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Tumor microenvironment-targeted therapies are emerging as promising treatment options for different cancer types. Tumor-associated macrophages and microglia (TAMs) represent an abundant nonmalignant cell type in brain metastases and have been proposed to modulate metastatic colonization and outgrowth. Here we demonstrate that targeting TAMs at distinct stages of the metastatic cascade using an inhibitor of colony-stimulating factor 1 receptor (CSF1R), BLZ945, in murine breast-to-brain metastasis models leads to antitumor responses in prevention and intervention preclinical trials. However, in established brain metastases, compensatory CSF2Rb–STAT5-mediated pro-inflammatory TAM activation blunted the ultimate efficacy of CSF1R inhibition by inducing neuroinflammation gene signatures in association with wound repair responses that fostered tumor recurrence. Consequently, blockade of CSF1R combined with inhibition of STAT5 signaling via AC4-130 led to sustained tumor control, a normalization of microglial activation states and amelioration of neuronal damage. Klemm et al. show that resistance to CSF1R inhibition in breast cancer brain metastasis is driven by compensatory activation of the CSF2Rb–STAT5 axis in macrophages, which can be alleviated by combined targeting of CSF1R and STAT5.

BackgroundChronic rhinosinusitis with nasal polyps (CRSwNP) is a common sinonasal inflammatory disorder with high heterogeneity. Increasing evidence have indicated that the infiltration of macrophages especially M2 macrophages play pivotal roles in the pathogenesis of CRSwNP, but the underlying mechanisms remain undetermined. This study sought to identify potential biomarkers related to M2 macrophages in CRSwNP.MethodsThe expression datasets of GSE136825 and GSE179265 were download from Gene Expression Omnibus (GEO) database and merged. Then, CIBERSORT and weighted gene co-expression network analysis (WGCNA) algorithms were applied to identify M2 macrophage-related gene modules. Thereafter, differentially expressed genes (DEGs) related to M2 macrophages were selected to perform functional enrichment analyses. A protein-protein interaction (PPI) network was built to identify hub genes and quantitative real-time reverse transcriptions PCR was used to verify the bioinformatics results.ResultsA total of 92 DEGs associated with M2 macrophages were identified for further analysis. The results of Gene ontology (GO) and Kyoto Encyclopedia of genes and genomes (KEGG) analyses illustrated that M2 macrophage-associated DEGs primarily enriched in immune responses and extracellular matrix structure. PPI network analysis identified 18 hub genes related to M2 macrophages that might be pivotal in the pathogenesis of CRSwNP. After verification, AIF1, C1QA, C1QB, C3AR1, CCR1, CD163, CD4, CD53, CD86, CSF1R, CYBB, FCER1G, FCGR3A, IL10RA, ITGB2, LAPTM5, PLEK, TYROBP were identified as potential M2 macrophage-related biomarkers for CRSwNP.ConclusionThese findings yield new insights into the hub genes and mechanisms related to M2 macrophages in the pathogenesis of CRSwNP. Further studies of these hub genes would help better understand the disease progression and identify potential treatment targets.

Sense-antisense mRNA pairs generated by convergent transcription is a way of gene regulation.

The proliferation and activation of microglia, the resident macrophages in the brain, is a hallmark of many neurodegenerative diseases such as Alzheimer's disease (AD) and prion disease. Colony stimulating factor 1 receptor (CSF1R) is critically involved in regulating microglial proliferation, and CSF1R blocking strategies have been recently used to modulate microglia in neurodegenerative diseases. However, CSF1R is broadly expressed by many cell types and the impact of its inhibition on the innate immune system is still unclear. CSF1R can be activated by two independent ligands, CSF-1 and interleukin 34 (IL-34). Recently, it has been reported that microglia development and maintenance depend on IL-34 signaling. In this study, we evaluate the inhibition of IL-34 as a novel strategy to reduce microglial proliferation in the ME7 model of prion disease. Selective inhibition of IL-34 showed no effects on peripheral macrophage populations in healthy mice, avoiding the side effects observed after CSF1R inhibition on the systemic compartment. However, we observed a reduction in microglial proliferation after IL-34 inhibition in prion-diseased mice, indicating that microglia could be more specifically targeted by reducing IL-34. Overall, our results highlight the challenges of targeting the CSF1R/IL34 axis in the systemic and central compartments, important for framing any therapeutic effort to tackle microglia/macrophage numbers during brain disease.

Models of macrophage subtypes require molecular characterization to reliably facilitate their differentiation. Although CD16+ (Fc-gamma III receptor) monocytes that express CD163 (a hemoglobin/haptoglobin receptor) have been implicated in a variety of disease states, the conditions necessary to establish lineages of these cell subtypes remains unknown. The current investigations utilize a cell line derived from acute myelogenous leukemia lineage, MonoMac-1, to interrogate the factors that promote the development of CD16+ macrophages that express CD163. Results implicate the glucocorticoid pathway as well as c-fms signaling based on the action of dexamethasone and macrophage colony-stimulating factor-1 in promoting CD16+ expression, in addition to phorbol myristate acetate and lipopolysaccharides treatment. The ability of glucocorticoid and c-fms receptor antagonists to inhibit CD16+ cell formation further establishes the role of these pathways in CD16 expression in this cell line. In view of the inherent difficulty in working with primary cells as well as donor variation, cell lines may be preferable to primary cells for their consistency. We envision that the process we use to induce CD16 expression in this cell type will be useful for screening and identification of drug candidates potentially useful for the treatment of diseases where the etiology involves the expansion of the CD16+ monocytes subset or the accumulation of CD163+ tissue macrophages.

The proliferation, differentiation and survival of mononuclear phagocytes depend on signals from the receptor for macrophage colony-stimulating factor, CSF1R. The mammalian Csf1r locus contains a highly conserved super-enhancer, the fms-intronic regulatory element (FIRE). Here we show that genomic deletion of FIRE in mice selectively impacts CSF1R expression and tissue macrophage development in specific tissues. Deletion of FIRE ablates macrophage development from murine embryonic stem cells. Csf1rΔFIRE/ΔFIRE mice lack macrophages in the embryo, brain microglia and resident macrophages in the skin, kidney, heart and peritoneum. The homeostasis of other macrophage populations and monocytes is unaffected, but monocytes and their progenitors in bone marrow lack surface CSF1R. Finally, Csf1rΔFIRE/ΔFIRE mice are healthy and fertile without the growth, neurological or developmental abnormalities reported in Csf1r−/− rodents. Csf1rΔFIRE/ΔFIRE mice thus provide a model to explore the homeostatic, physiological and immunological functions of tissue-specific macrophage populations in adult animals., The lineage-specific receptor CSF1R controls macrophage development and homeostasis. Here the authors show that deletion of a conserved Csf1r enhancer (FIRE) selectively depletes brain microglia and resident macrophages in the epidermis, kidney, heart and peritoneum of otherwise healthy mice.

