Clinical Implications of Molecular Heterogeneity of Gastric Cancer

Gastric cancer incidence has been steadily declining in countries with low frequencies of gastric carcinoma since early 1930s. In areas with higher incidences, the decline has been less obvious and slower. Nevertheless, gastric adenocarcinoma remains one of the most common causes of cancer‐related death worldwide. The poor outcome has been attributed to late detection of the condition, particularly in Americas and Europe, aggressive pathogenesis and lack of symptoms during early stages of the tumor development. In addition, sporadic stomach cancer mostly affects elderly individuals. In the majority of countries with low incidence, the average age at the disease presentation is above 65. Therefore, gastric adenocarcinoma, among other diseases associated with old age, raises health concerns in countries with changing demographic age profiles that show a trend of an increase in the proportion of the population aged over 60. The low 5‐year survival rate of patients underscores the critical need for the development of more accurate diagnostic tools and safe targeted chemotherapeutics. However, the heterogeneity of molecular changes represents one of the most pressing issues in the current research of gastric cancer, impeding the translation of genetic aberrations into novel applications for medical practice

Active Protein Aggregates Produced in Escherichia coli

Since recombinant proteins are widely used in industry and in research, the need for their low-cost production is increasing. Escherichia coli is one of the best known and most often used host organisms for economical protein production. However, upon over-expression, protein aggregates called inclusion bodies (IBs) are often formed. Until recently IBs formation represented a bottleneck in protein production as they were considered as deposits of inactive proteins. However, recent studies show that by choosing the appropriate host strain and designing an optimal production process, IBs composed from properly folded and biologically active recombinant proteins can be prepared. Such active protein particles can be further used for the isolation of pure proteins or as whole active protein particles in various biomedical and other applications. Therefore interest in understanding the mechanisms of their formation as well as their properties is increasing

Engineering inclusion bodies for non denaturing extraction of functional proteins

<p>Abstract</p> <p>Background</p> <p>For a long time IBs were considered to be inactive deposits of accumulated target proteins. In our previous studies, we discovered IBs containing a high percentage of correctly folded protein that can be extracted under non-denaturing conditions in biologically active form without applying any renaturation steps. In order to widen the concept of correctly folded protein inside IBs, G-CSF (granulocyte colony stimulating factor) and three additional proteins were chosen for this study: GFP (Green fluorescent protein), His7dN6TNF-α (Truncated form of Tumor necrosis factor α with an N-terminal histidine tag) and dN19 LT-α (Truncated form of Lymphotoxin α).</p> <p>Results</p> <p>Four structurally different proteins that accumulate in the bacterial cell in the form of IBs were studied, revealing that distribution of each target protein between the soluble fraction (cytoplasm) and insoluble fraction (IBs) depends on the nature of the target protein.</p> <p>Irrespective of the folding pattern of each protein, spectroscopy studies have shown that proteins in IBs exhibit similar structural characteristics to the biologically active pure protein when produced at low temperature. In the case of the three studied proteins, G-CSF, His7ΔN6TNF-α, and GFP, a significant amount of protein could be extracted from IBs with 0.2% N-lauroyl sarcosine (NLS) and the proteins retained biological activity although no renaturation procedure was applied.</p> <p>Conclusion</p> <p>This study shows that the presence of biologically active proteins inside IBs is more general than usually believed. A large amount of properly folded protein is trapped inside IBs prepared at lower temperatures. This protein can be released from IBs with mild detergents under non-denaturing conditions. Therefore, the active protein can be obtained from such IBs without any renaturation procedure. This is of great importance for the biopharmaceutical industry. Furthermore, such IBs composed of active proteins could also be used as pure nanoparticles in diagnostics, as biocatalysts in enzymatic processes, or even as biopharmaceuticals.</p

Proteomic Approaches in Biomarker Discovery: New Perspectives in Cancer Diagnostics

Despite remarkable progress in proteomic methods, including improved detection limits and sensitivity, these methods have not yet been established in routine clinical practice. The main limitations, which prevent their integration into clinics, are high cost of equipment, the need for highly trained personnel, and last, but not least, the establishment of reliable and accurate protein biomarkers or panels of protein biomarkers for detection of neoplasms. Furthermore, the complexity and heterogeneity of most solid tumours present obstacles in the discovery of specific protein signatures, which could be used for early detection of cancers, for prediction of disease outcome, and for determining the response to specific therapies. However, cancer proteome, as the end-point of pathological processes that underlie cancer development and progression, could represent an important source for the discovery of new biomarkers and molecular targets for tailored therapies

In vivo and in vitro Cleavage of Glucoamylase-TNFα Fusion Protein Secreted from Aspergillus niger

The most common expression strategy for secreting heterologous proteins from filamentous fungus Aspergillus niger is based on fusion with glucoamylase gene which contains cleavage site for kexin protease (KEX2). However, secretion of recombinant proteins in the form of a fusion-protein without a host-specific cleavage site is usually higher than secretion of the mature protein obtained after in vivo cleavage. We tried to take advantage of such a higher production by cleaving the fusion protein in vitro after fermentation, instead of in vivo during secretion. Similar level of production as after in vivo cleavage was found when human tumor necrosis factor α (TNFα) was produced as a fusion protein with glucoamylase having the enterokinase cleavage site. In addition to the correctly processed TNFα, some non-specific cleavage was observed, which resulted in a shortened N-terminus. This was still better than in vivo cleavage where only truncated forms of TNFα were obtained. Although the fusion protein was cleaved by enterokinase directly in the medium before purification, this shorter N-terminus was probably a consequence of aberrant enterokinase cleavage. Isolation of fusion protein with His-tag by affinity chromatography with immobilized metal chelate (although normally fast and easy) was not possible because the sequence of five consecutive histidines attached to the N-terminus of the glucoamylase fusion partner was completely cleaved off by proteolysis