RESUMEN
Understanding the mechanisms of cancer initiation will help to prevent and manage the disease. At present, the role of the breast microenvironment in transformation remains unknown. As BMP2 and BMP4 are important regulators of stem cells and their niches in many tissues, we investigated their function in early phases of breast cancer. BMP2 production by tumor microenvironment appeared to be specifically upregulated in luminal tumors. Chronic exposure of immature human mammary epithelial cells to high BMP2 levels initiated transformation toward a luminal tumor-like phenotype, mediated by the receptor BMPR1B. Under physiological conditions, BMP2 controlled the maintenance and differentiation of early luminal progenitors, while BMP4 acted on stem cells/myoepithelial progenitors. Our data also suggest that microenvironment-induced overexpression of BMP2 may result from carcinogenic exposure. We reveal a role for BMP2 and the breast microenvironment in the initiation of stem cell transformation, thus providing insight into the etiology of luminal breast cancer.
Asunto(s)
Proteína Morfogenética Ósea 2/genética , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/genética , Neoplasias de la Mama/genética , Transformación Celular Neoplásica/genética , Amplificación de Genes , Células Madre Neoplásicas/metabolismo , Nicho de Células Madre/genética , Proteína Morfogenética Ósea 2/metabolismo , Receptores de Proteínas Morfogenéticas Óseas de Tipo 1/metabolismo , Proteínas Morfogenéticas Óseas/genética , Proteínas Morfogenéticas Óseas/metabolismo , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Carcinógenos/farmacología , Línea Celular Tumoral , Transformación Celular Neoplásica/efectos de los fármacos , Transformación Celular Neoplásica/metabolismo , Células Epiteliales/metabolismo , Células Epiteliales/patología , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Inmunohistoquímica , Transducción de Señal , Microambiente Tumoral/genéticaRESUMEN
Here we describe a protocol established in our laboratory to quantify early common progenitors/stem cells grown as spheres in non-adherent culture conditions. This protocol is based on the combination of two functional tests: the mammosphere assay to maintain and enrich early mammary progenitors/stem cells, and the epithelial colony-forming cells (E-CFC) assay to identify and quantify further differentiated epithelial progenitors. Primary spheres mainly contain progenitors and rare stem/early common progenitor cells while secondary and tertiary spheres contain progenitor cells derived from the early common progenitor/stem cell population maintained through passages and partially differentiated. Spheres are enzymatically and mechanically dissociated; the derived cells are subsequently plated on irradiated NIH-3T3 fibroblasts for further processing, as in the E-CFC assay. The principle of this assay is to quantify the number of epithelial colonies generated by cells present in the different sequential spheres. This assay has therefore been named ECP-DC, standing for Early Common Progenitor-Derived Colonies assay.
Asunto(s)
Técnicas de Cultivo de Célula/métodos , Glándulas Mamarias Humanas/citología , Esferoides Celulares/citología , Células Madre/citología , Adulto , Animales , Diferenciación Celular , Ensayo de Unidades Formadoras de Colonias , Humanos , Ratones , Células 3T3 NIH , Esferoides Celulares/metabolismo , Células Madre/metabolismo , Factores de TiempoRESUMEN
CD10 is a remarkable member of the major class of widely expressed cell surface proteins, endopeptidases. First identified in leukemia as a tumor-specific antigen (common acute lymphoblastic leukemia antigen), CD10 has become largely used in cancer diagnosis. However, its function in oncogenesis remains unclear. We previously identified CD10 as a tool to access sphere-forming cells and showed its involvement in mammary stem cell (SC) regulation. We further illustrated that its enzymatic activity is involved, through signaling peptides, in SC maintenance. Therefore, CD10 is not only a cell surface marker in normal and malignant contexts but also affects the extracellular environment and plays a key role in regulation of a number of biological functions and likely in SC. In tumors, the "niche" favors the survival of sheltered cancer SC whose eradication has become the new challenge in oncology. This highlights the importance of understanding the role of CD10 in cancer SC. We will review the characteristics, main functions, and mechanism of action of CD10. Finally, we will review its clinical use and involvement in cancer.
Asunto(s)
Neoplasias/etiología , Neprilisina/fisiología , Células Madre/fisiología , Animales , Humanos , Sistema Inmunológico/metabolismo , Sistema Inmunológico/fisiología , Glándulas Mamarias Humanas/metabolismo , Glándulas Mamarias Humanas/patología , Glándulas Mamarias Humanas/fisiología , Neoplasias/metabolismo , Neoplasias/patología , Neprilisina/genética , Neprilisina/metabolismo , Sistema Nervioso/metabolismo , Sistema Nervioso/patología , Fenómenos Fisiológicos del Sistema Nervioso/genética , Células Madre/metabolismo , Células Madre/patología , Microambiente Tumoral/genética , Microambiente Tumoral/fisiologíaRESUMEN
The major components of the mammary ductal tree are an inner layer of luminal cells, an outer layer of myoepithelial cells, and a basement membrane that separates the ducts from the underlying stroma. Cells in the outer layer express CD10, a zinc-dependent metalloprotease that regulates the growth of the ductal tree during mammary gland development. To define the steps in the human mammary lineage at which CD10 acts, we have developed an in vitro assay for human mammary lineage progression. We show that sorting for CD10 and EpCAM cleanly separates progenitors from differentiated luminal cells and that the CD10-high EpCAM-low population is enriched for early common progenitor and mammosphere-forming cells. We also show that sorting for CD10 enriches sphere-forming cells from other tissue types, suggesting that it may provide a simple tool to identify stem or progenitor populations in tissues for which lineage studies are not currently possible. We demonstrate that the protease activity of CD10 and the adhesion function of beta1-integrin are required to prevent differentiation of mammary progenitors. Taken together, our data suggest that integrin-mediated contact with the basement membrane and cleavage of signaling factors by CD10 are key elements in the niche that maintains the progenitor and stem cell pools in the mammary lineage.
