Expression proteomic studies

A number of transgenic plants have been submitted to proteome analysis. For instance, in rice, Wang et al. (74) used classical two-dimensional electrophoresis and mass spectrometry to evidence that more than 50 proteins were differently expressed. Proteomics studies have been performed also in transgenic tomato (75), potato (76), and wheat (77) again by using standard analytical methods. 

Over recent years, oncology has been a key focus of proteomic technologies as applied in both expression and functional studies. Expression proteomic studies are screening for differences in protein patterns between tumor and control tissues. Functional proteomic studies are defined as the combination of readouts with proteomics data from the same sample at different points of time (under different conditions), with the aim of detecting and prioritizing certain proteins or polypeptides of functional relevance. 

As of today, expression proteomic studies are available for all common human cancers and some rare tumors. 

Many diseases are characterized by the expression of specific proteins1 in some cases, malignant cells yield unique protein profiles when total cellular protein extracts are analyzed by proteomic methods such as two-dimensional gel electrophoresis or matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS).2 High-throughput proteomic studies may be useful to differentiate normal cells from cancer cells, to identify and define the use of biomarkers for specific cancers, and to characterize the clinical course of disease. Proteomics can also be used to isolate and characterize potential drug targets and to evaluate the efficacy of treatments. 

A number of proteomic studies on archival material have utilized Liquid Tissue (Expression Pathology, Inc., Gaithersburg, MD), a commercial protein extraction kit for FFPE tissue.4,9,25-28 This kit is also based upon HIAR techniques and shares a similar work flow to the methods already discussed. Thin, typically 5-10pM, sections are cut from paraffin tissue blocks, the paraffin is removed, and the tissue deparaffinized and rehydrated in alcohols and distilled water before microdissection. The cellular material is then suspended in Liquid Tissue buffer and heated at 95°C for 90 min. Trypsin is added, and the material is digested overnight at 37°C prior to reduction with DTT and analysis by LC-MS/MS.26... 

Computational methods have been applied to determine the connections in systems that are not well-defined by canonical pathways. This is either done by semi-automated and/or curated literature causal modeling [1] or by statistical methods based on large-scale data from expression or proteomic studies (a mostly theoretical approach is given by reference [2] and a more applied approach is in reference [3]). Many methods, including clustering, Bayesian analysis and principal component analysis have been used to find relationships and "fingerprints" in gene expression data [4]. 

The application of the improved MS techniques presented above with highly resolving separation methods, such as 2-D electrophoresis, capillary HPLC, and CE, resulted in the creation of a new science, proteomics63 While genomics, described by DNA databases, represents the ground stage of the cell, the study of the differential status of the cell, due to various stimuli or disease states, reflects the functional expression of protein products or proteomics. Proteomics studies are aimed at identifying the proteome, the network of proteins that define the... 

The term proteome means the total protein complement of a genome, and pro-teomics means the analysis for proteome. The combination of two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) is a proteomic method of high-throughput analysis of protein expression. By using this 2-DE and MS, proteomic studies have identified many proteins that may be involved in the pathogenic mechanism of cancers. These studies analyzed cancer cell lines, as well as cancer tissues or serum from patients. 

Many proteomic studies have identified diverse proteins that may be involved in the pathogenic mechanism of disease and which may be disease markers. Most of the applications use expression proteomics to determine expression profiles of proteins in cells and tissues in normal or disease states. In the present study, we analyzed protein expression in cancer tissue samples and corresponding non-cancerous tissue samples to find proteins that might be involved in carcinogenesis or pathogenesis. 

It is within the context of finding products that have an effect on human health that a study has been published regarding the gene expression of prostate cancer cells treated with pomegranate fruit juice (70) where a comparative proteomics study provided insights for prostate cancer evolution. The involvement of pomegranate fruit products in the molecular mechanism of inducing prostate cancer cell apoptosis has been evidenced. Thus, a possible... 

In contrast, Functional Proteomics concerns the manner in which proteins interact and, in turn, how these interactions determine function, both normal and abnormal. This approach is less reductionist than Expression Proteomics as proteins are studied in the context of their complex cellular interactions. Finally, Structural Proteomics is concerned with the primary through tertiary structure of proteins, and modifications therein, largely determined by x-ray and NMR analysis of protein crystals (20). In this chapter we will concern ourselves only with Expression and Functional Proteomics. 

As mentioned earlier, Functional Proteomics is concern with the manner in which proteins interact and, in turn, how these interactions ultimately determine function and dysfunction. This approach is less reductionist than Expression Proteomics because proteins are studied in the context of their complex cellular interactions. 

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