Zhang K, Kim J P, Woodley D T, Waleh N S, Chen Y Q, Kramer R H
Department of Anatomy, University of California, San Francisco 94143, USA.
Cell Adhes Commun. 1996 Sep;4(3):159-74. doi: 10.3109/15419069609014220.
Squamous cell carcinoma of the oral cavity spreads by initial invasion of the laminin-rich basement membrane. We examined the adhesion and motility of human oral SCC cells and normal mucosal keratinocytes and found that the SCC cells readily attached and migrated on laminin 1 substrates but migrated poorly on collagen type I and fibronectin. The normal keratinocytes, however, adhered poorly to and were non-motile on laminin 1 yet readily and preferentially attached and migrated on fibronectin and collagen type I. Analysis with blocking anti-integrin antibodies showed that the SCC cells used the alpha 6 beta 1 complex to attach and migrate on laminin 1 and that this activity was confined to the E8 long arm fragment of laminin. Affinity chromatography on laminin-Sepharose columns revealed that the SCC cells, but not normal keratinocytes, expressed high levels of the alpha 6 beta 1 laminin 1 receptor. Metabolic pulse-chase analysis indicated that in contrast to the SCC cells, keratinocytes did not have a stable pool of beta 1 subunit precursor. Preferential pairing of alpha 6 with beta 4 and the deficiency in pre-beta 1 levels appear to account for the failure of keratinocytes to form significant alpha 6 beta 1 complex. Additionally, the presence of laminin 1 in co-coating experiments blocked keratinocyte adhesion to other immobilized ligands, such as collagen type I or fibronectin. This anti-adhesive effect seemed to reflect a general paralysis of cell adhesive function, since laminin 1 also diminished the adhesion of keratinocytes to substrates coated with immobilized anti-integrin subunit antibody. The inhibitory activity of laminin 1 resided in the E1' and E8 fragments, and not in the E3, E4 or G domains. Collectively, our results indicate that laminin 1 is a restrictive ligand for normal keratinocytes, apparently because of their failure to assemble and express the alpha 6 beta 1 complex or other functional laminin receptors and their sensitivity to the anti-adhesive activity of laminin itself. The elevated expression of alpha 6 beta 1 following malignant conversion of muscosal keratinocytes promotes their migration on laminin, a process important during invasion and metastasis.
口腔鳞状细胞癌通过最初侵袭富含层粘连蛋白的基底膜而扩散。我们检测了人口腔鳞状细胞癌细胞和正常黏膜角质形成细胞的黏附及运动能力，发现鳞状细胞癌细胞很容易在层粘连蛋白1底物上附着并迁移，但在I型胶原和纤连蛋白上迁移能力较差。然而，正常角质形成细胞在层粘连蛋白1上黏附性差且无运动能力，但在纤连蛋白和I型胶原上能快速且优先地附着并迁移。用阻断性抗整合素抗体进行分析表明，鳞状细胞癌细胞利用α6β1复合物在层粘连蛋白1上附着并迁移，且这种活性局限于层粘连蛋白的E8长臂片段。在层粘连蛋白-琼脂糖柱上进行亲和层析显示，鳞状细胞癌细胞而非正常角质形成细胞表达高水平的α6β1层粘连蛋白1受体。代谢脉冲追踪分析表明，与鳞状细胞癌细胞不同，角质形成细胞没有稳定的β1亚基前体池。α6与β4的优先配对以及前β1水平的缺乏似乎是角质形成细胞无法形成大量α6β1复合物的原因。此外，在共包被实验中层粘连蛋白1的存在会阻断角质形成细胞与其他固定化配体（如I型胶原或纤连蛋白）的黏附。这种抗黏附作用似乎反映了细胞黏附功能的普遍麻痹，因为层粘连蛋白1也会降低角质形成细胞与包被有固定化抗整合素亚基抗体的底物的黏附。层粘连蛋白1的抑制活性存在于E1'和E8片段中，而不存在于E3、E4或G结构域中。总体而言，我们的结果表明层粘连蛋白1对正常角质形成细胞是一种限制性配体，显然是因为它们无法组装并表达α6β1复合物或其他功能性层粘连蛋白受体，以及它们对层粘连蛋白自身抗黏附活性的敏感性。黏膜角质形成细胞恶性转化后α6β1表达升高促进了它们在层粘连蛋白上的迁移，这是侵袭和转移过程中的一个重要过程。
