FOXO1 Inhibits Tumor Cell Migration via Regulating Cell Surface Morphology in Non-Small Cell Lung Cancer Cells.

ABSTRACT

BACKGROUND/AIMS: Cell surface morphology plays pivotal roles in malignant progression and epithelial-mesenchymal transition (EMT). Previous research demonstrated that microvilli play a key role in cell migration of non-small cell lung cancer (NSCLC). In this study, we report that Forkhead box class O1 (FOXO1) is downregulated in human NSCLC and that silencing of FOXO1 is associated with the invasive stage of tumor progression. METHODS: The cell proliferation, migration, and invasion were characterized in vitro, and we tested the expression of the Epithelial-mesenchymal transition (EMT) marker by immunofluorescence staining and also identified the effect of FOXO1 on the microvilli by scanning electron microscopy (SEM). RESULTS: Functional analyses revealed that silencing of FOXO1 resulted in an increase in NSCLC cell proliferation, migration, and invasion; whereas overexpression of FOXO1 significantly inhibited the migration and invasive capability of NSCLC cells in vitro. Furthermore, cell morphology imaging showed that FOXO1 maintained the characteristics of epithelial cells. Immunofluorescence staining and western blotting showed that the E-cadherin level was elevated and Vimentin was reduced by FOXO1 overexpression. Conversely, the E-cadherin level was reduced and Vimentin was elevated in cells silenced for FOXO1. Furthermore, scanning electron microscopy (SEM) showed that FOXO1 overexpression increased the length of the microvilli on the cell surface, whereas FOXO1 silencing significantly reduced their length. CONCLUSIONS: FOXO1 is involved in human lung carcinogenesis and may serve as a potential therapeutic target in the migration of human lung cancer.