CAF-Driven Mechanotransduction via Collagen Remodeling Accelerates Tumor Cell Cycle Progression

Cancer-associated fibroblasts (CAFs) restructure collagen hydrogels via actomyosin-driven fibril bundling and crosslinking, increasing polymer density to generate mechanical stress that accelerates tumor proliferation. Conventional hydrogel models lack spatial heterogeneity, thus obscuring how localized stiffness gradients regulate cell cycle progression. To address this, we developed a collagen hydrogel-based microtissue platform integrated with programmable microstrings (single/double tethering), enabling real-time quantification of gel densification mechanics and force transmission efficiency. Using this system combined with FUCCI cell cycle biosensors and molecular perturbations, we demonstrate that CAF-polarized contraction increases hydrogel stiffness (350 → 775 Pa) and reduces pore diameter (5.0 → 1.9 μm), activating YAP/TAZ nuclear translocation via collagen-integrin-actomyosin cascades. This drives a 2.4-fold proliferation increase and accelerates G1/S transition in breast cancer cells. Pharmacological inhibition of YAP (verteporfin), actomyosin (blebbistatin), or collagen disruption (collagenase) reversed mechanotransduction and proliferation. Partial rescue upon CYR61 knockdown revealed compensatory effector networks. Our work establishes CAF-remodeled hydrogels as biomechanical regulators of tumor growth and positions gel-based mechanotherapeutics as promising anti-cancer strategies.