Abstract: In one embodiment, methods of theranostic classification of a breast cancer tumor are provided, wherein the classification is determined by detecting an expression level of FOXC1. In other embodiments, methods for predicting a prognosis of a basal-like breast cancer and methods of treating a basal-like breast cancer are provided. In other embodiments, methods for diagnosing metastatic breast cancer using the expression ratio of FOXC1/FOXA1 in a population of breast cancer tumor cells are provided. The methods also entail administering a treatment for metastatic breast cancer if the expression ratio of FOXC1/FOXA1 in the population of breast cancer tumor cells is elevated as compared to a control. Other embodiments provide methods for treating breast cancer with a proteasome inhibitor alone or in combination with a Wnt inhibitor in subjects with tumor cells expressing FOXC1 in a subject.