Colony-stimulating Factor mRNA Expression Research Articles

Abstract P180: Hypertension-linked Immune Activation Regulates Osteoclastogenesis

Osteoporosis is an age-related disease affecting 18% of adults. Hypertension is associated with increased risk for fragility fracture and accelerated bone loss in adults. We hypothesized that experimental hypertension would induce osteoporosis and examined the mechanisms involved. We used two preclinical models in 12-week-old male C57Bl/6J mice: angiotensin (ang) II infusion (490 ng/kg/min) and deoxycorticosterone acetate (DOCA)-salt. After 6 weeks of ang II or 3 weeks of DOCA-salt, the left femur and sixth lumbar vertebral body were studied. Mechanical testing showed that ang II reduced femoral ultimate strength (170.7±4.794 vs 157.3±3.670 MPa, p=0.0325; 154.1±7.403 vs. 119.9±4.375 MPa, p=0.0026) and peak moment (39.09±1.660 vs. 32.77±0.9380 Newton millimeters (Nmm), p=0.0018; 29.15±1.291 vs 19.58±1.308 Nmm, p=0.0004) with cortical and trabecular bone loss compared to controls. μCT showed that hypertension reduced vertebral body bone volume fraction (30.1±1.41 vs 25.1±0.992 %, p=0.0068; 25.9±2.03 vs 18.5±1.29 %, p=0.0119) and trabecular thickness (62±1.6 vs 57±1.4 μm, p=0.0105; 60±2.1 vs 51 ±1.6 μm, p=0.0069). Flow cytometry of bone marrow from ang II-treated mice revealed that CD4+ T cells and γδ T cells produce increased IL-17A which is known to induce osteoclastogenesis. Colony stimulating factor-1 (CSF1) is also known to stimulate osteoclast formation. Using in situ hybridization, we observed increased CSF1 mRNA in endothelial cells (ECs) of transcortical arterioles of hypertensive mice. Subsequent studies of cultured bone marrow derived ECs showed that CSF1 mRNA expression increased with 0% and 10% compared to 5% stretch. 5% stretch treated with endothelial nitric oxide synthase inhibitor, L-NAME, increased expression comparable to 0% and 10%, indicating that nitric oxide inhibits CSF1 production. Thus, T-cell activation and nitric oxide-dependent EC dysfunction in hypertension may skew the bone marrow to favor osteoclastogenesis, leading to bone loss. Understanding this mechanism will elucidate novel pharmacological targets to mitigate hypertension-induced bone loss.

Enhancer RNA Transcription Is Essential for a Novel CSF1 Enhancer in Triple-Negative Breast Cancer.

Simple SummaryIn cancer, regulatory regions of the genome are hijacked by the tumor cells for the activation of oncogenes that lead to cancer initiation and progression. One of the most salient regulatory elements of the genome are called enhancers, which are characterized by their ability to increase the expression of their target genes. In this study, we identified a novel enhancer that drives the expression of the oncogene CSF1 in triple-negative breast cancer patients, the most aggressive subtype of breast cancer. We demonstrate that this enhancer is specifically active in triple-negative breast cancer patients compared to other breast cancer subtypes and show that its target genes portend a worse clinical outcome in patients. We then use innovative CRISPR-based genome engineering techniques to systematically perturb various features of this enhancer to elucidate its mechanisms of action and determine the consequences on tumor cell growth. Furthermore, we test our model for CSF1 enhancer function in ovarian cancer cells and demonstrate that our findings can apply to other cancer types. These results demonstrate the significant impact of enhancers in cancer biology and highlight their potential as tractable targets for therapeutic intervention.Enhancers are critical regulatory elements in the genome that help orchestrate spatiotemporal patterns of gene expression during development and normal physiology. In cancer, enhancers are often rewired by various genetic and epigenetic mechanisms for the activation of oncogenes that lead to initiation and progression. A key feature of active enhancers is the production of non-coding RNA molecules called enhancer RNAs, whose functions remain unknown but can be used to specify active enhancers de novo. Using a combination of eRNA transcription and chromatin modifications, we have identified a novel enhancer located 30 kb upstream of Colony Stimulating Factor 1 (CSF1). Notably, CSF1 is implicated in the progression of breast cancer, is overexpressed in triple-negative breast cancer (TNBC) cell lines, and its enhancer is primarily active in TNBC patient tumors. Genomic deletion of the enhancer (via CRISPR/Cas9) enabled us to validate this regulatory element as a bona fide enhancer of CSF1 and subsequent cell-based assays revealed profound effects on cancer cell proliferation, colony formation, and migration. Epigenetic silencing of the enhancer via CRISPR-interference assays (dCas9-KRAB) coupled to RNA-sequencing, enabled unbiased identification of additional target genes, such as RSAD2, that are predictive of clinical outcome. Additionally, we repurposed the RNA-guided RNA-targeting CRISPR-Cas13 machinery to specifically degrade the eRNAs transcripts produced at this enhancer to determine the consequences on CSF1 mRNA expression, suggesting a post-transcriptional role for these non-coding transcripts. Finally, we test our eRNA-dependent model of CSF1 enhancer function and demonstrate that our results are extensible to other forms of cancer. Collectively, this work describes a novel enhancer that is active in the TNBC subtype, which is associated with cellular growth, and requires eRNA transcripts for proper enhancer function. These results demonstrate the significant impact of enhancers in cancer biology and highlight their potential as tractable targets for therapeutic intervention.

