Matrix stiffness is the mechanical rigidity of the extracellular matrix surrounding cells, raised by collagen deposition and by enzymatic crosslinking of matrix fibers. It is usually expressed as a Young’s modulus and measured, on tissues or on engineered substrates, by atomic force microscopy.
A dense, stiff, highly crosslinked matrix has been associated across many solid tumors with metastatic potential and poor survival, acting by two broad routes. Biochemically, it engages mechanosensitive receptors and downstream pathways including FAK, WNT, MAPK and PI3K, which disrupt cell polarity and favor epithelial-mesenchymal transition, proliferation and invasion. Physically, it impedes drug penetration and compresses blood vessels, depleting oxygen and nutrients and hindering lymphocyte activation.
Rigidity also varies enormously between normal tissues, from very compliant lung and brain to mineralized bone, so it is a property of the niche a cancer cell colonizes as much as of the tumor itself.
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Source papers
- Chemotherapy-induced senescence promotes stroma stiffness and antioxidant adaptation to promote chemoresistance in pancreatic ductal adenocarcinoma doi:10.1038/s41467-026-75772-5
- Activated fibroblasts in cancer: Perspectives and challenges doi:10.1016/j.ccell.2023.02.015
- Environmentally induced cell stiffening shapes metastatic site selection by tuning the immune vulnerability of cancer cells doi:10.1016/j.immuni.2026.06.025