Breast Tumor Microenvironment: Emerging Target of Therapeutic Phytochemicals

Triple negative breast cancer (TNBC) is the most aggressive and challenging form of breast cancers. Tumor microenvironment (TME) of TNBC is associated with induction of metastasis, immune system suppression, escaping immune detection and drug resistance. TME is highly complex and heterogeneous, consists of tumor cells, stromal cells and immune cells. The rapid expansion of tumors induce hypoxia, which concerns the reprogramming of TME components. The reciprocal communication of tumor cells and TME cells predisposes cancer cells to metastasis by modulation of developmental pathways, Wnt, notch, hedgehog and their related mechanisms in TME. Dietary phytochemicals are non-toxic and associated with various human health benefits and remarkable spectrum of biological activities. The phytochemicals serve as vital resources for drug discovery and also as a source for breast cancer therapy. The novel properties of dietary phytochemicals propose platform for modulation of tumor signaling, overcoming drug resistance, and targeting TME. Therefore, TME could serve as promising target for the treatment of TNBC. This review presents current status and implications of experimentally evaluated therapeutic phytochemicals as potential targeting agents of TME, potential nanosystems for targeted delivery of phytochemicals and their current challenges and future implications in TNBC treatment. The dietary phytochemicals especially curcumin with significant delivery system could prevent TNBC development as it is considered safe and well tolerated in phase II clinical trials.