The 78 kDa glucose-regulated protein (GRP78) is an endoplasmic reticulum chaperone, whose function is generally thought to be restricted to controlling the structural maturation of nascent glycoproteins. However, GRP78 also is expressed on the cell surface where it functions as a receptor for a wide variety of ligands, behaving as an autoantigen for several classes of autoantibodies. GRP78 is a signaling receptor for activated alpha2-macroglobulin, plasminogen kringle 5, and microplasminogen, and it plays a critical role in viral entry of coxsackie B, and dengue fever viruses. GRP78 is also implicated in the regulation of tissue factor procoagulant activity and functions as a receptor for angiogenic peptides via a mechanism independent of the VEGF receptor. Cell surface GRP78 is found associated with such diverse proteins as the voltage-dependent anion channel (VDAC), the major histocompatibility complex class I (MHC-I), the teratocarcinoma-derived growth factor I (Cripto), and the DnaJ-like protein MTJ-1. These associations suggest a unique GRP78 cell surface topography, which appears to be compartmentalized to respond differently to agonists that bind to its N- or C-terminal domains. Here, we discuss the significance of these associations, and the possible mechanisms involved in the transportation of GRP78 from the cytosol to the cell surface.
The Duke experience with 56 vulvar Paget disease patients was analyzed emphasizing pathologic features and controversial issues. Nearly all patients were Caucasian, and their mean age was 69 years. The average length of follow-up was 5.6 years. For each case, the following histologic features were evaluated and their association with disease course was examined: pseudo-invasion, adnexal involvement, signet-ring cells, cytologic atypia, glands formation, epidermal acantholysis, parakeratosis, hyperkeratosis, and chronic inflammation. The recurrence rate after surgical management was 32%, with epidermal acantholysis being the only statistically significant risk factor. Stromal invasion occurred in 10 patients (18%), and was not a statistically significant adverse prognostic indicator, although the single patient who died of the disease had the deepest stromal invasion. Recurrence was more common after resections with positive surgical margins, but this correlation was not statistically significant. Intraoperative frozen section analysis of the margins did not reduce recurrence rate, nor was it useful in attaining permanent free margins. The Paget cells were consistently reactive with cytokeratin-7 and carcinoembryonic antigen and unreactive with S-100 protein, HMB-45, and Mart-1. In addition, the tumor cells were usually positive for mucin stains. This profile helps distinguish vulvar Paget disease from its mimics, Pagetoid squamous cell carcinoma and malignant melanoma.
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