ABSTRACT
INTRODUCTION: Vascular progenitor cells contribute to repair of injured vasculature. In this study, we aimed to investigate the role of bone marrow-derived cells in the intimal formation after arterial injury. METHODS AND RESULTS: Balloon injury of the femoral artery of wild-type mice was followed by local delivery of bone marrow-derived cells from GFP transgenic mice. The arteries were collected 1, 4, 7, and 14 days after injury and studied for morphology, localization, and phenotypes of delivered cells. Bone marrow-derived cells were present in the intima only at the early stages of arterial injury and expressed endothelial progenitor cell markers (CD31, CD34, and VEGFR-2). In the areas where intima was thicker, bone marrow-derived cells differentiated to intimal smooth muscle cells but they did not fuse with intimal cells. Delivery of CD34+ cells contributed to a 1.5-fold inhibition of intimal hyperplasia. CONCLUSION: Bone marrow-derived endothelial cells differentiated but did not fuse with vascular smooth muscle cells at the early stages of intimal formation and contributed to intimal hyperplasia.
Subject(s)
Antigens, CD34/immunology , Bone Marrow Cells/physiology , Bone Marrow Transplantation , Vascular System Injuries/therapy , Animals , Bone Marrow Cells/immunology , Cell Differentiation , Endothelial Progenitor Cells/physiology , Femoral Artery/injuries , Hyperplasia , Male , Mice , Mice, Transgenic , Myocytes, Smooth Muscle/physiology , Stem Cells/physiology , Tunica Intima/injuries , Vascular System Injuries/immunologyABSTRACT
CCAAT-enhancer binding protein ß (C/EBPß) is a transcription factor that has a critical role in mammary gland development and breast cancer progression. Loss of C/EBPß increases metastatic dissemination of mouse mammary tumor cells. However, the mechanism by which C/EBPß expression affects metastasis formation remains unknown. This study aims at determining the relationship between C/EBPß and survival of breast cancer patients, and elucidating C/EBPß's link with metastasis formation. C/EBPß expression was evaluated in 137 cases of human breast cancer, and the correlation with overall survival was estimated by Kaplan-Meier analysis. Additionally, the mouse 4T1 tumor model was used for in vivo studies. Decreased C/EBPß expression was found to be associated with shorter overall survival of breast cancer patients. In the murine 4T1 model, loss of C/EBPß affects tumor growth, morphology and promotes metastatic spread to the lungs. Immunohistochemical analyses showed that C/EBPß inhibition leads to increased major histocompatibility complex II (MHCII) expression, followed by the accumulation of CD45-, CD3- and CD4-positive (CD4+) lymphocytes in the tumors. Inflammation involvement in C/EBPß-mediated metastasis formation was confirmed by DNA microarray and by experiments on CD4+ cell-deprived nude mice. Additionally, anti-CD3 and anti-CD4 treatments of C/EBPß-silenced tumor-bearing mice resulted in reverting the C/EBPß effect on tumor growth and metastasis. Altogether, C/EBPß is a predictor of overall survival in breast cancer patients, and affects tumor growth, morphology and lung metastasis formation in murine 4T1 model. The mechanism of metastasis formation involves immunologic response depending on C/EBPß-mediated activation of MHCII and accumulation of CD4+ lymphocytes in the tumor.
ABSTRACT
During breast cancer progression, transforming growth factor-beta (TGF-ß) switches from acting as a growth inhibitor to become a major promoter of epithelial-mesenchymal transition (EMT), invasion and metastasis. However, the mechanisms involved in this switch are not clear. We found that loss of CCAAT-enhancer binding protein beta (C/EBPß), a differentiation factor for the mammary epithelium, was associated with signs of EMT in triple-negative human breast cancer, and in invasive areas of mammary tumors in MMTV-PyMT mice. Using an established model of TGF-ß-induced EMT in mouse mammary gland epithelial cells, we discovered that C/EBPß was repressed during EMT by miR-155, an oncomiR in breast cancer. Depletion of C/EBPß potentiated the TGF-ß response towards EMT, and contributed to evasion of the growth inhibitory response to TGF-ß. Furthermore, loss of C/EBPß enhanced invasion and metastatic dissemination of the mouse mammary tumor cells to the lungs after subcutaneous injection into mice. The mechanism by which loss of C/EBPß promoted the TGF-ß response towards EMT, invasion and metastasis, was traced to a previously uncharacterized role of C/EBPß as a transcriptional activator of genes encoding the epithelial junction proteins E-cadherin and coxsackie virus and adenovirus receptor. The results identify miR-155-mediated loss of C/EBPß as a mechanism, which promotes breast cancer progression by shifting the TGF-ß response from growth inhibition to EMT, invasion and metastasis.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/pathology , CCAAT-Enhancer-Binding Protein-beta/genetics , Epithelial-Mesenchymal Transition/drug effects , Epithelial-Mesenchymal Transition/genetics , MicroRNAs/genetics , Transforming Growth Factor beta/pharmacology , Animals , Base Sequence , Binding Sites , Breast Neoplasms/metabolism , CCAAT-Enhancer-Binding Protein-beta/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Disease Models, Animal , Female , Gene Expression Regulation, Neoplastic , Gene Silencing , Humans , Mice , MicroRNAs/metabolism , Models, Biological , Molecular Sequence Data , Neoplasm Invasiveness , Neoplasm Metastasis , Protein Binding , RNA Interference , Transcriptional ActivationABSTRACT
High cytomegalovirus (CMV) IgG levels have been identified as a risk factor for arteriovenous fistula (AVF) failure. None of the 68 patents in our study were CMV IgM positive, although 96% were CMV IgG positive. CMV antigens were detected in the radial artery or cephalic vein of 46% of patients who received an AVF. The presence of CMV antigens or high serum CMV IgG levels had no prognostic value for AVF failure.