MEOX2 serves as a novel biomarker associated with macrophage infiltration in oesophageal squamous cell carcinoma and other digestive system carcinomas

Background Oesophageal squamous cell carcinoma (ESCC) is a malignant tumour of the digestive system that is associated with high morbidity and mortality rates worldwide. With the increased use of immunotherapy in cancer treatment, there is an urgent need to elucidate the immune-related mechanisms in ESCC and other digestive system carcinomas. Methods In our study, single-sample gene set enrichment analysis (ssGSEA) was first performed to analyse the expression profile downloaded from the NCBI Gene Expression Omnibus (GEO) database. Then, via a series of bioinformatic analyses, including the Mann-Whitney test, weighted gene co-expression network analysis (WGCNA), functional enrichment analysis and differentially expressed genes (DEGs) analysis, we identified target immunocytes and related genes. Finally, we validated the results with the TIMER database. Results Our analyses showed that the numbers of infiltrating macrophages were obviously higher in advanced stages in ESCC compared with other types of immunocytes. MEOX2 was identified as a biomarker correlated with macrophage infiltration in ESCC and other types of digestive system carcinomas. And MEOX2 expression was strongly associated with the mRNA expression of colony-stimulating factor 1 (CSF-1) and CSF-1 receptor (CSF-1R) in these kinds of carcinomas. Conclusion We speculated that MEOX2 could facilitate macrophage infiltration via CSF-1/CSF-1R signalling in ESCC and other kinds of digestive system carcinomas, and MEOX2 might serve as a novel target in prospective tumour immunotherapies.

RNAscope CSF1 chromogenic in situ hybridization: a potentially useful tool in the differential diagnosis of tenosynovial giant cell tumors

Colony stimulating factor-1 (CSF1) upregulation and CSF1/colony-stimulating factor 1 receptor (CSF1R) signaling pathway is central to the tumorigenesis of tenosynovial giant cell tumors (TGCT) of both localized (LTGCT) and diffuse (DTGCT) types, and has been demonstrated in a small number of malignant tumors (MTGCT) as well. In situ hybridization for CSF1 mRNA has been shown to be potentially useful in the diagnosis of TGCT, although only a relatively small number of cases have been studied. We studied CSF1 mRNA expression using RNAscope chromogenic in situ hybridization (CISH) in standard tissue sections from 31 TGCT and 26 non-TGCT, and in tumor microarray slides (Pantomics normal MN0341, Pantomics tumor MTU391, Pantomics melanoma MEL961). Among normal tissues, CSF1 mRNA expression was invariably present in synovium (10/10, 100%) and absent in all other normal tissues. All LTGCT and DTGCT were positive (24/24, 100%), exclusively in large, eosinophilic synoviocytes. MTGCT contained large clusters of CSF1-positive malignant synoviocytes (8/8, 100%); malignant spindled cells were also positive. Among non-TGCT, CSF1 CISH was less often positive with high specificity (90%). CSF1-positive cases included leiomyosarcoma, giant cell tumor of bone and of soft parts, pulmonary carcinoma and others. The sensitivity and specificity of RNAscope CSF1 mRNA CISH for the diagnosis of TGCT were 100% and 90%, respectively. We conclude that RNAscope CSF1 CISH may be a valuable adjunct for the diagnosis of TGCT of all types, especially those with atypical or malignant morphologic features. Detection of CSF1 mRNA expression may also have predictive significance in cases where use of the CSF1 inhibitor pexidartinib is considered.

