GEF-H1 drives tumor formation and metastasis in breast cancer cells

Abstract

RhoGTPases family is involved in several biological process includ- ing gene transcription, cell polarity, migration and invasion. RhoGT- Pases switch between on and off states and are regulated by sever- al GEFs (activators) and GAPs/RhoGDIs (inactivators). The aim of this work is to study the role of a particular RhoA-GEF, GEF-H1, in breast cancer (BC) progression. We observed by im- munostaining a significant increase in GEF-H1 protein expression in BC human biopsies compared with non-tumoral tissue (n=76, p=0.0287). In addition, GEF-H1 expression correlated with the inva- sive potential of human and murine BC cell lines. To further study the role of GEF-H1 in tumor development, we generated GEF-H1- knock out (KO) BC cells using CRISPR/Cas9 technology. A decrease in proliferation, migration, invasion and anchorage-independent colony formation rates was observed in GEF-H1-KO cells compared to wild type (WT) cells (p<0.001). These results correlated with reduced focal adhesion formation and its downstream signalling. Further- more, BALB/c mice were subcutaneously inoculated with GEF-H1 KO cells, showing a significant delay in tumor formation (p<0.01) and lung metastasis development compared with mice inoculated with WT cells. These results demonstrate that GEF-H1-RhoA activation mediates the signalling pathways involved in controlling cell proliferation, mi- gration and invasion of BC cells. In vivo assays and human biopsies studies suggest that GEF-H1 expression in BC cells might indeed contribute to tumor progression.