Colony stimulating factor-1 (CSF-1) is one of the most common proinflammatory cytokine responsible for various inflammatory disorders. It has a remarkable role in the development and progression of osteoarthritis, cancer and other autoimmune disease conditions. The CSF-1 acts by binding to the receptor, called colony stimulating factor-1 receptor (CSF-1R) also known as c-FMS resulting in the cascade of signalling pathway causing cell proliferation and differentiation. Interleukin-34 (IL-34), recently identified as another ligand for CSF-IR, is a cytokine protein. Both, CSF-1 and IL-34, although two distinct cytokines, follow the similar signalling pathway on binding to the same receptor, CSF-1R. Like CSF-1, IL-34 promotes the differentiation and survival of monocyte, macrophages and osteoclasts. This CSF-1R/c-FMS is over expressed in many cancers and on tumour associated macrophages, consequently, have been exploited as a drug target for promising treatment for cancer and inflammatory diseases. Some CSF-1R/c-FMS inhibitors such as ABT-869, Imatinib, AG013736, JNJ-40346527, PLX3397, DCC-3014 and Ki20227 have been successfully used in these disease conditions. Many c-FMS inhibitors have been the candidates of clinical trials, but suffer from some side effects like cardiotoxicity, vomiting, swollen eyes, diarrhoea, etc. If selectivity of cFMS inhibition is achieved successfully, side effects can be overruled and this approach may become a novel therapy for treatment of various therapeutic interventions. Thus, successful targeting of c-FMS may result in multifunctional therapy. With this background of information, the present review focuses on the recent developments in the area of CSF-1R/c-FMS inhibitors with emphasis on crystal structure, mechanism of action and various therapeutic implications in which c-FMS plays a pivotal role. The review on structure activity relationship of various compounds acting as the inhibitors of c-FMS which gives the selection criteria for the development of novel molecules is also being presented.

Breast cancer cells preferentially home to the bone microenvironment, which provides a unique niche with a network of multiple bidirectional communications between host and tumor, promoting survival and growth of bone metastases. In the bone microenvironment, the c-fms proto-oncogene that encodes for the CSF-1 receptor, along with CSF-1, serves as one critical cytokine/receptor pair, functioning in paracrine and autocrine fashion. Previous studies concentrated on the effect of inhibition of host (mouse) c-fms on bone metastasis, with resulting decrease in osteolysis and bone metastases as a paracrine effect. In this report, we assessed the role of c-fms inhibition within the tumor cells (autocrine effect) in the early establishment of breast cancer cells in bone and the effects of this early c-fms inhibition on subsequent bone metastases and destruction. This study exploited a multidisciplinary approach by employing two non-invasive, in vivo imaging methods to assess the progression of bone metastases and bone destruction, in addition to ex vivo analyses using RT-PCR and histopathology. Using a mouse model of bone homing human breast cancer cells, we showed that an early one-time application of anti-human c-fms antibody delayed growth of bone metastases and bone destruction for at least 31 days as quantitatively measured by bioluminescence imaging and computed tomography, compared to controls. Thus, neutralizing human c-fms in the breast cancer cell alone decreases extent of subsequent bone metastasis formation and osteolysis. Furthermore, we are the first to show that anti-c-fms antibodies can impact early establishment of breast cancer cells in bone.

Background and Objectives : Nucleophosmin gene mutations are frequently reported in acute myeloid leukemia (AML) patients with normal karyotype, which is also frequently associated with internal tandem duplication mutations in the FMS-like tyrosine kinase-3 gene. We sought to detect the nucleophosmin and FMS-like tyrosine kinase-3 (FLT3) internal tandem duplication (ITD) mutations among Iranian patients with AML and to assess the relationship between these mutations and the subtypes of the disease. Design and Setting : Cross-sectional study of patients referred during 2007 through 2009. Patients and Methods : Bone marrow and peripheral blood samples of 131 AML patients were randomly collected at the time of diagnosis and prior to treatment and the DNA extracted. After amplifying the nucleophosmin and FLT3 gene regions, positive cases were screened by conformation-sensitive gel electrophoresis and agarose gel electrophoresis techniques. Results : Of 131 patients, 23 (17.5%) (0.95% CI=0.107-0.244) had nucleophosmin gene mutations. The highest frequency of such mutations was found among the subtypes of M4 (30.4%), M3 (21.7%) and M5 (17.4%). There was a high frequency of these mutations in the M3 subtype as well as a high frequency of allele D in all subtypes. Also, 21 (16.0%) samples (0.95% CI=0.092-0.229) had FLT3/ITD mutation, of which 8 samples had mutant nucleophosmin (8 of 23, 35%), and another 13 samples had wild-type nucleophosmin gene (13 of 108, 12%). There was a high degree of association between the occurrence of nucleophosmin and FLT3/ITD mutations (P=.012). Conclusion : Our data showed a high frequency of NPM1 mutations in the monocytic subtypes of AML, as well as a high degree of association between the occurrence of NPM1 and FLT3/ITD mutations.

We generated double-transgenic mice carrying cointegrated tissue-specific Gal4 and Gal4 reporter transgenes to direct transgene overexpression in the mononuclear phagocyte system (MPS). A modified promoter of the Csf1r (c-fms) gene, containing a deletion of the trophoblast-specific promoter, was used to drive the expression of Gal4VP16 transcriptional activator specifically in macrophages. This module was cointegrated with a fluorescent reporter, enhanced cyan fluorescent protein (ECFP), driven by a Gal4-dependent promoter. ECFP fluorescence was first detected in forming blood islands of the yolk sac at 8 dpc, then in macrophages in the yolk sac and the embryo proper. In adult mice ECFP was detected primarily in monocytes, tissue macrophages, microglia, and dendritic cells, including Langerhans cells of the skin. Crossing of these mice to transgenics containing tagged protein under control of a Gal4-dependent promoter directed expression of that protein in mononuclear phagocytes of double-transgenic animals. The new mouse line provides a useful tool for overexpression of transgenes in cells of the myeloid lineage, while simultaneously labeling them by ECFP expression.

Osteoclasts are essential cells for bone erosion in inflammatory arthritis and are derived from cells in the myeloid lineage. Recently, we reported that tumor necrosis factor-alpha (TNFalpha) increases the blood osteoclast precursor (OCP) numbers in arthritic patients and animals, which are reduced by anti-TNF therapy, implying that circulating OCPs may have an important role in the pathogenesis of erosive arthritis. The aim of this study is to investigate the mechanism by which TNFalpha induces this increase in OCP frequency. We found that TNFalpha stimulated cell division and conversion of CD11b+/Gr-1-/lo/c-Fms- to CD11b+/Gr-1-/lo/c-Fms+ cells, which was not blocked by neutralizing macrophage colony-stimulating factor (M-CSF) antibody. Ex vivo analysis of monocytes demonstrated the following: (i) blood CD11b+/Gr-1-/lo but not CD11b-/Gr-1- cells give rise to osteoclasts when they were cultured with receptor activator NF-kappaB ligand and M-CSF; and (ii) TNF-transgenic mice have a significant increase in blood CD11b+/Gr-1-/lo cells and bone marrow proliferating CD11b+/Gr-1-/lo cells. Administration of TNFalpha to wild type mice induced bone marrow CD11b+/Gr-1-/lo cell proliferation, which was associated with an increase in CD11b+/Gr-1-/lo OCPs in the circulation. Thus, TNFalpha directly stimulates bone marrow OCP genesis by enhancing c-Fms expression. This results in progenitor cell proliferation and differentiation in response to M-CSF, leading to an enlargement of the marrow OCP pool. Increased marrow OCPs subsequently egress to the circulation, forming a basis for elevated OCP frequency. Therefore, the first step of TNF-induced osteoclastogenesis is at the level of OCP genesis in the bone marrow, which represents another layer of regulation to control erosive disease.