P2-01-11: Fish Oil Targets miR-21 To Increase PTEN Expression for Inhibition of Bone Metastatic CSF-1 in Breast Cancer Cells.

Abstract Current therapy for the breast cancer patients is aimed at treating the cancer mainly at the primary site with limited ability to block metastasis. We have recently shown that fish oil (FO) diet significantly prevents MDA MB-231 breast cancer cell (MDA) metastasis to bone in a mouse model. Colony stimulating factor-1 (CSF-1) is one of major osteoclastogenic cytokines responsible for osteolytic metastasis of breast cancer. Quantitative RT-PCR (qRT-PCR) analysis showed significant inhibition of CSF-1 mRNA expression in fish oil fed mice xenograft tumor samples and docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), two ω-3 fatty acids in fish oil, inhibited CSF-1 mRNA and protein expression in MDA cells. A positive correlation was observed between expression of CSF-1 and the bone metastatic potential of different breast cancer cells. We have demonstrated recently upregulation in PTEN expression by FO diet as a mechanism of breast tumor growth arrest in mice. Over expression of PTEN inhibited migration of MDA cells. PTEN is a negative regulator of PI 3 kinase/Akt signaling. We investigated the mechanism of CSF-1 expression by breast cancer cells. Cotransfection of the CSF-1 promoter-driven luciferase plasmid (CSF-1-Luc) in MDA with PTEN or dominant negative (DN) PI 3 kinase or DN Akt, inhibited the transcription of CSF-1, indicating requirement of PI 3 kinase/Akt signaling. Several oncogenic microRNAs including miR-21 have been shown to induce metastasis of cancer cells. Fish oil fed mice tumors and DHA- and EPA-treated MDA cells significantly blocked miR-21 expression in MDA. PTEN mRNA 3'UTR contains miR-21 recognition element. Over expression of miR-21 inhibited PTEN 3'UTR-Luc reporter activity but it was increased by downregulation of miR-21, indicating functional targeting of PTEN mRNA by miR-21 in MDA. Similarly, expression of either miR-21 or miR-21 Sponge (plasmid-coded anti-miR-21 sequences) in MDA significantly suppressed or increased PTEN protein, respectively. Moreover, DHA-increased PTEN expression is reversed by over expression of miR-21 indicating a critical regulation of PTEN by miR-21. miR-21 over expression increased migration of MDA cells and partially reversed DHA- or EPA-mediated inhibition of migration. Since PTEN regulates expression of CSF-1, we examined the involvement of miR-21. Expression of miR-21 enhanced while miR-21 Sponge reduced expression of CSF-1 mRNA and its transcription. Furthermore, DHA-inhibited CSF-1 mRNA expression is reversed by over expression of miR-21. Together these results uncover a novel function of fish oil, which beheads miR-21 signaling to dampen expression of CSF-1 thus preventing osteoclastogenesis and osteolytic lesions in breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-01-11.

