技术资料

Despite considerable success in treating newly diagnosed childhood acute lymphoblastic leukemia (ALL),relapsed disease remains a significant clinical challenge. Using a NOD/SCID mouse xenograft model,we report that immunostimulatory DNA oligonucleotides containing CpG motifs (CpG ODNs) stimulate significant immune activity against primary human ALL cells in vivo. The administration of CpG ODNs induced a significant reduction in systemic leukemia burden,mediated continued disease control,and significantly improved survival of mice with established human ALL. The death of leukemia cells in vivo was independent of the ability of ALL cells to respond directly to CpG ODNs and correlated with the production of IL-12p70,IFN-alpha,and IFN-gamma by the host. In addition,depletion of natural killer cells by anti-asialo-GM1 treatment significantly reduced the in vivo antileukemic activity of CpG ODN. This antileukemia effect was not limited to the xenograft model because natural killer cell-dependent killing of ALL by human peripheral blood mononuclear cells (PBMCs) was also increased by CpG ODN stimulation. These results suggest that CpG ODNs have potential as therapeutic agents for the treatment of ALL. View Publication

A cell-based screen of chemical libraries was carried out to identify small molecules that control the self-renewal of ES cells. A previously uncharacterized heterocycle,SC1,was discovered that allows one to propagate murine ES cells in an undifferentiated,pluripotent state under chemically defined conditions in the absence of feeder cells,serum,and leukemia inhibitory factor. Long-term SC1-expanded murine ES cells can be differentiated into cells of the three primary germ layers in vitro and also can generate chimeric mice and contribute to the germ line in vivo. Biochemical and cellular experiments suggest that SC1 works through dual inhibition of RasGAP and ERK1. Molecules of this kind may not only facilitate practical applications of stem cells in research and therapy,but also provide previously undescribed insights into the complex biology of stem cells. View Publication

Autoreactive memory T lymphocytes are implicated in the pathogenesis of autoimmune diseases. Here we demonstrate that disease-associated autoreactive T cells from patients with type-1 diabetes mellitus or rheumatoid arthritis (RA) are mainly CD4+ CCR7- CD45RA- effector memory T cells (T(EM) cells) with elevated Kv1.3 potassium channel expression. In contrast,T cells with other antigen specificities from these patients,or autoreactive T cells from healthy individuals and disease controls,express low levels of Kv1.3 and are predominantly naïve or central-memory (T(CM)) cells. In T(EM) cells,Kv1.3 traffics to the immunological synapse during antigen presentation where it colocalizes with Kvbeta2,SAP97,ZIP,p56(lck),and CD4. Although Kv1.3 inhibitors [ShK(L5)-amide (SL5) and PAP1] do not prevent immunological synapse formation,they suppress Ca2+-signaling,cytokine production,and proliferation of autoantigen-specific T(EM) cells at pharmacologically relevant concentrations while sparing other classes of T cells. Kv1.3 inhibitors ameliorate pristane-induced arthritis in rats and reduce the incidence of experimental autoimmune diabetes in diabetes-prone (DP-BB/W) rats. Repeated dosing with Kv1.3 inhibitors in rats has not revealed systemic toxicity. Further development of Kv1.3 blockers for autoimmune disease therapy is warranted. View Publication

Chaetocin,a thiodioxopiperazine natural product previously unreported to have anticancer effects,was found to have potent antimyeloma activity in IL-6-dependent and -independent myeloma cell lines in freshly collected sorted and unsorted patient CD138(+) myeloma cells and in vivo. Chaetocin largely spares matched normal CD138(-) patient bone marrow leukocytes,normal B cells,and neoplastic B-CLL (chronic lymphocytic leukemia) cells,indicating a high degree of selectivity even in closely lineage-related B cells. Furthermore,chaetocin displays superior ex vivo antimyeloma activity and selectivity than doxorubicin and dexamethasone,and dexamethasone- or doxorubicin-resistant myeloma cell lines are largely non-cross-resistant to chaetocin. Mechanistically,chaetocin is dramatically accumulated in cancer cells via a process inhibited by glutathione and requiring intact/unreduced disulfides for uptake. Once inside the cell,its anticancer activity appears mediated primarily through the imposition of oxidative stress and consequent apoptosis induction. Moreover,the selective antimyeloma effects of chaetocin appear not to reflect differential intracellular accumulation of chaetocin but,instead,heightened sensitivity of myeloma cells to the cytotoxic effects of imposed oxidative stress. Considered collectively,chaetocin appears to represent a promising agent for further study as a potential antimyeloma therapeutic. View Publication

