Stiff substrates increase YAP-signaling-mediated matrix metalloproteinase-7 expression.

Area of Science:

• Biomedical Engineering
• Cancer Biology
• Molecular Oncology

Background:

• Abnormally stiff substrates are increasingly recognized as a factor in cancer progression.
• The precise molecular mechanisms linking substrate stiffness to cancer progression remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which substrate stiffness influences colorectal cancer progression.
• To investigate the role of matrix metalloproteinase-7 (MMP-7) and the yes-associated protein (YAP) signaling pathway in response to substrate stiffness.

Main Methods:

• Cultured T84 human colorectal cancer cells on substrates of varying stiffness (plastic, collagen-I gel, polyacrylamide gels of 2, 67, and 126 kPa).
• Assessed matrix metalloproteinase-7 (MMP-7) expression levels.
• Utilized YAP knockdown, and inhibitors/knockdown of epidermal growth factor receptor (EGFR), myosin regulatory light chain (MRLC), integrin-α2, and integrin-β1.

Main Results:

• Stiff substrates significantly enhanced MMP-7 expression, a marker of poor prognosis.
• MMP-7 expression increased with substrate stiffness (126 kPa > 2 kPa).
• YAP knockdown reduced MMP-7 expression; inhibition of EGFR, MRLC, integrin-α2, or integrin-β1 also downregulated MMP-7.
• A positive feedback loop involving YAP, EGFR, integrin-α2β1, and MRLC was identified, which amplifies MMP-7 expression.

Conclusions:

• Substrate stiffness enhances colorectal cancer cell viability.
• Upregulation of MMP-7 expression via a YAP-driven positive feedback loop is a key mechanism mediating the pro-cancer effects of stiff substrates.