Phosphatidylinositol 3 Kinase/Akt Signal Relay Cooperates with Smad in Bone Morphogenetic Protein-2-Induced Colony Stimulating Factor-1 (CSF-1) Expression and Osteoclast Differentiation

Murine spleen cells produce mature osteoclasts when cocultured with osteoblastic cells. Colony-stimulating factor (CSF)-1 is the growth factor required for differentiating the monocyte-macrophage precursor cells into preosteoclasts. Bone morphogenic protein (BMP) signaling in osteoblasts regulates bone mass in mice, suggesting a role of BMP in osteoclastogenesis along with osteoblast activity. The intracellular signal transduction cross talk regulating the osteoblastic production of CSF-1 as a mechanism of BMP-induced osteoclastogenesis is described in this report. We have recently described the involvement of Smad 1/5 in BMP-2-induced CSF-1 expression and osteoclast formation. In this study, using the pharmacological inhibitors and the adenovirus (Ad) vectors expressing dominant-negative (DN) phosphatidylinositol 3 kinase (PI3K), the PI3K-signaling inhibitor, phosphatase and tensin homolog deleted in chromosome 10 (PTEN) or DN Akt kinase in the in vitro coculture assay, we show an essential role of the lipid kinase cascade in BMP-2-mediated multinucleated osteoclast formation and CSF-1 mRNA expression, transcription, and secretion. Inhibition of PI3K/Akt signaling blocked the binding of Smads 1/5 to the CSF-1 BMP-responsive element present in the CSF-1 promoter, resulting in attenuation of Smad-dependent CSF-1 transcription. Furthermore, PI3K inhibition and DN Akt prevented association of the transcriptional coactivator, CREB (cAMP response element binding protein) binding protein (CBP), with Smads 1/5. Together, these data for the first time demonstrate that PI3K-dependent Akt activation regulates BMP-2-induced CSF-1 expression and provides a mechanism for osteoblastic cell-assisted osteoclast differentiation.

Vitamin D 3 and analogues modulate the expression of CSF-1 and its receptor in human dendritic cells

The active vitamin D 3-metabolite 1,25(OH) 2D 3 inhibits the interleukin 4/granulocyte–macrophage colony-stimulating factor (IL-4/GM-CSF)-induced differentiation of human monocytes into dendritic cells without altering survival. Colony-stimulating factor 1 (CSF-1) is an important survival factor for cells of the monocytic lineage. We therefore investigated whether the inhibitory activity of 1,25(OH) 2D 3 is paralleled by a regulation of CSF-1 and its receptor. Purified human monocytes were cultured together with IL-4/GM-CSF in the presence of 1,25(OH) 2D 3, its analogue tacalcitol, the low-affinity vitamin D receptor ligand 24,25(OH) 2D 3, or the solvent ethanol for up to 5 days. Expression of CSF-1, CSF-1R, and GM-CSF mRNA was measured by RT-PCR. Protein secretion for CSF-1 was measured by ELISA, expression of CSF-1R by flow cytometry. The results showed that 1,25(OH) 2D 3 and tacalcitol significantly up-regulated CSF-1 mRNA-expression and protein secretion in a dose-dependent manner. The effect of 1,25(OH) 2D 3 occurred already after 1 h of pre-treatment. In contrast, CSF-1R mRNA- and cell surface-expression was down-regulated simultaneously. The solvent ethanol and 24,25(OH) 2D 3 were without effect. GM-CSF mRNA expression was not modulated in 1,25(OH) 2D 3-treated cells. These data point towards a distinct and specific regulation of CSF-1 and its receptor by 1,25(OH) 2D 3 and its analogue tacalcitol in human monocytes which parallels the inhibition of differentiation into dendritic cells without altering survival.

Colony-stimulating factor-1 (CSF-1) expression in the uteroplacental unit of mice with spontaneous and induced pregnancy loss.