Background We present a new mouse model for the study of peritoneal adhesions using macrophage Fasinduced apoptosis (Mafia) transgenic mice expressing a Fas-FKBP construct under control of the murine c-fms promoter. Mafia mice allow systemic macrophage depletion by dimerization of Fas with a synthetic dimerizer, AP20187. Results demonstrate that macrophage depletion in Mafia mice induces peritoneal adhesion formation when the peritoneal cavity is also exposed to an irritant. The Mafia mouse model presents a reproducible, non-surgical approach for research in adhesion formation and prevention. Materials and methods Mafia mice were treated with AP20187 using an intravenous (i.v.) or intraperitoneal (i.p.) injection. Control groups included mock-treated Mafia mice and both AP20187 and mock-treated wild type mice. Seven days after treatment, mice were observed for the presence of adhesions. Results After i.p. injection with AP20187, 76% of Mafia mice developed adhesions whereas none of the mock-treated Mafia or wild-type mice developed adhesions, and only one AP20187-treated wild-type mouse (5.8%) developed a mild adhesion. Mafia mice treated with AP20187 i.v. exhibited macrophage depletion not significantly different than i.p. treated mice, but did not develop adhesions. In contrast, Mafia mice treated with AP20187 i.v. developed adhesions when diluent was also injected into the peritoneal cavity, whereas i.p diluent alone had no effect. Conclusion Macrophage depletion, combined with a peritoneal irritant, results in peritoneal adhesion formation in transgenic Mafia mice. Macrophages appear to play a protective role in the development and/or repair of peritoneal adhesions.

MM-1 has been reported to repress the E-box-dependent transcription activity of c-Myc by recruiting histone deacetylase 1 complex via TIF1beta/KAP1. In this study, to identify target genes for c-Myc-MM-1-TIF1beta, we established rat-1 cells harboring the dominant-negative form of TIF1beta to abrogate the pathway from TIF1beta to MM-1-c-Myc. This cell line, in which transcription activity of c-Myc was activated, was found to be tumorigenic. By DNA-microarray analysis of this cell line, expression and promoter activity of the c-fms oncogene were found to be upregulated. Of the two promoters, pE1 and pE2, in the c-fms gene, pE1 promoter activity was found to be activated in an E-box-dependent manner.

Objective The purpose of this study was to determine the mechanism by which glucocorticoids stimulate c-fms proto-oncogene expression in JAR choriocarcinoma cells, which are reported to lack the glucocorticoid receptor. Study design Glucocorticoid action on c-fms was tested with the use of ligand binding assays, Northern and Western blotting, immunohistochemistry, quantitative reverse transcriptase–polymerase chain reaction, and nuclear run-off experiments. Results Dexamethasone stimulated c-fms (EC 50 =1 nmol/L) in JAR cells in a specific manner. Both RU 486 and actinomycin D inhibited dexamethasone stimulation, which suggests receptor-mediated and transcriptionally regulated actions. Neither cytosol or whole cell binding assays nor immunohistochemistry detected glucocorticoid receptor in JAR cells. However, Southern blot analysis of reverse transcriptase–polymerase chain reaction products revealed levels of glucocorticoid receptor messenger RNA in JAR cells that were approximately 100-fold lower than in HeLa control cells. In all but 1 clone among several JAR clones that were tested, there was concordance between presence or absence of glucocorticoid receptor messenger RNA and glucocorticoid sensitivity. Conclusion Some JAR cells contain low levels of glucocorticoid receptor, which mediate dexamethasone stimulation of c-fms expression. Such sensitivity to circulating glucocorticoids confers a survival advantage to these cells by stimulating the c-fms –related invasive behavior so characteristic of choriocarcinomas.

The fms oncogene encodes the macrophage colony-stimulating factor receptor (CSF1R), a transmembrane tyrosine kinase receptor, which is abnormally expressed in breast cancer. Transfection of wild-type CSF1R into HC11 mammary epithelial cells (HC11-CSF1R) renders the transfectants capable of in vitro local invasion and in vivo tumorigenesis. Transfection with CSF1R mutated to express phe at the tyr-721 autophosphorylation site (HC11-CSF1R-721) creates a phenotype that lacks metastastic competence but maintains local invasiveness. Conversely, HC11 cells transfected with CSF1R mutated at tyr-807 (HC11-CSF1R-807) retain their metastatic competence, but are not locally invasive. Our aims were to determine which genes were differentially expressed with transfection of HC11 with wild-type CSF1R, and to determine the effect of mutation at the autophosphorylation sites on gene expression, using 4.6 K cDNA microarrays. Complementary DNA from HC11, HC11-CSF1R-721 and HC11-CSF1R-807 were each hybridized together with HC11-CSF1R on individual arrays. A principal component spectral method combined with prenormalization procedures was used for sample clustering. Differentially expressed genes were identified by the analysis of variance. Confirmation by Northern blotting was performed for MAP kinase phosphatase-1, WDNM1 (extracellular proteinase inhibitor), Trop 2 (tumor-associated calcium signal transducer-2), procollagen type IV alpha, secretory leukoprotease inhibitor, prenylated snare protein Ykt6, ceruloplasmin and chaperonin 10. Many of these genes have not previously been associated with tumor invasion and metastasis. We have successfully identified genes that can be linked to the invasive phenotypes or to tumorigenesis. These genes provide a basis for further studies of metastatic progression and local invasiveness, and can be evaluated as therapeutic targets.

The mechanisms by which interleukin-6 (IL-6) family cytokines, which utilize the common receptor signaling subunit gp130, influence monocyte/macrophage development remain unclear. Here we have utilized macrophages devoid of either gp130-dependent STAT1/3 (gp130(Delta STAT/Delta STAT)) or extracellular signal-regulated kinases 1 and 2 (ERK1/2) mitogen-activated protein (MAP) kinase (gp130(Y757F/Y757F)) activation to assess the individual contribution of each pathway to macrophage formation. While the inhibition by IL-6 of macrophage colony-stimulating factor (M-CSF)-induced colony formation observed in gp130(wt/wt) mice was abolished in gp130(Delta STAT/Delta STAT) mice, inhibition of macrophage colony formation was enhanced in gp130(Y757F/Y757F) mice. In gp130(Delta STAT/Delta STAT) bone marrow-derived macrophages (BMMs), both IL-6- and M-CSF-induced ERK1/2 tyrosine phosphorylation was enhanced. By contrast, tyrosine phosphorylation of ERK1/2 in response to M-CSF was reduced in gp130(Y757F/Y757F) BMMs, and the pattern of ERK1/2 activation in gp130 mutant BMMs correlated with their opposing responsiveness to M-CSF-induced proliferation. When compared to the level of expression in gp130(wt/wt) BMMs, c-fms expression was elevated in gp130(Delta STAT/Delta STAT) BMMs but reduced in gp130(Y757F/Y757F) BMMs. Finally, an ERK1/2 inhibitor suppressed M-CSF-induced BMM proliferation, and this result corresponded to a reduction in c-fms expression. Collectively, these results provide a functional and causal correlation between gp130-dependent ERK MAP kinase signaling and c-fms gene activation, a finding that provides a potential mechanism underlying the inhibition of M-CSF-dependent macrophage development by IL-6 family cytokines in mice.

