ABSTRACT
Although protein kinase B (PKB, AKT) has been investigated extensively for its roles in oncogenic transformation and apoptotic prevention, controversial results are also reported. Here we assessed the role of AKT in the cell growth and expression of a key set of cell cycle regulators in the human normal uroepithelial cell line, SVHUC-1. AKT activity was suppressed by permanent transfection of dominent negative (DN)-AKT with Lipofectamine Plus. Cell viability was measured by the crystal violet assay. DNA contents stained by propidium iodide were measured by flow-cytometry for cell cycle analysis. Cell growth curve showed that overexpression of DN-AKT which suppressed the AKT activity decreased the cell growth. In the cell cycle analysis, overexpression of DN-AKT resulted in a 6% increase in the proportion of cells in G1 phase. Furthermore, DN-AKT overexpression increased the p27(Kip1) protein expression and the activation of a transcription factor FKHR, which induces p27(Kip1) transcription. Our results suggest that, in normal uroepithelial cells, AKT activation increases the cell growth through the influence on p27(Kip1) expression and FKHR activation. Thus, AKT may be used as a biomarker for tumor transformation of bladder uroepithelial cells.