CSF-1 plays an important role in female reproduction and normal embryo development. To understand further CSF-1 function in normal and, especially, in compromised pregnancy, we studied the pattern of its mRNA expression as well as expression of its receptor (c-fms) in the uteroplacental units of mice with induced (cyclophosphamide (CY)-treated) and spontaneous (CBA/J x DBA/2J mating combination) pregnancy loss. RNase protection analysis demonstrated the presence of two forms of CSF-1 mRNA in the uteroplacental unit corresponding to 1400- and 263-bp protective fragments. Densitometric analysis demonstrated that the level of 1400-bp mRNA form was decreased by 40% in the uteroplacental units of mice with CY-induced pregnancy loss compared with the control mice. About 20% decrease in 263-bp protective fragment was registered in resorbing versus non-resorbed placenta of CBA/J females mated to DBA/2J males. As judged by in situ hybridization assay, CSF-1 mRNA transcripts were localized in the uterine epithelium and stroma, while c-fms mRNA was found mainly in the trophoblast. The number of metrial gland cells as well as the number of uterine leucocytes expressing CSF-1 and c-fms mRNAs was substantially lower in the uteroplacental unit of mice with pregnancy loss than in control animals. Maternal immunostimulation, while significantly decreasing the resorption rate in mice with CY-induced pregnancy loss, also strengthened CSF-1 mRNA expression at the fetomaternal interface and resulted in reconstitution in the number of CSF-1+ uterine leucocytes and metrial gland cells. These data suggest a role for uterine CSF-1 in the physiology of normal and compromised pregnancy and demonstrate a possible involvement of CSF-1-associated signalling in mechanisms of placenta and endometrium repair following immunopotentiation.

The Cell-surface Form of Colony-stimulating Factor-1 Is Regulated by Osteotropic Agents and Supports Formation of Multinucleated Osteoclast-like Cells

Colony-stimulating factor-1 (CSF-1) is a hematopoietic growth factor that is released by osteoblasts and is recognized to play a critical role in bone remodeling in vivo and in vitro. CSF-1 is synthesized as a soluble or cell-surface protein. It is unclear, however, whether human osteoblasts express both molecular forms of CSF-1, and whether these isoforms can independently mediate osteoclastogenesis. In the present study, using a combination of quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and Western immunoblot analysis, we have demonstrated that human osteoblast-like cells as well as primary human osteoblasts express the cell-surface form of CSF-1 both constitutively and in response to parathyroid hormone and tumor necrosis factor. Furthermore, using an in vitro co-culture system, we have shown that cell-surface CSF-1 alone is sufficient to support osteoclast formation. These findings may be especially significant in view of evidence that direct cell-to-cell contact is critical for osteoclast formation, and suggest that differential regulation of expression of the CSF-1 isoforms may influence osteoclast function modulated by osteotropic hormones.

EFFECTS OF 15-DEOXYSPERGUALIN IN VITRO AND IN VIVO ON CYTOKINE GENE EXPRESSION

Reverse transcriptase-polymerase chain reaction showed that interleukin 3, IL-4, IL-5, IL-6, interferon-gamma and stem cell factor mRNA expression were higher in 15-deoxyspergualin-treated spleen cells than in control spleen cells. Increased IL-2 and IFN-gamma mRNA expression were observed in 15-deoxyspergualin-treated bone marrow cells. On the other hand, increased platelet counts in BALB/c-->C3H/He bone marrow chimeras were observed from days 20 to 33 in our previous work, when they were treated with 15-deoxyspergualin from days 14 to 25. In contrast, marked leukocytopenia and anemia were simultaneously observed, although a marked leukocytosis and a rapid recovery of anemia were observed on day 33 and thereafter. To analyze effects of 15-deoxyspergualin on hematopoiesis and the immune system, we examined mRNA expression in bone marrow and spleen cells from BALB/c-->C3H/He bone marrow chimeras treated with 15-deoxyspergualin from days 14 to 25. Reverse transcriptase-polymerase chain reaction showed that IL-3, IL-4, IL-6, stem cell factor, granulocyte colony-stimulating factor, and granulocyte/macrophage colony-stimulating factor mRNA expression were higher in 15-deoxyspergualin-treated chimeras than in control chimeras, indicating that these cytokines are responsible for an enhancement of hematopoiesis. It was conceivable that IL-6 supported thrombopoiesis in concert with other cytokines. On the contrary, increased IFN-gamma, IL-2, IL-3, IL-4, and IL-10 mRNA expression may play an immunosuppressive role in vivo.

