Background: Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier breakdown. In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state.

Purpose: Plasmalemmal vesicle associated protein-1 (PV-1) is up-regulated in the endothelium of human glioblastoma. We sought to further characterize the expression pattern of PV-1 in human brain tumors and interrogate its role in brain tumor angiogenesis. Experimental Design: Quantitative reverse transcription-PCR and in situ hybridization were used to measure PV-1 expression in a panel of 46 human brain tumors and related pathologic states. Matrigel tubulogenesis assays and cell migration assays were used to show function of PV-1 in primary human endothelial cells (HMVEC) under gene knockdown conditions. Results: PV-1is selectively up-regulated in a variety of high-grade human brain tumors, including glioblastoma and metastatic carcinoma, as well as other cerebral disorders associated with bloodbrain barrier disruption, such as acute ischemia. Expression levels were reduced in low-grade neoplasia; however, tumors associated with the ependyma and choroid plexus, known sites of PV-1 expression, also exhibited robust expression. Cerebral expression of PV-1 mRNA was confined to endothelial cells in all cases. PV-1 expression was induced in HMVEC cells in vitro by exposure to medium conditioned by U87MG and U251MG human brain tumor cell lines and by medium supplemented with exogenous vascular endothelial growth factor or scatter factor/hepatocyte growth factor. RNA interference^mediated inhibition of PV-1 induction in HMVEC cells blocked Matrigel-induced tubulogenesis and inhibited cell migration induced by conditioned medium or angiogenic growth factors. Conclusions: Our results confirm that PV-1 is preferentially induced in the endothelium of highgrade human brain tumors. Inhibition of PV-1 expression is associated with failure of endothelial differentiation in vitro. PV-1 represents a novel marker of brain tumor angiogenesis and integrity of the blood-brain barrier and is a potential therapeutic target.

FIBS is a rare myofibroblastic lesion with an immunohistochemical profile distinct from other epithelial and stromal neoplasms of the extrahepatic bile duct. A subset of these cases appear to represent IgG4-related sclerosing cholangitis. Because preoperative cytology is not diagnostic of FIBS, surgical resection remains the mainstay of diagnosis and treatment, while immunosuppression may reduce the risk of recurrence.