Analysis of mechanisms involved in cohort migration of human colon carcinoma cells

(1)队列迁移过程中细胞-细胞粘附的局部释放机制在由肝细胞生长因子/分散因子（HGF/SF）诱导的队列迁移（CM）过程中，迁移细胞在细胞的下部显示出细胞-细胞粘附的局部释放。这使得细胞可以延伸前缘从而移动。这种局部释放与IQGAP-1与E-cadherin/catenin复合物的结合有关。这导致α-连环蛋白从复合物中释放出来，该蛋白连接e -钙粘蛋白和肌动蛋白丝细胞骨架。这一机制目前正在使用显性活性/阴性Rac 1或cdc42转染细胞进行更详细的研究。（ii）增强了成纤维细胞共存时癌细胞队列迁移的诱导作用我们通过将癌细胞与成纤维细胞共培养，进行了更接近体内情况的体外CM实验。成纤维细胞的共存增强了HGF/ sf诱导的癌细胞CM。在共培养中，癌细胞刺激成纤维细胞分泌TGF-β1， TGF-β1的增加诱导细胞产生更多促运动的含eda的纤维连接蛋白。因此，细胞间相互作用在CM中起重要作用。（iii）队列迁移过程中基质金属蛋白酶（MMP）的前细胞特异性表达在HGF/ sf诱导的CM过程中，明胶酶A （GelA）和膜型1型基质金属蛋白酶（MT1-MMP）主要在迁移片的前细胞中呈阳性，随后的细胞呈阴性。这些MMPs引起明胶基质的重排，这是CM所必需的。由于当诱导细胞散射（单细胞运动）而不是CM时，MMPs的上述前细胞特异性表达模式被抹去，因此迁移细胞片中的细胞-细胞接触对该模式有响应。

(I) Mechanisms of localized release from cell-cell adhesion during cohort migrationDuring cohort migration (CM) induced by hepatocyte growth factor/scatter factor (HGF/SF), migrating cells show localized release from cell-cell adhesion in the lower portion of the cells. This enables cells to extend leading edges and hence move. This localized release was associated with binding of IQGAP-1 to the E-cadherin/catenin complex. This caused release of α-catenin, which connects E-cadherin to actin filament cell skeleton, from the complex. This mechanism is now under investigation more in detail using dominant active/negative Rac 1 or cdc42-transfected cells.(ii) Enhanced induction of cohort migration of carcinoma cells in the co-presence of fibroblastsWe made in vitro CM assays which are more similar to the in vivo situation by coculturing carcinoma cells with fibroblasts. Coexistence of fibroblasts enhanced HGF/SF-induced CM of carcinoma cells. In the coculture, carcinoma cells stimulated secretion of TGF-β1 by fibroblasts, and the increased TGF-β1 induced more production of motility-stimulating EDA-containing fibronectin by cells. Thus, cell-cell interaction is shown to play an important role in CM..(iii) Front-cell-specific expression of matrix metalloproteinases (MMP) during cohort migrationDuring HGF/SF-induced CM, gelatinase A (GelA) and membrane type-1 matrix metalloproteinase (MT1-MMP) were positively demonstrated predominantly in front cells of the migrating sheets, with the following cells being negative. These MMPs caused rearrangement of gelatin matrix, which was essential for CM. Since the above front-cell-specific expression pattern of MMPs was effaced when scattering (single cell locomotion) of cells was induced instead of CM, cell-cell contact in migrating cell sheets appeared responsive for the pattern.