A clonogenic progenitor with prominent plasmacytoid dendritic cell developmental potential.

Macrophage and dendritic cell (DC) progenitors (MDPs) and common DC progenitors (CDPs) are bone marrow (BM) progenitors with DC differentiation potential. However, both MDPs and CDPs give rise to large numbers of conventional DCs (cDCs) and few plasmacytoid DCs (pDCs), implying that more dedicated pDC progenitors remain to be identified. Here we have described DC progenitors with a prominent pDC differentiation potential. Although both MDPs and CDPs express the macrophage colony stimulating factor (M-CSF) receptor (M-CSFR), the progenitors were confined to a M-CSFR(-) fraction, identified as Lin(-)c-Kit(int/lo)Flt3(+)M-CSFR(-), and expressed high amounts of E2-2 (also known as Tcf4) an essential transcription factor for pDC development. Importantly, they appeared to be directly derived from either CDPs or lymphoid-primed multipotent progenitors (LMPPs). Collectively, our findings provide insight into DC differentiation pathways and may lead to progenitor-based therapeutic applications for infection and autoimmune disease.

Spatial distribution of CD115+ and CD11b+ cells and their temporal activation during oxygen-induced retinopathy in mice.

PURPOSE: The model of oxygen-induced retinopathy (OIR) is widely used to analyze pathomechanisms in retinal neovascularization. Previous studies have shown that macrophages (MP) play a key role in vessel formation in OIR, the influence of microglia (MG) having been discussed. The aim of our study was to analyze the spatial and temporal distribution and activation of MP/MG expressing CD115 and CD11b during the process of neovascularization in OIR. METHODS: We used MacGreen mice expressing the green fluorescence protein (GFP) under the promoter for CD115. CD115+ cells were investigated in vivo by scanning laser ophthalmoscopy at postnatal days (P) 17 and 21 in MacGreen mice with OIR (75% oxygen from P7 to P12), and were compared to MacGreen room-air controls. In addition MP/MG were examined ex vivo using immunohistochemistry for CD11b+ detection on retinal flatmounts at P14, P17, and P21 of wild type mice with OIR. RESULTS: In-vivo imaging revealed the highest density of activated MP/MG in tuft areas at P17 of MacGreen mice with OIR. Tufts and regions with a high density of CD115+ cells were detected close to veins, rather to arteries. In peripheral, fully vascularized areas, the distribution of CD115+ cells in MacGreen mice with OIR was similar to MacGreen room-air controls. Correspondingly, immunohistochemical analyses of retinal flatmounts from wild type mice with OIR induction revealed that the number of CD11b+ cells significantly varies between vascular, avascular, and tuft areas as well as between the retinal layers. Activated CD11b+ cells were almost exclusively found in avascular areas and tufts of wild type mice with OIR induction; here, the proportion of activated cells related to the total number of CD11b+ cells remained stable over the course of time. CONCLUSIONS: Using two different approaches to monitor MP/MG cells, our findings demonstrated that MP/MG concentrate within pathologically vascularized areas during OIR. We were able to clarify that reactive changes of CD11b+ cell distribution to OIR primarily occur in the deep retinal layers. Furthermore, we found the highest proportion of activated CD11b+ cells in regions with pathologic neovascularization processes. Our findings support previous reports about activated MP/MG guiding revascularization in avascular areas and playing a key role in the formation and regression of neovascular tufts.

Transcriptional mechanisms that control expression of the macrophage colony-stimulating factor receptor locus.