Although many leukaemia-associated nuclear oncogenes are well characterized, little is known about the molecular details of how they alter gene expression. Here we examined transcription factor complexes and chromatin structure of the human c-FMS gene in normal and leukaemic cells. We demonstrate by in vivo footprinting and chromatin immunoprecipitation assays that this gene is bound by the transcription factor AML1 (RUNX1). In t(8;21) leukaemic cells expressing the aberrant fusion protein AML1-ETO, we demonstrate that this protein is part of a transcription factor complex binding to extended sequences of the c-FMS intronic regulatory region rather than the promoter. The AML1-ETO complex does not disrupt binding of other transcription factors, indicating that c-FMS is not irreversibly epigenetically silenced. However, AML1-ETO binding correlates with changes in the histone modification pattern and increased association of histone deacetylases. Our experiments provide for the first time a direct insight into the chromatin structure of an AML1-ETO-bound target gene.

Heat shock factor 1 (HSF1), in addition to its pivotal role as a regulator of the heat shock response, functions as a versatile gene repressor. We have investigated the structural domains involved in gene repression using mutational analysis of the hsf1 gene. Our studies indicate that HSF1 contains two adjacent sequences located within the N-terminal half of the protein that mediate the repression of c-fos and c-fms. One region (NF) appears to be involved in quenching transcriptional activation factors on target promoters and binds to the basic zipper transcription factor NF-IL6 required for activation of c-fms and IL-1beta. The NF domain encompasses the leucine zipper 1 and 2 sequences as well as the linker domain between the DNA binding and leucine zipper regions. The function of this domain in gene repression is highly specific for HSF1, and the homologous region from conserved family member HSF2 does not restore repressive function in HSF2/HSF1 chimeras. In addition, HSF2 is not capable of binding to NF-IL6. The NF domain, although necessary for repression, is not sufficient, and a second region (REP) occupying a portion of the regulatory domain is required for repression. Neither domain functions independently, and both are required for repression. Furthermore, we constructed dominant inhibitors of c-fos repression by HSF1, which also blocked the repression of c-fms and IL-1beta, suggesting a shared mechanism for repression of these genes by HSF1. Our studies suggest a complex mechanism for gene repression by HSF1 involving the binding to and quenching of activating factors on target promoters. Mapping the structural domains involved in this process should permit further characterization of molecular mechanisms that mediate repression.

We have examined the functional antagonism between the regulator of the heat shock response, HSF1, and NF-IL6, which plays a major role in control of the acute phase response (APR). Agents that activate HSF1 such as heat shock and sodium salicylate inhibit NF-IL6 induced transcription while NF-IL6 activators such as lipopolysaccharide (LPS) and interleukin 6 (IL-6) repressed the stress responsive HSP70B promoter. In transfection studies, the inhibitory effects of HSF1 and NF-IL6 on the c-fms promoter were shown to be highly dose-dependent. Furthermore, heat shock is inhibitory to differentiation-linked expression of macrophage colony stimulating factor (M-CSF) receptor, product of the c-fms gene, which is transcriptionally activated by NF-IL6 but repressed by HSF1. Our studies suggest a strong mutual antagonism between the heat shock response and APR, which may influence the sensitivity and duration of inflammatory responses.

This paper reports on the modification of magnetic beads with oligonucleotide capture probes with a specially designed pendant toehold (overhang) aimed specifically to capture double-stranded PCR products. After capture, the PCR products were selectively released from the magnetic beads by means of a toehold-mediated strand displacement reaction using short artificial oligonucleotide triggers and analysed using capillary electrophoresis. The approach was successfully shown on two genes widely used in human DNA genotyping, namely human c-fms (macrophage colony-stimulating factor) proto-oncogene for the CSF-1 receptor (CSF1PO) and amelogenin.

PU.1 is a unique regulatory protein required for the generation of both the innate and the adaptive immune system. It functions exclusively in a cell-intrinsic manner to control the development of granulocytes, macrophages, and B and T lymphocytes. We demonstrate that mutation of the PU.1 gene causes a severe reduction in myeloid (granulocyte/macrophage) progenitors. PU.1 -/- myeloid progenitors can proliferate in vitro in response to the multilineage cytokines interleukin-3 (IL-3), IL-6 and stem cell factor but are unresponsive to the myeloid-specific cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF and M-CSF. The failure of PU.1 -/- progenitors to respond to G-CSF is bypassed by transient signaling with IL-3. In the presence of IL-3 and G-CSF, PU.1 -/- progenitors can differentiate into granulocytic precursors containing myeloperoxidase-positive granules. Thus PU.1 is not essential for specification of granulocytic precursors, but is required for their further differentiation. The failure of PU.1 -/- progenitors to respond to M-CSF is due to lack of c-fms gene transcription. Transduction of c-fms into PU.1 -/- myeloid progenitors bypasses the block to M-CSF-dependent proliferation but does not induce detectable macrophage differentiation. Therefore, PU. 1 appears to be essential for specification of monocytic precursors. Importantly, retroviral transduction of PU.1 into mutant progenitors restores responsiveness to myeloid-specific cytokines and development of mature granulocytes and macrophages. Thus PU.1 controls myelopoiesis by regulating both proliferation and differentiation pathways.

Myelodysplastic syndromes (MDS) are rare disorders in children. Molecular mechanisims underlying MDS in children are not yet completely understood. Considering the role of FMS and TP53 gene mutations in adult MDS patients, we analyzed nnutations of these genes in a cohort of 35 children with MDS. Single-strand conformation polymorphism polymerase chain reaction analysis performed on FMS codon 969 and TP53 exons 5-9 showed no mutations in the analyzed sequences. Our results Suggest that molecular mechanisms of MDS evolution in children are different from those in adults.

The macrophage colony stimulating factor receptor (CSF-1R), the product of the c-fms proto-oncogene, plays an important role in regulating the normal proliferation and differentiation of macrophages and trophoblasts. However, the abnormal expression of CSF-1R transcripts and protein by human breast carcinomas has been shown to correlate with advanced stage and poor prognosis. Ligand activated CSF-1R dimers transphosphorylate several tyrosines in their cytoplasmic domains which provide recognition sites for various effector proteins in multiple signal transduction pathways. In cells transformed by the c-fms oncogene, one of the major CSF-1R phosphotyrosines, pTyr723 is important for phenotypic expression of anchorage-independent growth and metastasis. In order to investigate the relationship between receptor activation/phosphorylation and cellular phenotypes in vitro and in vivo, we prepared a CSF-1R phosphorylation-state specific antibody raised against a specific phosphopeptide of CSF-1R, which included phosphorylated tyrosine 723. On immunoblots of lysates from cells expressing CSF-1R, this antibody recognizes phosphorylated CSF-IR in CSF-1 stimulated cells but not in unstimulated cells. As an immunohistochemical reagent, this antibody stained 52% of invasive human breast tumors (72% of CSF-1R positive cases) in a sample of 114 cases and 38% of carcinoma in situ. This data represents the first direct evidence of in vivo phosphorylation of CSF-1R in human breast carcinomas.

