Qi Hui-Ling, Zhang Ying, Ma Jun, Guo Peng, Zhang Xia-Ying, Chen Hui-Li
Department of Biochemistry, Shanghai Medical College of Fu-Dan University, Shanghai, China.
Eur J Biochem. 2003 Sep;270(18):3795-805. doi: 10.1046/j.1432-1033.2003.03767.x.
The effect of insulin on cancer metastatic potential was studied in a human hepatocarcinoma cell line, H7721. Cell adhesion to human umbilical vein endothelial cells (HUVECs) and laminin as well as chemotactic cell migration and invasion were selected as the indices of metastasis-related phenotypes for assessment of metastatic potential ex vivo. The results indicated that insulin enhanced all of these metastasis-related phenotypes. After the cells were treated with specific inhibitor of PI3K (LY294002) or transfected with antisense cDNA of PKB (AS-PKB), all of the above phenotypes were attenuated, and they could not be significantly stimulated by insulin, indicating that the insulin effect on metastatic potential was mediated by PI3K and PKB. Only the monoclonal antibody to the sialyl Lewis X (SLe(x)), but not antibodies to other Lewis antigens, significantly blocked the cell adhesion to HUVECs, cell migration and invasion, suggesting that SLe(x) played a crucial role in the metastatic potential of H7721 cells. The upregulation of cell surface SLe(x) and alpha-1,3-fucosyltransferase-VII (alpha-1,3 Fuc T-VII, enzyme for SLe(x) synthesis) was also mediated by PI3K and PKB, since LY294002 and AS-PKB also reduced the expressions of SLe(x) and alpha-1,3 FucT-VII, and attenuated the response to insulin. Furthermore, the alterations in the expressions of PKB protein and activity were correlated to the changes of metastatic phenotypes and SLe(x) expression. Taken together, the insulin/PKB signalling pathway participated in the enhancement of metastatic potential of H7721 cells, which was mediated by the upregulation of the expression of SLe(x) and alpha-1,3 FucT-VII.
在人肝癌细胞系H7721中研究了胰岛素对癌症转移潜能的影响。选择细胞与人脐静脉内皮细胞（HUVECs）和层粘连蛋白的粘附以及趋化性细胞迁移和侵袭作为转移相关表型的指标，用于体外评估转移潜能。结果表明，胰岛素增强了所有这些与转移相关的表型。在用PI3K特异性抑制剂（LY294002）处理细胞或用PKB反义cDNA转染后，上述所有表型均减弱，且不能被胰岛素显著刺激，这表明胰岛素对转移潜能的作用是由PI3K和PKB介导的。只有抗唾液酸化路易斯X（SLe(x)）单克隆抗体，而不是其他路易斯抗原的抗体，能显著阻断细胞与HUVECs的粘附、细胞迁移和侵袭，提示SLe(x)在H7721细胞的转移潜能中起关键作用。细胞表面SLe(x)和α-1,3-岩藻糖基转移酶-VII（α-1,3 Fuc T-VII，SLe(x)合成酶）的上调也由PI3K和PKB介导，因为LY294002和AS-PKB也降低了SLe(x)和α-1,3 FucT-VII的表达，并减弱了对胰岛素的反应。此外，PKB蛋白表达和活性的改变与转移表型和SLe(x)表达的变化相关。综上所述，胰岛素/PKB信号通路参与了H7721细胞转移潜能的增强，这是由SLe(x)和α-1,3 FucT-VII表达上调介导的。
