Molecular pathology of breast cancer progression and the tumor microenvironment

Tumor progression – tumor metastatic and malignant phenotype – depends on interactions between tumor cells and the tumor microenvironment. Different components of the tumor microenvironment may have stimulatory or inhibitory effects on tumor progression by regulating gene expression profiles in tumor and stromal cells.

The importance of the microenvironment in breast carcinogenesis is well-documented. Various experimental studies, as well as observations on patients showed that stromal component plays a crucial role during tumor development, and a wide range of pathways have been implicated in cancer including self-sufficiency in growth signals, insensitivity to antigrowth signals, limitless replicative potential, evasion of apoptosis, sustained angiogenesis, tissue invasion and metastasis. The dynamic and reciprocal interactions between tumor cells and cells of the microenvironment contribute critical events to tumor evolution toward metastasis, and many cellular and molecular elements of the microenvironment are emerging as attractive targets for therapeutic strategies.