The proliferation, differentiation, and survival of cells of the macrophage lineage depends upon signals from the macrophage colony-stimulating factor (CSF) receptor (CSF1R). CSF1R is expressed by embryonic macrophages and induced early in adult hematopoiesis, upon commitment of multipotent progenitors to the myeloid lineage. Transcriptional activation of CSF1R requires interaction between members of the E26 transformation-specific family of transcription factors (Ets) (notably PU.1), C/EBP, RUNX, AP-1/ATF, interferon regulatory factor (IRF), STAT, KLF, REL, FUS/TLS (fused in sarcoma/ranslocated in liposarcoma) families, and conserved regulatory elements within the mouse and human CSF1R locus. One element, the Fms-intronic regulatory element (FIRE), within intron 2, is conserved functionally across all the amniotes. Lineage commitment in multipotent progenitors also requires down-regulation of specific transcription factors such as MYB, FLI1, basic leucine zipper transcriptional factor ATF-like (BATF3), GATA-1, and PAX5 that contribute to differentiation of alternative lineages and repress CSF1R transcription. Many of these transcription factors regulate each other, interact at the protein level, and are themselves downstream targets of CSF1R signaling. Control of CSF1R transcription involves feed-forward and feedback signaling in which CSF1R is both a target and a participant; and dysregulation of CSF1R expression and/or function is associated with numerous pathological conditions. In this review, we describe the regulatory network behind CSF1R expression during differentiation and development of cells of the mononuclear phagocyte system.

Age and Expression of CD163 and Colony-Stimulating Factor 1 Receptor (CD115) Are Associated With the Biological Behavior of Central Giant Cell Granuloma.

PURPOSE: Central giant cell granulomas (CGCGs) are clinically classified as nonaggressive (nA-CGCGs) and aggressive (A-CGCGs). However, histopathologically, all lesions feature spindle mononuclear cells (MCs) and multinuclear giant cells (GCs) in a hemorrhage-rich stroma. We aimed to investigate the presence of cells with a monocyte- or macrophage-related phenotype and, together with clinical variables, to examine their predictive potential for the biological behavior of CGCGs. PATIENTS AND METHODS: For our investigation, we implemented a retrospective cohort study. Sections were immunohistochemically stained for colony-stimulating factor 1 receptor (CSF-1R) (CD115), CD163, CD68, and nuclear factor κB. The clinical variables included age, gender, and location of lesions. Associations between immunostains, clinical variables, and CGCG aggressiveness were analyzed by the Wilcoxon (Mann-Whitney) exact test and t test. Significant variables were further analyzed by a logistic regression model followed by receiver operating characteristic (ROC) curve analysis for diagnostic sensitivity. Significance was set at P < .05. RESULTS: Patients with A-CGCGs (n = 36) were younger than those with nA-CGCGs (n = 31) (P = .002). Logistic regression showed that CD163-GC (ß = -0.870, P = .031) and CD115-MC (ß = -0.783, P = .027) had a significant protection effect (odds ratio, 0.419 [95% confidence interval, 0.190 to 0.925], and odds ratio, 0.457 [95% confidence interval, 0.229 to 0.913], respectively). ROC curve analysis showed that CD163-GC and CSF-1R (CD115)-MC combined were the best predictor in distinguishing nA-CGCGs from A-CGCGs (area under ROC curve, 0.814; P < .001). At the optimal cutoff value (0.408), sensitivity was 87% and specificity, 65%. CONCLUSIONS: Increasing age and high expression of CD163-GC and CSF-1R (CD115)-MC can serve as significant predictors of nA-CGCGs. A functional link between CD163-GC and the characteristic areas of extravasation of erythrocytes is discussed.

Essential role of PU.1 in maintenance of mixed lineage leukemia-associated leukemic stem cells.

Acute myeloid leukemia is a clonal malignant disorder derived from a small number of leukemic stem cells (LSCs). Rearrangements of the mixed lineage leukemia (MLL) gene are found in acute myeloid leukemia associated with poor prognosis. The upregulation of Hox genes is critical for LSC induction and maintenance, but is unlikely to support malignancy and the high LSC frequency observed in MLL leukemias. The present study shows that MLL fusion proteins interact with the transcription factor PU.1 to activate the transcription of CSF-1R, which is critical for LSC activity. Acute myeloid leukemia is cured by either deletion of PU.1 or ablation of cells expressing CSF-1R. Kinase inhibitors specific for CSF-1R prolong survival time. These findings indicate that PU.1-mediated upregulation of CSF-1R is a critical effector of MLL leukemogenesis.

