No abstract

Cancer progression is dependent on heightened mechanical adaptation, both for the cells' ability to change shape and to interact with varying mechanical environments. This type of adaptation is dependent on mechanoresponsive proteins that sense and respond to mechanical stress, as well as their regulators. Mechanoresponsive proteins are part of the mechanobiome, which is the larger network that constitutes the cell's mechanical systems that are also highly integrated with many other cellular systems, such as gene expression, metabolism, and signaling. Despite the altered expression patterns of key mechanobiome proteins across many different cancer types, pharmaceutical targeting of these proteins has been overlooked. Here we review the biochemistry of key mechanoresponsive proteins, specifically nonmuscle myosin II, α-actinins, and filamins, as well as the partnering proteins 14-3-3 and CLP36. We also examined a wide range of data sets to assess how gene and protein expression levels of these proteins are altered across many different cancer types. Finally, we determined the potential of targeting these proteins to mitigate invasion or metastasis and suggest that the mechanobiome is a goldmine of opportunity for anti-cancer drug discovery and development.

Basement membrane is composed of ECM proteins that have viscoelastic properties. When the viscoelasticity is mimicked in vitro, epithelial cells coalesce by ''dragging'' the ECM protein through the PDMS substrate. This mechanosensing of viscoelasticity is achieved through the translocation of vinculin from the focal adhesions to the cell-cell junctions and is sensitive to the level of vinculin in the cell. Apart from the composition of cell-matrix and cell-cell adhesion complexes within the cell, we find that other biophysical and biochemical cues from environment affect the cell response on a viscoelastic substrate. By varying the interfacial force between ECM protein, fibronectin, and the PDMS substrate through physisorption or covalent linkage, we found that increasing the adhesion force hinders the coalescence of cells on a viscoelastic substrate as if on a soft-elastic substrate, suggesting the role of ECM-substrate interaction for in vitro models. Also, stronger cell-cell adhesions cause coalescence when coated with either fibronectin or collagen-1 alone but not when coated with Matrigel, consisting of collagen-IV, laminin, and other ECM proteins. To gain further insights into this phenomenon, we are using quantitative super-resolution microscopy to investigate how the difference in ECM anchoring is sensed by the cell at the molecular level and traction force microscopy to quantify the ECM remodeling and substrate deformation. These results on the viscoelastic substrate would provide new insights into in vivo basement membrane and cell-cell dynamics in general, and help to have better in vitro model, mimicking in vivo ECM arrangement and viscoelasticity, where these are crucial.

Nonmuscle myosin IIB (NMIIB) is considered a primary force generator during cell motility. Yet, many cell types, including motile cells, do not necessarily express NMIIB. Given the potential of cell engineering for the next wave of technologies, adding back NMIIB could be a strategy for creating super-cells with strategically altered cell morphology and motility. However, we wondered what unforeseen consequences could arise from such an approach. Here, we leveraged pancreatic cancer cells, which do not express NMIIB. We generated a series of cells where we added back NMIIB and strategic mutants that increase the ADP-bound time or alter the phosphorylation control of bipolar filament assembly. We characterized the cellular phenotypes and conducted RNA-seq analysis. The addition of NMIIB and the different mutants each has specific consequences for cell morphology, metabolism, cortical tension, mechanoresponsiveness, and gene expression. Major modes of ATP production are shifted, including alterations in spare respiratory capacity and the dependence upon glycolysis or oxidative phosphorylation. Several metabolic and growth pathways undergo significant changes in gene expression. This work demonstrates that NMIIB is highly integrated with many cellular systems and simple cell engineering has profound impact that extends beyond the primary contractile activity presumably being added to the cells.