Stimulation and inhibition of human mammary epithelial cell duct morphogenesis in vitro.

We previously determined that normal human mammary epithelial cells (HMECs) placed on the basement membrane-like substance Matrigel form structures, whereas malignant breast cells do not (1). In the present study, we determined that the structures formed by normal cells on Matrigel resembled breast ducts in vivo by electron microscopy, and the process of their formation recapitulated what is known of duct formation in vivo. We therefore used this model to study less well-understood aspects of breast morphogenesis.

Expression of hemidesmosomes and component proteins is lost by invasive breast cancer cells.

Hemidesmosomes are multiprotein structures that attach basal cells of stratified epithelia to basement membranes. Although normal human breast epithelia are not stratified, we observed expression of electron-dense hemidesmosomes and hemidesmosome protein components by breast epithelial and myoepithelial cells at the basal lamina in vivo. Primary cultured normal human breast epithelial cells also contained hemidesmosomes and component proteins, and could be used as a model for hemidesmosome assembly and regulation.

Alterations in integrin and basement-membrane protein expression by malignant breast cells.

We investigated expression of eight integrin subunits and four basement membrane proteins by normal and malignant human mammary epithelial cells (HMEC) in culture and in tissue sections. Normal HMEC expressed the same six integrin subunits in culture and in vivo. Expression of some of these was altered in vivo in breast carcinomas: alpha1 was not observed and beta4 was missing from some cells-changes that were not genetic, as malignant cells in primary culture could express these subunits.

Culture of normal and malignant primary human mammary epithelial cells in a physiological manner simulates in vivo growth patterns and allows discrimination of cell type.

We cultured primary human mammary epithelial cells from five reduction mammoplasties and five breast carcinomas and attempted to improve culture conditions and define cell populations grown. Normal cells cultured on Matrigel basement membrane-like substance formed multicellular three-dimensional structures reminiscent of tissue ducts and alveoli, while malignant cells remained as single cells crawling through Matrigel much as malignant cells separate and invade basement membrane in vivo. This re-creation of normal and malignant breast cell morphology may facilitate studies of breast cancer cell biology and determination of malignant cell authenticity in culture.

Comparison of fatty acid and triacylglycerol metabolism of macrophages and smooth muscle cells.

The response of macrophages and smooth muscle cells to culture in free fatty acid has been compared. Because oleate and linoleate promoted triacylglycerol enrichment of smooth muscle cells, whereas palmitate had little effect, oleate was used for these studies. The kinetics of the accumulation of triacylglycerol produced by oleate was comparable between smooth muscle cells and macrophages.