Role Of Myoepithelial Cells Research Articles

Alteration of myoepithelial cells during botulinum toxin typeA-inhibited salivary secretion.

Intraglandular injection of botulinum toxin type A (BoNT/A) effectively treats sialorrhea. Myoepithelial cells (MECs) are essential for salivary secretion. The role of MECs in BoNT/A-inhibited salivary secretion, and its underlying mechanisms remain unknown. BoNT/A was injected into rat submandibular glands (SMGs). At 1, 2, 4, 8, and 12 weeks postinjection, salivary flow rate of SMGs was measured. Electron microscopy, immunohistochemistry, immunofluorescence, and Western blot analysis were used to detect morphological and functional changes in MECs and chemical denervation in SMGs. BoNT/A temporarily decreased salivary secretion in rat SMGs and this inhibitory effect lasted 4 weeks. During the inhibitory period, MECs atrophied and expressed reduced α-smooth muscle actin (α-SMA), vimentin, and phosphorylated myosin light chain 2 (p-MLC2), suggesting that BoNT/A attenuated MEC contractility. Furthermore, BoNT/A cleaved synaptosome-associated protein 25 (SNAP-25) and decreased the expression and activity of acetylcholinesterase (AChE), indicating that BoNT/A-induced chemical parasympathetic denervation of SMGs by cleaving SNAP-25. BoNT/A temporarily caused MEC atrophy and decreased MEC contractility in rat SMGs, which contributed to reversible inhibition of salivary secretion. The underlying mechanisms involved temporary parasympathetic denervation caused by SNAP-25 cleavage. These findings provide new insights into the mechanisms of BoNT/A-inhibited salivary secretion.

Abstract SY02-01: Regulators of in situ to invasive breast carcinoma progression.

Abstract A major clinical diagnostic criterion that differentiates in situ from invasive breast carcinoma is the presence of a continuous myoepithelial cell layer and basement membrane. In pre-invasive lesions such as DCIS, a relatively intact myoepithelial cell layer and basement membrane are still observed, but we have found that the molecular profiles of DCIS-associated myoepithelial cells are distinct from those from normal breast. The mechanisms underlying the loss of myoepithelial cells during the in situ to invasive breast carcinoma transition are unknown. We hypothesized that the differentiation of breast epithelial progenitors into myoepithelial cells is progressively inhibited by signals from tumor epithelial cells and cells composing the microenvironment such as fibroblasts and leukocytes. As a consequence, the myoepithelial cell layer is progressively lost and eventually disappears resulting in progression to invasion. We have been testing this hypothesis by characterizing myoepithelial cells from normal human breast tissues from nulliparous and parous women, including BRCA1 and BRCA2 mutation carriers. To dissect the functional properties of different types of myoepithelial cells, we have been using the MCFDCIS xenograft model. Our results will not only improve the current understanding of the role of myoepithelial cells but also have the potential to provide new prognostic markers to predict risk of invasive progression in DCIS. Furthermore, our results may help identify new targets for chemoprevention aimed at decreasing the risk of invasive breast tumors. Citation Format: Kornelia Polyak. Regulators of in situ to invasive breast carcinoma progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr SY02-01. doi:10.1158/1538-7445.AM2013-SY02-01

Isolation, purification, culture and characterisation of myoepithelial cells from normal and neoplastic canine mammary glands using a magnetic-activated cell sorting separation system

Mammary gland tumours, the most common malignant neoplasm in bitches, often display myoepithelial (ME) cell proliferation. The aim of this study was to isolate, purify, culture and characterise ME cells from normal and neoplastic canine mammary glands. Monodispersed cells from three normal canine mammary glands and five canine mammary tumours were incubated with an anti-Thy1 antibody and isolated by magnetic-activated cell sorting (MACS). Cells isolated from two normal glands (cell lines CmME-N1 and CmME-N2) and four tumours (cell lines CmME-K1 from a complex carcinoma, CmME-K2 from a simple tubulopapillary carcinoma, and CmME-K3 and CmME-K4 from two carcinomas within benign tumours) were cultured in supplemented DMEM/F12 media for 40days. Cell purity was >90%. Tumour-derived ME cell lines exhibited heterogeneous morphology, growth patterns and immunocytochemical expression of cytokeratins, whereas cell lines from normal glands retained their morphology and levels of cytokeratin expression during culture. Cell lines from normal glands and carcinomas within benign tumours grew more slowly than those from simple and complex carcinomas. This methodology has the potential to be used for in vitro analysis of the role of ME cells in the growth and progression of canine mammary tumours.