CSF-1 expression is upregulated in astrocyte cultures by IL-1 and TNF and affects microglial proliferation and morphology in organotypic cultures

Astrocytes produce factors that control the growth and differentiation of many cell types within the CNS as well as play a role in the generation of the immune response. The extent to which these two functions interact has received less attention. We now report that astrocyte cultures established from rat brain endogenously express mRNA and low levels of secreted biologically active protein for the monocyte growth and differentiation factor colony stimulating factor-1 (CSF-1). Exposure of astrocytes to interleukin-1 (IL-1) and/or tumor necrosis factor (TNF) upregulated the expression of CSF-1 mRNA and protein. Following treatment with 100 U/ml of TNF, IL-1, or TNF+IL-1, maximum CSF-1 mRNA expression was observed at 3 hr. In the presence of IL-1 an increase in biologically active CSF-1 was detected in the astrocyte conditioned medium at 6 hr. These data indicate that the expression of CSF-1 by astrocytes can be modulated by exposure to the cytokines IL-1 and TNF. To determine whether CSF-1 provides a mitogenic signal for microglia during development, mouse spinal cord organotypic cultures were exposed to recombinant mouse CSF-1 (rmCSF-1), resulting in proliferation of microglia by 7 days and an increase in the number of ramified microglia over ameboid microglia by 14 days.

Interleukin-1 beta stimulates colony-stimulating factor-1 production in placental villous core mesenchymal cells.

The human placenta is known to produce hematopoietic growth factors, including colony-stimulating factor-1 (CSF-1). We have previously demonstrated interleukin-1 beta (IL-1 beta) production by decidualized endometrium during pregnancy. Since IL-1 stimulates CSF-1 production in fibroblasts, endothelial cells, and bone marrow stromal cells, our present study was designed to determine whether IL-1 could also regulate CSF-1 production by placental villous core mesenchymal cells. Initial studies using enzymatic digestion separation of the trophoblast and villous core demonstrated that CSF-1 mRNA is mainly expressed in the placental villous core. Subsequently, long term monolayer cultures of villous core mesenchymal cells isolated from 9- to 16-week gestation placentas were established after enzymatic dissociation of intact placental villi to study the regulation of villous core cell CSF-1 production. The morphology of the cells and immunohistochemical staining for vimentin, cytokeratin, and CD45 antigen confirmed that cultured cells were more than 95% mesenchymal fibroblasts. Time-course experiments demonstrated a maximal increase in CSF-1 mRNA expression of approximately 6.0-fold over baseline levels 3 h after IL-1 beta treatment (10 ng/mL), whereas increased CSF-1 protein production was first detected in the culture medium 3 h after IL-1 beta treatment and rose progressively over 42 hours. Villous core mesenchymal cells incubated with 0-10 ng/mL IL-1 beta demonstrated a specific dose-response relationship for CSF-1 mRNA expression and protein production, first seen at 0.10 ng/mL and maximal with 10 ng/mL IL-1 beta. These results demonstrate that production of CSF-1 by placental villous core mesenchymal cells can be stimulated by IL-1 beta in vitro and suggest that decidual IL-1 may regulate placental CSF-1 production in vivo.

Modulation of macrophage colony stimulating factor in cultured human retinal pigment epithelial cells

