FOXF2 deficiency promotes epithelial-mesenchymal transition and metastasis of basal-like breast cancer

Introduction: Our previous clinical study demonstrated that the under-expression of FOXF2 is associated with early-onset metastasis and poor prognosis of patients with triple-negative breast cancer. In this study, we further characterized the role of FOXF2 in metastasis of basal-like breast cancer (BLBC) and underlying molecular mechanisms. Methods: RT-qPCR, immunoblot, immunofluorescence and immunohistochemistry were performed to assess the expression of genes and proteins in cell lines and tissues. A series of in vitro and in vivo assays was performed in the cells with RNAi-mediated knockdown or overexpression to elucidate the function and transcriptional regulatory role of FOXF2 in breast cancer. Results: We found that FOXF2 was specifically expressed in most basal-like breast cells. FOXF2 deficiency enhanced the metastatic ability of BLBC cells in vitro and in vivo. Additionally, FOXF2 deficiency induced the epithelial-mesenchymal transition (EMT) of basal-like breast cells. Furthermore, we identified that TWIST1 is a transcriptional target of FOXF2. TWIST1 was negatively regulated by FOXF2 and mediated the FOXF2-regulated EMT phenotype of basal-like breast cells and aggressive property of BLBC. Conclusions: FOXF2 is a novel EMT-suppressing transcription factor in BLBC. FOXF2 deficiency enhances metastatic ability of BLBC cells by activating the EMT program through upregulating the transcription of TWIST1.