Expression of colony-stimulating factor 1 is associated with occurrence of osteochondral change in pigmented villonodular synovitis.

Pigmented villonodular synovitis (PVNS) is a benign, translocation-derived neoplasm. Because of its high local recurrence rate after surgery and occurrence of osteochondral destruction, a novel therapeutic target is required. The present study aimed to evaluate the significance of protein expression possibly associated with the pathogenesis during the clinical course of PVNS. In 40 cases of PVNS, positivity of colony-stimulated factor 1 (CSF1), its receptor (CSF1R), and receptor activator of nuclear factor kappa-B ligand (RANKL) were immunohistochemically determined. The relationship between the positivity and clinical outcomes was investigated. High positivity of CSF1 staining intensity was associated with an increased incidence of osteochondral lesions (bone erosion and osteoarthritis) (p = 0.009), but not with the rate of local recurrence. Positivity of CSF1R and RANKL staining was not associated with any clinical variables. The number of giant cells was not correlated with positivity of any of the three proteins, or with the clinical outcome. Focusing on knee cases, CSF1 positivity was also associated with the incidence of osteochondal change (p = 0.02). CSF1R positivity was high in cases which had local recurrence, but not significantly so (p = 0.129). Determination of CSF1 and CSF1R expression may be useful as a prognosticator of the clinical course and/or outcomes of PVNS.

Effect of age on regulation of human osteoclast differentiation.

Human skeletal aging is characterized as a gradual loss of bone mass due to an excess of bone resorption not balanced by new bone formation. Using human marrow cells, we tested the hypothesis that there is an age-dependent increase in osteoclastogenesis due to intrinsic changes in regulatory factors [macrophage-colony stimulating factor (M-CSF), receptor activator of NF-κB ligand (RANKL), and osteoprotegerin (OPG)] and their receptors [c-fms and RANK]. In bone marrow cells (BMCs), c-fms (r = 0.61, P = 0.006) and RANK expression (r = 0.59, P = 0.008) were increased with age (27-82 years, n = 19). In vitro generation of osteoclasts was increased with age (r = 0.89, P = 0.007). In enriched marrow stromal cells (MSCs), constitutive expression of RANKL was increased with age (r = 0.41, P = 0.049) and expression of OPG was inversely correlated with age (r = -0.43, P = 0.039). Accordingly, there was an age-related increase in RANKL/OPG (r = 0.56, P = 0.005). These data indicate an age-related increase in human osteoclastogenesis that is associated with an intrinsic increase in expression of c-fms and RANK in osteoclast progenitors, and, in the supporting MSCs, an increase in pro-osteoclastogenic RANKL expression and a decrease in anti-osteoclastogenic OPG. These findings support the hypothesis that human marrow cells and their products can contribute to skeletal aging by increasing the generation of bone-resorbing osteoclasts. These findings help to explain underlying molecular mechanisms of progressive bone loss with advancing age in humans.

C-X-C motif chemokine 12/C-X-C chemokine receptor type 7 signaling regulates breast cancer growth and metastasis by modulating the tumor microenvironment.