Abstract P6-02-06: A 3D tri-culture model of normal mammary gland. A tool for breast cancer initiation studies

Abstract The mechanisms involved in breast cancer initiation are not well understood. This may in part be due to a lack of an in vitro model that faithfully recapitulates the morphology, phenotype and in vivo architecture of the human mammary gland. Most in vitro models of normal breast have relied on the use of reconstituted basement membrane gels to induce luminal epithelial cell polarity and have neglected the role of myoepithelial cells and fibroblasts in this process. We aimed to develop a 3D in vitro culture system of normal breast which includes three of the major functional cell types embedded in a more physiologically relevant collagen 1 matrix. We used this system to investigate the mechanisms behind breast cancer initiation via genetic manipulation of some well known oncogenes and tumour suppressors involved in breast cancer progression. Myoepithelial cells (Myo1089) and fibroblasts (generated in house) were isolated and immortalised from breast reduction mammoplasty samples collected with ethical approval. Following characterisation, these were virally transfected with Enhanced Green Fluorescent Protein (EGFP) and dsRed protein respectively to enable tracking. 3D cultures were established in collagen 1 and included the non-tumorigenic luminal epithelial cell line HB2, EGFP Myo1089 cells and dsRed fibroblasts. Cells were cultured for 3 weeks in Transwell™ cell culture inserts. Following fixation these were analysed by H&E, confocal microscopy and immunohistochemistry. Morphology and immunostaining profiles were compared to sections of normal breast tissue. Immunohistochemical characterisation using the following antibodies: E-cadherin, epithelial membrane antigen, vimentin, laminin 5, collagen 4 plus luminal and basal cytokeratins, demonstrated polarised epithelial structures with lumen formation and basement membrane production with a similar immunostaining profile to normal breast tissue. The importance of including myoepithelial cells and fibroblasts in maintaining these structures was demonstrated. We established this model is amenable to genetic manipulation by overexpressing Her2 in HB2 cells, and knocking out ERβ1 in EGFP Myo1089 cells and Rac1 and Dock4 in dsRed fibroblast cell lines using shRNA techniques. These were included in separate models with morphological and phenotypic effects determined by confocal microscopy. In summary we have developed an in vitro model of normal breast tissue that includes three of the major functional breast cell types cultured in a physiologically relevant 3D matrix. We have validated the morphology and protein expression profile against human breast tissue specimens and confirm that this is a suitable model of normal breast. The model is suitable for experimental manipulation and cell behaviour can be easily visualised using standard laboratory techniques. We conclude this is a robust in vitro model of normal breast tissue offering an alternative cost-effective method of studying genes involved in breast cancer initiation. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-02-06.

Epithelial-mesenchymal Transition in Canine Mammary Tumours: The Role of Myoepithelial Cells

Epithelial-mesenchymal Transition in Canine Mammary Tumours: The Role of Myoepithelial Cells

In vitro influence of the extracellular matrix in myoepithelial cells stimulated by malignant conditioned medium

In order to investigate the role of myoepithelial cell and tumor microenvironment in salivary gland neoplasma, we have performed a study towards the effect of different extracellular matrix proteins (basement membrane matrix, type I collagen and fibronectin) on morphology and differentiation of benign myoepithelial cells from pleomorphic adenoma cultured with malignant cell culture medium from squamous cell carcinoma. We have also analyzed the expression of α-smooth muscle actin (α-SMA) and FGF-2 by immunofluorescence and qPCR. Our immunofluorescence results, supported by qPCR analysis, demonstrated that α-SMA and FGF-2 were upregulated in the benign myoepithelial cells from pleomorphic adenoma in all studied conditions on fibronectin substratum. However, the myoepithelial cells on fibronectin substratum did not alter their morphology under malignant conditioned medium stimulation and exhibited a stellate morphology and, occasionally focal adhesions with the substratum. In summary, our data demonstrated that the extracellular matrix exerts an important role in the morphology of the benign myoepithelial cells by the presence of focal adhesions and also inducing increase FGF-2 and α-SMA expression by these cells, especially in the fibronectin substratum.

