Modulation of Cell-Cell Adhesion by Integrin Signals in Oral Squamous Carcinoma Cells

当在涂有poly-HEMA的非贴壁培养皿中培养时，口腔鳞癌细胞MOK101形成多细胞聚集体（MCA）。在此过程中，E-cadherin在MCAs中的含量随着MCAs变得致密而增加。由于抗E-cadherin抑制抗体的存在延迟了MCAs的形成，因此E-cadherin介导的细胞间粘附在MCAs的形成中起重要作用。当MCAs被植入富含层粘连蛋白5的基质和I型胶原时，MCAs在这两种基质上重排为单层菌落。然而，仅在层粘连蛋白5上观察到细胞解离，而在I型胶原上没有。western blotting分析发现，细胞在层粘连蛋白5上的散射与0.2% Triton X-100可溶性组分中β catenin的增加有关，并且在层粘连蛋白5上的散射细胞中检测到β catenin酪氨酸磷酸化。此外，针对α3和β1整合素亚基的抗体阻断了细胞在层粘连蛋白5上的散射，而α2和α6整合素抗体则没有，这表明通过α3β1整合素的输入-输出信号主要参与了这一现象。最后，我们测试了α3或β1整合素亚基的激活是否可以通过这些整合素在MCAs表面的交联来触发MCAs的崩溃。在层粘连蛋白5上的MCAs重排过程中也观察到MCAs表面形成了一些微尖刺，尽管MCAs没有被分解。这些结果表明，整合素信号参与了口腔鳞癌细胞间粘附的调节。然而，生长因子的参与和细胞运动的增加在层粘连蛋白5上的MCAs解离仍有待澄清。

When cultured in the non-adherent dish coated with poly-HEMA, oral squamous carcinoma cells, MOK101, formed multicellular aggregates (MCA). In this process, the amount of E-cadherin in MCAs increased as MCAs became compact. Since the formation of MCAs was delayed by the existence of anti-E-cadherin inhibitory antibody, the cell-cell adhesion mediated by E-cadherin was important in the formation of MCAs. When MCAs were seeded on laminin 5 rich matrix and type I collagen, MCAs rearranged to monolayer colonies on both substrates. However, cell dissociation was observed only on laminin 5, but not on type I collagen. By western blotting analysis, the cell-scattering on laminin 5 was associated with the increase of β catenin in 0.2 % Triton X-100 soluble fraction, and tyrosine phosphorylation of β catenin was detected in scattering cells on laminin 5. Furthermore, antibodies against α3 and β1 integrin subunits blocked the cellscattering on laminin 5, while α2 and α6 integrin antibodies did not, suggesting that the in-out signal via α3β1 integrin was predominantly involved in this phenomenon. Finally, we tested if the activation of α3 or β1 integrin subunit could trigger the collapse of MCAs by cross-linking of these integrins on the surface of MCAs. A few microspikes, which was also observed during the rearrangement of MCAs on laminin 5, were formed on the surface of MCAs, although MCAs failed to be broken down.These results suggest that integrin signals are concerned in the modulation of cell-cell adhesion in oral squamous carcinoma cells. However, the involvement of growth factors and increased cellular motility in the dissociation of MCAs on laminin 5 remains to be clarified.