INTRODUCTION: Although C-X-C motif chemokine 12 (CXCL12) has been shown to bind to C-X-C chemokine receptor type 7 (CXCR7), the exact molecular mechanism regulations by CXCL12/CXCR7 axis in breast tumor growth and metastasis are not well understood. CXCR7 expression has been shown to be upregulated during pathological processes such as inflammation and cancer. METHODS: Breast cancer cell lines were genetically silenced or pharmacologically inhibited for CXCR7 and/or its downstream target signal transducer and activator of transcription 3 (STAT3). 4T1 or 4T1 downregulated for CXCR7 and 4T1.2 breast cancer cell lines were injected in mammary gland of BALB/c mice to form tumors, and the molecular pathways regulating tumor growth and metastasis were assessed. RESULTS: In this study, we observed that CXCL12 enhances CXCR7-mediated breast cancer migration. Furthermore, genetic silencing or pharmacologic inhibition of CXCR7 reduced breast tumor growth and metastasis. Further elucidation of mechanisms revealed that CXCR7 mediates tumor growth and metastasis by activating proinflammatory STAT3 signaling and angiogenic markers. Furthermore, enhanced breast tumorigenicity and invasiveness were associated with macrophage infiltration. CXCR7 recruits tumor-promoting macrophages (M2) to the tumor site through regulation of the macrophage colony-stimulating factor (M-CSF)/macrophage colony-stimulating factor receptor (MCSF-R) signaling pathway. In addition, CXCR7 regulated breast cancer metastasis by enhancing expression of metalloproteinases (MMP-9, MMP-2) and vascular cell-adhesion molecule-1 (VCAM-1). We also observed that CXCR7 is highly expressed in invasive ductal carcinoma (IDC) and metastatic breast tissue in human patient samples. In addition, high CXCR7 expression in tumors correlates with worse prognosis for both overall survival and lung metastasis-free survival in IDC patients. CONCLUSION: These observations reveal that CXCR7 enhances breast cancer growth and metastasis via a novel pathway by modulating the tumor microenvironment. These findings identify CXCR7-mediated STAT3 activation and modulation of the tumor microenvironment as novel regulation of breast cancer growth and metastasis. These studies indicate that new strategies using CXCR7 inhibitors could be developed for antimetastatic therapy.

MicroRNAs 17-5p-20a-106a control monocytopoiesis through AML1 targeting and M-CSF receptor upregulation.

We investigated the role of microRNAs (miRNA) 17-5p, 20a and 106a in monocytic differentiation and maturation. In unilineage monocytic culture generated by haematopoietic progenitor cells these miRNAs are downregulated, whereas the transcription factor acute myeloid leukaemia-1 (AML1; also known as Runt-related transcription factor 1, Runx1) is upregulated at protein but not mRNA level. As miRNAs 17-5p, 20a and 106a bind the AML1 mRNA 3'UTR, their decline may unblock AML1 translation. Accordingly, transfection with miRNA 17-5p-20a-106a suppresses AML1 protein expression, leading to M-CSF receptor (M-CSFR) downregulation, enhanced blast proliferation and inhibition of monocytic differentiation and maturation. Treatment with anti-miRNA 17-5p, 20a and 106a causes opposite effects. Knockdown of AML1 or M-CSFR by short interfering RNA (siRNA) mimics the action of the miRNA 17-5p-20a-106a, confirming that these miRNAs target AML1, which promotes M-CSFR transcription. In addition, AML1 binds the miRNA 17-5p-92 and 106a-92 cluster promoters and transcriptionally inhibits the expression of miRNA 17-5p-20a-106a. These studies indicate that monocytopoiesis is controlled by a circuitry involving sequentially miRNA 17-5p-20a-106a, AML1 and M-CSFR, whereby miRNA 17-5p-20a-106a function as a master gene complex interlinked with AML1 in a mutual negative feedback loop.

M-CSF increases proliferation and phagocytosis while modulating receptor and transcription factor expression in adult human microglia.

