Membranous Expression (membranous + expression)

Distribution by Scientific Domains


Selected Abstracts


Membranous expression of glucose transporter-1 protein (GLUT-1) in embryonal neoplasms of the central nervous system

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 1 2000
M. Loda
The human erythrocyte GLUT-1 is a transmembrane protein which facilitates transport of glucose in the cell in an energy-independent fashion. Neuroectodermal stem cells show strong membrane immunoreactivitry with this marker at early developmental stages in rodents. Membranous expression by undifferentiated neuroectodermal cells gradually decreases while GLUT-1 becomes confined to the endothelial cells, when these acquire blood,brain barrier function. We thus sought to determine whether GLUT-1 expression was limited to embryonal neoplasms of the central nervous system (CNS) which are presumably derived from developmentally arrested neuroectodermal stem cells. Archival material of 40 primary CNS neoplasms were examined for immunoreactivity with anti-GLUT-1. This included both non-embryonal neoplasms (18 astrocytic tumours, one ependymoma and three oligodendroglioma) and embryonal neoplasms (12 cerebellar medulloblastomas, four supratentorial PNETs and two atypical teratoid/rhabdoid tumours (AT/RhT)). In addition, cell lines and nude mice xenografts derived from both undifferentiated and differentiated tumours were assessed for GLUT-1 immunoreactivity by both immunohistochemistry and Western blotting. All embryonal tumours, MBs and PNET xenografts consistently showed GLUT-1 membrane staining. Non-embryonal neoplasms were negative except for vascular staining. Membrane protein fraction of embryonal tumours cell lines immunoreacted by immunoblot with GLUT-1, whereas the glioblastoma cell line was negative. Expression of GLUT-1 supports the stem cell nature of the cells of origin of MBs, supratentorial PNET and AT/RhTs. As a result, GLUT-1 is a useful marker to define the embryonal nature of CNS neoplasms. [source]


Role of E-cadherins in development of lymphatic tumor emboli

CANCER, Issue 9 2003
Anita Gupta M.D.
Abstract BACKGROUND E-cadherin (E-cad) is a cell adhesion molecule that is expressed in normal breast tissue. While loss of E-cad expression is a characteristic feature of lobular carcinoma, it also is observed in infiltrating ductal carcinoma (IDC). The presence of peritumoral intralymphatic emboli also is a poor prognostic feature in IDC. Invasive lobular carcinoma rarely is associated with intralymphatic emboli. In the current study, the authors assessed E-cad expression in cases of IDC with and without intralymphatic tumor emboli to examine the potential role played by these molecules in the development of lymphatic emboli. METHODS Fifty patients with high-grade invasive ductal carcinoma,25 with prominent lymphatic invasion (LVI) and intralymphatic tumor emboli and 25 without LVI,were tested for expression of E-cad. For both groups, the intensity and frequency of E-cad expression was evaluated in tumor cells and lymphatic emboli; normal lobules were used as internal controls. RESULTS Membranous expression of E-cad was observed in normal lobules and tumor cells in all patients, with the tumor cells exhibiting varying degrees of loss of expression. In the 25 LVI-positive patients, the majority of tumor cells (including intralymphatic emboli) expressed E-cad with an intensity and distribution similar to what was seen in normal lobules. In the LVI-negative patients, the intensity and the distribution of E-cad staining varied significantly. Tumor cells at the tumor-stroma interface showed a greater frequency and intensity of E-cad expression than did cells in the central region of the tumor. CONCLUSIONS Strong expression of E-cad was observed in LVI-positive patients with high-grade IDC but not in LVI-negative patients. Emboli also exhibited high-intensity expression. These findings, taken in conjunction with the knowledge that intralymphatic tumor emboli in lobular carcinoma (which is E-cad-negative) are rare, suggest that E-cad plays an important role in tumor development and growth within the lymphatics. Cancer 2003;97:2341,7. © 2003 American Cancer Society. DOI 10.1002/cncr.11332 [source]


Symplastic glomus tumor , a rare but distinct benign histological variant with analogy to other ,ancient' benign skin neoplasms

