Knott J C, Mahesparan R, Garcia-Cabrera I, Bølge Tysnes B, Edvardsen K, Ness G O, Mørk S, Lund-Johansen M, Bjerkvig R
Department of Anatomy and Cell Biology, University of Bergen, Norway.
Int J Cancer. 1998 Mar 16;75(6):864-72. doi: 10.1002/(sici)1097-0215(19980316)75:6<864::aid-ijc8>3.0.co;2-t.
Malignant gliomas are characterized by an extensive invasion of tumor cells into the normal brain parenchyma. A substantial amount of data indicates that cell movement in general is regulated by specific interactions between extracellular matrix components and specific cell-surface receptors. In the present work, multicellular spheroids from 4 human glioma cell lines (U-373Mg, A-172Mg, U-251Mg and HF-66) were confronted with normal rat brain cell aggregates in vitro, which resulted in a progressive invasion of tumor cells into the brain aggregates. The co-cultures were then sectioned and immuno-stained for specific extracellular matrix components (laminin, fibronectin and collagen type IV) and for specific cell-surface receptors which bind to these components (integrins beta1, beta4, alpha3, alpha6). In addition, flow-cytometric measurements and Northern blot analyses showed expression of several different integrins within the cell lines. The alpha3 subunit was expressed strongly in all cell lines. Whereas the beta1 subunit was expressed weakly in exponentially growing monolayer cultures, it showed a pronounced expression in multicellular spheroids, indicating that the integrin expression may vary depending on the micro-environment within a tumor. Furthermore, normal brain tissue was able to produce laminin when confronted with the glioma cells, which also was observed for fibronectin and collagen type IV. The relevance of our observations to the in vivo situation was investigated further by immuno-staining 5 human glioma biopsy samples for laminin. In some areas of the tumors, specific deposits of laminin were observed. In conclusion, we have shown that normal brain tissue has the ability to produce extracellular matrix components, such as laminin, collagen type IV and fibronectin, when confronted with invading glioma cells. Our results show that the glioma cells express specific integrins which can interact with these extracellular matrix components. Such interactions may facilitate tumor cell migration and invasion.
恶性胶质瘤的特征是肿瘤细胞广泛侵入正常脑实质。大量数据表明，一般来说，细胞运动受细胞外基质成分与特定细胞表面受体之间的特定相互作用调控。在本研究中，将来自4种人类胶质瘤细胞系（U-373Mg、A-172Mg、U-251Mg和HF-66）的多细胞球体与正常大鼠脑细胞聚集体在体外进行接触，结果导致肿瘤细胞逐渐侵入脑聚集体。然后将共培养物切片，并针对特定的细胞外基质成分（层粘连蛋白、纤连蛋白和IV型胶原）以及与这些成分结合的特定细胞表面受体（整合素β1、β4、α3、α6）进行免疫染色。此外，流式细胞术测量和Northern印迹分析显示细胞系内几种不同整合素的表达。α3亚基在所有细胞系中均强烈表达。虽然β1亚基在指数生长的单层培养物中表达较弱，但在多细胞球体中显示出明显的表达，表明整合素的表达可能因肿瘤内的微环境而异。此外，正常脑组织在与胶质瘤细胞接触时能够产生层粘连蛋白，纤连蛋白和IV型胶原也观察到这种情况。通过对5例人类胶质瘤活检样本进行层粘连蛋白免疫染色，进一步研究了我们的观察结果与体内情况的相关性。在肿瘤的一些区域观察到层粘连蛋白的特异性沉积。总之，我们已经表明，正常脑组织在面对侵袭性胶质瘤细胞时具有产生细胞外基质成分（如层粘连蛋白、IV型胶原和纤连蛋白）的能力。我们的结果表明，胶质瘤细胞表达特定的整合素，这些整合素可以与这些细胞外基质成分相互作用。这种相互作用可能促进肿瘤细胞的迁移和侵袭。
