技术资料

Although Th17 cells play critical roles in the pathogenesis of many inflammatory and autoimmune diseases,their prevalence among tumor-infiltrating lymphocytes (TILs) and function in human tumor immunity remains largely unknown. We have recently demonstrated high percentages of Th17 cells in TILs from ovarian cancer patients,but the mechanisms of accumulation of these Th17 cells in the tumor microenvironment are still unclear. In this study,we further showed elevated Th17 cell populations in the TILs obtained from melanoma and breast and colon cancers,suggesting that development of tumor-infiltrating CD4(+) Th17 cells may be a general feature in cancer patients. We then demonstrated that tumor microenvironmental RANTES and MCP-1 secreted by tumor cells and tumor-derived fibroblasts mediate the recruitment of Th17 cells. In addition to their recruitment,we found that tumor cells and tumor-derived fibroblasts produce a proinflammatory cytokine milieu as well as provide cell-cell contact engagement that facilitates the generation and expansion of Th17 cells. We also showed that inflammatory TLR and nucleotide oligomerization binding domain 2 signaling promote the attraction and generation of Th17 cells induced by tumor cells and tumor-derived fibroblasts. These results identify Th17 cells as an important component of human TILs,demonstrate mechanisms involved in the recruitment and regulation of Th17 cells in tumor microenvironments,and provide new insights relevant for the development of novel cancer immunotherapeutic approaches. View Publication

PURPOSE: To examine the role of cancer stem cells (CSC) in mediating metastasis in inflammatory breast cancer (IBC) and the association of these cells with patient outcome in this aggressive type of breast cancer. EXPERIMENTAL DESIGN: CSCs were isolated from SUM149 and MARY-X,an IBC cell line and primary xenograft,by virtue of increased aldehyde dehydrogenase (ALDH) activity as assessed by the ALDEFLUOR assay. Invasion and metastasis of CSC populations were assessed by in vitro and mouse xenograft assays. Expression of ALDH1 was determined on a retrospective series of 109 IBC patients and this was correlated with histoclinical data. All statistical tests were two sided. Log-rank tests using Kaplan-Meier analysis were used to determine the correlation of ALDH1 expression with development of metastasis and patient outcome. RESULTS: Both in vitro and xenograft assays showed that invasion and metastasis in IBC are mediated by a cellular component that displays ALDH activity. Furthermore,expression of ALDH1 in IBC was an independent predictive factor for early metastasis and decreased survival in this patient population. CONCLUSIONS: These results suggest that the metastatic,aggressive behavior of IBC may be mediated by a CSC component that displays ALDH enzymatic activity. ALDH1 expression represents the first independent prognostic marker to predict metastasis and poor patient outcome in IBC. The results illustrate how stem cell research can translate into clinical practice in the IBC field. View Publication

There is increasing evidence to suggest that embryonic stem cells (ESCs) are capable of differentiating into hepatocytes in vitro. In this study,we used a combination of cytokines and sodium butyrate in a novel three-step procedure to efficiently direct the differentiation of mouse ESCs into hepatocytes. Mouse ESCs were first differentiated into definitive endoderm cells by 3 days of treatment with Activin A. The definitive endoderm cells were then differentiated into hepatocytes by the addition of acidic fibroblast growth factor (aFGF) and sodium butyrate to the culture medium for 5 days. After 10 days of further in vitro maturation,the morphological and phenotypic markers of hepatocytes were characterized using immunohistochemistry,immunoblotting,and reverse transcription-polymerase chain reaction (RT-PCR). Furthermore,the cells were tested for functions associated with mature hepatocytes,including glycogen storage and indocyanine green uptake and release,and the ratio of hepatic differentiation was determined by counting the percentage of albumin-positive cells. In the presence of medium containing cytokines and sodium butyrate,numerous epithelial cells resembling hepatocytes were observed,and approximately 74% of the cells expressed the hepatic marker,albumin,after 18 days in culture. RT-PCR analysis and immunohistochemistry showed that these cells expressed adult liver cell markers,and had the abilities of glycogen storage and indocyanine green uptake and release. We have developed an efficient method for directing the differentiation of mouse ESCs into cells that exhibit the characteristics of mature hepatocytes. This technique will be useful for research into the molecular mechanisms underlying liver development,and could provide a source of hepatocytes for transplantation therapy and drug screening. View Publication

