Presence Of Conditioned Medium Research Articles

Variability of the paracrine‐induced osteoclastogenesis by human breast cancer cell lines

Breast cancer frequently metastasizes to the bone, often leading to the formation of osteolytic lesions. This work compares the paracrine-induced osteoclastogenesis mediated by four human breast cancer cell lines, the estrogen-receptor positive T47D and MCF-7 and the estrogen-negative SK-BR-3 and Hs-578T cell lines. Human osteoclast precursor cells were cultured in the presence of conditioned media from the breast cancer cell lines (10% and 20%), collected at different culture periods (48 h, 7 days, and 14 days). Cultures performed in the absence or the presence of M-CSF and RANKL served as negative and positive control, respectively. Results showed that the cell lines differentially expressed several osteoclastogenic genes. All cell lines exhibited a significant osteoclastogenic potential, evidenced by a high TRAP activity and number of osteoclastic cells, expression of several osteoclast-related genes, and, particularly, a high calcium phosphate resorption activity. Differences among the osteoclastogenic potential of the cell lines were noted. T47D and MCF-7 cell lines displayed the highest and the lowest osteoclastogenic response, respectively. Despite the variability observed, MEK and NF-κB signaling pathways, and, at a lesser extent, PGE2 production, seemed to have a central role on the observed osteoclastogenic response. In conclusion, the tested breast cancer cell lines exhibited a high osteoclastogenic potential, although with some variability on the cell response profile, a factor to be considered in the development of new therapeutic approaches for breast cancer-induced bone metastasis.

In Vitro Anti-Myeloma Activity of the Multitargeted Kinase Inhibitor Midostaurin in the Context of Heterotypic Cocultures of Myeloma Cells with Nonmalignant Microenvironmental Accessory Cells

Abstract 2923Midostaurin (PKC412; Novartis Pharmaceuticals) is a multi-targeted kinase inhibitor currently being evaluated in clinical trials in acute myelogenous leukemia (AML), because of its potent activity in cells expressing mutant FLT3. Prior preclinical studies from our groups have shown that PKC412 has FLT3-independent anti-MM activity, and the effects on AML cells is suppressed by the presence of conditioned media from bone marrow stromal cells (BMSCs), such as the immortalized BMSC line HS-5 (Weisberg et al. Mol Cancer Ther 2007). In this study, we evaluated whether the microenvironment-dependent drug resistance to PKC412 applies to not only AML cells, but also to cells from MM and other FLT3-negative malignant cells. We tested a panel of cells from MM (n=8), FLT-ITDneg AML (n=1), CML (n=2) and breast cancer (n=2) for their response to PKC412 in the presence or absence of BMSCs and other non-malignant accessory cells using tumor cell compartment-specific bioluminescence imaging (CS-BLI), as in our antecedent studies (McMillin et al. Nat Medicine 2010). We also compared the PKC412 response of the aforementioned neoplastic cells when cultured in vitro in the presence or absence of conditioned media (CM) from different types of BMSCs known to confer PKC412 resistance in FLT3-mutant AML cells. Consistent with our previous studies of PKC412 treatment in conventional cultures of MM cells in isolation, we observed that PKC412 exhibits an anti-proliferative effect within the first 24 hrs of treatment, with major reduction of the numbers of viable cells at 48 and 72 hrs. At sub-micromolar doses that did not significantly affect the viability of non-malignant accessory cells tested, PKC412 had similar (or for some MM cell lines had more pronounced) activity against the MM cells, both in the presence and absence of the non-malignant accessory cells tested (HS-5, HS-27a, NIH-3T3 cells with or without transfection with human CD40L, etc.). In contrast, under the same experimental conditions, coculture with either BMSCs or exposure to their conditional media, decreased the response of MM cells to dexamethasone. These results suggested in contrast to the impact on FLT3mut AML, that the anti-MM activity of PKC412 is preserved (and in some cases slightly enhanced) when the MM cells interact with microenvironmental accessory cells and/or their secreted growth/survival factors. To obtain insight on possible mechanistic foundations of these observations, we examined the pattern of kinases inhibited by PKC412 at sub-μM concentrations (using FLT3 and FGFR3, known targets of PKC412 as positive controls). The results of in vitro kinase activity assays showed that PKC412 potently suppresses the aforementioned positive controls, but also exerts >50% inhibitory effect on the in vitro activity of additional kinases such as Akt2, Pim1, GSK3a, PDK1, p70S6K, SRC and Aurora A. Many of these kinases are known to participate in proliferative/anti-apoptotic signaling cascades downstream of cytokine/growth factor receptors or cell adhesion-mediated events triggered during MM–stromal interactions. We therefore conclude that the influence of the tumor microenvironment on the anti-neoplastic effects of PKC412 may be tumor-type dependent. The anti-MM activity of PKC412 is not subject to drug resistance triggered by non-malignant accessory cells, and conversely is occasionally moderately enhanced by these MM-stromal interactions. Mechanistically, this observation may be attributed in part to the multi-targeted nature of this inhibitor and, in particular, its aggregate impact on several kinases known to mediate stroma-induced proliferative and antipoptotic signaling in MM. Disclosures:Griffin:Novartis Pharmaceuticals: Consultancy, Research Funding. Richardson:Millennium: ; Celgene: ; Johnson & Johnson: ; Novartis: ; Bristol Myers Squibb:. Anderson:Celgene: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Mitsiades:EMD Serono: Research Funding; AVEO Pharma: Research Funding; Amgen: Research Funding; OSI Pharmaceuticals: Research Funding; PharmaMar: licensing royalties; Amnis Therapeutics: Consultancy, Honoraria; Centocor: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Kosan: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Millennium Pharmaceuticals: Consultancy, Honoraria; Sunesis: Research Funding; Gloucester Pharmaceuticals: Research Funding; Genzyme: Research Funding; Johnson & Johnson: Research Funding.

