Rowat, A. C. | bioRxiv Science

bioRxiv2019

Cancer cells resist mechanical destruction in the circulation via RhoA-myosin II axis

During metastasis cancer cells are exposed to potentially destructive hemodynamic forces including fluid shear stress (FSS) while en route to distant sites. However, prior work indicates that cancer cells are more resistant to brief pulses of high-level fluid shear stress (FSS) in vitro relative to non-transformed epithelial cells. Herein we identify a mechanism of FSS resistance in cancer cells, and extend these findings to mouse models of circulating tumor cells (CTCs). We show that cancer cells acutely isolated from primary tumors are resistant to FSS. Our findings demonstrate that cancer cells activate the RhoA-myosin II axis in response to FSS, which protects them from FSS-induced plasma membrane damage. Moreover, we show that the myosin II activity is protective to CTCs in mouse models. Collectively our data indicate that viable CTCs actively resist destruction by hemodynamic forces and are likely to be more mechanically robust than is commonly thought.

cancer biology↗

bioRxiv2018

DYT1 dystonia patient-derived fibroblasts have increased deformability and susceptibility to damage by mechanical forces.

DYT1 dystonia is a neurological movement disorder that is caused by a loss-of-function mutation in the DYT1/TOR1A gene, which encodes torsinA, the luminal ATPase-associated (AAA+) protein. TorsinA is required for the assembly of functional linker of nucleoskeleton and cytoskeleton (LINC) complexes, and consequently the mechanical integration of the nucleus and the cytoskeleton. Despite the potential implications of altered mechanobiology in dystonia pathogenesis, the role of torsinA in regulating cellular mechanical phenotype, or mechanotype, in DYT1 dystonia remains unknown. Here, we define the mechanotype of mouse fibroblasts lacking functional torsinA as well as human fibroblasts isolated from DYT1 dystonia patients. We find that the deletion of torsinA or the expression of torsinA containing the DYT1 dystonia-causing {Delta}E302/303 ({Delta}E) mutation results in a more deformable cellular mechanotype. We observe a similar increased deformability of mouse fibroblasts that lack lamina-associated polypeptide 1 (LAP1), which interacts with and stimulates the ATPase activity of torsinA in vitro; as well as with depletion of the LINC complex proteins, Sad1/UNC-84 (SUN)1 and SUN2, lamin A/C, or lamin B1. Moreover, we report that DYT1 dystonia patient-derived fibroblasts are more compliant than fibroblasts isolated from unafflicted individuals. DYT1 fibroblasts also exhibit increased nuclear strain and decreased viability following mechanical stretch. Taken together, our results support a model where the physical connectivity between the cytoskeleton and nucleus contributes to cellular mechanotype. These findings establish the foundation for future mechanistic studies to understand how altered cellular mechanotype may contribute to DYT1 dystonia pathogenesis; this may be particularly relevant in the context of how neurons sense and respond to mechanical forces during traumatic brain injury, which is known to be a major cause of acquired dystonia.

biophysics↗