搜索结果: 'NeuroCult Proliferation'

BACKGROUND Glioblastomas (GBMs) are a heterogeneous group of primary brain tumors. These tumors are resistant to therapeutic interventions and invariably recur after surgical resection. The multifunctional protein transglutaminase 2 (TG2) has been shown to promote cell survival in a number of different tumors. There is also evidence that TG2 may be a pro-survival factor in GBMs. However,the roles that TG2 plays in facilitating GBM survival and proliferation have not yet been clearly delineated . METHODS The functions of TG2 are often cell- and context-specific. Therefore,in this study we examined the ability of TG2 to facilitate GBM proliferation using colony formation assays and 5-ethynyl-2'-deoxyuridine (EdU) incorporation in several different GBM cell lines as well as neurospheres derived from patient tumors representing the 3 major subtypes of GBM tumors (mesenchymal,proneural,and classical) and maintained in the absence of serum. TG2 knockdown or selective TG2 inhibitors were used to modulate TG2 expression and activity. RESULTS We show that TG2 plays differential roles in the proliferative process depending on the cell type. In most,but not all,GBM models TG2 plays a crucial role in the proliferative process,and some but not all TG2 inhibitors were highly effective at reducing proliferation in a large subset of the GBM models. CONCLUSION Our results show that TG2 plays an important-but notoriously context-specific-role in GBM cell biology. Nonetheless,as future studies unravel the genetic fingerprints" that make TG2 inhibitors effective this information could be exploited to develop TG2 inhibitors into personalized GBM therapies. View Publication

The aryl hydrocarbon receptor (AhR),a transcription factor known for mediating xenobiotic toxicity,is expressed in B cells,which are known targets for environmental pollutants. However,it is unclear what the physiological functions of AhR in B cells are. We show here that expression of Ahr in B cells is up-regulated upon B-cell receptor (BCR) engagement and IL-4 treatment. Addition of a natural ligand of AhR,FICZ,induces AhR translocation to the nucleus and transcription of the AhR target gene Cyp1a1,showing that the AhR pathway is functional in B cells. AhR-deficient (Ahr(-/-)) B cells proliferate less than AhR-sufficient (Ahr(+/+)) cells following in vitro BCR stimulation and in vivo adoptive transfer models confirmed that Ahr(-/-) B cells are outcompeted by Ahr(+/+) cells. Transcriptome comparison of AhR-deficient and AhR-sufficient B cells identified cyclin O (Ccno),a direct target of AhR,as a top candidate affected by AhR deficiency. View Publication

Adult hematopoietic stem cells (HSCs) are routinely used to reconstitute hematopoiesis after myeloablation; however,transplantation efficacy and multilineage reconstitution can be limited by inadequate HSC number,or poor homing,engraftment,or self-renewal. Here we report that mouse and human HSCs express prostaglandin E2 (PGE2) receptors,and that short-term ex vivo exposure of HSCs to PGE2 enhances their homing,survival,and proliferation,resulting in increased long-term repopulating cell (LTRC) and competitive repopulating unit (CRU) frequency. HSCs pulsed with PGE2 are more competitive,as determined by head-to-head comparison in a competitive transplantation model. Enhanced HSC frequency and competitive advantage is stable and maintained upon serial transplantation,with full multilineage reconstitution. PGE2 increases HSC CXCR4 mRNA and surface expression,enhances their migration to SDF-1 in vitro and homing to bone marrow in vivo,and stimulates HSC entry into and progression through cell cycle. In addition,PGE2 enhances HSC survival,associated with an increase in Survivin mRNA and protein expression and reduction in intracellular active caspase-3. Our results define novel mechanisms of action whereby PGE2 enhances HSC function and supports a strategy to use PGE2 to facilitate hematopoietic transplantation. View Publication

BACKGROUND Neonatal hypoxia-ischemia induces massive brain damage during the perinatal period,resulting in long-term consequences to central nervous system structural and functional maturation. Although neural progenitor cells (NPCs) migrate through the parenchyma and home in to injury sites in the rodent brain,the molecular mechanisms are unknown. We examined the role of chemokines in mediating NPC migration after neonatal hypoxic-ischemic brain injury. METHODS Nine-day-old mice were exposed to a 120-minute hypoxia following unilateral carotid occlusion. Chemokine levels were quantified in mouse brain extract. Migration and proliferation assays were performed using embryonic and infant mouse NPCs. RESULTS The neonatal hypoxic-ischemic brain injury resulted in an ipsilateral lesion,which was extended to the cortical and striatal areas. NPCs migrated toward an injured area,where a marked increase of CC chemokines was detected. In vitro studies showed that incubation of NPCs with recombinant mouse CCL11 promoted migration and proliferation. These effects were partly inhibited by a CCR3 antagonist,SB297006. CONCLUSIONS Our data implicate an important effect of CCL11 for mouse NPCs. The effective activation of NPCs may offer a promising strategy for neuroregeneration in neonatal hypoxic-ischemic brain injury. View Publication