Macrophage colony-stimulating factor (M-CSF) is a hematopoietin whose actions are essential for growth and survival of macrophages, placental development, ramification of microglia and tumor progression. The expression of the receptor for macrophage colony-stimulating factor (c-fms) is regulated by two distinct promoters: distal and proximal. The distal promoter is active in trophoblasts during embryogenesis and the proximal promoter directs expression to the cells of myeloid lineage. Here we report the generation of transgenic mice expressing beta-galactosidase under the control of the human proximal c-fms promoter and demonstrate the promoter activity in astrocytes, cells of neurological origin that partially take over the role of the macrophages in the central nervous system. Enzymatic activity of beta-galactosidase was detected in homogenated spleen, bone marrow and brain and in the cell extracts from peritoneal macrophages of transgenic mice. Immunohistochemical staining of brain showed the presence of beta-galactosidase in astrocytes. We hypothesize that M-CSF released by astrocytes, upon stimulation by lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF alpha) or interleukin-1 (IL-1), regulates the expression of its own receptor.

Co-expression of macrophage colony-stimulating factor (M-CSF) and its receptor (c-fms) is often found in ovarian epithelial carcinoma, suggesting the existence of autocrine regulation of cell growth by M-CSF. To block this autocrine loop, we have developed hammerhead ribozymes against c-fms mRNA. As target sites of the ribozyme, we chose the GUC sequence in codon 18 and codon 27 of c-fms mRNA. Two kinds of ribozymes were able to cleave an artificial c-fms RNA substrate in a cell-free system, although the ribozyme against codon 18 was much more efficient than that against codon 27. We next constructed an expression vector carrying a ribozyme sequence that targeted the GUC sequence in codon 18 of c-fms mRNA. It was introduced into TYK-nu cells that expressed M-CSF and its receptor. Its transfectant showed a reduced growth potential. The expression levels of c-fms protein and mRNA in the transfectant were clearly decreased with the expression of ribozyme RNA compared with that of an untransfected control or a transfectant with the vector without the ribozyme sequence. These results suggest that the ribozyme against GUC in codon 18 of c-fms mRNA is a promising tool for blocking the autocrine loop of M-CSF in ovarian epithelial carcinoma. Images Figure 2 Figure 3 Figure 5 Figure 6

Colony stimulating factor-1 (CSF-1) was initially identified as a growth factor for mononuclear phagocytes. This study examines the role of CSF-1 in the development of the central nervous system (CNS). CSF-1 treatment of neurons cultured from embryonic brain promoted survival and process outgrowth in a dose-dependent manner. By contrast, CSF-1 treatment of neurons cultured from the osteopetrotic (op/op) mouse, a null mutant for CSF-1, promoted significantly less process outgrowth, suggesting that there are neural abnormalities in op/op animals. Nuclease protection assays were used to determine whether CSF-1 and its receptor are expressed at times appropriate to regulate neural development. Both CSF-1 and its receptor are expressed in developing mouse brain, with a unique pattern of CSF-1 mRNA splice variant expression encoding secreted, and not membrane-bound, growth factor. To determine whether brain function is altered by null mutation of CSF-1, op/op mice were examined using electrophysiologic assays. Brainstem auditory and visual evoked potentials were both abnormal in op/op mice. Further, intracortical recordings revealed aberrant neuronal function within visual cortex and alterations in the cortical circuitry that balances excitation and inhibition. Daily CSF-1 injection of postnatal op/op mice largely rescued the abnormal neural phenotype, confirming that the absence of CSF-1 during development is responsible for the abnormalities. The effects of CSF-1 on cultured embryonic neural cells, the developmentally appropriate expression of CSF-1 and its receptor, and the neurological abnormalities in op/op mice suggest a role for CSF-1 in brain development.

The mouse CD5 positive pre-B cell line SPGM-1 can be induced to switch its lineage commitment towards macrophage differentiation by treatment with a combination of phorbol ester and a calcium ionophore. When cultured with these reagents the pre-B cells ceased to proliferate and rapidly became adherent to plastic surfaces. This morphological change was accompanied by the loss of pre-B cell-specific surface markers, such as PB76 and most prominently the mu heavy chain of the immunoglobulin receptor complex. In addition, the mRNA of the surrogate light chain lambda 5 disappeared while the induction of lysozyme mRNA could be detected. Differentiated SPGM-1 cells phagocytosed latex beads and showed nonspecific esterase activity. The high efficiency and speed of differentiation in this cellular system makes SPGM-1 a highly suitable model for studying the phenomenon of lineage switching during hemopoesis.

Expression of the v-fms oncogene of feline sarcoma virus in fibroblasts causes surface exposure of an activated receptor tyrosine kinase, v-Fms, that is autophosphorylated at multiple sites within its cytoplasmic domain. Cellular proteins interacting with this part of v-Fms modulate the mitogenic activity and morphology of the cells. We show here that the tyrosine residue in position 807 (Y-807) of the v-Fms molecule constitutes a major autophosphorylation site. The replacement of this residue by phenylalanine (Y807F mutation) allowed us to functionally dissect v-Fms-specific mitogenic and morphogenic cascades. Cells expressing the mutant v-Fms molecule resembled wild-type (wt) v-Fms-transformed (wt-v-Fms) cells in terms of [3H]thymidine uptake rates and activation of the Ras/Raf-1 mitogenic cascade. Such cells showed, however, a flat morphology and contained intact actin cables and fibronectin network. Our studies indicate that the v-Fms molecule controls cell morphology by a cascade that involves a direct interaction with p120RasGAP and p190RhoGAP: (i) in contrast to wt v-Fms molecules, the Y807F v-Fms protein failed to associate with and phosphorylate p120RasGAP; (ii) tight complexes between p120RasGAP and p190RhoGAP as well as detectable RhoGAP activity were present exclusively in wt-v-Fms cells; and (iii) p190RhoGAP was dispersed throughout the cytoplasm of wt-v-Fms cells, whereas its distribution was restricted to perinuclear regions of cells expressing the mutant v-Fms gene.

The osteoclast is a cell type that is highly specialized for its bone resorption function. In order to decipher the numerous biochemical functions of osteoclasts, a description of the gene expression profile of osteoclasts would be beneficial. We have sought to identify genes that are highly expressed in osteoclasts by partially sequencing 194 randomly chosen cDNA clones from a representative rabbit osteoclast cDNA library. Comparison to nucleic acid and protein sequence databases indicates that 135 of these cDNAs are identical to or homologous to known mammalian genes. Reverse transcription-polymerase chain reaction (RT-PCR) assays with micro-isolated osteoclasts were used to verify the osteoclast expression of some of these genes. Fifty-nine cDNAs, including two abundantly expressed species, have no significant similarity to the sequence databases and likely represent novel genes. The most abundant of the osteoclast expressed genes encode cofilin and the vacuolar H + -ATPase 16 kd subunit. Each were represented at a frequency of 4.1 % of the clones in the library (95% confidence interval = 2.4–6.6%). The high expression of these gene products is consistent with the high motility of osteoclasts and their very active hydrogen ion secretion. Other abundantly expressed sequences include (3-actin (95% C.I. = 2.0–6.0%), creatine kinase B (95% C.I. = 1.2–4.9%), c- fms and ribosomal protein L18 (95% C.I. = 0.8–4.3%), and cathepsin-OC2, cyclophilin, δ-aminolevulinate synthetase, 165 mitochondrial rRNA, and two novel gene sequences (95% C.I. = 0.5–3.6%).

