  The extra-cellular microenvironment has a fundamental role in tumor growth
and progression, strongly affecting the migration strategies adopted by single
cancer cells during metastatic invasion. In this study, we use a novel
microfluidic device to investigate the ability of mesenchymal and epithelial
breast tumor cells to fluidize and migrate through narrowing microstructures
upon chemoattractant stimulation. We compare the migration behavior of two
mesenchymal breast cancer cell lines and one epithelial cell line, and find
that the epithelial cells are able to migrate through the narrowest
microconstrictions as the more invasive mesenchymal cells. In addition, we
demonstrate that migration of epithelial cells through a highly compressive
environment can occur in absence of a chemoattractive stimulus, thus evidencing
that they are just as prone to react to mechanical cues as invasive cells.