Endothelial derived factors inhibit anoikis of head and neck cancer stem cells

Recent evidence demonstrated that cancer stem cells reside in close proximity to blood vessels in human head and neck squamous cell carcinomas (HNSCC). These findings suggest the existence of a supporting perivascular niche for cancer stem cells. The purpose of this study was to evaluate the effect of endothelial cell-secreted factors on the behavior of head and neck cancer stem-like cells (HNCSC). HNCSC were identified by sorting UM-SCC-22A (cell line derived from a primary squamous cell carcinoma of the oropharynx) and UM-SCC-22B (derived from the metastatic lymph node of the same patient) for CD44 expression and ALDH (aldehyde dehydrogenase) activity. HNCSC (ALDH+CD44+) and control (ALDH-CD44-) cells were cultured in ultra-low attachment plates in presence of conditioned medium from primary human endothelial cells. ALDH+CD44+ generated more orospheres than control cells when cultured in suspension. The growth factor milieu secreted by endothelial cells protected HNCSC against anoikis. Mechanistic studies revealed that endothelial cell-secreted vascular endothelial growth factor (VEGF) induces proliferation of HNCSC derived from primary UM-SCC-22A, but not from the metastatic UM-SCC-22B. Likewise, blockade of VEGF abrogated endothelial cell-induced Akt phosphorylation in HNCSC derived from UM-SCC-22A while it had a modest effect in Akt phosphorylation in HNCSC from UM-SCC-22B. This study revealed that endothelial cells initiate a crosstalk that protect head and neck cancer stem cells against anoikis, and suggest that therapeutic interference with this crosstalk might be beneficial for patients with head and neck cancer.

Liver sinusoidal endothelial cells support the survival and undifferentiated growth of the CGR8 mouse embryonic stem cell line: Possible role of leukemia inhibitory factor (LIF)

Murine embryonic stem cells (muESC) are maintained and expanded in vitro by culturing in the presence of leukemia inhibitory factor (LIF) or by coculturing on murine embryonic fibroblast (MEF). Previously we have shown that liver sinusoidal endothelial cells (LSEC) promote the survival, proliferation and differentiation of hematopoietic stem cells. In the present study we investigated whether LSEC might promote the survival and undifferentiated growth of muESC. For these purposes, muESC (CGR8 cell line) were cultured on LSEC monolayers (muESC/LSEC) or in the presence of conditioned medium from LSEC cultures (muESC/LSEC-CM), both in the absence of LIF. Microscopic observation showed the growth of undifferentiated ESC colonies in both muESC/LSEC or muESC/LSEC-CM cultures. A significant reduction in the growth of undifferentiated ESC colonies was observed when ESC were cultured in LSEC-CM previously incubated with anti-LIF. RT-PCR and Western blot analysis showed that LSEC constitutively express LIF at the mRNA and protein level. At different times of culture, muESC were harvested and analyzed for the expression of embryonic markers (SSEA-1 and Oct-4) and differentiation capacity. Flow cytometry analysis showed the presence of a higher percentage of muESC (>90%) expressing SSEA-1 in muESC/LSEC-CM, as compared with muESC/LSEC cocultures. muESC obtained from both types of cultures formed embryoid bodies in vitro, and form teratomas in testicles of mice. These results provide the first evidence that LSEC support the in vitro survival, self-renewal, undifferentiated growth and differentiation capacity of the muESC CGR8 cell line.