Synthetic materials that promote the growth or differentiation of cells have advanced the fields of tissue engineering and regenerative medicine. Most functional biomaterials are based on a handful of peptide sequences derived from protein ligands for cell surface receptors. Because few proteins possess short peptide sequences that alone can engage cell surface receptors,the repertoire of receptors that can be targeted with this approach is limited. Materials that bind diverse classes of receptors,however,may be needed to guide cell growth and differentiation. To provide access to such new materials,we utilized phage display to identify novel peptides that bind to the surface of pluripotent cells. Using human embryonal carcinoma (EC) cells as bait,approximately 3 x 10(4) potential cell-binding phage clones were isolated. The pool was narrowed using an enzyme-linked immunoassay: 370 clones were tested,and seven cell-binding peptides were identified. Of these,six sequences possess EC cell-binding ability. Specifically,when displayed by self-assembled monolayers (SAMs) of alkanethiols on gold,they mediate cell adhesion. The corresponding soluble peptides block this adhesion,indicating that the identified peptide sequences are specific. They also are functional. Synthetic surfaces displaying phage-derived peptides support growth of undifferentiated human embryonic stem (ES) cells. When these cells were cultured on SAMs presenting the sequence TVKHRPDALHPQ or LTTAPKLPKVTR in a chemically defined medium (mTeSR),they expressed markers of pluripotency at levels similar to those of cells cultured on Matrigel. Our results indicate that this screening strategy is a productive avenue for the generation of materials that control the growth and differentiation of cells. View Publication

Deregulation of the phosphoinositide-3-OH kinase (PI(3)K) pathway has been implicated in numerous pathologies including cancer,diabetes,thrombosis,rheumatoid arthritis and asthma. Recently,small-molecule and ATP-competitive PI(3)K inhibitors with a wide range of selectivities have entered clinical development. In order to understand the mechanisms underlying the isoform selectivity of these inhibitors,we developed a new expression strategy that enabled us to determine to our knowledge the first crystal structure of the catalytic subunit of the class IA PI(3)K p110 delta. Structures of this enzyme in complex with a broad panel of isoform- and pan-selective class I PI(3)K inhibitors reveal that selectivity toward p110 delta can be achieved by exploiting its conformational flexibility and the sequence diversity of active site residues that do not contact ATP. We have used these observations to rationalize and synthesize highly selective inhibitors for p110 delta with greatly improved potencies. View Publication

PURPOSE: To evaluate the expression of stem cell-related markers at the cellular level in human breast tumors of different subtypes and histologic stage. EXPERIMENTAL DESIGN: We performed immunohistochemical analyses of 12 proteins [CD44,CD24,ALDH1,vimentin,osteonectin,EPCR,caveolin 1,connexin 43,cytokeratin 18 (CK18),MUC1,claudin 7,and GATA3] selected based on their differential expression in breast cancer cells with more differentiated and stem cell-like characteristics in 47 cases of invasive ductal carcinoma (IDC) only,135 cases of IDC with ductal carcinoma in situ (DCIS),35 cases of DCIS with microinvasion,and 58 cases of pure DCIS. We also analyzed 73 IDCs with adjacent DCIS to determine the differences in the expression of markers by histology within individual tumors. CD44+/CD24- and CD24-/CD24+ cells were detected using double immunohistochemistry. RESULTS: CD44 and EPCR expression was different among the four histologic groups and was lower in invasive compared with in situ tumors,especially in luminal A subtype. The expression of vimentin,osteonectin,connexin 43,ALDH1,CK18,GATA3,and MUC1 differed by tumor subtype in some histologic groups. ALDH1-positive cells were more frequent in basal-like and HER2+ than in luminal tumors. CD44+/CD24- cells were detected in 69% of all tumors with 100% of the basal-like and 52% of HER2+ tumors having some of these cells. CONCLUSIONS: Our findings suggest that in breast cancer,the frequency of tumor cells positive for stem cell-like and more differentiated cell markers varies according to tumor subtype and histologic stage. View Publication