FGF-2 is overexpressed in myoepithelial cells of carcinoma ex-pleomorphic adenoma in situ structures

Increasing emphasis has been placed on the role of myoepithelial cells, the contractile components of secretory glands, in the in situ to invasive carcinoma transition. These cells are placed at the interface between luminal epithelial cells and the stromal compartment, which favors their cross-talk with all other cell types comprising the tumor micro-environment. To obtain some clues about this cross-talk and also to better understand our previous immunoprofile study of myoepithelial cells in salivary gland carcinoma ex-pleomorphic adenoma (CXPA), we investigated FGF-2 expression in CXPA in situ structures as well as in cells cultured under conditions attempting to simulate the cellular interactions of this tumor stage. We have observed by immunohistochemistry that myoepithelial cells of CXPA in situ structures overexpress FGF-2. In addition, our results supported by qPCR and Western blotting, demonstrated that the expression of FGF-2 in the benign myoepithelial cells was in fact increased by stimulation with the conditioned medium from malignant cells. Low molecular weight FGF-2, known to be primarily released from the cells to exert its biological activity through receptors, was the predominant FGF-2 form detected in the benign myoepithelial cells. Specific FGF-2 receptors were found in the malignant epithelial but not in the benign myo-epithelial cells of CXPA, indicating a paracrine role for benign myoepithelial cell-derived FGF-2. Abnormal paracrine myo-epithelial/epithelial cell interactions and also myoepithelial/ stromal cell interactions could favor tumor growth, invasion and metastasis.

Role of myoepithelial cells in breast tumor progression

Myoepithelial cells form a semi-continuous protective sheet separating the human breast epithelium and the surrounding stroma. They suppress stromal invasion of tumor cells by the secretion of various anti-angiogenic and anti-invasive factors. The disruption of this cell layer results in the release of the growth factors, angiogenic factors, and reactive oxygen species causing an alteration in the microenvironment. This helps in the proliferation of surrounding cells and increases the invasiveness of tumor cells. Two theories are proposed for the mechanism of tumor epithelial cells progression from in situ to invasive stage. According to the first theory, tumor cell invasion is triggered by the overproduction of proteolytic enzymes by myoepithelial cells and surrounding tumor cells. The second theory states that tumor invasion is a multistep process, the interactions between damaged myoepithelial cells and the immunoreactive cells trigger the release of basement membrane degrading enzymes causing tumor progression. Further studies in understanding of molecular mechanism of myoepithelial cell functions in tumor suppression may lead to the identification of novel therapeutic targets for breast cancer.

Assessment of angiogenesis by CD105 antigen in epithelial salivary gland neoplasms with diverse metastatic behavior

BackgroundInformation on the biology of metastasis development in salivary gland tumors is scarce. Since angiogenesis seems associated with this phenomenon in other tumors, we sought to compare salivary gland tumors with diverse metastatic behavior in order to improve the knowledge and management of these lesions.MethodsSamples from the most important salivary gland tumors were segregated according to its metastatic behavior and submitted to routine immunohistochemistry to identify vessels positive for CD105 expression. Frequency of positive cases and intratumoral microvessel density (IMD) was compared among the group of lesions.ResultsCD105 positive vessels were absent in normal salivary gland tissue, were rare in pleomorphic adenomas and adenoid cystic carcinomas (ACC), more common in polymorphous low-grade adenocarcinomas and highest in mucoepidermoid carcinomas. Only ACC with such feature were metastatic. IMD was higher in malignant rather than benign tumors.ConclusionImmunostaining of CD105 in salivary gland tumors implies participation of angiogenesis in the development of malignant lesions, as well as some role for myoepithelial cells in the control of new vessel formation. In addition, suggest that ACC with positive CD105 vessels are at higher risk for metastasis.

Introduction: The Role of Myoepithelial Cells in Integration of Form and Function in the Mammary Gland

The importance of the microenvironment and context in regulation of tissueand organ-specific functions, as well as in progression to malignancy, is beginning to be recognized by the larger scientific community. It is true that no cell is an island, and this fact has been clearly demonstrated for the mammary gland, an organ that has provided much of the pioneering work in this area and lends itself to detailed analysis of the molecular mechanisms involved. This issue of Journal of Mammary Gland Biology and Neoplasia was conceived to bring more balance to the research on the breast and breast diseases. For decades, there has been an overwhelming emphasis on the luminal epithelial/secretory cells of the mammary gland, but the myoepithelial cell has largely been ignored. Even when believed to be important, its significance has been explored only in lactation, where it facilitates milk secretion via oxytocin-induced contraction. Only recently has a serious study of the myoepithelial cell as a legitimate contributor to normal function and breast cancer begun. The invited chapters in this issue show that until we begin to see the breast as the integrated organ that it is, we will not be able to understand either breast cancer or normal breast function. This integration is not just among the different cell types of the