The immunosuppressive macrolide rapamycin shows marked structural similarity to FK-506,and like FK-506 inhibits the activation of cultured T and B lymphocytes at concentrations as low as 10(-10) M. However,rapamycin blocks T-lymphocyte proliferation at a much later stage than FK-506. It also inhibits human,porcine and murine T- and B-lymphocyte activation by all pathways tested,including pathways which are insensitive to FK-506,such as interleukin-2 (IL-2)-mediated proliferation of IL-2-dependent T-cell lines,activation of human peripheral blood T lymphocytes by phorbol ester and anti-CD28 and activation of murine B lymphocytes by bacterial lipopolysaccharide. Thus these two macrolides that bind competitively to the same major intracellular receptor protein inhibit T- and B-lymphocyte activation by quite distinct mechanisms. View Publication

Stem cell differentiation involves critical changes in gene expression. Identification of these should provide endpoints useful for optimizing stem cell propagation as well as potential clues about mechanisms governing stem cell maintenance. Here we describe the results of a new meta-analysis methodology applied to multiple gene expression datasets from three mouse embryonic stem cell (ESC) lines obtained at specific time points during the course of their differentiation into various lineages. We developed methods to identify genes with expression changes that correlated with the altered frequency of functionally defined,undifferentiated ESC in culture. In each dataset,we computed a novel statistical confidence measure for every gene which captured the certainty that a particular gene exhibited an expression pattern of interest within that dataset. This permitted a joint analysis of the datasets,despite the different experimental designs. Using a ranking scheme that favored genes exhibiting patterns of interest,we focused on the top 88 genes whose expression was consistently changed when ESC were induced to differentiate. Seven of these (103728at,8430410A17Rik,Klf2,Nr0b1,Sox2,Tcl1,and Zfp42) showed a rapid decrease in expression concurrent with a decrease in frequency of undifferentiated cells and remained predictive when evaluated in additional maintenance and differentiating protocols. Through a novel meta-analysis,this study identifies a small set of genes whose expression is useful for identifying changes in stem cell frequencies in cultures of mouse ESC. The methods and findings have broader applicability to understanding the regulation of self-renewal of other stem cell types. View Publication

Histone deacetylase inhibitors (HDI) have been shown to increase differentiation-related gene expression in several tumor-derived cell lines by hyperacetylating core histones. Effects of HDI on primary cultured cells,however,have hardly been investigated. In the present study,the ability of trichostatin A (TSA),a prototype hydroxamate HDI,to counteract the loss of liver-specific functions in primary rat hepatocyte cultures has been investigated. Upon exposure to TSA,it was found that the cell viability of the cultured hepatocytes and their albumin secretion as a function of culture time were increased. TSA-treated hepatocytes also better maintained cytochrome P450 (CYP)-mediated phase I biotransformation capacity,whereas the activity of phase II glutathione S-transferases (GST) was not affected. Western blot and qRT-PCR analysis of CYP1A1,CYP2B1 and CYP3A11 protein and mRNA levels,respectively,further revealed that TSA acts at the transcriptional level. In addition,protein expression levels of the liver-enriched transcription factors (LETFs) hepatic nuclear factor 4 alpha (HNF4alpha) and CCAAT/enhancer binding protein alpha (C/EBPalpha) were accordingly increased by TSA throughout culture time. In conclusion,these findings indicate that TSA plays a major role in the preservation of the differentiated hepatic phenotype in culture. It is suggested that the effects of TSA on CYP gene expression are mediated via controlling the expression of LETFs. View Publication

The success rate is generally higher when cloning mice from embryonic stem (ES) cell nuclei than from somatic cell nuclei,suggesting that the embryonic nature or the undifferentiated state of the donor cell increases cloning efficiency. We assessed the developmental ability of cloned embryos derived from cultured neural stem cell (NSC) nuclei and compared the success rate with that of embryos cloned from other donor cells such as differentiated NSCs,cumulus cells,Sertoli cells and ES cells in the mouse. The transfer of two-cell cloned embryos derived from cultured NSC nuclei into surrogate mothers produced five live cloned mice. However,the success rate (0.5%) was higher in embryos cloned from cultured NSC nuclei than from differentiated NSCs (0%),but lower than that obtained by cloning mice from other cell nuclei (2.2-3.5%). Although the in vitro developmental potential to the two-cell stage of the cloned embryos derived from NSC nuclei (73%) was similar to that of the cloned embryos derived from other somatic cell nuclei (e.g.,85% in Sertoli cells and 75% in cumulus cells),the developmental rate to the morula-blastocyst stage was only 7%. This rate is remarkably lower than that produced from other somatic cells (e.g.,50% in Sertoli cells and 54% in cumulus cells). These results indicate that the undifferentiated state of neural cells does not enhance the cloning efficiency in mice and that the arrest point for in vitro development of cloned embryos depends on the donor cell type. View Publication