Steady-state mRNA expression and protein production of macrophage colony stimulating factor were measured in visually confluent monolayers of unstimulated cultured human retinal pigment epithelial cells and after cells were stimulated with recombinant cytokines. Using reverse transcription polymerase chain reaction, macrophage colony stimulating factor mRNA expression was detected in unstimulated cells obtained from each of four separate donors. In these cells, mRNA expression was accompanied by secretion of macrophage colony stimulating factor protein into cell-conditioned medium; 48 hr after cells were switched to fresh medium, the mean (± s.d.) quantity of macrophage colony stimulating factor, measured by enzyme-linked immunoassay, was 5·1±2·3 ng 10 −6 cells. There was a dose- and time-dependent induction of macrophage colony stimulating factor mRNA after cells were exposed to recombinant human interleukin-1 and tumor necrosis factor α. Maximal mRNA induction was observed in cells exposed for 4 hr to interleukin-1β (5U ml −1) or for 4–8 hr to tumor necrosis factor α; under these conditions, macrophage colony stimulating factor mRNA was induced up to 23- and 46-fold after exposure to interleukin-1β and tumor necrosis factor α, respectively. Similarly, macrophage colony stimulating factor protein production was enhanced after cells were exposed to recombinant cytokines. Protein secretion increased 1·3–2·5-fold ( P < 0·001) after exposure to interleukin-1β (5 U ml −1), and 1·2–1·6-fold after exposure to tumor necrosis factor α ( P < 0.03). This cytokine mediated induction of macrophage colony stimulating factor secretion was preceded by an increase in cell-associated macrophage colony stimulating factor measured in cell lysates. The macrophage colony stimulating factor secreted by retinal pigment epithelial cells was biologically active, as determined by a bone marrow stimulation bioassay. The average number of macrophage specific colonies produced (± s.d.) was 190±42 10 −5 bone marrow cells plated. In contrast, colonies were not produced with medium alone. The bioactivity was entirely due to macrophage colony stimulating factor activity, because colony growth was completely suppressed when the assay was conducted in the presence of neutralizing antibody to human macrophage colony stimulating factor. We conclude that human retinal pigment epithelial cells express macrophage colony stimulating factor mRNA, and synthesize and secrete biologically active protein under basal conditions; mRNA expression and protein production are modulated by the inflammatory cytokines interleukin-1β and tumor necrosis factor α.

Expression of Colony-Stimulating Factor-1 (CSF-1) Messenger RNA in Human Endometrial Glands during the Menstrual Cycle: Molecular Cloning of a Novel Transcript That Predicts a Cell Surface Form oF CSF-1

Colony-stimulating factor-1 (CSF-1) has been primarily characterized as a hematopoietic growth factor required for the proliferation and differentiation of monocytic cells. Recent immunohistological observations have shown that this growth factor is also synthesized by the glandular epithelial cells of the pregnant human endometrium and by first trimester human trophoblasts. In the present study endometrial glands were purified from nonpregnant human endometria collected through the menstrual cycle and examined for CSF-1 mRNA expression. The two major mRNAs (4.0 and 3.0 kilobases in length) detected in midproliferative and midsecretory phases differed in the size of the exon 6 and coded, respectively, for a secreted and a cell surface form of CSF-1. The 3.0-kilobase transcript represented a novel CSF-1 mRNA species that was molecularly cloned and sequenced. These data raise the possibility that CSF-1 may be involved in both distant and cell to cell regulatory pathways of cell proliferation and differentiation in the human endometrium.

Temporal expression and location of colony-stimulating factor 1 (CSF-1) and its receptor in the female reproductive tract are consistent with CSF-1-regulated placental development.

During pregnancy the mouse uterine epithelial synthesis of the mononuclear phagocyte growth factor designated colony-stimulating factor 1 (CSF-1) is regulated by female sex steroids. To study the role of CSF-1 in the pregnant female reproductive tract, the temporal expression and cellular sites of synthesis of CSF-1 and CSF-1 receptor (CSF-1R) mRNA were determined. CSF-1 mRNA, predominantly the 2.3-kilobase (kb) form, was first detected by in situ hybridization in uterine epithelium prior to implantation on day 3 and subsequently increased, reaching a peak at days 14-15. Its expression was restricted to the uterine epithelium at all stages of gestation and was not localized to areas of implantation. CSF-1R mRNA was first detected in maternal decidua at day 6. It was expressed in the decidua basalis during placentation, after which its expression declined. At day 7.5, trophectodermal cells also expressed CSF-1R mRNA; during placentation, it was found also in the diploid trophoblasts. The high level of CSF-1R mRNA expression by trophoblast giant cells was independent of their location around the conceptus. There was a differential distribution of CSF-1R mRNA expression in the mature placenta, with expression in the giant trophoblastic layer greater than spongiotrophoblastic layer greater than labyrinthine layer until term. Yolk sac cells also expressed low levels of CSF-1R mRNA. The coincidence of uterine CSF-1 mRNA expression and CSF-1 synthesis with both placental growth and CSF-1R mRNA expression in decidual cells and trophoblasts strongly implicates CSF-1 in the regulation of placental growth and differentiation.