EGF-receptor signaling and epithelial-mesenchymal transition in human carcinomas.

The epidermal growth factor receptor (EGF-R) signaling pathway maintains a balance between cell proliferation, differentiation and apoptosis, and thus it is believed that EGF-R signaling pathways play an important role in the development and progression of several human carcinomas. Epithelial-mesenchymal transition (EMT) describes the dedifferentiation switch between polarized epithelial cancer cells and contractile and motile mesenchymal (invasive) cells during cancer progression and metastasis. Activation of EGF-R signaling regulates EMT-associated invasion and migration in normal and malignant epithelial cells. In contrast, blocking EGF-R and consequently its pathways, by a monoclonal antibody (mAb) or a tyrosine kinase inhibitor (TKI), inhibit cellular migration and invasion, suggesting an essential role for EGF-R inhibitors in the control of cancer metastasis. The purpose of this review is to summarize current information regarding the role of EGF-R signaling on EMT during human cancer progression and metastasis.