Point mutations at codons 301 and 969 of the FMS proto-oncogene have been reported in both myelodysplasia (MDS) and acute myeloid leukaemia (AML). We report here the incidence of such mutations in patients at risk of developing secondary MDS and AML. Peripheral blood DNA from 70 patients in remission from lymphoma was screened for mutations by oligonucleotide (ONH) using mutant specific probes. Codon 969 mutations were detected in 11 of the 70 (15.7%) cases. No codon 301 mutations were detected. Five of these mutations were confirmed using an independent technique (single nucleotide primer extension analysis, SNPE) and a further mutation was detected in a single patient using single-stranded conformational polymorphism analysis (SSCP). No codon 969 mutations were detected in 62 lymphoma biopsy specimens from these patients or from three patients with detectable FMS mutations where pre-therapy marrow was investigated by ONH. No mutations at either codons 301 or 969 were detected by ONH in 61 normal controls. Somatic mutations at codon 969 of the FMS gene occur commonly following cytotoxic therapy for lymphoma and their detection indicates the presence of a clonally expanded population of abnormal cells.

To address the role of ras signaling in monocytic phagocytes in vivo, the expression of two dominant suppressors of in vitro ras signaling pathways, the carboxyl-terminal region of the GTPase-activating protein (GAP-C) and the DNA binding domain of the transcription factor ets-2, were targeted to this cell compartment. A 5-kb portion of the human c-fms proximal promoter was shown to direct expression of the transgenes to the monocytic lineage. As a result of the GAP-C transgene expression, ras-GTP levels were reduced in mature peritoneal macrophages by 70%. The terminal differentiation of monocytes was altered, as evidence by the accumulation of atypical monocytic cells in the blood. Mature peritoneal macrophages exhibited changes in colony-stimulating factor 1-dependent survival and structure. Further, expression of the colony-stimulating factor 1-stimulated gene urokinase plasminogen activator was inhibited in peritoneal macrophages. The results indicate that ras action is critical in monocytic cells after these cells have lost the capacity to traverse the cell cycle.

Abstract To elucidate mechanisms of myocardial hypertrophy in spontaneously hypertensive rats (SHR), we examined by Northern blotting the expression of the proto-oncogenes c- myc , c- fos , c- sis , and c- fms in the hearts of 4- and 14-week-old SHR and normotensive Wistar-Kyoto (WKY) rats. No difference in c- myc or c- fos expression could be found between SHR and WKY rats. In SHR, c- sis gave a weak and c- fms a very strong signal at 14 weeks, whereas no signal for these oncogenes was found in either WKY rats or Sprague-Dawley controls. Since c- fms codes for the receptor of monocyte colony-stimulating factor, we next used in situ hybridization to localize the presence of c- fms in hearts of SHR at 14 weeks. We found strong signals for c- fms around small blood vessels and between cardiac myocytes in 14-week-old SHR but none in WKY rats. Immunohistochemical staining corroborated the presence of clusters of monocyte infiltration at these same perivascular sites in significantly greater numbers in SHR than in WKY rats. We conclude that c- fms expression and macrophage infiltration are increased in the perivascular space of hypertrophied hearts from SHR. We suggest that mononuclear cell recruitment and induction of c- fms may play a role in the development of hypertension-associated myocardial hypertrophy.

FMS, first discovered as the oncogene responsible for Feline McDonough Sarcoma, is a type III receptor tyrosine kinase that binds to the macrophage or monocyte colony-stimulating factor (M-CSF or CSF-1). Signal transduction through that binding results in survival, proliferation, and differentiation of monocyte/macrophage lineage. Overexpression of CSF-1 and/or FMS has been implicated in a number of disease states such as the growth of metastasis of certain types of cancer, in promoting osteoclast proliferation in bone osteolysis, and many inflammatory disorders. Inhibition of CSF-1 and/or FMS may help treat these pathological conditions. This article reviews FMS gene, FMS kinase, CSF-1, IL-34, and their roles in bone osteolysis, cancer biology, and inflammation. Monoclonal antibodies, FMS crystal structure, and small molecule FMS kinase inhibitors of different chemical scaffolds are also reviewed.

Density-dependent cell proliferation and cluster formation are growth phenotypes frequently associated with leukemia cells. The secretion of autocrine growth factor, such as granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin 1 (IL-1), has been implicated as one possible mechanism in leukemogenesis. In many cases, however, leukemia cells do not appear to produce autocrine growth stimulators. J6-1 is an established human myeloid leukemia cell line that exhibits both density-dependent and cluster-forming growth characteristics. The effect of direct cell-cell contact on J6-1 cell proliferation was investigated. We have isolated from J6-1 cells a membrane-bound factor (designated as MAF-J6-1) that promoted the colony formation by both J6-1 cells and mouse bone marrow CFU-GM. The growth-promoting activity of MAF-J6-1 can be neutralized by either anti-macrophage-CSF (M-CSF or CSF-1) or anti-MAF-J6-1 monoclonal antibodies (MAb), suggesting that MAF-J6-1 is related to M-CSF. Using an immunoblot analysis with anti-MAF-J6-1 MAb, the MW of this membrane-associated factor was estimated to be 80 kDa. Both antibodies also induced a modest growth inhibition on J6-1 cells in vitro. Similarly, addition of exogenous recombinant human M-CSF augmented the colony formation by J6-1 cells, an effect also neutralized by both antibodies. Using an in situ hybridization technique, J6-1 cells were found to express a high level of c-fms proto-oncogene, which encodes the receptor for the M-CSF. Taken together, our results suggest that the membrane-bound MAF-J6-1 promote J6-1 cell proliferation and cluster formation through a 'juxtacrine' mechanism.

During sequence analysis of the first intron of the human c-fms oncogene, we identified an open reading frame encoding the ribosomal protein L7 (RPL7). The presence of this sequence within intron 1 of the c-fms gene was confirmed by Southern blot hybridization and by sequence analysis of two independent cosmid clones (cos2-e and cos1-22) that span the human genomic c-fms locus. The RPL7 sequence was detected in a region of sequence overlapped by the cos2-e and cos1-22 cosmid clones but oriented opposite to the c-fms gene. We demonstrate that the sequence is identical to the full-length RPL7 cDNA sequence, but lacks any recognizable introns, has a 30-bp poly(A) tail, and is bracketed by two perfect direct repeats of 14 bp. We also showed that despite the fact that the 5{prime} flanking region of the RPL7 sequence contains a potential TATA box upstream of an intact open reading frame, this pseudogene (RPL7P) is not actively transcribed. 28 refs., 4 figs.

