Immortalized Human Mammary Fibroblasts (HMF3A)

CBFB-Rich Exosomes Promote the Acquisition of a CAF-Like Phenotype

Metastasis is the leading cause of breast cancer death. Breast cancer cells are known to experience high oxidative stress. Circulating exosomes have a variety of roles in tumorigenesis and metastasis. Hsu et al. studied CBFB and its role in breast cancer bone metastasis and how it might affect oxidative stress-related targets. In this study, HMF3A cells cocultured with exosomes demonstrated a significantly higher expression of the CAF markers vimentin, α-SMA, and FAP, and a lower cytokeratin 1 (KRT1) expression (Fig. 1a). Flow cytometry also showed a significant increase in the proportion of CAF-like (VIM+/α-SMA+) cells in HMF3A exosome cocultured cells compared to those not cocultured with exosomes (Fig. 1b). Western blot analysis revealed higher CBFB expression in HMF3A cells cocultured with exosomes (Fig. 1c). These results show that exosomes are rich in CBFB and that CBFB is the driver for the CAF-like phenotype in HMF3A cells. After HMF3A cells were made CAF-like through coculture, they were cocultured with T47D or MCF12A cells. Cocultured HMF3A cells significantly increased the migration and invasion (Fig. 1d and e). Exosome-cocultured HMF3A cells secreted significantly more IL-6 and OPN into the culture medium than singly cultured HMF3A cells (Fig. 1f).