Inductive signals in branching morphogenesis - lessons from mammary and salivary glands.

Branching morphogenesis is a fundamental developmental program that generates large epithelial surfaces in a limited three-dimensional space. It is regulated by inductive tissue interactions whose effects are mediated by soluble signaling molecules, and cell-cell and cell-extracellular matrix interactions. Here, we will review recent studies on inductive signaling interactions governing branching morphogenesis in light of phenotypes of mouse mutants and ex vivo organ culture studies with emphasis on developing mammary and salivary glands. We will highlight advances in understanding how cell fate decisions are intimately linked with branching morphogenesis. We will also discuss novel insights into the molecular control of cellular mechanisms driving the formation of these arborized ductal structures and reflect upon how distinct spatial patterns are generated.

The female adolescent breast: disorders of development.

PURPOSE OF REVIEW: This article will provide an overview on female breast development and focus on common abnormalities of growth, the emerging role of breast self-awareness, and discuss trends in the evaluation and treatment of the breast masses and disorders most often encountered in the female adolescent population. RECENT FINDINGS: Although the embryology of breast development is unchanged, data are emerging on the role of environmental factors on the timing of puberty and thelarche. As breast development occurs, the role of breast self-awareness is also a new trend that allows teens to be cognizant of changes in their own breast and to become more comfortable with their own anatomy. Finally, when breast treatments are needed or desired, the timing of breast treatments is a subject that must be individualized. SUMMARY: There are numerous conditions that can result from disruption of normal breast development. These resultant breast disorders are generally benign but can still cause emotional distress to both the patient and family. It is thus imperative that healthcare providers be educated on breast development, the common breast masses that occur in the adolescent population and be prepared to discuss breast self-awareness and shared decision-making in this population.

Membrane-tethered syntaxin-4 locally abrogates E-cadherin function and activates Smad signals, contributing to asymmetric mammary epithelial morphogenesis.

Spatial and temporal epithelial-mesenchymal transition (EMT) is a critical event for the generation of asymmetric epithelial architectures. We found that only restricted cell populations in the morphogenic mammary epithelia extrude syntaxin-4, a plasmalemmal t-SNARE protein, and that epithelial cell clusters with artificial heterogenic presentation of extracellular syntaxin-4 undergo asymmetric morphogenesis. A previous study revealed that inducible expression of cell surface syntaxin-4 causes EMT-like cell behaviors in the clonal mammary epithelial cells, where laminin-mediated signals were abolished so that cells readily succumb to initiate EMT. The present study added new mechanistic insight into syntaxin-4-driven EMT-like cell behaviors. Extracellular syntaxin-4 directly perturbs E-cadherin-mediated epithelial cell-cell adhesion and activates Smad signals. We found that the epithelial cells activated Smad2/3 upon induction of expression of extracellular syntaxin-4, leading to the upregulation of certain transcriptional targets of these TGF-ß signaling mediators. Intriguingly, however, mRNA expression of canonical EMT initiators, such as Snail and Slug, was unchanged. In addition, E-cadherin protein was steeply decreased, yet its transcriptional expression remained constant for a couple of days. We found that extracellular syntaxin-4 directly bound to E-cadherin and sequestered ß-catenin from cell-cell contact sites, perturbing intercellular adhesive property. The functional ablation of E-cadherin by syntaxin-4 was further validated by L cells with stably expressing E-cadherin, in which cells shows intercellular adhesive property solely by E-cadherin. These results underline the role of local exportation of syntaxin-4 for onset of complex epithelial morphogenesis.

Transcriptional coregulator RIP140: an essential regulator of physiology.

Transcriptional coregulators drive gene regulatory decisions in the transcriptional space. Although transcription factors including all nuclear receptors provide a docking platform for coregulators to bind, these proteins bring enzymatic capabilities to the gene regulatory sites. RIP140 is a transcriptional coregulator essential for several physiological processes, and aberrations in its function may lead to diseased states. Unlike several other coregulators that are known either for their coactivating or corepressing roles, in gene regulation, RIP140 is capable of acting both as a coactivator and a corepressor. The role of RIP140 in female reproductive axis and recent findings of its role in carcinogenesis and adipose biology have been summarised.