BACKGROUND: Microglia are the primary immune cells of the brain whose phenotype largely depends on their surrounding micro-environment. Microglia respond to a multitude of soluble molecules produced by a variety of brain cells. Macrophage colony-stimulating factor (M-CSF) is a cytokine found in the brain whose receptor is expressed by microglia. Previous studies suggest a critical role for M-CSF in brain development and normal functioning as well as in several disease processes involving neuroinflammation. METHODS: Using biopsy tissue from patients with intractable temporal epilepsy and autopsy tissue, we cultured primary adult human microglia to investigate their response to M-CSF. Mixed glial cultures were treated with 25 ng/ml M-CSF for 96 hours. Proliferation and phagocytosis assays, and high through-put immunocytochemistry, microscopy and image analysis were performed to investigate microglial phenotype and function. RESULTS: We found that the phenotype of primary adult human microglia was markedly changed following exposure to M-CSF. A greater number of microglia were present in the M-CSF- treated cultures as the percentage of proliferating (BrdU and Ki67-positive) microglia was greatly increased. A number of changes in protein expression occurred following M-CSF treatment, including increased transcription factors PU.1 and C/EBPß, increased DAP12 adaptor protein, increased M-CSF receptor (CSF-1R) and IGF-1 receptor, and reduced HLA-DP, DQ, DR antigen presentation protein. Furthermore, a distinct morphological change was observed with elongation of microglial processes. These changes in phenotype were accompanied by a functional increase in phagocytosis of Aß1-42 peptide. CONCLUSIONS: We show here that the cytokine M-CSF dramatically influences the phenotype of adult human microglia. These results pave the way for future investigation of M-CSF-related targets for human therapeutic benefit.

CSF-1R as an inhibitor of apoptosis and promoter of proliferation, migration and invasion of canine mammary cancer cells.

BACKGROUND: Tumor-associated macrophages (TAMs) have high impact on the cancer development because they can facilitate matrix invasion, angiogenesis, and tumor cell motility. It gives cancer cells the capacity to invade normal tissues and metastasize. The signaling of colony-stimulating factor-1 receptor (CSF-1R) which is an important regulator of proliferation and differentiation of monocytes and macrophages regulates most of the tissue macrophages. However, CSF-1R is expressed also in breast epithelial tissue during some physiological stages i.g.: pregnancy and lactation. Its expression has been also detected in various cancers. Our previous study has showed the expression of CSF-1R in all examined canine mammary tumors. Moreover, it strongly correlated with grade of malignancy and ability to metastasis. This study was therefore designed to characterize the role of CSF-1R in canine mammary cancer cells proliferation, apoptosis, migration, and invasion. As far as we know, the study presented hereby is a pioneering experiment in this field of veterinary medicine. RESULTS: We showed that csf-1r silencing significantly increased apoptosis (Annexin V test), decreased proliferation (measured as Ki67 expression) and decreased migration ("wound healing" assay) of canine mammary cancer cells. Treatment of these cells with CSF-1 caused opposite effect. Moreover, csf-1r knock-down changed growth characteristics of highly invasive cell lines on Matrigel matrix, and significantly decreased the ability of these cells to invade matrix. CSF-1 treatment increased invasion of cancer cells. CONCLUSION: The evidence of the expression and functional role of the CSF-1R in canine mammary cancer cells indicate that CSF-1R targeting may be a good therapeutic approach.

Bone marrow chimeras and c-fms conditional ablation (Mafia) mice reveal an essential role for resident myeloid cells in lipopolysaccharide/TLR4-induced corneal inflammation.

The mammalian cornea contains an extensive network of resident macrophages and dendritic cells. To determine the role of these cells in LPS-induced corneal inflammation, TLR4(-/-) mice were sublethally irradiated and reconstituted with bone marrow cells from either enhanced GFP (eGFP)(+)/C57BL/6 or eGFP(+)/TLR4(-/-) mice. The corneal epithelium was abraded, LPS was added topically, and cellular infiltration to the corneal stroma and development of corneal haze were examined after 24 h. TLR4(-/-) mice reconstituted with C57BL/6, but not TLR4(-/-) bone marrow cells donor cells were found to cause infiltration of eGFP(+) cells to the cornea, including neutrophils, and also increased corneal haze compared with saline-treated corneas. In a second experimental approach, corneas of transgenic macrophage Fas induced apoptosis (Mafia) mice were stimulated with LPS. These mice express eGFP and a suicide gene under control of the c-fms promoter, and systemic treatment with the FK506 dimerizer (AP20187) causes Fas-mediated apoptosis of monocytic cells. AP20187-treated mice had significantly fewer eGFP(+) cells in the cornea than untreated mice. After stimulation with LPS neutrophil recruitment and development of corneal haze were impaired in AP20187-treated mice compared with untreated controls. Furthermore, LPS induced CXCL1/KC and IL-1alpha production within 4 h in corneas of untreated Mafia mice, which is before cellular infiltration; however, cytokine production was impaired after AP20187 treatment. Together, results from both experimental approaches demonstrate an essential role for resident corneal monocytic lineage cells (macrophages and dendritic cells) in development of corneal inflammation.

