Epithelial-Mesenchymal Crosstalk Influences Cancer-Related Cell Behavior: A 3D Lung Alveolus-Fibroblast Co-Culture System

Lung cancer is a devastating disease that kills more individuals in the United States than any other cancer. The tumor microenvironment is increasingly recognized as playing a major role in the progression of cancer. Thus, studying the interactions among lung cancer cells, non-malignant cells and the surrounding matrix is critical for understanding and treating lung cancer. Three-dimensional in vitro co-culture systems allow for tissue-relevant platforms that better recapitulate the native cell environment. In this work, we employed a cyst templating technique to culture alveolar epithelial cells on photodegradable microspheres and subsequently encapsulated the cell-covered spheres within poly(ethylene glycol) (PEG) hydrogels laden with pulmonary fibroblasts. A healthy fibroblast cell line was co-cultured with either normal mouse alveolar epithelial primary cells or a cancerous alveolar epithelial cell line to probe the influence of tumor-stromal co-culture on cell behavior. We found that cancerous epithelial cells and normal fibroblasts have significantly higher proliferation rates in co-culture, normal fibroblasts migrate significantly faster when co-cultured with cancerous A549 cells, and there is a synergistic increase in matrix metalloproteinase (MMP) activity in this cancer co-culture. None of these changes in cell behavior were observed in a parallel healthy epithelial-cyst/fibroblast co-culture. Further, when MMP activity was reduced via a chemical inhibitor and when cells were cultured in gels with a non-degradable crosslinker, the increase in cancer cell proliferation in co-culture was abrogated and fibroblast migration was dramatically suppressed. The results presented here suggest a nuanced chemical signaling exchange between lung cancer epithelial cells and pulmonary fibroblasts within our 3D hydrogel system and points to potential signaling routes that merit further investigation