Incipient angiogenesis in Barrett's epithelium and lymphangiogenesis in Barrett's adenocarcinoma.

PURPOSE: Barrett's esophagus (BE), a precancerous condition for Barrett's adenocarcinoma, is classically characterized by flames of salmon-colored mucosa extending into normal pale esophageal mucosa. This flaming is thought to be a consequence of continuous erosis of mucosa caused by chronic reflux. Another characteristic feature of Barrett's adenocarcinoma patients is the frequent development of lymph node metastases. We addressed whether onset of angiogenesis occurs in BE and if the lymphatic system might provide a route for Barrett's adenocarcinoma cells to infiltrate regular lymph nodes. PATIENTS AND METHODS: Fifteen surgically resected Barrett's dysplasia or adenocarcinoma patients were included. Immunohistochemistry and a modified whole mount analysis were used. RESULTS: The incipient angiogenesis originates from the pre-existing vascular network in the lamina propria and infiltrates Barrett's epithelium, giving its ominous salmon-red color. Barrett's epithelium-specific goblet cells express vascular endothelial growth factor (VEGF)-A. The immature blood vessels show a relative absence of smooth muscle actin (SMA)-positive mural cells and express VEGF receptor (VEGFR)-2 and matrix metalloproteinase (MMP)-9 on their exterior. Coexpression of VEGF-C and its receptor VEGFR-3 on lymphatic vessels is demonstrated. CONCLUSION: BE is strongly neovascularized not eroded. This novel concept of a molecular mechanism of the origin of BE might emphasize why precancerous BE can give rise to the more cancerous dysplasia and Barrett's adenocarcinoma stages. In addition, adenocarcinoma cells induce lymphangiogenesis. The new lymphangiogenic vessels might provide a systemic route for adenocarcinoma cells to invade circulation and induce lymph node metastasis.

Expression of the novel Golgi protein GoPro49 is developmentally regulated during mesenchymal differentiation.

The Golgi complex is the major cell organelle responsible for protein glycosylation and secretion. In this article, we show that GoPro49 is a new gene expressed specifically in mesenchymal and cartilaginous tissues during development. The corresponding human homologue was identified in our previous Golgi proteomics study and was shown to localize to the Golgi complex as an EGFP-fusion protein. Furthermore, we show using in situ hybridization that GoPro49 expression pattern is both restricted and developmentally regulated. It is specific in vertebrae, ribs, and limbs, and in the craniofacial area in nasal septum and dental follicle. In the trunk, GoPro49 expression decreases before final chondrocyte differentiation, while in the craniofacial area expression is still observed in postnatal tissues. This is the first time a Golgi membrane protein is shown to be expressed in a developmentally regulated manner during mesenchymal and cartilage development in mammals.

Identification of new Golgi complex specific proteins by direct organelle proteomic analysis.

The Golgi complex is in the crossroad of the endocytic and secretory pathways. Its function is to post-translationally modify and sort proteins and lipids, and regulate the membrane balance in the cell. To understand the structure-function relationship of the Golgi complex the Golgi proteome has to be identified first. We have used a direct organelle proteomic analysis to identify new Golgi complex proteins. Enriched stacked Golgi membrane fractions from rat livers were isolated, and the proteins from these membranes were subsequently digested into peptides. The peptides were fractionated by cation-exchange chromatography followed by protein identification by automated capillary-LC/ESI-MS/MS analysis and database searches. Two different search programs, ProID and MASCOT were used. This resulted in a total of 1125 protein identifications in two experiments. In addition to the known Golgi resident proteins, a significant number of unknown proteins were identified. Some of these were further characterized in silico using different programs to provide insight into their structure, intracellular localization and biological functions. The Golgi localization of two of these newly identified proteins was also confirmed by indirect immunofluorescence.