Macrophage-colony stimulating factor as an inducer of microglial proliferation in axotomized rat facial nucleus.

We analyzed the mechanism of microglial proliferation in rat axotomized facial nucleus (axotFN). In immunoblotting analysis for possible mitogens, we noticed that the amounts of macrophage-colony stimulating factor (M-CSF) increased in the axotFN for 3-7 days after transection. In contrast, the amounts of granulocyte macrophage-CSF and interleukin-3 did not significantly increase. A potential source for M-CSF was immunohistochemically verified to be microglia. Immunoblotting showed that the amounts of receptor for M-CSF (cFms) increased in the axotFN for 3-14 days after injury, and immunohistochemical staining showed that cFms is expressed in microglia. Proliferating cell nuclear antigen as a marker of proliferation was immunohistochemically identified in microglia in axotFN, and the level was found to peak 3 days after transection in immunoblotting. Hypothesizing that up-regulated M-CSF triggers the above phenomena, we investigated the effects of M-CSF on cFms and proliferating cell nuclear antigen levels in primary microglia. The biochemical experiments revealed that M-CSF induces cFms and drives the cell cycle in microglia. The neutralization of M-CSF in microglia derived from axotFN significantly reduced the proliferation. These results demonstrate that up-regulated M-CSF triggers the induction of cFms in microglia and causes the microglia to proliferate in the axotFN.

Opposing actions of c-ets/PU.1 and c-myb protooncogene products in regulating the macrophage-specific promoters of the human and mouse colony-stimulating factor-1 receptor (c-fms) genes.

The receptor for macrophage colony stimulating factor (CSF-1), the c-fms gene product, is a key determinant in the differentiation of monocytic phagocytes. Dissection of the human and mouse c-fms proximal promoters revealed opposing roles for nuclear protooncogenes in the transcriptional regulation of this gene. On the one hand, c-ets-1, c-ets-2, and the macrophage-specific factor PU.1, but not the ets-factor PEA3, trans-activated the c-fms proximal promoter. On the other hand c-myb repressed proximal promoter activity in macrophages and blocked the action of c-ets-1 and c-ets-2. Basal c-fms promoter activity was almost undetectable in the M1 leukaemia line, which expressed high levels of c-myb, but was activated as cells differentiated in response to leukemia inhibitory factor and expressed c-fms mRNA. The repressor function of c-myb depended on the COOH-terminal domain of the protein. We propose that ets-factors are necessary for the tissue-restricted expression of c-fms and that c-myb acts to ensure correct temporal expression of c-fms during myeloid differentiation.

High expression of macrophage colony-stimulating factor-1 receptor in peritumoral liver tissue is associated with poor outcome in hepatocellular carcinoma after curative resection.

