Stem Cell Antigen-1 (Sca-1) Regulates Mammary Tumor Development and Cell Migration

Interdepartmental Program in Cell & Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America.
PLoS ONE (Impact Factor: 3.23). 11/2011; 6(11):e27841. DOI: 10.1371/journal.pone.0027841
Source: PubMed


Stem cell antigen-1 (Sca-1 or Ly6A) is a glycosyl phostidylinositol (GPI)-anchored cell surface protein associated with both stem and progenitor activity, as well as tumor initiating-potential. However, at present the functional role for Sca-1 is poorly defined.
To investigate the role of Sca-1 in mammary tumorigenesis, we used a mammary cell line derived from a MMTV-Wnt1 mouse mammary tumor that expresses high levels of endogenous Sca-1. Using shRNA knockdown, we demonstrate that Sca-1 expression controls cell proliferation during early tumor progression in mice. Functional limiting dilution transplantations into recipient mice demonstrate that repression of Sca-1 increases the population of tumor propagating cells. In scratch monolayer assays, Sca-1 enhances cell migration. In addition, knockdown of Sca-1 was shown to affect cell adhesion to a number of different extracellular matrix components. Microarray analysis indicates that repression of Sca-1 leads to changes in expression of genes involved in proliferation, cell migration, immune response and cell organization.
Sca-1 exerts marked effects on cellular activity and tumorgenicity both in vitro and in vivo. A better understanding of Sca-1 function may provide insight into the broader role of GPI-anchored cell surface proteins in cancer.

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    • "Loss of Sca1+ cells does not appear to impede tumor formation in vivo, because tumors formed efficiently with both late and early passage MMTV-Neu ME-CRCs. Sca1 has been described as an important marker of tumor-initiating cells in luminal breast cancer [30]. It may be that the HER2/neu-driven subtype of breast cancer is less dependent on Sca1+ tumor-initiating cells than other breast cancer subtypes. "
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    ABSTRACT: Mammary epithelial (ME) cells cultured under conventional conditions senesce after several passages. Here, we demonstrate that mouse ME cells isolated from normal mammary glands or from mouse mammary tumor virus (MMTV)-Neu-induced mammary tumors, can be cultured indefinitely as conditionally reprogrammed cells (CRCs) on irradiated fibroblasts in the presence of the Rho kinase inhibitor Y-27632. Cell surface progenitor-associated markers are rapidly induced in normal mouse ME-CRCs relative to ME cells. However, the expression of certain mammary progenitor subpopulations, such as CD49f+ ESA+ CD44+, drops significantly in later passages. Nevertheless, mouse ME-CRCs grown in a three-dimensional extracellular matrix gave rise to mammary acinar structures. ME-CRCs isolated from MMTV-Neu transgenic mouse mammary tumors express high levels of HER2/neu, as well as tumor-initiating cell markers, such as CD44+, CD49f+, and ESA+ (EpCam). These patterns of expression are sustained in later CRC passages. Early and late passage ME-CRCs from MMTV-Neu tumors that were implanted in the mammary fat pads of syngeneic or nude mice developed vascular tumors that metastasized within 6 weeks of transplantation. Importantly, the histopathology of these tumors was indistinguishable from that of the parental tumors that develop in the MMTV-Neu mice. Application of the CRC system to mouse mammary epithelial cells provides an attractive model system to study the genetics and phenotype of normal and transformed mouse epithelium in a defined culture environment and in vivo transplant studies.
    PLoS ONE 05/2014; 9(5):e97666. DOI:10.1371/journal.pone.0097666 · 3.23 Impact Factor
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    • "Sca-1, which stands for stem cell antigen-1, is a glycosyl phostidylinositol-anchored cell surface protein that is associated with both stem cell and progenitor cell activities as well as with tumor initiating potential [29]. CD44, a hyaluronic acid receptor, is a multifunctional class I transmembrane glycoprotein. "
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    ABSTRACT: In vivo, the transforming growth factor-beta1 (TGF-beta1)-induced epithelial to mesenchymal transition (EMT) occurs in seconds during cancer cells intravasation and extravasation. Although it has been established that cellular stiffness can change as a cancer cell transformed, the precise relationship between TGF-beta1-induced mesenchymal stem cell mechanics and cancer prognosis remains unclear. Accordingly, it is hard to define the effects of EMT on cell mechanical properties (CMs), tumor recurrence and metastasis risks. This study bridges physical and pathological disciplines to reconcile single-cell mechanical measurements of tumor cells.Methods and results: We developed a microplate measurement system (MMS) and revealed the intrinsic divergent tumor composition of retrieval cells by cell stiffness and adhesion force and flow cytometry analysis. After flow cytometry sorting, we could measure the differences in CMs of the Sca-1+-CD44+ (mesenchymal-stem-cell-type) and the other subgroups. As well as the stiffer and heterogeneous compositions among tumor tissues with higher recurrence risk were depicted by MMS and atomic force microscopy (AFM). An in vitro experiment validated that Lewis lung carcinoma (LLC) cells acquired higher CMs and motility after EMT, but abrogated by SB-505124 inhibition. Concomitantly, the CD31, MMP13 and TGF-beta1 enriched micro-environment in the tumor was associated with higher recurrence and distal lung metastasis risks. Furthermore, we report a comprehensive effort to correlate CMs to tumor-prognosis indicators, in which a decreased body weight gain ratio (BWG) and increased tumor weight (TW) were correlated with increased CMs. Together, we determined that TGF-beta1 was significantly associated with malignant tumor progressing. In terms of clinical applications, local tumor excision followed by MMS analysis offers an opportunity to predict tumor recurrence and metastasis risks.
    Cancer Cell International 03/2014; 14(1):20. DOI:10.1186/1475-2867-14-20 · 2.77 Impact Factor
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    • "Ly6A (Sca-1), the best characterized family member, also upregulated here, is associated with stem/progenitor cells [41] and is localized to lipid rafts where it regulates signaling complexes [42]. Recent data have shown that the knockdown of Sca-1 in the mammary gland affects cell adhesion to a number of different extracellular matrix components [43]. "
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    ABSTRACT: MicroRNA (miRNA) are negative regulators of gene expression, capable of exerting pronounced influences upon the translation and stability of mRNA. They are potential regulators of normal mammary gland development and of the maintenance of mammary epithelial progenitor cells. This study was undertaken to determine the role of miR-30b on the establishment of a functional mouse mammary gland. miR-30b is a member of the miR-30 family, composed of 6 miRNA that are highly conserved in vertebrates. It has been suggested to play a role in the differentiation of several cell types. The expression of miR-30b was found to be regulated during mammary gland development. Transgenic mice overexpressing miR-30b in mammary epithelial cells were used to investigate its role. During lactation, mammary histological analysis of the transgenic mice showed a reduction in the size of alveolar lumen, a defect of the lipid droplets and a growth defect of pups fed by transgenic females. Moreover some mammary epithelial differentiated structures persisted during involution, suggesting a delay in the process. The genes whose expression was affected by the overexpression of miR-30b were characterized by microarray analysis. Our data suggests that miR-30b is important for the biology of the mammary gland and demonstrates that the deregulation of only one miRNA could affect lactation and involution.
    PLoS ONE 09/2012; 7(9):e45727. DOI:10.1371/journal.pone.0045727 · 3.23 Impact Factor
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