Fibroblast Spheroids Induce the Epithelial-mesenchymal Transition of Breast Epithelial Cells in a Paracrine Manner

다국어 초록 (Multilingual Abstract)

Nemosis is a peculiar state of activated fibroblasts, achieved when fibroblasts are forced to form spheroidal aggregation in vitro, expressing dramatically upregulated COX2. Recent studies have shown notable cases of COX2 overexpression in the tumor microenvironment (TME) of different tumor types, suggesting the possible link between nemosis and tumorigenesis. For epithelial-origin tumors, the epithelial-mesenchymal transition (EMT) is a crucial step during tumorigenesis and metastasis, but a complex interplay between the transformation of epithelial cancer cells and TME has not been fully understood. In this research, we show the EMT of breast epithelial cells induced by conditioned media harvested from fibroblast spheroids, which mimics the paracrine signaling between normal epithelial cells and the TME. First, we verify the monolayer expansion characteristics of the epithelial cells with live imaging and traction force microscopy. In addition, we demonstrate the different single-cell morphological features. Finally, we validate the EMT of the epithelial cells with mesenchymal markers and transcription factors inducing EMT with immunostaining and polymerase chain reaction. These results suggest the plausible positive feedback loop of tumorigenesis in the high COX2 expression TME.