Purpose: Ewing sarcoma is a tumor of the bone and soft tissue characterized by diffuse cell membrane expression of CD99 (MIC2). Single-site, surgically resectable disease is associated with an excellent 5-year event-free survival; conversely, patientswith distantmetastases have a poor prognosis.Noninvasive imaging is the standard approach to identifying sites of metastatic disease. We sought to...

Purpose: Ewing sarcoma is a tumor of the bone and soft tissue characterized by diffuse cell membrane expression of CD99 (MIC2). Single-site, surgically resectable disease is associated with an excellent 5-year event-free survival; conversely, patientswith distantmetastases have a poor prognosis.Noninvasive imaging is the standard approach to identifying sites of metastatic disease. We sought to...

Human CD99 is a small highly O-glycosylated cell-surface protein expressed on most leukocytes. It was recently found to be expressed at endothelial cell contacts and to participate in the transendothelial migration (TEM) of monocytes in vitro. In order to analyze the physiologic relevance of CD99 in vivo we searched for the mouse homolog. We cloned a mouse cDNA coding for a protein 45% identica...

Ewing sarcoma (EWS) is an aggressive bone tumor of uncertain cellular origin. CD99 is a membrane protein that is expressed in most cases of EWS, although its function in the disease is unknown. Here we have shown that endogenous CD99 expression modulates EWS tumor differentiation and malignancy. We determined that knocking down CD99 expression in human EWS cell lines reduced their ability to fo...

We have assessed the functional effect of CD99 engagement on resting human peripheral blood (PB) T cells. CD99, as detected by the mAb 3B2/TA8, is constitutively expressed on all PB T cells and becomes further up-regulated upon cellular activation. In this study we demonstrate that cross-linking of the CD99 molecule with the agonistic mAb 3B2/TA8 cooperates with suboptimal TCR/CD3 signals, but ...

To verify the spectrum of CD99-expressing lymphoid malignancy, an immunohistochemical study for CD99 was carried out in 182 cases of non-Hodgkin's lymphoma, including 21 lymphoblastic lymphomas, 11 small lymphocytic lymphomas, 9 mantle cell lymphomas, 12 follicular lymphomas, 37 diffuse large B cell lymphomas, 18 Burkitt's lymphomas, 28 NK/T-cell lymphomas, 8 angioimmunoblastic T-cell lymphomas...

CD99 is characteristically expressed in Ewing's sarcoma/primitive neuroectodermal tumor. Recently its immunoreactivity has also been reported in other tumors. However, the significance of CD99 isoforms expressed in these tumors has not been elucidated. In this study, we evaluated the expression of CD99 isoforms and its relationship with histopathologic parameters in gastric adenocarcinomas. Par...

CD99 is a critical regulator of leukocyte transendothelial migration (TEM). How CD99 signals during this process remains unknown. We show that during TEM, endothelial cell (EC) CD99 activates protein kinase A (PKA) via a signaling complex formed with the lysine-rich juxtamembrane cytoplasmic tail of CD99, the A-kinase anchoring protein ezrin, and soluble adenylyl cyclase (sAC). PKA then stimula...

We investigated the expression of CD99 in 35 hyperplastic perigastric lymph nodes, which were resected for gastric carcinoma or chronic peptic ulcer. Essentially, all lymphocytes in lymph nodes expressed CD99, but there were two populations with respect to the intensity of CD99 expression--CD99high and CD99low cells. We showed CD99high cells were distributed in paracortical and medullary cords ...

CD99 is a cell surface molecule that has emerged as a novel target for Ewing sarcoma (EWS), an aggressive pediatric bone cancer. This report provides the first evidence of methuosis in EWS, a non-apoptotic form of cell death induced by an antibody directed against the CD99 molecule. Upon mAb triggering, CD99 induces an IGF-1R/RAS/Rac1 complex, which is internalized into RAB5-positive endocytic ...