The mammalian target of rapamycin (mTOR) kinase forms two multiprotein complexes,mTORC1 and mTORC2,which regulate cell growth,survival,and autophagy. Allosteric inhibitors of mTORC1,such as rapamycin,have been extensively used to study tumor cell growth,proliferation,and autophagy but have shown only limited clinical utility. Here,we describe AZD8055,a novel ATP-competitive inhibitor of mTOR kinase activity,against all class I phosphatidylinositol3-kinase (PI3K) and other members of the PI3K-like kinase family. The study was to determine the effect of AZD8055 on proliferation and apoptosis on Hep-2,a human laryngeal cancer cell line and to investigate the underlying mechanism(s) of action. Hep-2 cells were treated with AZD8055 for 24,48 or 72 h. MTT was used to determine cell proliferation. Rhodamine 123 and TUNEL staining were used to determine mitochondrial membrane potential and cell apoptosis analyzed by fluorescence-activated cell sorting (FACS). Protein expressions were examined by western blotting. Treatment with AZD8055 inhibited proliferation and induced apoptosis in Hep-2 cells in a dose- and time-dependent manner. During the prolonged treatment with AZD8055,AZD8055 inhibits the mammalian target of rapamycin mTOR. Further experiments showed which signaling cascade p-4EBP1 and substrate EIF4E as well as downstream proteins were down regulated. Furthermore,our study showed that the expression profiles of various BH3-only proteins including Bid,Bad,and Bim,apoptosis regulatory protein cleaved caspase3 was up regulated in a time-dependent manner in Hep-2 cells treated with AZD8055. Thus,in vitro,AZD8055 potently inhibits proliferation and induces apoptosis in head and neck squamous cell carcinoma. View Publication

Histone deacetylase inhibitors have attracted considerable attention because of their ability to overcome the differentiation block in leukemic blasts,an effect achieved either alone or in combination with differentiating agents,such as all-trans retinoic acid. We have previously reported favorable effects of the potent histone deacetylase inhibitor valproic acid in combination with all-trans retinoic acid in patients with advanced acute myeloid leukemia leading to blast cell reduction and improvement of hemoglobin. These effects were accompanied by hypergranulocytosis most likely due to an enhancement of nonleukemic myelopoiesis and the suppression of malignant hematopoiesis rather than enforced differentiation of the leukemic cells. These data prompted us to investigate the effect of valproic acid on normal hematopoietic stem cells (HSC). Here we show that valproic acid increases both proliferation and self-renewal of HSC. It accelerates cell cycle progression of HSC accompanied by a down-regulation of p21(cip-1/waf-1). Furthermore,valproic acid inhibits GSK3beta by phosphorylation on Ser9 accompanied by an activation of the Wnt signaling pathway as well as by an up-regulation of HoxB4,a target gene of Wnt signaling. Both are known to directly stimulate the proliferation of HSC and to expand the HSC pool. In summary,we here show that valproic acid,known to induce differentiation or apoptosis in leukemic blasts,stimulates the proliferation of normal HSC,an effect with a potential effect on its future role in the treatment of acute myeloid leukemia. View Publication

A liquid culture system is described whereby proliferation of haemopoietic stem cells (CFU-S),production of granulocyte precursor cells (CFU-C),and extensive granulopoiesis can be maintained in vetro for several months. Such cultures consist of adherent and non-adherent populations of cells. The adherent population contains phagocytic mononuclear cells,epithelial" cells� View Publication

Wnt/$$-catenin signalling has been suggested to be active in basal-like breast cancer. However,in highly aggressive metastatic triple-negative breast cancers (TNBC) the role of $$-catenin and the underlying mechanism(s) for the aggressiveness of TNBC remain unknown. We illustrate that WNT10B induces transcriptionally active $$-catenin in human TNBC and predicts survival-outcome of patients with both TNBC and basal-like tumours. We provide evidence that transgenic murine Wnt10b-driven tumours are devoid of ER$$,PR and HER2 expression and can model human TNBC. Importantly,HMGA2 is specifically expressed during early stages of embryonic mammogenesis and absent when WNT10B expression is lost,suggesting a developmentally conserved mode of action. Mechanistically,ChIP analysis uncovered that WNT10B activates canonical $$-catenin signalling leading to up-regulation of HMGA2. Treatment of mouse and human triple-negative tumour cells with two Wnt/$$-catenin pathway modulators or siRNA to HMGA2 decreases HMGA2 levels and proliferation. We demonstrate that WNT10B has epistatic activity on HMGA2,which is necessary and sufficient for proliferation of TNBC cells. Furthermore,HMGA2 expression predicts relapse-free-survival and metastasis in TNBC patients. View Publication