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 10 2009
Jivko Kamarashev
A 78-year-old woman presented with a nail deformity of the index finger of the left hand associated with paroxysmal pain upon cold exposure. Histologically, a well-circumscribed tumor of 3 mm diameter was found in the dermis. The neoplastic cells in some areas were of pronouncedly variable size and cytomorphology, mostly epithelioid in shape, with eosinophilic cytoplasm and indistinctly defined cell borders. Pronounced nuclear pleomorphism and atypia were striking features, but no mitotic figures were noted. Multinuclear cells were present as were numerous small-to-medium vessels throughout the tumor. The tumor stroma showed myxoid areas. Immunohistochemistry showed cytoplasmic and membranous expression of smooth muscle actin and vimentin. The histological features and immunoprofile were consistent with the diagnosis of symplastic glomus tumor, a rare histological variant, which has been defined as a glomus tumor exhibiting marked nuclear atypia, in the absence of any other criteria for malignancy. The biological behavior of the tumor is benign. It is essential to differentiate this entity from malignant glomus tumor, which has metastatic potential. Even prominent cellular atypia and nuclear pleomorphism in a glomus tumor as in our case is not a marker of malignancy in the absence of additional criteria. [source]


Immunoreactivity of CD99 in invasive malignant melanoma

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 10 2006
Anne E. Wilkerson
Background:, CD99, also known as p30/32, is a glycoprotein product of the MIC2 gene. It was originally utilized in immunohistochemistry as a unique marker for Ewing sarcoma, other primitive neuroectodermal tumors, and subsequently in other tumors. Its expression in malignant melanoma (MM) has not been well documented, with just two isolated cases of MM recently reported. Recent studies have documented CD99 expression in a significant percentage of atypical fibroxanthomas (AFX), posing potential diagnostic problems in differentiating these two entities. As mistaking MM for AFX based on immunohistochemical staining pattern has significant consequences, we sought to determine the percentage of invasive MM in our archives that have this staining pattern. Methods:, Seventy-eight cases of invasive melanoma were retrieved from our files. Each case was stained with mouse anti-human CD99 and evaluated for membranous expression. Results:, Our evaluation revealed that 47 of 78 MM cases (60%) stain positive for CD99. Conclusion:, This study is the first to demonstrate, in a large series, the prevalence of CD99 expression in primary cutaneous melanoma. Additionally, this introduces in the histologic differential diagnosis of CD99 expressing dermal spindle cell lesions. [source]


Serotonin decreases HIV-1 replication in primary cultures of human macrophages through 5-HT1A receptors

BRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2008
B Manéglier
Background and purpose: 5-HT (serotonin) is known to be involved in neuroinflammation and immunoregulation. The human immunodeficiency virus (HIV) targets cells such as monocytes/macrophages, which colocalize with 5-HT-releasing cell types, mostly platelets. In this study, we investigated the effects of 5-HT on HIV-1-infected macrophages in vitro. Experimental approach: Human macrophages cultured in serum-free medium were treated over 7 days with 5-HT at three concentrations (0.01, 1 and 100 ,M) with or without agonists and antagonists of 5-HT1A and 5-HT2 receptors. After 7 days of treatment, macrophages were infected with HIV-1/Ba-L and virus replication was monitored over 16 days and expression of proviral HIV DNA was investigated by PCR after 24 h of infection. Cell surface expression of HIV-1/Ba-L receptor (CD4) and coreceptor (CCR5) was investigated by flow cytometry. The CCR5 ligand, macrophage inflammatory protein-1, (MIP-1,), was quantified by ELISA in cell culture supernatants and MIP-1, mRNA expression was assessed by reverse transcriptase-PCR. Key results:In vitro, 5-HT downregulated the membranous expression of CCR5 and led to a decrease of HIV-1 infection, probably through its action on 5-HT1A receptors. 5-HT (100 ,M) was also able to induce overexpression of MIP-1, mRNA leading to an increase of MIP-1, secretion by human macrophages. Conclusions and implications: The effects of 5-HT on HIV infection could be a consequence of the increase in MIP-1, concentrations and/or CCR5 receptor downregulation. These results suggest that 5-HT can inhibit the replication of HIV-1 in primary culture of human macrophages through its action on 5-HT1A receptors. [source]