The Blood Supply of the Breast Revisited.

BACKGROUND: Many surgeons are under the impression that the blood supply is clearly defined in textbooks. Unfortunately, the majority of textbooks supply inadequate information and illustrations can be misleading in many instances. None of the textbooks describe a segmental pattern of blood supply when in actual fact a basic segmental pattern does exist. The reason for inadequate information is the perpetuation of facts since the work of the pioneers Cooper and Manchot from one textbook to another. A paucity of research studies thereafter and the fact that the results of some of these studies did not find their way into textbooks is another contributing factor. METHODS: The findings of research studies since the descriptions by Cooper and Manchot are analyzed and compared in an effort to find common ground and its clinical implication. RESULTS: Researchers concurred on the main sources of blood supply; these are internal thoracic, lateral thoracic, anterior intercostal, and acromiothoracic (thoracoacromial) arteries. However, the different research studies showed considerable variation in the branches from the main sources to supply the nipple-areola complex. CONCLUSIONS: Even though the locations of the main sources of blood supply are constant, partial or complete absence of branches from the main sources does occur and therefore the blood supply to the nipple-areola complex is unpredictable. Cognizance of the basic segmental pattern and the variations resulting from embryologic development will be helpful for the surgeon to use or adapt a technique to minimize the risk of nipple necrosis.

Pluripotency Genes and Their Functions in the Normal and Aberrant Breast and Brain.

Pluripotent stem cells (PSCs) attracted considerable interest with the successful isolation of embryonic stem cells (ESCs) from the inner cell mass of murine, primate and human embryos. Whilst it was initially thought that the only PSCs were ESCs, in more recent years cells with similar properties have been isolated from organs of the adult, including the breast and brain. Adult PSCs in these organs have been suggested to be remnants of embryonic development that facilitate normal tissue homeostasis during repair and regeneration. They share certain characteristics with ESCs, such as an inherent capacity to self-renew and differentiate into cells of the three germ layers, properties that are regulated by master pluripotency transcription factors (TFs) OCT4 (octamer-binding transcription factor 4), SOX2 (sex determining region Y-box 2), and homeobox protein NANOG. Aberrant expression of these TFs can be oncogenic resulting in heterogeneous tumours fueled by cancer stem cells (CSC), which are resistant to conventional treatments and are associated with tumour recurrence post-treatment. Further to enriching our understanding of the role of pluripotency TFs in normal tissue function, research now aims to develop optimized isolation and propagation methods for normal adult PSCs and CSCs for the purposes of regenerative medicine, developmental biology, and disease modeling aimed at targeted personalised cancer therapies.

The mammary stem cell hierarchy: a looking glass into heterogeneous breast cancer landscapes.

The mammary gland is a dynamic organ that undergoes extensive morphogenesis during the different stages of embryonic development, puberty, estrus, pregnancy, lactation and involution. Systemic and local cues underlie this constant tissue remodeling and act by eliciting an intricate pattern of responses in the mammary epithelial and stromal cells. Decades of studies utilizing methods such as transplantation and lineage-tracing have identified a complex hierarchy of mammary stem cells, progenitors and differentiated epithelial cells that fuel mammary epithelial development. Importantly, these studies have extended our understanding of the molecular crosstalk between cell types and the signaling pathways maintaining normal homeostasis that often are deregulated during tumorigenesis. While several questions remain, this research has many implications for breast cancer. Fundamental among these are the identification of the cells of origin for the multiple subtypes of breast cancer and the understanding of tumor heterogeneity. A deeper understanding of these critical questions will unveil novel breast cancer drug targets and treatment paradigms. In this review, we provide a current overview of normal mammary development and tumorigenesis from a stem cell perspective.

SLUG: Critical regulator of epithelial cell identity in breast development and cancer.