Peroxisome proliferator-activated receptor gamma (PPARgamma) plays an important role in insulin sensitivity,tissue homeostasis,and regulating cellular functions. We found high-level expression of PPARgamma in embryo mouse brain and neural stem cells (NSCs),in contrast to extremely low levels in adult mouse brain. Here,we show that PPARgamma mediates the proliferation and differentiation of murine NSCs via up-regulation of the epidermal growth factor receptor and activation of the ERK pathway. Cell growth rates of NSCs prepared from heterozygous PPARgamma-deficient mouse brains,PPARgamma-RNA-silenced NSCs,and PPARgamma dominant-negative NSCs were significantly decreased compared with those of wild-type NSCs. Physiological concentrations of PPARgamma agonists,rosiglitazone and pioglitazone,stimulated NSC growth,whereas antagonists caused cell death in a concentration-dependent manner via activation of the caspase cascade. The stimulation of cell growth by PPARgamma was associated with a rapid activation of the ERK pathway by phosphorylation and up-regulation of epidermal growth factor receptor and cyclin B protein levels. In contrast,activation of PPARgamma by agonists inhibited the differentiation of NSCs into neurons. The inhibition of differentiation was associated with an activation of STAT3. These data indicate that PPARgamma regulates the development of the central nervous system during early embryogenesis via control of NSC proliferation. View Publication

Erythropoietin (EPO) regulates the proliferation and differentiation of erythroid cells by binding to its specific transmembrane receptor (EPOR). The presence of EPO and its receptor in the CNS suggests a different function for EPO other than erythropoiesis. The purpose of the present study was to examine EPOR expression and the role of EPO in the proliferation of neonatal spinal cord-derived neural progenitor cells. The effect of EPO on cell cycle progression was also examined,as well as the signaling cascades involved in this process. Our results showed that EPOR was present in the neural progenitor cells and EPO significantly enhanced their proliferation. Cell cycle analysis of EPO-treated neural progenitor cells indicated a reduced percentage of cells in G0/G1 phase,whereas the cell proliferation index (S phase plus G2/M phase) was increased. EPO also increased the proportion of 5-bromo-2-deoxyuridine (BrdU)-positive cells. With respect to the cell cycle signaling,we examined the cyclin-dependent kinases D1,D2 and E,and cyclin-dependent kinase inhibitors,p21cip1,p27kip1 and p57kip2. No significant differences were observed in the expression of these transcripts after EPO administration. Interestingly,the anti-apoptotic factors,mcl-1 and bcl-2 were significantly increased twofold. Moreover,these specific effects of EPO were eliminated by incubation of the progenitor cells with anti-EPO neutralizing antibody. Those observations suggested that EPO may play a role in normal spinal cord development by regulating cell proliferation and apoptosis. View Publication

Adoptive immunotherapy is evolving to assume an increasing role in treating cancer. Most imaging studies in adoptive immunotherapy to date have focused primarily on locating tumor-specific T cells rather than understanding their effector functions. In this study,we report the development of a noninvasive imaging strategy to monitor T-cell activation in living subjects by linking a reporter gene to the Granzyme B promoter (pGB),whose transcriptional activity is known to increase during T-cell activation. Because pGB is relatively weak and does not lead to sufficient reporter gene expression for noninvasive imaging,we specifically employed 2 signal amplification strategies,namely the Two Step Transcription Amplification (TSTA) strategy and the cytomegalovirus enhancer (CMVe) strategy,to maximize firefly luciferase reporter gene expression. Although both amplification strategies were capable of increasing pGB activity in activated primary murine splenocytes,only the level of bioluminescence activity achieved with the CMVe strategy was adequate for noninvasive imaging in mice. Using T cells transduced with a reporter vector containing the hybrid pGB-CMVe promoter,we were able to optically image T-cell effector function longitudinally in response to tumor antigens in living mice. This methodology has the potential to accelerate the study of adoptive immunotherapy in preclinical cancer models. View Publication

Polymorphonuclear neutrophils (PMNs) are critical for the formation,maintenance,and resolution of bacterial abscesses. However,the mechanisms that regulate PMN survival and proliferation during the evolution of an abscess are not well defined. Using a mouse model of Staphylococcus aureus abscess formation within a cutaneous wound,combined with real-time imaging of genetically tagged PMNs,we observed that a high bacterial burden elicited a sustained mobilization of PMNs from the bone marrow to the infected wound,where their lifespan was markedly extended. A continuous rise in wound PMN number,which was not accounted for by trafficking from the bone marrow or by prolonged survival,was correlated with the homing of c-kit(+)-progenitor cells from the blood to the wound,where they proliferated and formed mature PMNs. Furthermore,by blocking their recruitment with an antibody to c-kit,which severely limited the proliferation of mature PMNs in the wound and shortened mouse survival,we confirmed that progenitor cells are not only important contributors to PMN expansion in the wound,but are also functionally important for immune protection. We conclude that the abscess environment provides a niche capable of regulating PMN survival and local proliferation of bone marrow-derived c-kit(+)-progenitor cells. View Publication