Memantine is classified as an NMDA receptor antagonist. We recently reported that memantine promoted the proliferation of neural progenitor cells and the production of mature granule neurons in the adult hippocampus. However,the molecular mechanism responsible for the memantine-induced promotion of cellular proliferation remains unknown. In this study we searched for a factor that mediates memantine-induced cellular proliferation,and found that pigment epithelium-derived factor (PEDF),a broad-acting neurotrophic factor,is up-regulated in the dentate gyrus of adult mice after the injection of memantine. PEDF mRNA expression increased significantly by 3.5-fold at 1 day after the injection of memantine. In addition,the expression level of PEDF protein also increased by 1.8-fold at 2 days after the injection of memantine. Immunohistochemical study using anti-PEDF antibody showed that the majority of the PEDF-expressing cells were protoplasmic and perivascular astrocytes. Using a neurosphere assay,we confirmed that PEDF enhanced cellular proliferation under the presence of fibroblast growth factor-2 (FGF-2) and epidermal growth factor (EGF) but was not involved in the multilineage potency of hippocampal progenitor cells. Over expression of PEDF by adeno-associated virus,however,did not stimulate cellular proliferation,suggesting PEDF per se does not promote cellular proliferation in vivo. These findings suggest that the memantine induced PEDF up-regulation is involved in increased proliferation of hippocampal progenitor cells. View Publication

Activating mutations in KRAS and BRAF are found in more than 30% of all human tumours and 40% of melanoma,respectively,thus targeting this pathway could have broad therapeutic effects. Small molecule ATP-competitive RAF kinase inhibitors have potent antitumour effects on mutant BRAF(V600E) tumours but,in contrast to mitogen-activated protein kinase kinase (MEK) inhibitors,are not potent against RAS mutant tumour models,despite RAF functioning as a key effector downstream of RAS and upstream of MEK. Here we show that ATP-competitive RAF inhibitors have two opposing mechanisms of action depending on the cellular context. In BRAF(V600E) tumours,RAF inhibitors effectively block the mitogen-activated protein kinase (MAPK) signalling pathway and decrease tumour growth. Notably,in KRAS mutant and RAS/RAF wild-type tumours,RAF inhibitors activate the RAF-MEK-ERK pathway in a RAS-dependent manner,thus enhancing tumour growth in some xenograft models. Inhibitor binding activates wild-type RAF isoforms by inducing dimerization,membrane localization and interaction with RAS-GTP. These events occur independently of kinase inhibition and are,instead,linked to direct conformational effects of inhibitors on the RAF kinase domain. On the basis of these findings,we demonstrate that ATP-competitive kinase inhibitors can have opposing functions as inhibitors or activators of signalling pathways,depending on the cellular context. Furthermore,this work provides new insights into the therapeutic use of ATP-competitive RAF inhibitors. View Publication

Human embryonic stem (hES) cell production of heparan sulfate influences cell fate and pluripotency. Human ES cells remain pluripotent in vitro through the action of growth factors signaling,and the activity of these factors depends on interaction with specific receptors and also with heparan sulfate. Here,we tested the hypothesis that matrix-associated heparan sulfate is enough to maintain hES cells under low fibroblast growth factor-2 concentration in the absence of live feeder cells. To pursue this goal,we compared hES cells cultured either on coated plates containing live murine embryonic fibroblasts (MEFs) or on a matrix derived from ethanol-fixed MEFs. hES cells were analyzed for the expression of pluripotency markers and the ability to form embryoid bodies. hES cells cultured either on live mouse fibroblasts or onto a matrix derived from fixed fibroblasts expressed similar levels of Oct-4,SOX-2,Nanog,TRA-1-60 and SSEA-4,and they were also able to form cavitated embryoid bodies. Heparan sulfate-depleted matrix lost the ability to support the adherence and growth of hES cells,confirming that this glycosaminoglycan,bound to the extracellular matrix,is enough for the growth and attachment of hES cells. Finally,we observed that the ethanol-fixed matrix decreases by 30% the levels of Neu5Gc in hES cells,indicating that this procedure reduces xeno-contamination. Our data suggest that matrix-bound heparan sulfate is required for the growth and pluripotency of hES cells and that ethanol-fixed MEFs may be used as a live cell"-free substrate for stem cells." View Publication

