Dual Regulation of Breast Tubulogenesis Using Extracellular Matrix Composition and Stromal Cells

Abstract

Epithelial-mesenchymal interactions during embryogenesis are critical in defining the phenotype of tissues and organs. The initial elongation of the mammary bud represents a central morphological event requiring extensive epithelial-mesenchymal crosstalk. The precise mechanism orchestrating this outgrowth is still unknown and mostly animal models have been relied upon to explore this process. Highly tunable three-dimensional (3D) culture models are a complementary approach to address the question of phenotypic determination. Here, we used a 3D in vitro culture to study the roles of stromal cells and extracellular matrix components during mammary tubulogenesis. Fibroblasts, adipocytes, and type I collagen actively participated in this process, whereas reconstituted basement membrane inhibited tubulogenesis by affecting collagen organization. We conclude that biochemical and biomechanical signals mediate the interaction between cells and matrix components and are necessary to induce tubulogenesis in vitro.

Hormonal Regulation of Epithelial Organization in a Three-Dimensional Breast Tissue Culture Model

“…8,9 In our current study, we observed that hormonal treatment influenced collagen fiber organization. Quantitative analysis showed that the changes in epithelial organization induced by mammogenic hormones were accompanied by differences in collagen organization.…”

“…35 In the conditions of our 3D model, promegestone induced the formation of chain-like structures, which are considered an early step of ductal formation according to Meyer et al 35 The fact that side branching is only partially recapitulated in our model containing epithelial cells and in the model containing epithelial and myoepithelial cells, 34,35 suggests that stromal components such as fibroblasts and/or adipocytes may significantly contribute to this morphogenetic event, as shown in the MCF10A model. 9 We have previously shown that mammary fibroblasts normalize the structures formed by the ER + /PR + MCF7 cells. 12 The stimulation of budding by prolactin was successfully reproduced in our culture model.…”

“…These models have increased the understanding of matrix-epithelial cell interactions 7 and the role of stromal cells and collagen fiber organization on epithelial morphogenesis. 8,9 For example, our previous work using MCF10A cells in type I collagen showed that collagen fiber organization is important for the development of elongated (ductal) structures. 8 Additionally, we observed that basement membrane proteins (Matrigel) hinder fiber organization and result in the formation of round (acinar) structures.…”

A Hormone-responsive 3D Culture Model of the Human Mammary Gland Epithelium

“…The hormone-sensitive 3D culture model described herein also allows for the addition of cell types considered of relevance in breast tissue morphogenesis, such as fibroblasts, adipocytes and circulating blood cells 6,8,10 . Finally, testing of hormonal influence on the breast epithelium in this 3D culture model is not limited to endogenous hormones alone.…”

“…3D cultures of the mammary gland have helped elucidate many aspects of mammary gland development and neoplasia. However, most of the 3D culture models currently available are unsuitable to study hormone action because the human epithelial cell lines used for the task lack hormone receptor expression 6,7,9 .…”