Retrovirus-mediated gene transfer was used to obtain expression of the macrophage colony-stimulating factor (MCSF) receptor, c-fms, on hematopoietic lineages that normally do not express this receptor. Cultures of murine fetal liver cells infected with the c-fms retrovirus developed erythroid colonies in cultures stimulated with M-CSF. However, these colonies were fewer and less hemoglobinized than colonies in parallel cultures stimulated by erythropoietin. Culture of isolated clones demonstrated a direct action of M-CSF on erythroid clones. Culture of c-fms retrovirus-infected adult murine bone marrow cells showed megakaryocyte and novel macrophage-megakaryocyte clones when stimulated by M-CSF. Culture of isolated clones again confirmed a direct action of M-CSF on megakaryocyte clones. In contrast, M-CSF stimulation of c-fms-infected granulocytes and granulocyte progenitor cells did not elicit proliferation, enhanced survival, or functional stimulation of granulocytes. These findings provide evidence for both conservation and lineage restriction of signal transduction in normal hematopoietic cells.

Macrophages (M phi)3 function by a two-step process that includes priming (induction of cytokine and enzyme mRNA) and activation (production of effector molecules). The initial steps in M phi priming involve the expression of certain proto-oncogenes that regulate expression of other genes. Because tumor growth primes M phi to produce several suppressor monokines, we determined if cancer induced M phi expression of these proto-oncogenes. Unstimulated peritoneal M phi from tumor-bearing hosts (TBH) constitutively expressed the proto-oncogenes c-fms, c-fos, c-myc, and c-myb, whereas normal host (NH) M phi had little or no expression of these proto-oncogenes. When M phi were given a 24-h adherence priming stimulus, NH M phi expressed c-fms and c-fos at levels equivalent to TBH M phi constitutive expression. Adherence had little or no effect on c-fms and c-fos expression in TBH M phi or on NH and TBH M phi c-myc expression. c-myb expression was not induced in NH M phi during adherence and was strongly decreased in TBH M phi. Activation with a 1-h lipopolysaccharide-treatment increased NH and TBH M phi expression of c-fms, c-fos, and c-myc, with higher expression of these proto-oncogenes in TBH M phi. Activation failed to induce c-myb expression in NH M phi and completely inhibited expression in TBH M phi. Because c-fms, c-fos, and c-myc are normally expressed early during M phi activation, our results suggest that tumor growth primes M phi by inducing expression of these proto-oncogenes. c-myb is expressed in immature M phi and is downregulated during M phi activation. These observations explain why NH M phi expression of c-myb was not induced and are consistent with reports that suggest TBH M phi have not reached full developmental maturity. The induction of M phi proto-oncogene expression during cancer may put M phi in a primed state, which leads to earlier and stronger production of adverse suppressor and cytotoxic molecules.

The relationship between human immunodeficiency virus type 1 (HIV-1) infection and the induction of NF-kappa B binding activity was examined in a myeloid cell model of HIV-1 infection derived from the PLB-985 cell line. Chronic infection of PLB-985 cells led to increased monocyte-specific surface marker expression, increased c-fms gene transcription, and morphological alterations consistent with differentiation along the monocytic pathway. PLB-IIIB cells displayed a constitutive NF-kappa B-like binding activity that was distinct from that induced by tumor necrosis factor alpha or phorbol 12-myristate 13-acetate treatment of the parental PLB-985 cell line. This unique DNA binding activity consisted of proteins of 70, 90, and 100 kDa with a high degree of binding specificity for the NF-kappa B site within the PRDII domain of beta interferon. In this report, we characterize the nature of these proteins and demonstrate that binding of these proteins is also induced following Sendai paramyxovirus infection. The 70-kDa protein corresponds to the NF-kappa B RelA (p65) subunit, which is activated in response to an acute paramyxovirus infection or a chronic HIV-1 infection. Virus infection does not appear to alter the amount of RelA (p65) or NFKB1 (p50) but rather affects the capacity of I kappa B alpha to sequester RelA (p65), therefore leading to constitutive levels of RelA DNA binding activity and to increased levels of NF-kappa B-dependent gene activity. The virally induced 90- to 100-kDa proteins have a distinct binding specificity for the PRDII domain and an AT-rich sequence but do not cross-react with NF-kappa B subunit-specific antisera directed against NFKB1 (p105 or p50), NFKB2 (p100 or p52), RelA (p65), or c-rel. DNA binding of the 90- to 100-kDa proteins was not inhibited by recombinant I kappa B alpha/MAD-3 and was resistant to tryptic digestion, suggesting that these proteins may not be NF-kappa B related. Transient cotransfection experiments demonstrated that RelA and NFKB1 expression maximally stimulated HIV-1 LTR- and NF-kappa B-dependent reporter genes; differences in NF-kappa B-like binding activity were also reflected in higher constitutive levels of NF-kappa B-regulated gene expression in HIV-1-infected myeloid cells.

The gene encoding the receptor for macrophage colony-stimulating factor 1 (CSF-1), the c-fms protooncogene, is selectively expressed in immature and mature mononuclear phagocytes and trophoblasts. Exon 1 is expressed only in trophoblasts. Isolation and sequencing of genomic DNA flanking exon 2 of the murine c-fms gene revealed a TATA-less promoter with significant homology to human c-fms. Reverse transcriptase primer extension analysis using exon 2 primers identified multiple clustered transcription initiation sites. Their position was confirmed by RNase protection. The same primer extension products were detected in equal abundance from macrophage or nonmacrophage sources of RNA. c-fms mRNA is acutely down-regulated in primary macrophages by CSF-1, bacterial lipopolysaccharide (LPS), and phorbol myristate acetate (PMA). Each of these agents reduced the abundance of c-fms RNA detectable by primer extension using an exon 3 primer without altering the abundance of presumptive short c-fms transcripts detected with exon 2 primers. Primer extension analysis with an intron 2 primer detected products at greater abundance in nonmacrophages. Templates detected with the intronic primer were induced in macrophages by LPS, PMA, and CSF-1, suggesting that each of the agents caused a shift from full-length c-fms mRNA production to production of unspliced, truncated transcripts. The c-fms promoter functioned constitutively in the RAW264 macrophage cell line, the B-cell line MOPC.31C, and several nonhematopoietic cell lines. Macrophage-specific expression and responsiveness to selective repression by LPS and PMA was achieved by the incorporation of intron 2 into the c-fms promoter-reporter construct. The results suggest that expression of the c-fms gene in macrophages is controlled by sequences in intron 2 that act by regulating transcription elongation.

