ROCK isoforms differentially modulate cancer cell motility by mechanosensing the substrate stiffness

Area of Science:

• Biophysics
• Cell Biology
• Cancer Research

Background:

• Tumor progression involves extracellular matrix (ECM) remodeling and stiffening.
• The role of ECM stiffness in cancer is recognized, but tumor cell biomechanics and mechanotransduction pathways are not fully understood.

Purpose of the Study:

• To investigate the impact of substrate stiffness on breast cancer cell motility and elucidate the underlying mechanotransduction pathways.
• To differentiate the roles of ROCK1 and ROCK2 isoforms in regulating cell migration and cytoskeletal dynamics.

Main Methods:

• Utilized polyacrylamide (PAA) substrates to mimic varying tissue stiffness relevant to breast cancer stages.
• Observed breast cancer cell behavior and quantified changes in focal adhesion maturation and cytoskeletal organization.
• Investigated signaling pathways including integrin β1, FAK, RhoA, ROCK1, ROCK2, MRLC, and cofilin.

Main Results:

• Moderate substrate stiffness enhanced breast cancer cell motility.
• Substrate stiffness activated integrin β1 and FAK, promoting focal adhesion maturation.
• Identified distinct roles for ROCK1 (phosphorylating MRLC, facilitating traction force) and ROCK2 (phosphorylating cofilin, regulating F-actin).
• Demonstrated that RhoA/ROCK1/p-MLC and RhoA/ROCK2/p-cofilin pathways were differentially regulated in a stiffness-dependent manner.

Conclusions:

• Breast cancer cell motility is modulated by substrate stiffness through integrin β1-FAK signaling and differential ROCK isoform activity.
• Findings provide novel insights into how matrix mechanical properties influence cancer cell migration and malignant behavior.
• Understanding these interactions may lead to new strategies for inhibiting metastasis as an adjuvant cancer therapy.