SLUG, a member of the SNAIL family of transcriptional repressors, is known to play a diverse number of roles in the cell, and its deregulation has been observed in a variety of cancers including breast. Here, we focus on SLUG's role as a master regulator of mammary epithelial cell (MEC) fate and lineage commitment in the normal mammary gland, and discuss how aberrant SLUG expression can influence breast tumor formation, phenotype, and progression. Specifically, we discuss SLUG's involvement in MEC differentiation, stemness, cellular plasticity, and the epithelial to mesenchymal transition (EMT), and highlight the complex connection between these programs during development and disease progression. Undoubtedly, delineating how molecular factors influence lineage identity and cell-state dynamics in the normal mammary gland will contribute to our understanding of breast tumor heterogeneity.

Stromal regulation of embryonic and postnatal mammary epithelial development and differentiation.

The stroma, which is composed of supporting cells and connective tissue, comprises a large component of the local microenvironment of many epithelial cell types, and influences several fundamental aspects of cell behaviour through both tissue interactions and niche regulation. The significance of the stroma in development and disease has been increasingly recognised. Whereas normal stroma is essential for various developmental processes during vertebrate organogenesis, it can be deregulated and become abnormal, which in turn can initiate or promote a disease process, including cancer. The mouse mammary gland has emerged in recent years as an excellent model system for understanding stromal function in both developmental and cancer biology. Here, we take a systematic approach and focus on the dynamic interactions that the stroma engages with the epithelium during mammary specification, cell differentiation, and branching morphogenesis of both the embryonic and postnatal development of the mammary gland. Similar stromal-epithelial interactions underlie the aetiology of breast cancer, making targeting the cancer stroma an increasingly important and promising therapeutic strategy to pursue for breast cancer treatment.

The adolescent female: Breast and reproductive embryology and anatomy.

Congenital breast and genital tract anomalies are seen frequently in the care of children and adolescents. Breast and internal gynecologic anomalies more often present in adolescence than in early childhood. Management is best delivered through a multidisciplinary team approach. Carefully timed surgical intervention is of importance to optimize psychological, aesthetic and functional outcomes. An understanding of the female breast and genital tract embryology and anatomy is important for a meticulous clinical examination and appropriate surgical treatment. This article will review the normal embryology and anatomy of the adolescent female breast and genital tract.

Breast diseases in adolescents.

Fibroadenomas and breast growth disorders are the most common breast diseases in adolescent women. Assessment of breast disorders in this age group generally involves clinical evaluation through history and physical examination and when is needed ultrasonography. Due to the absence of breast cancer in adolescent women, it is easy to reassure women at the first consultation. Breast growth disorders can lead great psychological and physical embarrassment. Treatment consists of surgical procedures when the cosmetic defect is severe. According to the ANDI classification, small fibroadenomas are normal, clinical fibroadenomas are a mild aberration of the normal processes, and giant or multiple fibroadenomas are placed to the disease end of the spectrum. Fibroadenomas can be treated conservatively provided diagnosis is confident. Giant fibroadenomas are treated by surgical enucleation. Breast abscess is mainly due to the duct ectasia. In adolescence, ectasia has been described as an exaggeration of sinus duct development and can be considered as a variant of normality. Diseases of the adolescent breast are usually benign and their management are simple using medical strategy and more rarely surgical therapy.

Novel image analysis approach quantifies morphological characteristics of 3D breast culture acini with varying metastatic potentials.

Prognosis of breast cancer is primarily predicted by the histological grading of the tumor, where pathologists manually evaluate microscopic characteristics of the tissue. This labor intensive process suffers from intra- and inter-observer variations; thus, computer-aided systems that accomplish this assessment automatically are in high demand. We address this by developing an image analysis framework for the automated grading of breast cancer in in vitro three-dimensional breast epithelial acini through the characterization of acinar structure morphology. A set of statistically significant features for the characterization of acini morphology are exploited for the automated grading of six (MCF10 series) cell line cultures mimicking three grades of breast cancer along the metastatic cascade. In addition to capturing both expected and visually differentiable changes, we quantify subtle differences that pose a challenge to assess through microscopic inspection. Our method achieves 89.0% accuracy in grading the acinar structures as nonmalignant, noninvasive carcinoma, and invasive carcinoma grades. We further demonstrate that the proposed methodology can be successfully applied for the grading of in vivo tissue samples albeit with additional constraints. These results indicate that the proposed features can be used to describe the relationship between the acini morphology and cellular function along the metastatic cascade.