Apoptotic osteocytes regulate osteoclast precursor recruitment and differentiation in vitro

Fatigue loading causes a spatial distribution of osteocyte apoptosis co-localized with bone resorption spaces peaking around microdamage sites. Since osteocytes have been shown to regulate osteoclast formation and activity, we hypothesize that osteocyte apoptosis regulates osteoclastogenesis. In this study, we used serum-starvation to mimic reduced nutrient transport in microdamaged bone and induce apoptosis in MLO-Y4 osteocyte-like cells; conditioned medium was used to apply soluble factors released by apoptotic osteocytes (aOCY) to healthy non-apoptotic MLO-Y4 cells. Osteoclast precursor (RAW264.7 monocyte) migration and differentiation were assessed in the presence of conditioned media (CM) from: (A) aOCY, (B) osteocytes treated with apoptosis conditioned medium (i.e., healthy osteocytes in the presence of apoptosis cues; apoptosis CM-treated osteocytes (atOCY)), and (C) osteocytes treated with non-apoptosis conditioned medium (i.e., healthy osteocytes in the absence of apoptosis cues; non-apoptosis CM-treated osteocytes (natOCY)). Receptor activator for nuclear factor-κB ligand (RANKL), macrophage colony stimulating factor (M-CSF), vascular endothelial growth factor (VEGF) and osteoprotegerin (OPG) mRNA, and protein expression were measured. Our findings indicate that soluble factors released by aOCY and atOCY promoted osteoclast precursor migration (up to 64% and 24% increase, respectively) and osteoclast formation (up to 450% and 265% increase, respectively). Osteoclast size increased up to 233% in the presence of aOCY and atOCY CM. Recruitment, formation and size were unaltered by natOCY. RANKL mRNA and protein expression were upregulated only in aOCY, while M-CSF and VEGF increased in atOCY. Addition of RANKL-blocking antibody abolished aOCY-induced osteoclast precursor migration and osteoclast formation. VEGF and M-CSF blocking antibodies abolished atOCY-induced osteoclastogenesis. These findings suggest that aOCY directly and indirectly (through atOCY) initiate targeted bone resorption by regulating osteoclast precursor recruitment and differentiation.

Serum Amyloid A Activates the NLRP3 Inflammasome and Promotes Th17 Allergic Asthma in Mice

IL-1β is a cytokine critical to several inflammatory diseases in which pathogenic Th17 responses are implicated. Activation of the NLRP3 inflammasome by microbial and environmental stimuli can enable the caspase-1-dependent processing and secretion of IL-1β. The acute-phase protein serum amyloid A (SAA) is highly induced during inflammatory responses, wherein it participates in systemic modulation of innate and adaptive immune responses. Elevated levels of IL-1β, SAA, and IL-17 are present in subjects with severe allergic asthma, yet the mechanistic relationship among these mediators has yet to be identified. In this study, we demonstrate that Saa3 is expressed in the lungs of mice exposed to several mixed Th2/Th17-polarizing allergic sensitization regimens. SAA instillation into the lungs elicits robust TLR2-, MyD88-, and IL-1-dependent pulmonary neutrophilic inflammation. Furthermore, SAA drives production of IL-1α, IL-1β, IL-6, IL-23, and PGE(2), causes dendritic cell (DC) maturation, and requires TLR2, MyD88, and the NLRP3 inflammasome for secretion of IL-1β by DCs and macrophages. CD4(+) T cells polyclonally stimulated in the presence of conditioned media from SAA-exposed DCs produced IL-17, and the capacity of polyclonally stimulated splenocytes to secrete IL-17 is dependent upon IL-1, TLR2, and the NLRP3 inflammasome. Additionally, in a model of allergic airway inflammation, administration of SAA to the lungs functions as an adjuvant to sensitize mice to inhaled OVA, resulting in leukocyte influx after Ag challenge and a predominance of IL-17 production from restimulated splenocytes that is dependent upon IL-1R signaling.

