Morphology and intermediate filament composition of human mammary epithelial cells treated with stable butyrate derivative.

A new stable butyrate derivative monobut-3 was previously shown to inhibit proliferation and promote differentiation in human mammary established cell lines. The present study on monobut-3's effects on mammary epithelial cells cultured from human non-malignant and malignant breast tissues demonstrated pronounced morphological alterations suggestive of cellular differentiation. In addition, some degree of architectural differentiation was also evident in treated primary cultures. Monobut-3 did not affect the expression of vimentin and cytokeratin 18 when assessed in human breast cell lines expressing one or both types of intermediate filaments. However, it did induce expression of cytokeratin 19, characteristic of fully differentiated mammary cells, in one of the two cell lines devoid of this cytokeratin subtype. Furthermore, the network of intermediate filaments was often more largely extended in cells treated with monobut-3 than in untreated ones. These results indicate that monobut-3 can induce subtle changes in intermediate filaments which may contribute to its ability to promote differentiation in human mammary cells.