Effect of flow on chemical sensing for directed cell migration*

Directed cell migration, including in cancer metastasis, occurs in response to a complex microenvironment consisting of multiple chemical and mechanical cues. Therefore, it is important to understand cell migration in response to multiple cues present simultaneously in the environment. But most experiments, particularly on cancer cell migration, have been performed using single cues. In this study we analyze cancer cell migration in response to the simultaneous presence of fluid flow and a chemical attractant. We find that when the chemical signal is present above a detectable limit, a cell always follows the chemical gradient, not the flow, and that the cells can only sense the flow when the chemical signal is very weak. We explain this behavior with a mathematical model, and we also map the system to a simple logical circuit that describes the decision-making underlying this migratory behavior.