Essential role of p53 of stromal fibroblasts (fibs) in the reciprocal interaction between PC3 prostate cancer cells and stromal fibs.

e21009 Background: The p53/p21 regulatory network is frequently deregulated in stromal cells and aberrant expression of p53/p21 has been reported in stromal fibs in various cancers. Methods: In order to provide hints regarding the mode of the paracrine interaction between p53 in stromal fibs and cancer cells (ccs), primary fibs from mice differing in the status of p53 were cultured in the presence of conditioned media from PC3 human prostate ccs and the rate of cell growth was evaluated. In addition, in vitro wound healing assays were performed to assess motility and migration of ccs. Considering the effects of p53-deficient (p53d) fibs in the phenotype of PC3 cells, we also searched if this paracrine stimulatory mechanism also affects viability of PC3 cells bearing stem cell-like properties by flow-cytometry. Therefore, PC3 cells that is CD44(hi)/CD44(low) were assessed in cells co-cultured with wild-type or p53d fibs. Results: We showed that p53d fibs acquire proliferative advantage when cultured in the presence of PC3 media, an observation likely related to the predominance of cells bearing this alteration in the microenvironment. The reverse experiment, i.e. the culture of PC3 cells in the presence of conditioned media from wild-type or p53-null fibs indicated that the latter stimulate the proliferation of ccs establishing a paracrine reciprocal stimulatory network that facilitates tumor growth. In vitro wound healing assays revealed that media from p53d cells significantly stimulated PC3 cell migration that reflects the degree of cellular motility which is associated with the metastatic potential of ccs. Flow-cytometry demonstrated that although wild fibs reduced the fraction of CD44(hi)/CD44(low) cells compared to that of PC3 cells cultured alone, the presence of p53d fibs restored the CD44(hi)/CD44(low) cell content to levels similar to those of the controls. Conclusions: Our findings pose that deregulated expression and mutations in p53 and/or p21 in stromal fibs are causatively linked to tumor growth, affecting not only cellular proliferation but also migration and stem-cell content. Therefore, modulation of p53/p21 activity in stromal fibs merits further investigation.

Abstract 1213: Neuropeptide Y, adipose tissue and breast cancer

Abstract Adipose tissue contributes to obesity-associated risk in breast cancer progression. Recent work has demonstrated the involvement of preadipocytes in promoting the induction of breast tumor cell migration and invasion. Neuropeptide Y (NPY) stimulates proliferation of preadipocytes in vitro by the Y1 receptor. NPY receptors are present in almost all primary breast cancers and in lymph node metastases from ER-positive primary cancers. By contrast, the peptide has been shown to inhibit the invasion of certain tumor cells. However, the relative contribution of adipose and NPY to breast tumor survival remains to be determined. Using the highly metastatic ER-negative human breast cancer cell line MDA-MB-231, we found that NPY significantly inhibited cell proliferation, an effect that was reversed by treatment with the Y1-receptor antagonist BIBP-3226 (P<0.05). Breast tumor cells treated with NPY exhibited changes in cell morphology and demonstrated a two-fold increase in early apoptosis. When breast tumor cells were incubated in the presence of conditioned media harvested from 3T3-L1 preadipocytes, NPY enhanced apoptosis. Significantly more breast tumor cells migrated toward the preadipocytes compared to conditioned media alone (P<0.0001), but less in the presence of NPY. In conclusion, it appears that adipose tissue promotes breast tumor survival and migration, while NPY limits its. It will be of interest to determine whether the tumor migration-promoting activity of preadipocytes varies among breast cancer subtypes, and if so, whether it serves as a predisposing factor for breast cancer progression. In addition, the targeting of NPY-Y1 receptors in breast tumors may have a diagnostic and possibly therapeutic value. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1213. doi:10.1158/1538-7445.AM2011-1213

Paracrine-mediated osteoclastogenesis by the osteosarcoma MG63 cell line: is RANKL/RANK signalling really important?

