open access

Vol 69, No 1 (2010)
REVIEW ARTICLES
Published online: 2010-03-09
Submitted: 2012-02-06
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The myoepithelial cell: its role in normal mammary glands and breast cancer

M. Sopel
Folia Morphol 2010;69(1):1-14.

open access

Vol 69, No 1 (2010)
REVIEW ARTICLES
Published online: 2010-03-09
Submitted: 2012-02-06

Abstract

Mammary gland epithelium is composed of an inner layer of secretory cells (luminal) and an outer layer of myoepithelial cells (MEC) bordering the basal lamina which separates the epithelial layer from the extracellular matrix. Mature MECs morphologically resemble smooth muscle cells; however, they exhibit features typical for epithelial cells, such as the presence of specific cytokeratin filaments. During lactation, secretory cells synthesize milk components, which are collected in alveoli and duct lumen, and transported to the nipple as a result of MEC contraction. Although the induction of MEC contraction results from oxytocin action, also other, still unknown auto/paracrine mechanisms participate in the regulation of this process. As well as milk ejection, MECs are involved in mammary gland morphogenesis in all developmental stages, modulating proliferation and differentiation of luminal cells. They take part in the formation of extracellular matrix, synthesizing its components and secreting proteinases and their inhibitors. In addition, MECs are regarded as natural cancer suppressors, stabilizing the normal structure of the mammary gland, they secrete suppressor proteins (e.g. maspin) limiting cancer growth, invasiveness, and neoangiogenesis. The majority of malignant breast cancers are derived from luminal cells, whereas neoplasms of MEC origin are the most seldom and usually benign form of breast tumours. MECs are markedly resistant to malignant transformation and they are able to suppress the transformation of neigh boring luminal cells. Therefore, a deeper insight into the role of MECs in the physiology and pathology of mammary glands would allow a better understanding of cancerogenesis mechanisms and possible application of specific MEC markers in the diagnosis and therapy of breast cancer.
Folia Morphol 2010; 69, 1: 1-14

Abstract

Mammary gland epithelium is composed of an inner layer of secretory cells (luminal) and an outer layer of myoepithelial cells (MEC) bordering the basal lamina which separates the epithelial layer from the extracellular matrix. Mature MECs morphologically resemble smooth muscle cells; however, they exhibit features typical for epithelial cells, such as the presence of specific cytokeratin filaments. During lactation, secretory cells synthesize milk components, which are collected in alveoli and duct lumen, and transported to the nipple as a result of MEC contraction. Although the induction of MEC contraction results from oxytocin action, also other, still unknown auto/paracrine mechanisms participate in the regulation of this process. As well as milk ejection, MECs are involved in mammary gland morphogenesis in all developmental stages, modulating proliferation and differentiation of luminal cells. They take part in the formation of extracellular matrix, synthesizing its components and secreting proteinases and their inhibitors. In addition, MECs are regarded as natural cancer suppressors, stabilizing the normal structure of the mammary gland, they secrete suppressor proteins (e.g. maspin) limiting cancer growth, invasiveness, and neoangiogenesis. The majority of malignant breast cancers are derived from luminal cells, whereas neoplasms of MEC origin are the most seldom and usually benign form of breast tumours. MECs are markedly resistant to malignant transformation and they are able to suppress the transformation of neigh boring luminal cells. Therefore, a deeper insight into the role of MECs in the physiology and pathology of mammary glands would allow a better understanding of cancerogenesis mechanisms and possible application of specific MEC markers in the diagnosis and therapy of breast cancer.
Folia Morphol 2010; 69, 1: 1-14
Get Citation

Keywords

myoepithelial cell; mammary gland; milk ejection; breast cancer; myoepithelial tumours

About this article
Title

The myoepithelial cell: its role in normal mammary glands and breast cancer

Journal

Folia Morphologica

Issue

Vol 69, No 1 (2010)

Pages

1-14

Published online

2010-03-09

Bibliographic record

Folia Morphol 2010;69(1):1-14.

Keywords

myoepithelial cell
mammary gland
milk ejection
breast cancer
myoepithelial tumours

Authors

M. Sopel

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