TGF-β1短时处理降低肝癌细胞与Fn的粘附及FAK的磷酸化

TGF-β1 RAPIDLY REDUCED HEPATOCARCINOMA CELLS ADHESION ON TO FIBRONECTIN AND STIMULATED FAK DEPHOSPHORYLATION

为了研究TGF-β1对α5β1整合蛋白所介导的信号转导通路是否有快速的信号调节作用,本文用TGF-β1短时(10min)处理SMMC-7721细胞,发现当经TGF-β1预处理的细胞与Fn粘附时,细胞与Fn的粘附力下降,由Fn与整合蛋白的结合而诱导发生的FAK的酪氨酸磷酸化随着TGF-β1浓度的增加而降低。而TGF-β1短时处理并未改变整合蛋白α5、β1亚基的表达。此外,贴壁生长于培养皿的细胞的FAK磷酸化程度在TGF-β1短时处理后也下降,甚至检测不出。提示TGF-β1可能通过某种信号通路快速调节了整合蛋白与配体的亲和力以及下游信号分子FAK的磷酸化。从而影响了细胞内骨架蛋白结构的完整性,使细胞发生去极性化,有利于细胞在迁移早期的松脱。

In order to investigate whether TGF-β1 could rapidly regulate integrin induced signaling, we treated SMMC-7721 human hepatocellular carcinoma cells with human recombinant TGF-β1 for 10 min, and examined cell adhesion, integrin amount and FAK tyrosine phosphorylation. We used cell adhesion assay to estimate the affinity of α5β1 integrin with fibronectin, and analyzed the amount of integrin α5 and β1 subunits by performing FACS analysis. Then western blot analysis was carried out to examine tyrosine phospho- rylation level of FAK. Our results showed that TGF-β1 could rapidly attenuated cell adhesion onto Fn without changing the expression of α5β1 integrin, and at the meantime dephosphorylated FAK. It suggested that TGF-β1 rapidly regulated the activation of integrin, and stimulated FAK dephosphorylation, which might induce depolarization in SMMC-7721 hepatocellular carcinoma cells, then facilitates the detachment of tumor cells at early stages of migration.