Unveiling the Mechanotransduction Mechanism of Substrate Stiffness‐modulated Cancer Cell Motility via ROCK1 and ROCK2 Differentially Regulated Manner

Abstract

In addition to soluble factors and stromal cells, the mechanical properties of extracellular matrix (ECM) are considered to be an important component of tumor microenvironment. In particular, substrate stiffness is a mechanical characteristic of the ECM by which certain anchorage cells sense and respond to a variety of cellular behaviors. At the same time, clinical studies have observed that substrate stiffness was increased during tumorigenesis, which could promote tumor malignant transformation and metastasis. However, the biomechanical behavior of tumor cells and the underlying mechanotransduction pathways remain unclear. Here, using stiffness‐regulable polyacrylamide (PAA) substrates to simulate the tissue stiffness at different progress stages of breast cancer in vitro, we found that moderate substrate stiffness induced the emergence of malignant phenotypes and further unregulated breast cancer cell motility. Subcellular structure observation showed that moderate substrate stiffness promote the formation of leading‐edge protrusion by accelerating focal adhesion maturation and polarizing intracellular traction force distribution. Moreover, the substrate stiffness directly activated integrin β1 and focal adhesion kinase (FAK), which accelerate focal adhesion (FA) maturation and induce the downstream cascades of intracellular signals of the RhoA/ROCK pathway. Interestingly, the differential regulatory mechanism between two ROCK isoforms (ROCK1 and ROCK2) in cell motility and mechanotransduction was clearly identified. ROCK1 phosphorylated the myosin‐regulatory light chain (MRLC) and facilitated the generation of traction force, while ROCK2 phosphorylated cofilin and regulated the cytoskeletal remodeling by suppressing F‐actin depolymerization. The ROCK isoforms differentially regulated the pathways of RhoA/ROCK1/p‐MLC and RhoA/ROCK2/p‐cofilin in a coordinate fashion to modulate breast cancer cell motility in a substrate stiffness‐dependent manner via integrin β1‐activated FAK signaling. Our findings provide new insights into the mechanisms of matrix mechanical property‐induced cancer cell migration and malignant behaviors. Taming these physical forces by implanting scaffolds with specific stiffness or by inhibiting specific ROCK isoforms could have potential implications for improving therapeutic outcomes in cancer.Support or Funding InformationThis work was supported, in part or in whole, by the National Natural Science Foundation of China (11772088, 31470906, 31700811, 11802056, and 31800780).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.