PubMed · 11987616
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P P Liberski, T Fiks. 2001. [Embryonal astroblastoma].. https://pubmed.ncbi.nlm.nih.gov/11987616/
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Cadherins are key Ca(2+)-dependent cell-cell adhesion molecules at adherens junctions (AJs) in fibroblasts and epithelial cells, whereas claudins are key Ca(2+)-independent cell-cell adhesion molecules at tight junctions (TJs) in epithelial cells. The formation and maintenance of TJs are dependent on the formation and maintenance of AJs. Nectins are Ca(2+)-independent immunoglobulin-like cell-cell adhesion molecules which comprise a family of four members, nectin-1, -2, -3, and -4, and are involved in the formation of AJs in cooperation with cadherins, and the subsequent formation of TJs. We show here that the velocity of the formation of the E-cadherin-based AJs is increased by overexpression of nectin-1 and is reduced by addition of the nectin-1 inhibitors to the medium in L cells stably expressing E-cadherin and Madin-Darby canine kidney cells. Moreover, the velocity of the formation of the claudin-based TJs is increased by overexpression of nectin-1 and is reduced by addition of the nectin-1 inhibitors to the medium in Madin-Darby canine kidney cells. These results indicate that nectins regulate the velocity of the formation of the E-cadherin-based AJs and the subsequent formation of the claudin-based TJs.
A chordoid glioma in the third ventricle was studied immunohistochemically and ultrastructurally. In this report, special attention is paid to the histogenesis in relation to the pathological appearance and unique anatomic location of this tumor. Light microscopic and immunohistochemical findings were similar to those reported previously. Ultrastructurally, microvilli were frequently seen, but three types of abnormal cilia were rarely observed. Basement membrane around the tumor cells and microvessels was extensive. Poorly to moderately developed intermediate (adherent) junctions were frequently seen. Resemblance of these ultrastructural features of the tumor to embryonic tanycytes suggests the tanycytic differentiation of chordoid glioma. Neuroradiologically, all of the previously reported cases of chordoid gliomas seem to arise in the anterior part of the third ventricular floor. This region includes the lamina terminalis, infundibular recess and median eminence, which corresponds to a tanycyte-rich area. These findings suggest a tanycytic origin of chordoid glioma.
Cells are held together either by direct cell-cell contact or adhesion to extra-cellular matrix. Cell-cell adhesion in epithelial cell sheets consists of junctions, i.e. tight-, adherens- and gap-junctions. The adherens junctions, which are build up by the cadherin/catenin complex, are the main topic of this review, especially the aspect of its role in ovarian tumor biology. The ovarian surface epithelium is the origin for approximately 90% of the malignant ovarian tumors. The tumors arise from the inclusion cysts, localized in the ovarian stroma and grow solid, cystic or in mixed formations. Intra-abdominal spread of the ovarian cancer is common and this is a process that theoretically could be closely connected with impaired cell-cell adhesion. However, as we stand today, descriptive and functional studies on the cadherin-catenin complex and its cell signaling role in ovarian tumorigenesis reveals data that suggests a conversion of the mesothelial-like cells of the ovarian surface to a more epithelial phenotype with normal cell-cell adhesion prior to tumor differentiation. In later stages, invasive ovarian tumors still strongly express several cadherins, which are contrary to many other tumors, i.e. prostate and thyroid adenocarcinomas.