The human monomyelocytic HL-60 cell line differentiates along a monocytic lineage when cultured in the presence of phorbol myristate acetate (PMA) or 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. The protooncogene c-fms, coding for the macrophage colony-stimulating factor (M-CSF) receptor, is characteristically expressed in cells of monocytic lineage, but is not present in HL-60 cells. Since M-CSF has an undefined role in osteoclast development, we wished to examine the effect of 1,25-(OH)2D3, a strong promoter of osteoclast development, on the induction of M-CSF receptor. Treatment of HL-60 cells with 10-50 ng/ml PMA for 3 days stimulated expression of c-fms, as measured by steady state mRNA levels. Treatment with 10 nM 1,25-(OH)2D3 for 4-72 h did not promote c-fms expression. In fact, 1,25-(OH)2D3 attenuated PMA-stimulated c-fms expression in a dose-dependent manner (ED50, 1 nM). Along with attenuation of c-fms expression, 1,25-(OH)2D3 induced expression of mRNA for the osteoclastic enzyme carbonic anhydrase-II (CA II) almost 2-fold over the level expressed in untreated HL-60 cells. The addition of PMA to the culture diminished the basal expression of CA II mRNA, but did not affect 1,25-(OH)2D3-stimulated CA II induction. PMA and 1,25-(OH)2D3, thus, promote divergent phenotype development in the HL-60 cell. Induction of c-fms mRNA by PMA should ensure further macrophage development. The effect of 1,25-(OH)2D3 to attenuate expression of c-fms mRNA and stimulate CA II mRNA suggests that 1,25-(OH)2D3 activates osteoclast, rather than macrophage, development. 1,25-(OH)2D3-induced phenotypic changes may, therefore, involve modulation of the M-CSF effect.

cis-acting elements found in 3′-untranslated regions (UTRs) are regulatory signals determining mRNA stability and translational efficiency. By binding a novel non-AU-rich 69-nucleotide (nt) c-fms 3′ UTR sequence, we previously identified HuR as a promoter of c-fms proto-oncogene mRNA. We now identify the 69-nt c-fms mRNA 3′ UTR sequence as a cellular vigilin target through which vigilin inhibits the expression of c-fms mRNA and protein. Altering association of either vigilin or HuR with c-fms mRNA in vivo reciprocally affected mRNA association with the other protein. Mechanistic studies show that vigilin decreased c-fms mRNA stability. Furthermore, vigilin inhibited c-fms translation. Vigilin suppresses while HuR encourages cellular motility and invasion of breast cancer cells. In summary, we identified a competition for binding the 69-nt sequence, through which vigilin and HuR exert opposing effects on c-fms expression, suggesting a role for vigilin in suppression of breast cancer progression.

FLT3, a receptor belonging to the FMS/KIT family and localized to 13q12, could play a role in the biology of early hematopoietic progenitor cells. Because FMS and KIT are expressed in both normal progenitors and myeloid leukemias, we looked for FLT3 expression in fresh human leukemic cells using Northern blot analysis. High levels of FLT3 expression were detected in 92% of the cases of acute myeloid leukemia (AML) tested, ranging from the M1 to the M5 stages of differentiation assessed in the French-American-British classification. Immature (MO) AML cells, biphenotypic leukemias, and AML with megakaryocytic differentiation (M7 subtype) also expressed the FLT3 transcript. FLT3 was also expressed at high levels in acute lymphoid leukemias of T and B origins. Finally, it was not expressed in chronic myeloid leukemias in chronic phase, whereas it was expressed in most blast crisis samples. This pattern of expression of FLT3 contrasts with the expression of FMS and KIT restricted to myeloid leukemias, and suggests that the FLT3 product could play a role in the expansion of the leukemic blasts of both the myeloid and lymphoid lineages.

We analyzed six different tissue DNA samples from a leukemic individual who received an injection of Thorotrast for alterations in proto-oncogene or tumor-suppressor gene structure. Our examination of the DNA indicated an alteration of the c-fms gene in the blood sample from this individual. This locus showed a deletion in which the 3' end of the deleted region maps between exons 11 and 12. In this particular case, the type of leukemia is unknown but myeloid leukemia is a neoplasm associated with individuals injected with Thorotrast. It is possible that the alteration in the c-fms gene of this individual is a consequence of the radiation exposure. No apparent alterations in the c-mos gene were observed in any of the tissues from the individual. This is in contrast to previous studies that described alterations in methylation patterns associated with the c-mos locus in radium-exposed individuals. A number of the individuals exposed to radium also had alterations of the retinoblastoma gene while no such alterations were observed in any tissue DNA samples from this Thorotrast case. It is possible that our inability to detect alterations of the c-mos and retinoblastoma gene may be attributable to the nature of alpha-emitting radionuclides or their distribution, or to the limited set of tissues available for analysis.

Cells found within atherosclerotic lesions can produce in culture protein mediators that may participate in atherogenesis. To test whether human atheromata actually contain transcripts for certain of these genes, we compared levels of mRNAs in carotid or coronary atheromata and in nonatherosclerotic human vessels by polymerase chain reaction (PCR) amplification of cDNAs reverse-transcribed from RNA. We measured PCR products (generated during exponential amplification) by incorporation of 32P-labeled primers. Levels of interleukin 1 alpha, 1 beta, or 6 mRNAs in plaques and controls did not differ. Compared to uninvolved vessels, plaques did contain higher levels of mRNA encoding platelet-derived growth factor A chain (42 +/- 24 vs. 12 +/- 10 fmol of product; mean +/- SD; n = 8 and 8, respectively; P = 0.007) and B chain (41 +/- 36 vs. 4 +/- 3 fmol of product, n = 14 and 6, respectively; P = 0.024). Atherosclerotic lesions consistently had much higher levels of apolipoprotein E (apoE) mRNA than did control vessels (131 +/- 71 vs. 5 +/- 3 fmol of product; n = 12 and 10, respectively; P less than 0.001). Direct RNA blot analyses confirmed elevated levels of apoE mRNA in plaque extracts. To test whether mononuclear phagocytes might be a source of the apoE mRNA, we studied a selective marker for cells of the monocytic lineage, the c-fms protooncogene, which encodes the receptor for macrophage colony-stimulating factor. Plaques also contained elevated levels of c-fms mRNA (30 +/- 17 vs. 5 +/- 3 fmol of product; n = 10 and 7, respectively; P = 0.002). Immunohistochemical colocalization demonstrated apoE protein in association with macrophages in plaques, whereas nonatherosclerotic vessels showed no immunoreactive apoE. ApoE produced locally in atheroma might modulate the functions of lesional T cells or promote "reverse cholesterol transport" by associating with high density lipoprotein particles, thus targeting them for peripheral uptake. Macrophages within the advanced human atheroma appear to exhibit a selective program of activation as they express high levels of apoE, whereas overall levels of interleukin 1 or 6 mRNAs in plaques are not elevated.

The genomic organization of four oncogenes, i.e., c-myc, c-myb, c-Ha-ras, and c-fms, was investigated in fresh surgical specimens from 10 patients with cartilaginous tumors. Among nine chondrosarcomas, six were primary lesions and three local recurrences. The remaining case was a chondroblastoma. Amplification of the c-myc proto-oncogene was the sole abnormality detected in this series, occurring in two chondrosarcomas (four- and eight-fold). No other genetic alteration such as oncogene rearrangement was found. Nor was there any amplification of the other oncogenes studied. Both c-myc-amplified tumors were primary lesions and histologically classified as grade II; according to flow DNA cytometry, one was diploid and the other aneuploid. In our limited series, there was no overall relationship between c-myc amplification, on the one hand, and histologic subtype, malignancy grade, surgical stage, or ploidy level, on the other. Our study shows that amplification of the c-myc oncogene, presumed to be involved in the development of malignancy, is encountered in occasional human chondrosarcomas, however, without any relationship to other well-known features of this tumor entity. The clinical significance of this gene amplification remains to be established.