| Abstract |
Growth and differentiation in the mammary epithelium depend on a network
of signals that emanate from circulating lactogenic hormones, locally
acting growth factors, and the tissue-specific glandular microenvironment.
Here, we describe the characteristics of two clonally derived homogeneous
cell lines isolated from a functional, but heterogeneous, mouse mammary
epithelial cell strain CID-9. One cell line, SCp2, is composed of small
cuboidal epithelial cells that express keratin intermediate filaments.
When cultured alone on tissue culture plastic, SCp2 cells form a flat
monolayer. However, after the addition of an exogenously supplied basement
membrane-derived extracellular matrix, >90% of these cells aggregate and
form clusters. In the presence of lactogenic hormones, these SCp2 cell
clusters express beta-casein, a specific marker of mammary epithelial
differentiation. Interestingly, under the same conditions, a small
proportion of cells located outside of these clusters does not express
beta-casein. The second cell line, SCg6, is composed of large, flat cells
that express vimentin intermediate filaments exclusively. SCg6 cells do not
synthesize beta-casein under any circumstances. When the two cell lines are
mixed and cocultured, SCp2 cells become competent to make beta-casein in the
absence of exogenously added extracellular matrix. Here also, cell-cell
interactions associated with cellular clustering appear to be important.
These homogeneous populations of cells should prove valuable for the study
of mechanisms and the hierarchy involved in cell-cell, cell-ECM, and cell-
hormone interactions.
|
|---|
