Harvard University PS-OP
If cancer cells did not migrate –and instead just stayed put– then cancer in most instances would be a more manageable disease. But cancer cells do migrate, and that migration accounts for much of cancer’s morbidity and mortality. Unfortunately, we understand little about how, why, and when this aberrant cellular migration plays out. Cancer cells tend to migrate not as individual units but rather as a cellular collective –in multicellular strings, ducts, strands and clusters. We propose that a controlling factor in that collective cellular migration is a newly discovered phenomenon called “cell jamming”. From cars streaming in highway traffic to coffee beans flowing in a chute at the supermarket to cells migrating within a living tissue, a wide variety of collective systems –both inert and living– are now known to have the capacity to jam. Within a living cell cluster, in particular, cells can jam to become quiescent, solid-like, and virtually frozen in place, or instead can unjam to become mobilized, fluid-like, and migratory. In the physiological case of healthy tissues, we do not yet know if the transition from a jammed to an unjammed state is an essential part of organogenesis, pattern formation, and wound healing. And in the pathophysiological case of malignant tissues, neither do we know if the transition from a jammed to an unjammed state is a prerequisite for invasion or metastasis.