Evaluating the indirect crosstalk between triple-negative breast cancer and fibroblasts

Tumor metastasis and proliferation is dependent on the crosstalk among the tumor and various cell types in the tumor microenvironment, among which are fibroblasts. This research focuses on the reciprocal interactions between naïve human foreskin fibroblasts (HFF) and the TNBC MDA-MB-468 cells. By incubating the tumor and fibroblast cell lines in the conditioned media (CM) derived from one another, the phenotypic and functional changes of each cell lines following exposure to CM from the other were assessed. Expression levels of PCNA, Vimentin, and E-cadherin were assessed for proliferation, epithelial-to-mesenchymal transition (EMT), and adhesion, respectively using flow cytometry. The effect of CM exposure on migration rates, cell viability following chemotherapeutics treatment, and cell-cell adhesion were also assessed. The results showed that following exposure to tumor-derived CM, the HFF cells exhibited about 50% decrease in vimentin expression. This may be correlated with mesenchymal-epithelial-transition (MET). The tumor cells may be secreting factors to have fibroblasts become less mobile in their surroundings to reprogram them and have support for tumor progression and metastasis. Tumor cells exposed to HFF-derived CM showed a twofold increase in migratory rate. The in vitro results signify that the secreted factors each cell line affect the functional changes in the other. Understanding the specific pathways and factors involved in these reciprocal effects could lead to novel therapeutic strategies targeting the tumor microenvironment.