Obesity reduces mammary epithelial cell TGFβ1 activity through macrophage‐mediated extracellular matrix remodeling

The mammary epithelium is composed of a luminal epithelium and a basal layer containing myoepithelial cells and undifferentiated precursors. Basal cells express specific protein markers, such as keratin 14 (K14) and P-cadherin. To study the factors that regulate the basal mammary epithelial cell phenotype, we have established two clonal derivatives of the mouse HC11 cell line, BC20 and BC44, expressing high levels of K14 and P-cadherin. Unlike the parental HC11 cells, these basal cells did not produce beta-casein in response to lactogenic hormone treatment; however their phenotype appeared to be plastic. Cultured in EGF-free medium, they exhibited enhanced cell-extracellular matrix adhesions and deficient cell-cell junctions, whereas long-term treatment with EGF induced a decrease of focal contact number and establishment of cell-cell junctions, resulting in downregulation of K14 and P-cadherin expression at the protein and mRNA levels. To determine whether cell-extracellular matrix interactions mediated by integrins have a role in the regulation of the expression of K14 and P-cadherin, the amounts of transcripts for the two proteins were analysed in the basal cells, which were plated on the function-blocking antibodies against beta1 and alpha6 integrin chains, on fibronectin and on laminin 5. The amount of P-cadherin transcript was 2- to 4-fold higher in cells plated on the function-blocking anti-integrin antibodies and on the extracellular matrix proteins, as compared to cells plated on poly-L-lysine, whereas the K14 transcript levels were not significantly modified in response to adhesion. The data demonstrate that integrin-mediated cell interaction with extracellular matrix is directly implicated in the control of P-cadherin expression, and that EGF and cell-extracellular matrix adhesion events are important regulators of the basal mammary epithelial cell phenotype.

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Dynamic reciprocity revisited: a continuous, bidirectional flow of information between cells and the extracellular matrix regulates mammary epithelial cell function

Biochemistry and Cell Biology ◽

10.1139/o95-046 ◽

1995 ◽

Vol 73 (7-8) ◽

pp. 391-397 ◽

Cited By ~ 66

Author(s):

C. D. Roskelley ◽

M. J. Bissell

Keyword(s):

Extracellular Matrix ◽

Epithelial Cell ◽

Mammary Epithelial Cell ◽

Cell Function ◽

Mammary Epithelium ◽

Mammary Epithelial ◽

Biochemical Signals ◽

Bidirectional Flow ◽

Flow Of Information

Interactions between cells and the extracellular matrix (ECM) generate two classes of signals, mechanical and biochemical. In the case of the mammary epithelial cell, both are required to initiate ECM-dependent expression of the abundant milk protein β-casein. Mechanical signals induce a cellular rounding, while functional biochemical signals are associated with an increase in tyrosine phosphorylation. These individual components are part of a complex signalling hierarchy that leads to the emergence of the fully functional lactational phenotype. Interestingly, both the assembly and disassembly of this hierarchy, which occur cyclically in vivo, are constantly modulated by dynamic and reciprocal interactions that take place within a functional unit composed of both the cell and the ECM.Key words: mammary epithelium, differentiation, extracellular matrix, casein.

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In vitro differentiation of a cloned bovine mammary epithelial cell

Journal of Dairy Research ◽

10.1017/s0022029902005551 ◽

2002 ◽

Vol 69 (3) ◽

pp. 345-355 ◽

Cited By ~ 49

Author(s):

MICHAEL T. ROSE ◽

HISASHI ASO ◽

SHINICHI YONEKURA ◽

TOKUSHI KOMATSU ◽

AKIHIKO HAGINO ◽

...

Keyword(s):

Extracellular Matrix ◽

Epithelial Cell ◽

Mammary Epithelial Cell ◽

Limit Of Detection ◽

Cell Clone ◽

Mammary Epithelial ◽

Bovine Mammary Epithelial Cell ◽

The Media ◽

Lactogenic Hormones

The aim of the study was to establish in vitro a bovine mammary epithelial cell (MEC) clone, able to respond to mitogenic growth factors and to lactogenic hormones. Mammary tissue from a 200-d pregnant Holstein cow was used as a source of MEC, from which a clone was established through a process of limiting dilution. When plated on plastic, the cells assumed a monolayer, cobblestone, epithelial-like morphology, with close contact between cells. Inclusion of IGF-1 and EGF in the media significantly increased the number of cells 5 d after plating. All cells stained strongly for cytokeratin and moderately for vimentin at young and old passage stages, indicating the epithelial nature of this cell clone. When the cells were plated at a high density on a thin layer of a commercial extracellular matrix preparation (Matrigel), lobular, alveoli-like structures developed within approximately 5 d, with a clearly visible lumen. When cells were plated onto Matrigel in differentiation media (containing lactogenic hormones), detectable quantities of α-casein were present in the media and particularly on the lumen side of the structures. Omission of one of the lactogenic hormones (insulin, prolactin or hydrocortisone) reduced α-casein release to the limit of detection of the assay used. Lactoferrin was also produced when the cells were plated on Matrigel, again principally on the lumen side of the lobules, though this was independent of the lactogenic hormones. By passage 40, the cells had senesced, and it was not possible to induce α-casein or lactoferrin production. This study notes the establishment of a functional bovine mammary epithelial cell clone, which is responsive to mitogenic and lactogenic hormones and an extracellular matrix.

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