Participation and role of myoepithelial cells in benign and malignant salivary gland tumors

Participation and role of myoepithelial cells in benign and malignant salivary gland tumors

PAPILLARY CYSTADENOCARCINOMA OF SALIVARY-GLANDS - AN IMMUNOHISTOCHEMICAL STUDY

The immunohistochemical features of 16 cases of papillary cystadenocarcinoma of salivary glands using a panel of monoclonal and polyclonal antibodies were evaluated. The specimens were from patients postoperatively diagnosed as papillary cystadenocarcinoma of salivary glands where the age of the patients ranged from 20-70 years, males were more commonly affected than the females and parotid gland was the most commonly affected site. The cytokeratins detected by MoAb KL1 and K8.12 were positive in all cases showing a heterogeneity in intensity of reaction. A coexpression of vimentin with cytokeratin was found in 10 cases. The tumor cells had a coexpression of S-100 protein and neuron specific enolase (NSE). Glial fibrillary acidic protein (GFAP) was positive in one case with multiple expression of cytokeratins, vimentin NSE, S-100 protein. The polymorphic mucin MAM-6 was positive in all cases and MAM-3 in 8 cases showing different intensity of reaction. The tumor cells were positive for lysozyme (8 cases), lactoferrin (10 cases) and alpha-1-antichymotrypsin (10 cases). The immunoreactive c-erbB-2 oncoprotein on the cell surface membrane was detected in 2 cases. The labeling index of proliferating cell nuclear antigen in the tumor cells ranged from 3.8 to 43.2% (mean 14.2 +/- standard deviation 9.8). Histopathological feature and a heterogeneity of multiple expression of tissue markers may suggest that a population of cells in papillary cystadenocarcinoma may be counterparts of modified myoepithelial cells of pleomorphic adenoma that express epithelial, mesenchymal and neuronal differentiation although the role of myoepithelial cells in the genesis of this tumor is not clear. However, disorganized stratification and malignant transformation of ductal cells may be the most likely possibility in the histogenesis of this tumor.

The role of myoepithelial cells in the morphogenesis of pleomorphic adenomas of the salivary glands and their identification

The morphogenesis of 15 pleomorphic adenomas was studied. Identification of myoepithelial cells was carried out by immunohistochemical method using polyclonal antibodies to myosin, human carbonic anhydrase III, monoclonal antibodies to proteins of intermediate filaments of cytokeratin polypeptides No. 8 (clone H 1), No. 17 (clone E 3) and No. 18 (clone C 12). Myoepithelial, epithelial and other cells are involved in the morphogenesis of the studied tumors. It is recommended to use antibodies to myosin, carbonic anhydrase III, keratins No. 8, 17, 18 in the diagnosis of pleomorphic adenomas of the salivary glands.

Spindle cell carcinoma of the breast

A case of spindle cell carcinoma of the breast in association with myoepithelial cell hyperplasia is presented. Immunocytochemistry demonstrated labelling of tumour cells for cytokeratin, vimentin and S-100 protein. Electronmicroscopy showed desmosomes and bundles of tonofilaments as well as fine filaments in the cytoplasm. The findings in the present case point to the metaplastic spindle cell nature of squamous carcinoma of the breast. The possible role of myoepithelial cells in the origin of the spindle cell component is discussed.

The role of myoepithelial cells in the morphogenesis of induced mammary tumours

The localization and cytomorphology of myoepithelial (ME) cells and their role in the morphogenesis of the mammary gland tumours of Wistar rats induced by 7,12-Dimethylbenz-a-anthracene-DMBA- were studied. Cells which do not participate in secretion and contain cytoplasmic myofibrillar bundles in a typical arrangement are considered to be of ME origin. In the histogenesis of induced mammary gland tumours no difinite role can be attributed to mature ME cells or their precursors. Decreased differentiation is associated with reduced numbers of ME cells. No ME cells can be detected in the anaplastic, stromafree portions of the solid tumour. The sarcomatous component of the induced carcinosarcomas originates from connective tissue. ME cells may give rise to leiomyoma-like tumours comparable with the human benign mammary myoepithelioma. The atrophic areas of mammary gland tumours consisted mostly of preserved ME cells. The ME cells of induced mammary gland tumours were, in every respect, identical with the normal ME cells of control mammary glands.

Role of myoepithelial cells in the development of salivary gland tumors.

It has been shown that myoepithelial cells play an important role in the composition and growth of many salivary gland tumors. Increased knowledge of this fact leads to a better understanding of the confusing complexity in the morphology of salivary gland tumors.