UC San Diego

Metastatic pancreatic ductal adenocarcinoma (PDAC) is caused by invasive cell clusters that collectively migrate from the primary tumor to distant tissue. Efforts to characterize this invasion phenotype rely on assays to measure functional morphology or prognostic tumor markers, both of which have been shown to be regulated by the matrix microenvironment via physical properties such as stiffness, confinement, and degradability. However, it is unclear how physical properties intersect with the unique metabolic reprogramming of cancer cells within these environments to contribute to a widely heterogeneous array of phenotypes within the same tumor. In particular, high density collagen I (HDC) induces heterogenous collective cell morphology in vitro when seeded as single cells, which grow into multicellular structures with a range of collective morphologies depending on invasive phenotype. By systematically varying the density of fibrillar collagen I, we first show that collective invasion is modulated by matrix architecture, and that this invasive phenotype is more prominently modeled in HDC than in gold-standard basement membrane extract (Matrigel), but not through suppression of epithelial traits. Using 3D HDC gels as invasion assays, we then pharmacologically inhibited oxidative phosphorylation, which reduced the frequency of collectively invasive structures but not their proliferation. Interestingly, categorizing multicellular structures by morphology reveals that proliferation is correlated with invasive phenotype. Finally, we show that PDAC that is resistant to KRAS inhibitors is also more collectively invasive in collagen I.