Although in the past little attention has been paid to the influence of osteosarcoma cells in osteoclast function, recent studies suggest a close relationship between osteosarcoma aggressiveness and osteoclastic activity. The present study addresses the paracrine effects of MG63 cells, a human osteosarcoma-derived cell line, on the differentiation of peripheral blood osteoclast precursor cells (PBMC). PBMC were cultured for 21days in the presence of conditioned media from MG63 cell cultures (CM) collected at 48h (CM_MG1), 7days (CM_MG2) and 14days (CM_MG3). MG63 cell cultures displayed the expression of ALP and BMP-2 and, also, the osteoclastogenic genes M-CSF and RANKL, although with a low expression of RANKL. PBMC cultures supplemented with CM presented an evident osteoclastogenic behavior, which was dependent on the culture period of the MG63 cells. The inductive effect appeared to be more relevant for the differentiation and activation genes, c-myc and c-src, and lower for genes associated with osteoclast function. In addition, PBMC cultures displayed increased functional parameters, including calcium phosphate resorbing activity. Assessment of the PBMC cultures in the presence of U0126, PDTC, and indomethacin suggested that in addition to MEK and NFkB pathways, other signaling mechanisms, probably not involving RANKL/RANK interaction, might be activated in the presence of conditioned medium from MG63. In conclusion, MG63 cell line appears to induce a significant paracrine-mediated osteoclastogenic response. Understanding the mechanisms underlying the interaction of osteosarcoma cells and osteoclasts may contribute to the development of new potential approaches in the treatment of such bone metabolic diseases.

Mutually beneficial crosstalk between muscle cells and osteocytes

Integrative biological approaches have led to the discovery of new physiological roles for bone and skeletal muscle that might have implications for our understanding of osteoporosis and sarcopenia. We recently investigated the crosstalk between bone and muscle cells by testing the effects of conditioned media (CM) from MLO-Y4 osteocytes and we found that MLO-Y4 CM induced myogenic differentiation of C2C12 myoblasts along with changes in calcium handling and gene expression suggesting activation of the MURF-NF-kB pathway. Here, we tested the response of MLO-Y4 osteocytes subjected to fluid flow shear stress in the presence of CM from C2C12 myotubes. We found that C2C12 myotubes CM modulate the expression of genes related to calcium homeostasis, heat shock response, apoptosis, and apparently enhancement of osteocytes differentiation program. These data along with our recent ASBMR abstract showing that CM from C2C12 myotubes enhanced the effects of shear stress on MLO-Y4 release of PGE2, activation of Akt and translocation of β-catenin indicate that molecular signaling between muscle and bone has the potential to be mutually beneficial. Support: NIH RC2 AR058962 and Missouri Life Sciences Research Board.

Reduced Staphylococcus aureus proliferation and biofilm formation on zinc oxide nanoparticle PVC composite surfaces

Conventional particulate zinc oxide (ZnO) is a known antibacterial agent. Studies have shown that reducing the size of ZnO particles to nanoscale dimensions further enhances their antibacterial properties. Polymers, like all biomaterials, run the risk of harboring bacteria which may produce an antibiotic-resistant biofilm. The addition of ZnO nanoparticles to form a polymer composite material may thus reduce undesirable bacteria activity. The purpose of the present in vitro study was to investigate the antibacterial properties of ZnO nanoparticles when incorporated into a traditional polymeric biomaterial. For this purpose, Staphylococcus aureus were seeded at a known cell density onto coverslips coated with a film of polyvinyl chloride (PVC) with varying concentrations of ZnO nanoparticles. Samples were cultured for 24 or 72 h. Methods of analysis, including optical density readings and crystal violet staining, indicated a reduced presence of a biofilm on ZnO nanoparticle polymer composites compared to pure polymer controls. Live/dead bacteria assays provided images to confirm the reduced presence of active bacteria on samples with zinc oxide nanoparticles. Conditioning of the cell culture medium by the composites was also investigated by measuring concentrations of elemental zinc (Zn 2+) and bacteria growth in the presence of conditioned medium. This study demonstrated that the development of ZnO polymer composites may improve biomaterial effectiveness for numerous applications, such as endotracheal tubes, catheterp and implanted biomaterials, which are prone to bacterial infection.

Angiogenic properties of aged adipose derived mesenchymal stem cells after hypoxic conditioning

