Compressive Stress Enhances Invasive Phenotype of Cancer Cells via Piezo1 Activation

In this study,we hypothesized that Piezo 1 channels mediate the compression-enhanced invasive phenotype of cancer cells via a caveolae-dependent mechanism.To test this hypothesis,we examined in vitro cultured human breast cancer cells for their ability to invade and degrade extracellular matrix in the presence or absence of compressive stress,together with corresponding changes in Piezo1 as well as cytoskeletal remodeling and calcium signaling.Here we show that compressive stress enhanced invasion,matrix degradation,and invadopodia formation of breast cancer cells.We further identified Piezo1 as the putative mechanosensitive cellular component that transmits compression to induce calcium influx,which in turn triggers several downstream pathways.Interestingly,for the first time we observed inv-adopodia with matrix degradation ability on the apical side of the cells, similar to those commonly observed at the cell s ventral side.Furthermore,we demonstrate that Piezo1 and caveolae were both involved in mediating the compressive stress-induced cancer cell invasive phenotype as Piezo 1 and caveolae were often colocalized,and reduction of Cav-1 expression or disruption of caveolae with methyl-β-cyclodextrin led to not only reduced Piezo1 expression but also attenuation of the invasive phenotypes promoted by compressive stress.Taken together,we first observed that in breast cancer cells,simulating uncontrolled growth-induced compressive stress enhanced cancer cell invasion,matrix degradation,and invadopodia and stress fiber formation.Our study also confirmed that Piezo1 channels are highly expressed in breast cancer cells compared to normal breast cells,and is consistent with the data that compressive stress regulates cell migration of breast cancer cells but not normal breast cells.Additionally,we identified that Piezol mediated these processes and the invasive phenotypes also depended on the integrity of caveolae.These findings provide the first demonstration that compressive stress enhances matrix degradation by breast cancer cells and Piezo1 is an essential mechanosensor and transducer for such stress in breast cancer.Additionally,our data supports the model where caveolae might be the'mechanical force foci'which concentrates Piezol to facilitate force sensing and transduction in mammalian cells.Our work may have relevance to human tumors in vivo.As solid tumor experiences high compressive stress due to uncontrolled proliferation and confinement by the stiff extracellular matrix environment,this microenvironment facilitates compression-enhanced cell invasion.The identification of Piezo1’s crucial role in this process provides the first demonstration of the dependence of Piezo1 channels on the response of breast cancer cells to physiological compressive stress.The functional dependence of Piezo1 on caveolae further highlights the importance of membrane organization and composition on forcegated ion channels.Both of these findings underscore the cardinal role that Piezo1 channels play in regulating cell invasion and may inspire further development targeting Piezol as a potential cancer therapeutic target.