The mammalian embryonic zeta-globin genes,including that of humans,are expressed at the early embryonic stage and then switched off during erythroid development. This autonomous silencing of the zeta-globin gene transcription is probably regulated by the cooperative work of various protein-DNA and protein-protein complexes formed at the zeta-globin promoter and its upstream enhancer (HS-40). We present data here indicating that a protein-binding motif,ZF2,contributes to the repression of the HS-40-regulated human zeta-promoter activity in erythroid cell lines and in transgenic mice. Combined site-directed mutagenesis and EMSA suggest that repression of the human zeta-globin promoter is mediated through binding of the zinc finger factor RREB1 to ZF2. This model is further supported by the observation that human zeta-globin gene transcription is elevated in the human erythroid K562 cell line or the primary erythroid culture upon RNA interference (RNAi)(2) knockdown of RREB1 expression. These data together suggest that RREB1 is a putative repressor for the silencing of the mammalian zeta-globin genes during erythroid development. Because zeta-globin is a powerful inhibitor of HbS polymerization,our experiments have provided a foundation for therapeutic up-regulation of zeta-globin gene expression in patients with severe hemoglobinopathies. View Publication

INTRODUCTION: The molecular mechanisms that control the mobilization of specific stem cell subsets from the bone marrow are currently being intensely investigated. It is anticipated that boosting the mobilization of these stem cells via pharmacological intervention will not only produce more effective strategies for bone marrow transplant patients,but also provide novel therapeutic approaches for tissue regeneration. METHODS: Measurement of stem cell mobilization by sampling peripheral blood is problematic because it is technically difficult to accurately determine absolute numbers of rare progenitor cells by blood sampling. Furthermore a rise in progenitors may be caused by release of stem cells from tissues other than the bone marrow (e.g. spleen and adipose),or indeed an inhibition of stem cell homing back to the bone marrow or other tissues. Finally it is not possible to distinguish whether the pharmacological agent is acting directly at the level of the bone marrow or mobilizing progenitors by a distinct indirect mechanism. To resolve these problems,we have developed a technique that allows perfusion of the vasculature of the hind limb bone marrow in situ in mice. In this system,the femoral artery and vein are cannulated in situ such that the femur and tibia bone marrow are perfused in isolation under anaesthesia. As such,pharmacological agents can be administered directly into the bone marrow vasculature. Mobilized cells are then collected via the femoral vein and colony assays performed in defined growth media to allow identification of haematopoietic,endothelial,and mesenchymal progenitor cells. We have used this system to determine the ability of a CXCR4 antagonist to mobilize these distinct types of progenitor cells from the bone marrow of mice pre-conditioned with either G-CSF or VEGF. RESULTS AND CONCLUSION: This isolated hind limb perfusion system has allowed comparisons to be made between cytokines (G-CSF and VEGF) that act chronically,either alone or in combination with agents that act acutely on the bone marrow (CXCR4 antagonist) on their ability to directly mobilize specific populations of stem cells. Data obtained therefore gives a more accurate understanding of the efficacy of different mobilizing strategies compared to peripheral blood analysis. View Publication

The umbilical cord and placenta are extra-embryonic tissues of particular interest for regenerative medicine. They share an early developmental origin and are a source of vast amounts of cells with multilineage differentiation potential that are poorly immunogenic and without controversy. Moreover,these cells are likely exempt from incorporated mutations when compared with juvenile or adult donor cells such as skin fibroblasts or keratinocytes. Here we report the efficient generation of induced pluripotent stem cells (iPSCs) from mesenchymal cells of the umbilical cord matrix (up to 0.4% of the cells became reprogrammed) and the placental amniotic membrane (up to 0.1%) using exogenous factors and a chemical mixture. iPSCs from these 2 tissues homogeneously showed human embryonic stem cell (hESC)-like characteristics including morphology,positive staining for alkaline phosphatase,normal karyotype,and expression of hESC-like markers including Nanog,Rex1,Oct4,TRA-1-60,TRA-1-80,SSEA-3,and SSEA-4. Selected clones also formed embryonic bodies and teratomas containing derivatives of the 3 germ layers,and could as well be readily differentiated into functional motor neurons. Among other things,our cell lines may prove useful for comparisons between iPSCs derived from multiple tissues regarding the extent of the epigenetic reprogramming,differentiation ability,stability of the resulting lineages,and the risk of associated abnormalities. View Publication