BACKGROUND: Macrophage colony-stimulating factor 1 receptor (CSF-1R) expression in hepatocellular carcinoma (HCC) and its prognostic values are unclear. This study evaluated the prognostic values of the intratumoral and peritumoral expression of CSF-1R in HCC patients after curative resection. METHODS: Tissue microarrays containing material from cohort 1 (105 patients) and cohort 2 (32 patients) were constructed. Immunohistochemistry was performed and prognostic values of these and other clinicopathological data were evaluated. The CSF-1R mRNA level was assessed by quantitative real-time polymerase chain reaction in cohort 3 (52 patients). RESULTS: Both the CSF-1R density and its mRNA level were significantly higher in peritumoral liver tissue than in the corresponding tumor tissue. CSF-1R was distributed in a gradient in the long-distance peritumoral tissue microarray, with its density decreasing as the distance from the tumor margin increased. High peritumoral CSF-1R was significantly associated with more intrahepatic metastases and poorer survival. Peritumoral CSF-1R was an independent prognostic factor for both overall survival and time to recurrence and affected the incidence of early recurrence. However, intratumoral CSF-1R did not correlate with any clinicopathological feature. Peritumoral CSF-1R was also associated with both overall survival and time to recurrence in a subgroup with small HCCs (< or =5 cm). CONCLUSIONS: Peritumoral CSF-1R is associated with intrahepatic metastasis, tumor recurrence, and patient survival after hepatectomy, highlighting the critical role of the peritumoral liver milieu in HCC progression. CSF-1R may become a potential therapeutic target for postoperative adjuvant treatment.

Coordinate expression of colony-stimulating factor-1 and colony-stimulating factor-1-related proteins is associated with poor prognosis in gynecological and nongynecological leiomyosarcoma.

Previously, we showed that the presence of high numbers of macrophages correlates with poor prognosis in nongynecological leiomyosarcoma (LMS). In gynecological LMS, a similar trend was noted but did not reach statistical significance. Colony-stimulating factor-1 (CSF1) is a major chemoattractant for macrophages. Here we show that in a subset of LMS cases, CSF1 is expressed by the malignant cells. Previously, we found that CSF1 is translocated and highly expressed in tenosynovial giant cell tumors (TGCTs), and this observation allowed us to identify genes that showed a coordinate expression with CSF1. Here, we evaluated the expression of CSF1 and TGCT-associated proteins in 149 cases of LMS. The coordinate expression of CSF1 and three TGCT-associated proteins (CD163, FCGR3a, and CTSL1) identified cases with poor prognosis in both gynecological LMS (P = 0.00006) and nongynecological LMS (P = 0.03). In gynecological LMS, the coordinate expression of these four markers was the only independent prognosticator in multivariate analysis (hazard ratio, 4.2; 95% CI, 1.12 to 16; P = 0.03). Our findings indicate that CSF1 may play an important role in the clinical behavior of LMS that may open a window for new therapeutic reagents.

Increased invasive phenotype of CSF-1R expression in glioma cells via the ERK1/2 signaling pathway.

Glioma is a common malignant tumor of the central nervous system (CNS) that has no effective treatment. In this study, we report that colony-stimulating factor-1 receptor (CSF-1R) is a key mediator of malignant features in glioma via modulation of the activity of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. In general, CSF-1R upregulation in glioma is associated with poor histologic grade and sursvival. Enforced expression of CSF-1R is sufficient to enhance cell growth, migration, invasion, and epithelial-mesenchymal transition, while CSF-1R silencing suppresses the above-described malignant phenotypes. Mechanistic investigations show that CSF-1R promotes activation of the ERK1/2 signaling pathway. Inhibition of the ERK1/2 pathway by SCH772984 reduces CSF-1R-induced migration, invasion, and lung metastasis of glioma cells, thus establishing a role of the ERK1/2 signaling pathway in mediating the CSF-1R effect. In summary, our results suggest that CSF-1R overexpression in gliomas contributes to the malignant behaviors of cancer cells.

Up-regulation of VEGF, c-fms and COX-2 expression correlates with severity of cervical cancer precursor (CIN) lesions and invasive disease.

