Browsing by Subject "Human breast"

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    Changed lineage composition is an early event in breast carcinogenesis
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2013) Hilton, Heidi N.; Kantimm, Silke; Graham, J. Dinny; Clarke, Christine L.
    The epithelium compartment of the human breast is made up of a branching ductal-lobular system, which is lined by a single layer of luminal epithelial cells surrounded by contractile myoepithelial cells. The coordinated development of these two cell types, and maintenance of their relative proportions, is fundamentally important for normal breast morphogenesis. Changes in cell type composition is one of the hallmark features of breast cancer progression, and the vast majority of breast tumors are comprised of luminal cells only, with a complete absence of myoepithelial cells. Despite this striking alteration in relative proportions of luminal and myoepithelial cells in invasive breast cancers compared with normal breast tissue, the steps in this dramatic change in cellular composition remain poorly characterised, nor is it known whether loss of myoepithelial cells is an early event in carcinogenesis. In a panel of breast tissues, we quantitated the proportion of luminal cells relative to the surrounding myoepithelial cell layer in a panel of normal and pre-invasive breast tissue samples, including lesions with proliferative disease without atypia (PDWA), columnar cell lesions (CCL), atypical ductal hyperplasia (ADH), and DCIS, and correlated these findings with proliferation in the same lesions. The study findings showed that changes in lineage composition correlate with increased proliferation, and are one of the earliest events in breast carcinogenesis. Therefore not only are myoepithelial cells important in distinguishing between invasive and non-invasive tumors, their relative proportion compared with luminal cell numbers may provide a new potential indicator of which premalignant lesions are at higher risk of progression to invasive disease.
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    Expression of enzymes involved in synthesis and metabolism of estradiol in human breast as studied by immunocytochemistry and in situ hybridization
    (Murcia : F. Hernández, 2009) Li, Zhuo; Luu-The, Van; Poisson-Paré, David; Ouellet, Johanne; Li, Songyun; Labrie, Fernand; Pelletier, Georges
    It is well documented that human breast is actively involved in the local formation of estrogens. To determine the site(s) of action of enzymes involved in synthesis and metabolism of the most potent estrogen estradiol (E2), we have studied the expression of the following enzymes: 3ß-hydroxysteroid dehydrogenase (3-HSD), 17ß-HSD types 1, 2, 5, 7 and 12, aromatase, steroid sulfatase (STS) and estrogen sulfotransferase (EST) 1E1 at the cellular level in breast. Both in situ hybridization and immunocytochemistry were used for enzyme localization in normal breast tissues. For immunocytochemistry, we used rabbit antibodies, while in situ hybridization studies were performed using (35S)- labeled cRNA probes. Similar results were obtained with both approaches. All the enzymes (3ß-HSD; 17ß-HSD types 1, 5, 7 and 12; aromatase) involved in the conversion of circulating dehydroepiandrosterone (DHEA) to E2 as well as STS which converts estradiol sulfate (E2-S) to E2 have been found to be expressed in epithelial cells of acini and/or ducts as well as the stromal cells. Moreover, 17ß-HSD type 2 and EST1E1, two enzymes which inactivate E2, have been also localized in the same cell types. The present results indicate the enzymes which play a role in the synthesis and metabolism of E2 are expressed in both epithelial and stromal cells in human breast.