Compression enhances invasive phenotype and matrix degradation of breast Cancer cells via Piezo1 activation.

BACKGROUND: Uncontrolled growth in solid breast cancer generates mechanical compression that may drive the cancer cells into a more invasive phenotype, but little is known about how such compression affects the key events and corresponding regulatory mechanisms associated with invasion of breast cancer cells including cellular behaviors and matrix degradation. RESULTS: Here we show that compression enhanced invasion and matrix degradation of breast cancer cells. We also identified Piezo1 as the putative mechanosensitive cellular component that transmitted compression to not only enhance the invasive phenotype, but also induce calcium influx and downstream Src signaling. Furthermore, we demonstrated that Piezo1 was mainly localized in caveolae, and both Piezo1 expression and compression-enhanced invasive phenotype of the breast cancer cells were reduced when caveolar integrity was compromised by either knocking down caveolin1 expression or depleting cholesterol content. CONCLUSIONS: Taken together, our data indicate that mechanical compression activates Piezo1 channels to mediate enhanced breast cancer cell invasion, which involves both cellular events and matrix degradation. This may be a critical mechanotransduction pathway during breast cancer metastasis, and thus potentially a novel therapeutic target for the disease.

Myofibrillar Structural Variability Underlies Contractile Function in Stem Cell-Derived Cardiomyocytes.

Disease modeling and pharmaceutical testing using cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs) requires accurate assessment of contractile function. Micropatterning iPSC-CMs on elastic substrates controls cell shape and alignment to enable contractile studies, but determinants of intrinsic variability in this system have been incompletely characterized. The objective of this study was to determine the impact of myofibrillar structure on contractile function in iPSC-CMs. Automated analysis of micropatterned iPSC-CMs labeled with a cell-permeant F-actin dye revealed that myofibrillar abundance is widely variable among iPSC-CMs and strongly correlates with contractile function. This variability is not reduced by subcloning from single iPSCs and is independent of the iPSC-CM purification method. Controlling for myofibrillar structure reduces false-positive findings related to batch effect and improves sensitivity for pharmacologic testing and disease modeling. This analysis provides compelling evidence that myofibrillar structure should be assessed concurrently in studies investigating contractile function in iPSC-CMs.