OBJECTIVES: To describe the expression of vascular endothelial growth factor (VEGF), proto-oncogene macrophage colony-stimulating factor receptor (c-fms) and cyclooxygenase-2 (COX-2) in cervical carcinogenesis and to analyze the correlation of VEGF with c-fms and COX-2 expression. METHODS: In this study, 26 cases of benign cervix, 28 low-grade cervical intraepithelial neoplasia (CIN; CIN 1), 30 high-grade CIN (CIN 2/3) and 28 squamous cervical carcinomas (SCC) were examined by immunohistochemistry (IHC) and analysis was performed separately for epithelium and stroma. RESULTS: Positive epithelial expressions in normal cervix, low-grade CIN, high-grade CIN and SCC were, respectively: VEGF - 11.5%, 39.3%, 53.3% and 75% (P<0.001); c-fms - 0%, 10.7%, 40% and 67.9% (P<0.001); COX-2 - 7.7%, 39.3%, 80% and 100% (P<0.001). Stromal VEGF expression was higher than epithelial expression in all CIN grades and was also associated with the lesion grade, while c-fms and COX-2 stromal expression was weak. VEGF expression was statistically correlated to c-fms and COX-2 expression in high-grade CIN (P=0.020 and P=0.027, respectively) and SCC (P=0.015 and P=0.005, respectively). CONCLUSIONS: On the basis of our findings, these factors may participate in the development and progression of CIN lesions, with possible interaction of c-fms and COX-2 on VEGF expression, and may be potential molecular targets for studies of cervical cancer prevention and treatment.

Osteoclast differentiation during experimental tooth movement by a short-term force application: an immunohistochemical study in rats.

OBJECTIVE: The origin of osteoclasts responsible for bone resorption during orthodontic tooth movement is not yet clear. Their precursors may reside within the periodontal ligament (PDL) or could be recruited from the circulation or the bone marrow. The aim of this study was to investigate the spatial and sequential distribution of osteoclast precursors during experimental tooth movement by using three differentiation markers: receptor for macrophage colony stimulating factor (c-Fms), receptor activator of nuclear factor-kappaB (RANK), and calcitonin receptor (CTR). MATERIAL AND METHODS: Six-week-old Wistar rats were used. Elastic bands were inserted between the upper 1st and 2nd molars for 1, 2, 3, and 6 days. Immunohistochemical staining for c-Fms, RANK, or CTR was performed on parasagittal sections and positive cells were counted. RESULTS: Before force application, many c-Fms+ and a few RANK+ precursors were present in the bone marrow. No c-Fms+ osteoclast precursors were observed in the PDL. After force application, the number of RANK+ but not c-Fms+ precursors increased rapidly in the PDL. In bone marrow, the number of c-Fms+ and RANK+ precursors also increased rapidly, as did multinuclear c-Fms+, RANK+, and CTR+ cells. Subsequently, the number of c-Fms+, RANK+, and CTR+ multinuclear cells in the PDL increased. After 6 days, the expression profiles tended to return to baseline levels. CONCLUSION: Osteoclast precursors differentiate within the bone marrow and then migrate into the PDL during early tooth movement.

Hemangioblastomas share protein expression with embryonal hemangioblast progenitor cell.

Hemangioblastomas are central nervous system (CNS) tumors of unknown histogenesis, which can occur sporadically or in von Hippel-Lindau disease. Hemangioblastomas are composed of neoplastic "stromal" cells of unknown origin, accompanied by intensive reactive angiogenesis. Failure to specify the cytologic origin of the stromal cell has precluded the development of nonsurgical therapies and limits understanding of its basic biology. We report that the stromal cells express proteins (Scl, brachyury, Csf-1R, Gata-1, Flk-1, and Tie-2) that characterize embryonic progenitor cells with hemangioblastic differentiation potential and conclude that embryonic progenitors with hemangioblast potential represent a possible cytologic equivalent of the stromal cell. We also identified a new autocrine/paracrine stimulatory loop between the receptor Tie-2 and the hypoxia-inducible factor target Ang-1, which, combined with previous observations, suggests that a variety of autocrine loops may be initiated in hemangioblastomas, depending on the differentiation status of the tumor cells and the extent of HIF downstream activation. Finally, the consistent identification of Scl in the stromal cells may help explain the unique and characteristic topographical distribution of hemangioblastomas within the CNS.