Peri-foci adipose-derived stem cells promote chemoresistance in breast cancer.

BACKGROUND: Mesenchymal stem cells in tumor microenvironment can influence therapeutic responses in various types of cancers. For triple negative breast cancer, chemotherapy remains the mainstay of standard treatment. Our aim was to investigate the correlation between human adipose-derived stem cells (hAdSCs) and chemoresistance in triple negative breast cancer.

METHOD: Conditioned medium was collected from hAdSCs, which was isolated from breast cancer patients who had had breast mastectomy. The expression of selected CD markers was evaluated by flow cytometry to characterize hAdSCs. By array analyses of the secreted cytokines and chemokines of hAdSCs, we identified CXCL1 that mediated doxorubicin resistance and the expression of ATP-binding cassette transporters ABCG2 in TNBC. By microRNA microarray, the association between hAdSC-mediated doxorubicin resistance in TNBC was also revealed.

RESULTS: Conditioned medium collected from hAdSCs elicited doxorubicin resistance and enhanced the expression of ABCG2, which is a transporter responsible for the efflux of doxorubicin. CXCL1 secreted by hAdSCs downregulated miR-106a expression in triple negative breast cancer, and resulted in ABCG2 upregulation and doxorubicin resistance.

CONCLUSIONS: Our findings suggest that CXCL1 secreted by hAdSCs elicits doxorubicin resistance through miR-106a-mediated ABCG2 upregulation in triple negative breast cancer. These findings provide a better understanding of the importance of adipose-derived stem cells in breast cancer microenvironment regarding to the development of chemoresistance and reveal the potential of discovering novel therapeutic strategies to overcome drug resistance in TNBC.