BackgroundMesenchymal stem cells derived from adipose tissue (ADSC) are multipotent stem cells, originated from the vascular-stromal compartment of fat tissue. ADSC are used as an alternative cell source for many different cell therapies, however in ischemic cardiovascular diseases the therapeutic benefit was modest. One of the reasons could be the use of autologous aged ADSC, which recently were found to have impaired functions. We therefore analysed the effects of age on age markers and angiogenic properties of ADSC. Hypoxic conditioning was investigated as a form of angiogenic stimulation.MethodsADSC were harvested from young (1-3 month), adult (12 month) and aged (18-24 month) mice and cultured under normoxic (20%) and hypoxic (1%) conditions for 48 h. Differences in proliferation, apoptosis and telomere length were assessed in addition to angiogenic properties of ADSC.ResultsProliferation potential and telomere length were decreased in aged ADSC compared to young ADSC. Frequency of apoptotic cells was higher in aged ADSC. Gene expression of pro-angiogenic factors including vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and hepatic growth factor (HGF) were down-regulated with age, which could be restored by hypoxia. Transforming growth factor (TGF-β) increased in the old ADSC but was reduced by hypoxia.Expression of anti-angiogenic factors including thrombospondin-1 (TBS1) and plasminogen activator inhibitor-1 (PAI-1) did increase in old ADSC, but could be reduced by hypoxic stimulation. Endostatin (ENDS) was the highest in aged ADSC and was also down-regulated by hypoxia. We noted higher gene expression of proteases system factors like urokinase-type plasminogen activator receptor (uPAR), matrix metalloproteinases (MMP2 and MMP9) and PAI-1 in aged ADSC compared to young ADSC, but they decreased in old ADSC. Tube formation on matrigel was higher in the presence of conditioned medium from young ADSC in comparison to aged ADSC.ConclusionsADSC isolated from older animals show changes, including impaired proliferation and angiogenic stimulation. Angiogenic gene expression can be partially be improved by hypoxic preconditioning, however the effect is age-dependent. This supports the hypothesis that autologous ADSC from aged subjects might have an impaired therapeutic potential.

In Vitro Sarcoma Cells Release a Lipophilic Substance That Activates the Pain Transduction System via TRPV1

Despite success in treating many forms of cancer, pain associated with malignancy remains a serious clinical issue with a poorly understood etiology. This study determined if certain sarcoma cell lines produced a soluble factor that activates the TRPV1 ion channel expressed on nociceptive sensory neurons, thereby activating a major pain transduction system. Trigeminal ganglia were harvested from rats and cultured. A rhabdomyosarcoma (CRL1598) and osteosarcoma (CRL 1543) cell line were grown to 75% confluency. Conditioned media (CM) was collected after 24h of exposure and subjected to reverse phase chromatography. Neuronal activation in the presence of CM was measured using iCGRP RIA and calcium imaging after treatment with vehicle or I-RTX, a potent TRPV1 antagonist. Data were analyzed by ANOVA/Bonferroni or t test. The rhabdomyosarcoma CM produced a 4-fold increase in iCGRP release compared with control media (P<0.001). The osteosarcoma cell line CM produced a 7-fold increase in iCGRP release compared with control media (P<0.001). This evoked iCGRP release was via TRPV1 activation since the effect was blocked by the antagonist I-RTX. The application of rhabdomyosarcoma CM produced about a 4-fold increase in [Ca(2+)]I levels (P<0.001), and this effect was blocked by pretreatment with the TRPV1 antagonist, I-RTX. We have shown that certain sarcoma cell lines produce a soluble, lipophilic factor that activates the peripheral nociceptor transduction system via TRPV1 activation, thereby contributing to cancer pain. Further investigations are needed to develop tumor-specific analgesics that do not produce unwanted or harmful side-effects.

Adipocyte differentiation influences the proliferation and migration of normal and tumoral breast epithelial cells

Stromal tissue regulates the development and differentiation of breast epithelial cells, with adipocytes being the main stromal cell type. The aim of the present study was to evaluate the effect of adipocyte differentiation on proliferation and migration, as well as to assess the activity of heparanase and metalloproteinase-9 (MMP-9), in normal (NMuMG) and tumoral (LM3) murine breast epithelial cells. NMuMG and LM3 cells were grown on irradiated 3T3-L1 cells (stromal support, SS) at various degrees of differentiation [preadipocytes (preA), poorly differentiated adipocytes (pDA) and mature adipocytes (MA)] and/or were incubated in the presence of conditioned medium (CM) derived from each of these three types of differentiated cells. Cells grown on a plastic support or in fresh medium served as the controls. Cell proliferation was measured with a commercial colorimetric kit, and the motility of the epithelial cells was evaluated by means of a wound-healing assay. Heparanase activity was assessed by quantifying heparin degradation, and the expression of MMP-9 was determined using Western blotting. The results indicate that cell proliferation was increased after 24 and 48 h in the NMuMG and LM3 cells grown on preA, pDA and MA SS. In the NMuMG cells cultured on SS in the presence of all three types of CM, proliferation was enhanced. LM3 cell migration was increased in the presence of all three types of CM and in cells grown on preA SS. Heparanase activity was increased in the NMuMG cells incubated with all three types of CM, and in the LM3 cells incubated with the CM from pDA and MA. Both the NMuMG and LM3 cell lines presented basal expression of MMP-9; however, a significant increase in MMP-9 expression was observed in the LM3 cells incubated with each of the three types of CM. In conclusion, adipocyte differentiation influences normal and tumoral breast epithelial cell proliferation and migration. Heparanase and MMP-9 appear to be involved in this regulation. The experimental model presented in this study is in keeping with the characteristics of the physiological environment of breast epithelial cells, in terms of both the soluble and insoluble factors present and the stromal structure per se.

