Collective cell migration in morphogenesis, regeneration and cancer

Key Points Collective cell migration is defined as the coordinated movement of multiple cells that retain cell–cell contacts while coordinating their actin dynamics and intracellular signalling. Because the cells form a structural and functional unit, both active and passive cell translocation occur. The movement of connected cells contributes to morphogenesis, wound healing and cancer invasion and each process underlies homologous but distinct molecular mechanisms of cell–cell interaction and pro-migratory extracellular signalling. The concept of collective movement explains how the body forms and reshapes as well as how cancer cells destructively invade as a 'socially' organized mass. The collective migration of cells as cohesive groups is prevalent during embryogenesis, organ development, wound repair and tumour invasion. The mechanisms that underlie different forms of collective cell migration are not well understood, but some general principles are emerging. The collective migration of cells as a cohesive group is a hallmark of the tissue remodelling events that underlie embryonic morphogenesis, wound repair and cancer invasion. In such migration, cells move as sheets, strands, clusters or ducts rather than individually, and use similar actin- and myosin-mediated protrusions and guidance by extrinsic chemotactic and mechanical cues as used by single migratory cells. However, cadherin-based junctions between cells additionally maintain 'supracellular' properties, such as collective polarization, force generation, decision making and, eventually, complex tissue organization. Comparing different types of collective migration at the molecular and cellular level reveals a common mechanistic theme between developmental and cancer research.