FIGURE 2.

Breast cancer (BC) microenvironment. (A) Myeloid-derived suppressor cells (MDSCs) and tumor-associated platelets (TAPs) inhibit the anti-tumor immunity of T and natural killer (NK) cells, secrete interleukin (IL)-10 and TGF-β, induce Treg cells proliferation, and form an immunosuppressive microenvironment that promotes the establishment of BC lung metastases. (B) The BC metabolic microenvironment, including abnormalities in glucose metabolism, amino acid metabolism, and lipid metabolism, is a key factor leading to tumor microenvironment immunosuppression as well as tumor immune escape. (C) MDSCs and TAPs increase angiogenesis and vascular permeability, induce BC cell dormancy, promote tumor cell extravasation and survival, increase the risk of BC recurrence, participate in BC proliferation, and ultimately promote lung metastasis. Figure was created by Figdraw (www.figdraw.com).