Cofilin is required for organization of sarcomeric actin filaments in chicken skeletal muscle cells.

Cofilin is an actin regulatory protein that plays a critical role in actin filament dynamics in a variety of cells. We have previously demonstrated that excess cofilin in skeletal muscle cells leads to disruption of actin filaments, followed by actin-cofilin rod formation in the cytoplasm. In this study, to further clarify the role of cofilin in actin assembly during myofibrillogenesis, cofilin expression was suppressed in cultured chicken skeletal muscle cells. First, we confirmed that turnover of cofilin in myotubes was much higher than that of actin, and that the cofilin level could be decreased drastically within 2 days when cofilin de novo synthesis was suppressed. Next, cofilin expression in individual myotubes was suppressed by introducing antisense morpholino oligonucleotides into the cells by microinjection. Cofilin depletion at the early phase of myofibrillogenesis caused abnormal actin aggregates in myotubes and impaired actin organization into cross-striated myofibril structures. However, when cofilin expression was suppressed in developed myotubes, actin localization in striated myofibrils was scarcely affected. These results indicate that cofilin plays a critical role in the regulation of actin assembly at the early process of myofibrillogenesis.

Human breast development.

This review is intended to give an overview of current knowledge on human breast development. It focuses on the limitations of our understanding on the origins of human breast cancer in the context of this mainly morphological and static assessment of what is known about human breast development. The world literature is very limited and caution is needed in drawing analogies with the mouse. There is an increasing emphasis on research to understand normal stem cells in the breast on the assumption that these are the targets for the initiation of breast cancer. It is thus a priority to understand normal human breast development, but there are major obstacles to such studies mainly due to ethical considerations and to tissue acquisition.

Yin Yang 1 positively regulates BRCA1 and inhibits mammary cancer formation.

Expression of the breast cancer-associated gene 1 (BRCA1) in sporadic breast cancers is usually reduced, yet the underlying mechanisms remains elusive. To identify factors that are responsible for reduced BRCA1 expression, we screened 92 known transcription factors for their ability to regulate expression of BRCA1. Among several potential regulators, the Gli-Krueppel-related transcription factor Yin Yang 1 (YY1) showed the most dramatic transactivation of the BRCA1 promoter. YY1 binds to the promoter of BRCA1, and its overexpression resulted in increased expression of BRCA1 and a number of BRCA1 downstream genes. We further showed that overexpression of YY1 in cancer cells inhibited cell proliferation, foci formation and tumor growth in nude mice. To assess the clinical relevance between YY1 and BRCA1, we studied expression of YY1 and BRCA1 from human breast cancer samples and tissue arrays, and detected a significant positive correlation between the level of YY1 and BRCA1 expression in these cancers. Taken together, these findings suggest that YY1 is a key regulator of BRCA1 expression and may be causally linked to the molecular etiology of human breast cancer.

[Accessory breast on the vulva]. / Mama ectópica vulvar.

We describe a 24-year-old woman with a subcutaneous swelling in the left inferior pubic region. Histology revealed ectopic breast tissue. Vulvar tumors are uncommon and the presence of ectopic breast tissue in this region is extremely rare. In these cases, patients usually consult for a mass that varies in size with hormonal changes, typically during pregnancy or breast-feeding, or that has associated neoplastic changes. In our patient, the mass had grown progressively with no identifiable underlying hormonal association or neoplasm. We therefore classified it as ectopic breast tissue presenting as a subcutaneous mass.

Insulin-like growth factor binding proteins and mammary gland development.

