Adaptive epithelial-mesenchymal bi-directional transition: A key invasive plasticity for tumor metastasis

Epithelial-mesenchymal transition (EMT) is a reversible cellular program that allows epithelium-derived cells to acquire mesenchymal phenotypes, whereas mesenchymal-epithelial transition (MET) enables mesenchymal cells to regain epithelial properties. The capacity for EMT and MET, known as epithelial-mesenchymal plasticity (EMP), represents an indispensable mechanism of invasive plasticity for tumor progression during the spatiotemporal invasion-metastasis cascade. In this review, we elucidate the pivotal role of EMP in tumor metastasis and treatment resistance, as well as the latest understanding of the molecular mechanisms that regulate this cellular characteristic. We further summarize the methodology and technology for evaluating EMP and discuss the clinical translational potential of targeting EMP-related signaling pathways as a personalized anti-metastasis therapeutic strategy.