Estrogen-related cancer microenvironment of breast carcinoma.

Stromal cells establish the microenvironment based on interaction with tumor cells, which is essential for cancer growth, invasion and metastasis. Fibroblasts are the primary component of stroma, and carcinoma-associated fibroblasts (CAFs) demonstrate tumor-promoting activities compared with normal counterparts. In breast cancers, stromal fibroblasts adjacent to the tumor express aromatase, a key enzyme in the synthesis of estrogen, resulting in in situ estrogen production, and aromatase is a primary target of endocrine therapy. Thus, stromal fibroblasts demonstrate multiple functions in the genesis and progression of breast cancers. In this paper, we discuss the importance of tumor-stromal crosstalk in breast cancers, and describe our system to predict the efficacy of endocrine therapy and to analyze estrogen signals in individual breast cancers.