In pancreatic cancer, the incidence and mortality curves coincide. One major reason for this high mortality rate in pancreatic ductal adenocarcinoma (PDAC) patients is the dearth of effective diagnostic, prognostic, and diseasemonitoring biomarkers. Unfortunately, existing tumor markers, as well as current imaging modalities, are not sufficiently sensitive and/or specific for early-stage diagnosis. There is, therefore, an urgent need for improved serum markers of the disease. Herein, we performed Orbitrap® mass spectrometry proteomic analysis of four PDAC tissues and their adjacent benign tissues and identified a total of 2190 nonredundant proteins. Sixteen promising candidates were selected for further scrutiny using a systematic scoring algorithm. Our preliminary serum verification of the top four candidates (DSP, LAMC2, GP73, and DSG2) in 20 patients diagnosed with pancreatic cancer and 20 with benign pancreatic cysts, showed a significant (p < 0.05) elevation of LAMC2 in pancreatic cancer serum. Extensive validation of LAMC2 in healthy, benign, and PDAC sera from geographically diverse cohorts (n ؍ 425) (Japan, Europe, and USA) demonstrated a significant increase in levels in early-stage PDAC compared with benign diseases. The sensitivity of LAMC2 was comparable to CA19.9 in all data sets, with an AUC value greater than 0.85 in discriminating healthy patients from early-stage PDAC patients. LAMC2 exhibited diagnostic complementarity with CA19.9 by showing significant (p < 0.001 in two out of three cohorts) elevation in PDAC patients with clinically low CA19.9 levels. Molecular & Cellular
Cells in which insulin is not required for glucose uptake are susceptible to the long-term complications of diabetes. Even in these tissues, however, the major perturbations that would otherwise be engendered by the greatly increased intracellular glucose concentration are mollified by adaptive changes in the enzymes of intermediary metabolism. These include allosteric regulation, product inhibition, and covalent modification as well as alterations in gene transcription. More recently, advances in proteomic technology have shown that reversible acetylation of the 3-amino group of lysine provides an additional means of modulating protein function and, in particular, enzyme activity. Here, we explored the extent of protein acetylation in an organ susceptible to the long-term complications of diabetes, examining the kidneys of rats with streptozotocininduced diabetes and kidney cells exposed to high glucose. Using high-resolution mass spectrometry coupled with immunoaffinity enrichment, we identified 47 lysineacetylated proteins in the kidneys of diabetic rats compared with 11 in control kidneys. Bioinformatic interrogation of the acetylome from diabetic animals showed a predominance of metabolic pathway involvement including the citrate acid cycle, glycolysis/ gluconeogenesis, and metabolism of branched chain amino acids. Increased lysine acetylation was also noted in mesangial and tubular cells exposed to 25 mmol/L compared with 5.6 mmol/L glucose. These findings highlight acetylation as a posttranslational modification affecting numerous proteins. Current drug discovery efforts to develop small molecule inhibitors and activators of various lysine acetylases and deacetylases offer a new potential strategy to reduce the likelihood of diabetes complications.As a consequence of their direct contact with the external environment, unicellular organisms need to rapidly regulate intermediary metabolism in response to wide fluctuations in ambient nutrient concentration. Complex metazoa, on the other hand, maintain a relatively constant milieu intérieur, despite changes in nutrient availability. This stability is dramatically eroded in diabetes where inappropriate hyperglycemia leads to profoundly disordered intermediary metabolism. In cells that require insulin for glucose uptake, such as the liver, muscle, or adipose tissue, insulin deficiency or resistance leads to a diminution in intracellular glucose that accelerates gluconeogenesis, lipolysis, and ketogenesis. These tissues, pivotal to the development of the acute complications of diabetes, are, however, not subject to the chronic complications of the disease. Instead, it is the cells that continue to transport glucose in the face of hyperglycemia, such as those of the eye, kidney, nervous system, and endothelium, that face long-term damage.Intermediary metabolism, with its central role in providing cells with energy and the building blocks of macromolecules, is regulated at multiple levels. Its enzymes, for instance, may be modulated by allosteric regulation, produ...
Aberrant and dysregulated protein glycosylation is a well-established event in the process of oncogenesis and cancer progression. Years of study on the glycobiology of cancer have been focused on the development of clinically viable diagnostic applications of this knowledge. However, for a number of reasons, there has been only sparse and varied success. The causes of this range from technical to biological issues that arise when studying protein glycosylation and attempting to apply it to practical applications. This review focuses on the pitfalls, advances, and future directions to be taken in the development of clinically applicable quantitative assays using glycan moieties from serum-based proteins as analytes. Topics covered include the development and progress of applications of lectins, mass spectrometry, and other technologies towards this purpose. Slowly but surely, novel applications of established and development of new technologies will eventually provide us with the tools to reach the ultimate goal of quantification of the full scope of heterogeneity associated with the glycosylation of biomarker candidate glycoproteins in a clinically applicable fashion.
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