The hepatitis C virus core protein indirectly induces alpha-smooth muscle actin expression in hepatic stellate cells via interleukin-8

Progressive deposition of liver fibrosis is a common feature of chronic hepatitis associated with hepatitis C virus (HCV) infection, and it may eventually lead to cirrhosis and liver failure. Although this fibrogenic process appears to be linked to HCV protein expression and replication via indirect mechanisms, i.e., to be mediated by virally-driven inflammation, a direct role of HCV in inducing fibrosis deposition has never been entirely excluded. We established an in vitro system in which the human hepatic stellate cell line LX-2 was cultured in the presence of conditioned medium from human hepatoma Huh-7 cells transduced with a lentiviral vector expressing HCV core proteins of different genotypes. Treatment of LX-2 cells, with conditioned medium from Huh-7 cells expressing HCV core protein, led to the activation of alpha-smooth muscle actin expression. Among the chemokines secreted by cells transduced with HCV core, interleukin-8 was identified as the strongest inducer of alpha-smooth muscle actin expression in LX-2 and primary hepatic stellate cells. This effect was accompanied by a decrease in cell migration and increased focal contact organisation. The expression of the HCV core in hepatocytes may contribute to the establishment of a profibrogenic microenvironment.

Abstract 5805: Adenosine Down-Regulates Soluble Vascular Endothelial Growth Factor Receptor-1

Background: The cardioprotective nucleoside adenosine acts through 4 types of receptors: A1, A2a, A2b, A3. An emerging concept is that adenosine is a major factor driving angiogenesis, thus contributing to the repair of the ischemic heart. Angiogenesis is controlled by a plethora of vasculogenic factors, among which Vascular Endothelial Growth Factor (VEGF) and its receptor VEGFR1 (or Flt-1). A soluble form of VEGFR1 (sFlt-1) traps circulating VEGF, thereby preventing its binding to VEGF receptors. Both VEGF and sFlt-1 are induced by Hypoxia Inducible Factor 1 α . The aim of the present study was to characterize the effect of adenosine on the production sFlt-1. Methods: Primary blood monocytes obtained from healthy volunteers and patients with acute myocardial infarction (MI) were differentiated to macrophages in vitro. Treatments included: adenosine (10 μ M), CGS21680 (A2a receptor agonist, 0.1–10 μ M), SCH58261 (A2a receptor antagonist, 0.1–10 μ M), and/or LPS (100 ng/mL). ELISA, immuno-blotting and TransAM™ assay were used to measure expression levels and activation of sFlt-1 and HIF-1 α . In vitro formation of microtubules by human coronary artery endothelial cells (HCAEC) was used to evaluate angiogenesis. Results: LPS induced sFlt-1 production by macrophages from healthy volunteers and adenosine inhibited this induction (43% decrease, P=0.006, n=12). This inhibition was replicated by the A2a agonist and reversed by the A2a antagonist. The formation of a network of microtubules by HCAEC was enhanced in the presence of conditioned medium from adenosine-treated macrophages and impaired by exogenous sFlt-1. Adenosine inhibited the LPS-induced nuclear translocation of HIF-1 α , thereby preventing its activation. The effect of adenosine was replicated in macrophages isolated from acute MI patients. Conclusion: We show here for the first time that adenosine down-regulates the production of sFlt-1. This mechanism involves the adenosine A2a receptor and the transcriptional activator HIF-1 α . Our data suggest that this effect of adenosine may play a significant role in angiogenesis.

