Matrix Stiffness Directs Stemness Signatures in Breast Cancer

Area of Science:

• Biomedical Engineering
• Cancer Biology
• Mechanobiology

Background:

• Phenotypic plasticity is crucial for tumor progression and metastasis.
• The tumor microenvironment, particularly extracellular matrix (ECM) stiffness, provides dynamic cues regulating cancer cell behavior.

Purpose of the Study:

• To investigate how ECM mechanics influence breast cancer cell phenotypes, stemness, and drug resistance.
• To develop and utilize advanced in vitro models for studying biomechanics in cancer.

Main Methods:

• Fabrication of 2D microtumors using hydrogel micropatterning to control spatial confinement and stiffness.
• Creation of mechanically tuneable 3D matrices via drop-on-demand bioprinting.
• Assessment of phenotypic markers (plasticity, stemness, CD44 isoforms) and drug resistance (doxorubicin, enzalutamide) in response to matrix stiffness.

Main Results:

• Soft matrices promoted stem-like phenotypes, increased aldehyde dehydrogenase 1 (ALDH1) expression, and enhanced drug resistance.
• Stiff matrices maintained a more differentiated cancer cell profile.
• CD44 standard isoform expression was enriched in soft matrices, while CD44 variant 9 isoform expression was enriched in stiff matrices.
• 3D models recapitulated the mechanical regulation observed in 2D models.

Conclusions:

• Matrix stiffness is a key regulator of breast cancer phenotypic heterogeneity, influencing stemness and drug resistance.
• Microengineered synthetic matrices offer a physiologically relevant platform for high-throughput investigation of biomechanics in cancer progression, metastasis, and drug resistance.