ABSTRACT
Aim The aim of this study is to determine effect of ST2325 on HER2/neu tyrosine kinase signal pathway and cell cycle in breast cancer BT474 cells. Methods Protein expression was detected with immunoblot analysis. Cell cycle distribution was examined using flow cytometry.Results ST2325 inhibited tyrosine phosphorylation of HER-2/neu in a dose-dependent manner with half maximal inhibition occurring at a concentration of 8.7 ?mol?L -1 without reduced HER-2/neu receptor protein expression. Activation of MAPK and AKT, downstream molecules of HER-2/neu-mediated signal transduction pathway was inhibited following exposure to ST2325. After BT474 cells were treated with different concentrations of ST2325 for 24 h, the results of flow cytometry analysis showed cell cycle arrest in G 1 phase. Western blot assay showed up-regulation of p27 protein expression and decrease of hyperphosphorylated Rb and cyclin D1 protein expression.Conclusions ST2325 inhibits HER2 tyrosine kinase phosphorylation and induces G 1 arrest in BT474 cells. Cell cycle arrest in G 1 is associated with p27 up-regulation, decrease of cyclin D1 protein and hyperphosphorylated Rb.