of NADP+ to NADPH. Moreover, tracing of mitochondrial one-carbon metabolism revealed complete oxidation of 10-formyl-tetrahydrofolate to make NADPH. As folate metabolism has not previously been considered an NADPH producer, confirmation of its functional significance was undertaken through knockdown of methylenetetrahydrofolate dehydrogenase (MTHFD) genes. Depletion of either the cytosolic or mitochondrial MTHFD isozyme resulted in decreased cellular NADPH/NADP+ and reduced/oxidized glutathione ratios (GSH/GSSG) and increased cell sensitivity to oxidative stress. Thus, although the importance of folate metabolism for proliferating cells has been long recognized and attributed to its function of producing one-carbon units for nucleic acid synthesis, another crucial function of this pathway is generating reducing power.