Project description:The intent of this experiment was to determine the similarities and differences in expression signatures of normal breast cells that express markers associated with an epithelial-like (ALDH+) and mesenchymal-like (CD44+CD24-) stem cells in the normal human breast. Briefly, tissues were collected from women undergoing voluntary reduction mammoplasty. Tissues were dissociated using chemical and enzymatic methods to yield single cells. These cells were sorted by flow cytometry for aldehyde hydrogenase activity (ALDH+), CD44, and CD24, as well as viability, following depletion of hematopoeitc cells, endothelial cells, and fibroblasts.
Project description:It has been suggested that breast cancers are driven and maintained by a cellular subpopulation with stem cell properties. These breast cancer stem cells (BCSCs) mediate metastasis and by virtue of their resistance to radiation and chemotherapy, contribute to relapse. Although several BCSC markers have been described, it is unclear whether these markers identify the same or independent BCSC populations. Based on established breast cancer cell lines, as well as primary tumor xenografts, we show that BCSCs exist in distinct mesenchymal-like (epithelial-mesenchymal transition, EMT) and epithelial-like (mesenchymal-epithelial transition, MET) states characterized by expression of distinct markers, proliferative capacity and invasive characteristics. The gene expression profiles of mesenchymal-like and epithelial-like BCSCs are remarkably similar across the different molecular subtypes of breast cancer and resemble those of distinct basal and luminal stem cells found in the normal breast. We propose that the plasticity of BCSCs allowing them to transition between EMT- and MET-like states endows these cells with the capacity for tissue invasion, dissemination and growth at metastatic sites. Breast cancer cell lines, primary xenografts and normal breast cells from patient were sorted using flow cytometry to select for cells that were CD24-,CD44+ and ALDH+. Gene expression profiles of CD24-CD44+ cells were compared with non-CD24-CD44+ cells. Gene expression profiles of ALDH+ cells were compared with ALDH- cells.
Project description:Deregulation of Src kinases is associated with cancer. We previously showed that SrcDN conditional expression in MCF7 cells diminished tumorigenesis and causes tumor regression in mice. However, it remained unclear whether SrcDN affected breast cancer stem cell functionality or it reduced tumor mass. Here, we address this question by isolating an enriched population of BCSCs (ESA+-CD44+-CD24-) and the tumor-differentiated cells (ESA+-CD44+-CD24+) from MCF7-Tet-On-SrcDN. ESA+-CD44+-CD24- grew in suspension forming mammospheres, and producing tumors in nude mice, while ESA+-CD44+-CD24+ were poorly/non-tumorigenic. Doxycycline-induction of SrcDN inhibited BCSC tumorigenesis, selfrenewal, and stem-cell markers expression. SrcDN significantly inhibited SFE, and stem-cell markers expression in triple-negative breast cancer (TNBC) MDA-MB-231 and SUM159PT cells. Inducible depletion of c-Src caused similar effects in MDA-MB-231 cells. In MCF7-Tet-On-SrcDN derived mammospheres SrcDN-induction inhibited expression, and activity of hexokinase, pyruvate kinase and lactate dehydrogenase, resulting in diminished glucose consumption and lactate production, which restricted Warburg effect. Thus, c-Src functionality is important for breast cancer stem cell maintenance and renewal, tumorigenicity, and stem cell transcription factor expression, effects linked to glucose metabolism reduction.
Project description:Recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) has a poor prognosis with less than 1-year median survival. Platinum-based chemotherapy (cisplatin or carboplatin) remains the first-line treatment for HNSCC. The cancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self-renewing CSC population that is also capable of differentiating into non-self renewing cell populations that constitute the bulk of the tumor. A small population of CSCs exists within HNSCC that are relatively resistant to chemotherapy and clinically predicted to mediate tumor recurrence. These CSCs are identified by high cell-surface expression of CD44 and high intracellular activity of aldehyde dehydrogenase (ALDH) and termed ALDHhighCD44high. We investigated the molecular pathways active in ALDHhighCD44high cells, which remain poorly studied. Additionally, we performed a molecular examination of cisplatin-resistant ALDHhighCD44high cells, which has not been reported. Two HNSCC cell lines, UM-SCC-1 and UM-SCC-22b, were utilized in this study. For microarray analysis, UM-SCC-22b cells were treated for 5 days in vitro with 2uM cisplatin and analyzed by flow cytometry, sorted and submitted for microarray analysis of ALDHhighCD44high and ALDHlowCD44low cells from untreated and cisplatin treated cells. Four separate flow cytometry experiments were performed using Affymetrix Human Gene ST 2.1 microarrays. Microarray data was analyzed using R/Bioconductor. Files were preprocessed by Robust Multiarray Average (RMA) with background substraction, quantile normalization, and median polish (oligo package). Data was fitted with robust probe level linear models to all the probesets (oligo package). Experiment and processing batch differences were accounted for using 'ComBat' within the SVA package. Differentially expressed genes were identified using univariate comparisons after fitting data to a linear model (limma package). Initial statistics were determined using an empirical Bayesian model. Multiple testing comparisons were adjusted using Benjamini and Hochberg (aka FDR). Probes with an adjusted p-value <0.05 were considered statistically significant. Unsupervised hierarchical clustering with complete linkage and Euclidean distance was performed on only statistically significant probes. In four separate experiments, the head and neck squamous cell carcinoma cell line UM-SCC-22b were cultured for 5 days with or without 2uM (micromolar) cisplatin in 6-well plates. Media was replaced every other day. Control and cisplatin treated cells were trypsinized, procesed, and stained for CD44 cell-surface expression and intracellular aldehyde dehydrogenase (ALDH) activity to identify cancer stem cells (ALDH+CD44+). CSCs and non-CSCs (ALDH-CD44-) were collected by flow cytometry from both groups. Total RNA was collected from each fraction (ALDH+CD44+, ALDH-CD44-), treatment (control, cisplatin), and experiment (#1-4). A total of 16 samples were analyzed. One set of 4 (experiment #4) were analyzed on a Human Gene ST 2.1 strip and the rest on a Human Gene ST 2.1 plate. Differential gene expression was determined with R/Bioconductor with Robust Multiarray Average (RMA) and fitting the data to linear models (limma). Experimental and processing batch effects were accounted for using ComBat. Four sets of univariate comparisons were made: 1) Cisplatin ALDH+CD44+ vs Control ALDH+CD44+; 2) Control ALDH+CD44+ vs Control ALDH-CD44-; 3) Cisplatin ALDH+CD44+ vs Cisplatin ALDH-CD44-; 4) Cisplatin ALDH-CD44- vs Control ALDH-CD44-. Multiple testing comparisons were adjusted using Benjamini and Hochberg (aka FDR). Probes with an adjusted p-value <0.05 were considered statistically significant.
Project description:To understand the role of p53 in regulating stem cell population (CD24-CD44+) and stemness-associated miRNAs, we first compared miRNA expression profiles between human mammary epithelical cells knocked-down p53 and control cells. We then cross-referenced p53-regulated miRNAs with stemness-associated miRNAs analyzed from expression profiling of sorted CD24-CD44+ and non-CD24-CD44+ cell populations. Further biological experiments were performed with the miRNAs that are altered in CD24-CD44+ stem cell populations and also regulated by p53.