Murakami N, Fukuchi S, Takeuchi K, Hori T, Shibamoto S, Ito F
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Setsunan University, Osaka, Japan.
J Cell Physiol. 1998 Jul;176(1):127-37. doi: 10.1002/(SICI)1097-4652(199807)176:1<127::AID-JCP15>3.0.CO;2-4.
Epidermal growth factor (EGF) induced the disruption and scattering of colonies of TMK-1, a cell line derived from a human gastric carcinoma. A stimulatory action of EGF on cell migration was also observed as determined by a wound assay. However, these actions of EGF were inhibited if the cells were pretreated with dexamethasone, a synthetic glucocorticoid. Dexamethasone increased cell adhesion to collagen type IV and laminin, but not to poly-L-lysine and fibronectin. In contrast, EGF did not affect cell adhesion to these extracellular matrices whether dexamethasone was present or not. Dexamethasone enhanced the protein levels of both alpha1 and beta1 integrin subunits, and that of the alpha1 beta1 heterodimer. Further, flow cytometric analysis revealed that dexamethasone increased the expression of beta1 and alpha1 integrin subunits at the cell surface, whereas EGF increased expression of beta1 and alpha2 subunits at the cell surface. Antibodies against alpha1 and beta1 integrin subunits inhibited the increased cell adhesion seen in the presence of dexamethasone. An immunofluorescence study indicated that dexamethasone increased the formation of focal adhesions along the entire edges of cell colonies. In contrast, EGF led to the formation of focal adhesions preferentially at the cell front, and this EGF-induced preferential formation was not observed if the cells were pretreated with dexamethasone. These results suggest that glucocorticoid increased cell adhesion to the extracellular matrix via alpha1 beta1 integrin, and thereby antagonized EGF-induced cell migration.
表皮生长因子（EGF）可诱导源自人胃癌的细胞系TMK-1的集落分散和解聚。通过划痕试验测定，还观察到EGF对细胞迁移具有刺激作用。然而，如果细胞用合成糖皮质激素地塞米松预处理，EGF的这些作用会受到抑制。地塞米松增加细胞与IV型胶原和层粘连蛋白的粘附，但不增加与聚-L-赖氨酸和纤连蛋白的粘附。相反，无论是否存在地塞米松，EGF均不影响细胞与这些细胞外基质的粘附。地塞米松提高了α1和β1整合素亚基以及α1β1异二聚体的蛋白水平。此外，流式细胞术分析显示，地塞米松增加了细胞表面β1和α1整合素亚基的表达，而EGF增加了细胞表面β1和α2亚基的表达。针对α1和β1整合素亚基的抗体抑制了在地塞米松存在下观察到的细胞粘附增加。免疫荧光研究表明，地塞米松增加了沿细胞集落整个边缘的粘着斑形成。相反，EGF优先在细胞前端导致粘着斑形成，如果细胞用地塞米松预处理，则未观察到这种EGF诱导的优先形成。这些结果表明，糖皮质激素通过α1β1整合素增加细胞与细胞外基质的粘附，从而拮抗EGF诱导的细胞迁移。
