The Influence of the Normal Mammary Microenvironment on Breast Cancer Cells.

The tumor microenvironment is recognized as performing a critical role in tumor initiation, progression, and metastasis of many cancers, including breast cancer. The breast cancer microenvironment is a complex mixture of cells consisting of tumor cells, immune cells, fibroblasts, and vascular cells, as well as noncellular components, such as extracellular matrix and soluble products. The interactions between the tumor cells and the tumor microenvironment modulate tumor behavior and affect the responses of cancer patients to therapies.

Asymmetric cell division of mammary stem cells.

Somatic stem cells are distinguished by their capacity to regenerate themselves and also to produce daughter cells that will differentiate. Self-renewal is achieved through the process of asymmetric cell division which helps to sustain tissue morphogenesis as well as maintain homeostasis. Asymmetric cell division results in the development of two daughter cells with different fates after a single mitosis.

Redirecting Normal and Cancer Stem Cells to a Mammary Epithelial Cell Fate.

Tissue microenvironments, also known as stem cell niches, influence not only resident cells but also cells in surrounding tissues. Physical and biochemical intercellular signals originating from resident stem cells or non-stem cells participate in the homeostasis of the tissue regulating cell proliferation, differentiation, wound healing, tissue remodeling, and tumorigenesis. In recent publications it has been demonstrated that the normal mouse mammary microenvironment can provide development and differentiation guidance to not only resident mammary cells but also cells of non-mammary origin including tumor-derived cells.

Amphiregulin regulates proliferation and migration of HER2-positive breast cancer cells.

Purpose: Tumor initiation and progression rely on cellular proliferation and migration. Many factors are involved in these processes, including growth factors. Amphiregulin (AREG) is involved in normal mammary development and the development of estrogen receptor (ER)-positive breast cancer.

Validation of an in vitro model of erbB2(+) cancer cell redirection.

Overexpression of the oncoprotein erbB2/HER2 is present in 20-30% of breast cancer patients and inversely correlates with patient survival. Reports have demonstrated the deterministic power of the mammary microenvironment where the normal mammary microenvironment redirects cells of non-mammary origin or tumor-derived cells to adopt a mammary phenotype in an in vivo model. This phenomenon is termed tumor cell redirection.