Mammary gland development is dependent upon insulin-like growth factors (IGFs) as survival factors. The actions of the IGFs are modulated by a family of IGF-binding proteins (IGFBP1-6). Expression of the IGFBPs is both time-dependent and cell-specific during both the developmental phases and the involution of the mammary gland. Although studied extensively in vitro, understanding the roles of IGFBPs in vivo has been difficult, largely due to the fact that IGFBP knock-out mice have no dramatic phenotypes. This review examines the evidence from in vitro studies and the attempts to examine in vivo actions utilising models with IGFBP deficiency or over-expression. In vitro studies demonstrate that IGFBPs can act by inhibition of the survival effects of IGFs, as well as by enhancing the effects of IGFs. Because the IGFBPs are found associated with the extracellular matrix, a role for IGFBPs as a reservoir of IGFs or, alternatively as a potential barrier to IGFs, thereby restricting their entry into particular tissues or cellular compartments was postulated. We also provide evidence with respect to the IGF-independent actions of the IGFBPs which include receptors, nuclear localization, and interaction with the extracellular matrix and cell surface proteins including integrins. We believe that recent findings place some of the IGFBPs in a larger family of extracellular proteins, the secreted cysteine-rich protein (CCN) family, which have similar structural domains (involved in binding to IGFs, extracellular matrix and integrins) and are heavily implicated in tissue re-modeling and morphogenesis.

P-cadherin role in normal breast development and cancer.

P-cadherin is a cell-cell adhesion molecule, whose expression is highly associated with undifferentiated cells in normal adult epithelial tissues, as well as with poorly differentiated carcinomas. Its expression has been already reported in human embryonic stem cells and it is presumed to be a marker of stem or progenitor cells of some epithelial tissues. In normal breast, P-cadherin has an essential role during ductal mammary branching, being expressed by the monolayer of epithelial cap cells at the end buds. In mature mammary tissue, its expression is restricted to the myoepithelium; it has been postulated that it may also be present in early luminal progenitor cells. In breast cancer, P-cadherin is frequently overexpressed in high-grade tumours, being a well-established indicator of poor patient prognosis. It has been reported as an important inducer of cancer cell migration and invasion, with underlying molecular mechanisms involving the signalling mediated by its juxtamembrane domain, the secretion of matrix metalloproteases to the extracellular media, and the cleavage of a P-cadherin soluble form with pro-invasive activity. Intracellularly, this protein interferes with the endogenous cadherin/catenin complex, inducing p120-catenin delocalization to the cytoplasm, and the consequent activation of Rac1/Cdc42 and associated alterations in the actin cytoskeleton. Considering P-cadherin's role in cancer cell invasion and metastasis formation, a humanized monoclonal antibody was recently produced to antagonize P-cadherin-associated signalling pathways, which is currently under Phase I clinical trials. In this review, the most important findings about the role of P-cadherin in normal breast development and cancer will be illustrated and discussed, with emphasis on the most recent data.

Stem cells and breast cancer, where we are? A concise review of literature.

There is an analogy between embryogenesis and cancer and the attention is on increasing the rate of cell division and on a small percentage of perennial cells . The key to understanding is to be found in the properties of these cells developed in the form of perennial totipotency, multipotency and unipotent. The normal life cycle involves epigenetic mechanisms that are deregulated in cancer cells, these tumor cells appear to belong to deregulation since its progeny. Here is a review of the literature on embryogenesis of the breast, endocrine system interactions Delna the proper development and functioning of the various cell lines and to the importance of cancer stem cells.

Methods in Mammary Gland Development and Cancer: the second ENDBC meeting--intravital imaging, genomics, modeling and metastasis.

The second meeting of the European Network for Breast Development and Cancer (ENBDC) on 'Methods in Mammary Gland Development and Cancer' was held in April 2010 in Weggis, Switzerland. The focus was on genomics and bioinformatics, extracellular matrix and stroma-epithelial cell interactions, intravital imaging, the search for metastasis founder cells and mouse models of breast cancer.