Fast-Relaxing Hydrogels Promote Pancreatic Adenocarcinoma Cell Aggressiveness through Integrin β1 Signaling

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense extracellular matrix (ECM) exhibiting high stiffness and fast stress relaxation. In this work, gelatin-based viscoelastic hydrogels were developed to mimic the compositions, stiffness, and fast stress relaxation of PDAC tissues. The hydrogels were cross-linked by gelatin-norbornene-boronic acid (GelNB-BA), thiolated macromers, and a 1,2-diol-containing linear synthetic polymer PHD. Controlling the thiol–norbornene cross-linking afforded tunable stiffness, whereas increasing PHD content led to hydrogels with PDAC-mimicking fast stress relaxation. In vitro studies, including proliferation, morphology, and mRNA-sequencing, showed that fast-relaxing hydrogels supported PDAC cell proliferation, epithelial–mesenchymal transition (EMT), and integrin β1 activation. Blocking integrin β1 in vitro led to upregulating EMT markers in both slow and fast-relaxing hydrogels. However, this strategy profoundly impacted tumor growth rate and reduced tumor size but did not alter metastasis patterns in an orthotopic mouse model. This suggests a need to further evaluate the antitumor effect of integrin β1 blockade.