Osteoclast differentiation of human peripheral mononuclear cells in the presence of conditioned media from fibroblast cell cultures

Osteoclast differentiation of human peripheral mononuclear cells in the presence of conditioned media from fibroblast cell cultures

Prostaglandin E2 released from activated microglia enhances astrocyte proliferation in vitro

Microglial activation has been implicated in many astrogliosis-related pathological conditions including astroglioma; however, the detailed mechanism is not clear. In this study, we used primary enriched microglia and astrocyte cultures to determine the role of microglial prostaglandin E 2 (PGE 2) in the proliferation of astrocytes. The proliferation of astrocytes was measured by BrdU incorporation. The level of PGE 2 was measured by ELISA method. Pharmacological inhibition or genetic ablation of COX-2 in microglia were also applied in this study. We found that proliferation of astrocytes increased following lipopolysaccharide (LPS) treatment in the presence of microglia. Furthermore, increased proliferation of astrocytes was observed in the presence of conditioned media from LPS-treated microglia. The potential involvement of microglial PGE 2 in enhanced astrocyte proliferation was suggested by the findings that PGE 2 production and COX-2 expression in microglia were increased by LPS treatment. In addition, activated microglia-induced increases in astrocyte proliferation were blocked by the PGE 2 antagonist AH6809, COX-2 selective inhibitor DuP-697 or by genetic knockout of microglial COX-2. These findings were further supported by the finding that addition of PGE 2 to the media significantly induced astrocyte proliferation. These results indicate that microglial PGE 2 plays an important role in astrocyte proliferation, identifying PGE 2 as a key neuroinflammatory molecule that triggers the pathological response related to uncontrollable astrocyte proliferation. These findings are important in elucidating the role of activated microglia and PGE 2 in astrocyte proliferation and in suggesting a potential avenue in the use of anti-inflammatory agents for the therapy of astroglioma.

Combined mTOR inhibition and post-transplant infusion of alloantigen-specific Treg promotes long-term graft survival in otherwise unmanipulated hosts (141.42)

Abstract Protocols that achieve donor-specific tolerance of MHC-mismatched organ grafts remain an unmet clinical goal. We report a strategy that combines post-transplant administration of alloAg-specific Treg (AAsTreg) with inhibition of the mammalian target of rapamycin (Rapa) (mTOR) to promote long-term, donor-specific heart graft survival. AAsTreg selection was achieved by co-culture of CD4+CD25+ Treg with immature dendritic cells (DC) in the presence of conditioned media. This rendered cells that potently inhibited T cell proliferation in an Ag-specific manner. However, AAsTreg remained unable to control T cell activation when stimulated by mature DC, - a phenomenon dependent on IL-6 release. Exploiting the in vivo inhibitory effects of Rapa on inflammatory cytokine (IL-6) production, T cell proliferation and graft infiltration, AAsTreg were administered post-transplant (d7) in combination with short-term Rapa. AAsTreg exerted a pro-tolerogenic effect: &amp;gt;80% long-term graft survivors [LTS] (MST&amp;gt;150d). Polyclonal Treg exerted an inferior protective effect: 40% LTS (MST=45d). Moreover, the pro-tolerogenic effect was Ag-specific as AAsTreg selected against third party DC failed to prolong graft survival. Significantly, LTS exhibited alloreactive T cell anergy. Thus, combination of mTOR inhibition with AAsTreg is an effective, clinically-applicable approach to promote long-term graft survival.

Estrogen stimulates the human endometrium to express a factor(s) that promotes vascular smooth muscle cell migration as an early step in microvessel remodeling

Vascular smooth muscle cell (VSMC) migration is a pivotal early step in blood vessel remodeling; however, very little is known about the regulation of this process in the human endometrium during the menstrual cycle. In this study, explants of human endometrium were incubated with estradiol and/or progesterone and the conditioned medium (CM) applied to cultures of VSMC to test the hypothesis that estrogen and progesterone stimulate endometrial cells to secrete a factor(s) that promotes VSMC migration. Endometrial explants were composed of highly organized glands and stroma. VSMC migration (cells migrated in 21 h/mm(2) fibronectin-coated semipermeable membrane) in the presence of CM from human endometrial explants obtained in the proliferative phase of the menstrual cycle and incubated for 24 h with estradiol was approximately threefold greater (P < 0.001) than with medium alone and greater (P < 0.05) than with CM from explants treated with estradiol plus progesterone or progesterone. It is concluded, therefore, that estrogen stimulates endometrial secretion of a factor(s) that promotes VSMC migration as an early step in vessel remodeling within the endometrium.