BACKGROUND: Endothelial progenitor cells (EPCs) are present in peripheral blood and can promote postnatal angiogenesis. The number and function of circulating EPCs are altered in diabetics. This study sought to investigate whether the number and functional properties of EPCs from patients with type II diabetes could be improved by pioglitazone. METHODS: For this randomized controlled study,we recruited 36 type II diabetic patients on metformin monotherapy with a glycohemoglobin A1c of textless7%. Patients were separated into pioglitazone (n = 24) and control (n = 12) groups. The number and functional activity of EPCs,and the brachial artery flow-mediated dilation were determined before and after pioglitazone treatment (8 weeks) as an add-on therapy to metformin. In addition,direct effects of pioglitazone on EPCs were also investigated. RESULTS: After pioglitazone treatment,the numbers of circulating EPCs significantly increased (from 0.44% +/- 0.14% to 0.89% +/- 0.29%,P = .01). The migratory response and the adhesive capacity to fibronectin and collagen were improved by 158%,34%,and 83%,respectively (all P textless .05). Treatment with pioglitazone significantly lowered triglyceride,very low density lipoprotein cholesterol,and high-sensitivity C-reactive protein (hsCRP) levels,and increased high-density lipoprotein levels and insulin sensitivity (all P textless .05). The increase in the number of circulating EPCs and the improvement in the migratory response after pioglitazone treatment were independently correlated to the decrease in hsCRP levels (P textless or = .01). The increase in the adhesive capacity was independently correlated to the decreases in very low density lipoprotein cholesterol (P = .01) and hsCRP levels (P = .03). In addition,pioglitazone was also demonstrated to have direct effects on increasing EPC proliferation and colony formation,and attenuating EPC apoptosis (all P textless .05,versus the controls). There were no significant changes in flow-mediated dilation in either group. CONCLUSIONS: Pioglitazone significantly increased the number and improved the functional properties of EPCs in type II diabetic patients through direct effects and/or anti-inflammation and lipid modification effects. View Publication

Human embryonic stem cells (hESCs) provide great opportunities for regenerative medicine,pharmacological and toxicological investigation,and the study of human embryonic development. These applications require proper derivation,maintenance,and extensive characterization of undifferentiated cells before being used for differentiation into cells of interest. Undifferentiated hESCs possess several unique features,including their extensive proliferation capacity in the undifferentiated state,ability to maintain a normal karyotype after long-term culture,expression of markers characteristic of stem cells,high constitutive telomerase activity,and capacity to differentiate into essentially all somatic cell types. This chapter will summarize the current development in culture conditions and provide technical details for the evaluation and characterization of hESCs. View Publication

The mTOR complex 2 (mTORC2) containing mTOR and rictor is thought to be rapamycin insensitive and was recently shown to regulate the prosurvival kinase AKT by phosphorylation on Ser473. We investigated the molecular effects of mTOR inhibition by the rapamycin derivatives (RDs) temsirolimus (CCI-779) and everolimus (RAD001) in acute myeloid leukemia (AML) cells. Unexpectedly,RDs not only inhibited the mTOR complex 1 (mTORC1) containing mTOR and raptor with decreased p70S6K,4EPB1 phosphorylation,and GLUT1 mRNA,but also blocked AKT activation via inhibition of mTORC2 formation. This resulted in suppression of phosphorylation of the direct AKT substrate FKHR and decreased transcription of D-cyclins in AML cells. Similar observations were made in samples from patients with hematologic malignancies who received RDs in clinical studies. Our study provides the first evidence that rapamycin derivatives inhibit AKT signaling in primary AML cells both in vitro and in vivo,and supports the therapeutic potential of mTOR inhibition strategies in leukemias. View Publication

OBJECTIVE Pancreatic cancer continues to be an urgent clinical problem. We used the novel DNA methyltransferase inhibitor Zebularine and the histone deacetylase inhibitor SAHA to investigate the epigenetic influence on viability and differentiation of the pancreatic cancer cell lines YAP C,DAN G and Panc-89 in vitro and in vivo. MATERIAL AND METHODS Cell vitality,proliferation and expression of PDX-1,cytokeratin 7 and 20,chromogranin A,vimentin,bax and bcl-2 were determined on the protein and mRNA level in vitro and in a subcutaneous xenograft model. RESULTS A time- and dose-dependent increase of apoptosis,paralleled by decreased proliferation,was observed after incubation with single agents or a combination therapy with lower concentrations. This was associated with up-regulation of pro-apoptotic bax and a phenotypic stabilization by the enhanced expression of cytokeratin 7. In vivo,growth of xenografts was delayed with the most pronounced effect in Panc-89 after 1 week of daily intraperitoneal injections of Zebularine paralleled with CK7 up-regulation and down-regulation of dedifferentiation markers. CONCLUSIONS Epigenetic modulation via inhibition of DNA methyltransferase and histone deacetylase induces apoptosis in human pancreatic cancer cells in vitro and delays xenograft growth in vivo,which is associated with a morphological/molecular phenotypic stabilization. These compounds may therefore be suitable as adjunctive therapeutic agents in the treatment of pancreatic cancer. View Publication