(The) effect of 3D fibrous gelatin network property in activation of Cancer Associated Fibroblasts (CAF)

Abstract

Cancer-associated fibroblasts (CAFs) are one of the most abundant and predominant cell types within the tumor microenvironment (TME). CAFs are originated from diverse cell populations through different mechanisms. CAF activation is considered a multi-step process from tissue-resident fibroblasts, where enhanced ECM production facilitates desmoplasia under inflammation, promoting tumor growth and CAF activation in a feed-forward loop. However, the specific mechanism on how the ECM modulates CAF initiation remains unclear. Here we developed a 3D in vitro model using the electrospun gelatin matrix to mimic the tumor’s paracrine interaction to investigate the effect of ECM density in CAF activation. Interestingly, we found a lower density network facilitated CAF activation more than a high-density network, possibly promoting their cell spreading and the contractile phenotype. We analyzed the mechanism that correlates the cell spreading and CAF activation in a mechanosignalling process. We found that the Akt/mTOR pathway is upregulated in NHDF on a lower density matrix, which induces higher tensional integrity to the fibroblasts resulting CAF activation. We also attempted to induce the CAF heterogeneity in the proposed 3D model. We assume that corresponding to the matrix density and CAF activation mechanism, the NHDF activation of CAF in low density and high-density matrix has its tumor-promoting/suppressive role in promoting tumorigenesis. Overall, our results demonstrate that matrix network density plays a critical role in the CAF activation mechanism and defining their heterogeneity within the ECM of TME. The proposed model can further understand more about the complex physical interaction between cancer cells, CAF, and ECM in promoting tumor progression.