A self-assembled 3D model demonstrates how stiffness educates tumor cell phenotypes and therapy resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense and stiff extracellular matrix (ECM) associated with tumor progression and therapy resistance. To further our understanding of how stiffening of the tumor microenvironment (TME) contributes to aggressiveness, we develop a three-dimensional (3D) self-assembling hydrogel disease model based on peptide amphiphiles (PAs, PA-E3Y) designed to tailor stiffness. The model displays nanofibrous architectures reminiscent of native TME and enables the study of the invasive behavior of PDAC cells. We demonstrate enhanced tuneability of stiffness by interacting thermally annealed aqueous solutions of PA-E3Y (PA-E3Y h ) with divalent cations to create hydrogels with mechanical properties and ultrastructure similar to native tumor ECM. We show that stiffening of PA-E3Y h hydrogels to levels found in PDAC induces ECM deposition, promotes epithelial-to-mesenchymal transition, enriches for CD133 + /CXCR4 + cancer stem cells, and subsequently enhances drug resistance. Our findings reveal how a stiff 3D environment renders PDAC cells more aggressive and therefore more faithfully recapitulates in vivo tumors. This article is protected by copyright. All rights reserved.