Levels Of Colony-stimulating Factor-1 Receptor Research Articles

Evaluation of a Positron Emission Tomography Tracer Targeting Colony-Stimulating Factor 1 Receptor for Detecting Pulmonary Inflammation.

Colony-stimulating factor 1 receptor (CSF1R) is a type III receptor tyrosine kinase that is crucial for immune cell activation, survival, proliferation, and differentiation. Its expression significantly increases in macrophages during inflammation, playing a crucial role in regulating inflammation resolution and termination. Consequently, CSF1R has emerged as a critical target for both therapeutic intervention and imaging of inflammatory diseases. Herein, we have developed a radiotracer, 1-[4-((7-(dimethylamino)quinazolin-4-yl)oxy)phenyl]-3-(4-[18F]fluorophenyl)urea ([18F]17), for in vivo positron emission tomography (PET) imaging of CSF1R. Compound 17 exhibits a comparable inhibitory potency against CSF1R as the well-known CSF1R inhibitor PLX647. The radiosynthesis of [18F]17 was successfully performed by radiofluorination of aryltrimethyltin precursor with a yield of approximately 12% at the end of synthesis, maintaining a purity exceeding 98%. In vivo stability and biodistribution studies demonstrate that [18F]17 remains >90% intact at 30 min postinjection, with no defluorination observed even at 60 min postinjection. The PET/CT imaging study in lipopolysaccharide-induced pulmonary inflammation mice indicates that [18F]17 offers a more sensitive characterization of pulmonary inflammation compared to traditional [18F]FDG. Notably, [18F]17 shows a higher discrepancy in uptake ratio between mice with pulmonary inflammation and the sham group. Furthermore, the variations in [18F]17 uptake ratio observed on day 7 and day 14 correspond to lung density changes observed in CT imaging. Moreover, the expression levels of CSF1R on day 7 and day 14 follow a trend similar to the uptake pattern of [18F]17, indicating its potential for accurately characterizing CSF1R expression levels and effectively monitoring the pulmonary inflammation progression. These results strongly suggest that [18F]17 has promising prospects as a CSF1R PET tracer, providing diagnostic opportunities for pulmonary inflammatory diseases.

Abstract 1581: Colony-stimulating factor-1 receptor as a potential therapeutic target in pancreatic ductal adenocarcinoma

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis, rising incidence and suffers from limited existing treatment options. Currently, salient features of PDAC are being investigated that can potentially predict immunotherapy outcomes, to identify small patient populations that can benefit from such strategies. Preliminary studies show that colony-stimulating factor-1 receptor (CSF1R), a surface receptor tyrosine kinase that drives survival, function, proliferation and differentiation of several myeloid lineage cell types can be a potentially interesting target for combination immunotherapy. Methods: PDAC patients from the TCGA PanCancer Atlas were stratified into CSF1Rhi and CSF1Rlo cohorts and clinically relevant characteristics were compared between the two. The mRNA expression of CSF1R and immunological markers of interest were evaluated and Gene Set Enrichment Analysis (GSEA) was run on the two groups to analyze differential expression of gene sets. Results: mRNA expression z-scores were used to classify 129 patient samples in the TCGA PanCancer Atlas dataset into CSF1Rhi (z-score>1, n=20) and CSF1Rlo (z-score<0, n=109) cohorts. Both have similar disease staging, MSI MANTIS scores, tumor mutation burden, median diagnosis age, sex and race distribution. However, the CSF1Rhi cohort has a distinct, non-conventional PDAC driver gene mutation profile (genomic alteration frequencies in CSF1Rhi vs CSF1Rlo cohorts respectively: a) KRAS: 30% vs 73% b) CDKN2A: 15% vs 57% and c) SMAD4: 5% vs 42%) (p-value<0.01 for each). CSF1R correlates with markers of CD8+ T-cell function (R2 values: CD8A: 0.683, GZMB: 0.508, PRF1: 0.673), CD8+ T-cell infiltration (CXCL9: 0.596, CXCL10: 0.483, CCL5: 0.666) and expression of immune checkpoint genes (PDCD1: 0.602, CD274: 0.544, CTLA4: 0.613). CD8A, GZMB, PRF1, CXCL9, CXCL10, CCL5, PDCD1, CD274, CTLA4 are significantly upregulated in the CSF1Rhi group (log2Fold changes respectively: 2.07, 1.57, 1.48, 2.51, 1.71, 1.75, 1.63, 1.34, 1.80). GSEA against the hallmark gene set database shows that KRAS signaling, Inflammatory response, IL6 JAK STAT3 and Interferon-gamma signaling are significantly upregulated in the CSF1R high patient group (FDR q-value <0.01 for each). Conclusion: Preliminary in silico analysis suggests that PDAC patients with higher levels of CSF1R may be more immune infiltrated. Future studies will evaluate the potential of CSF1R as a biomarker to identify an immune infiltrated subset of PDAC patients ex vivo and the mechanism of immune infiltration in CSF1Rhi PDACs in vivo. Citation Format: Somak Chaudhuri, Dustin A. Deming, Cheri A. Pasch, Katherine A. Johnson, Chelsie K. Sievers, Philip B. Emmerich. Colony-stimulating factor-1 receptor as a potential therapeutic target in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1581.

Lysosomal acid lipase, CSF1R, and PD-L1 determine functions of CD11c+ myeloid-derived suppressor cells.

Lysosomal acid lipase (LAL) is a key enzyme in the metabolic pathway of neutral lipids. In the blood of LAL-deficient (Lal–/–) mice, increased CD11c+ cells were accompanied by upregulated programmed cell death ligand 1 (PD-L1) expression. Single-cell RNA sequencing of Lal–/– CD11c+ cells identified 2 distinctive clusters with a major metabolic shift toward glucose utilization and reactive oxygen species overproduction. Pharmacologically blocking pyruvate dehydrogenase in glycolysis not only reduced CD11c+ cells and their PD-L1 expression but also reversed their capabilities of T cell suppression and tumor growth stimulation. Colony-stimulating factor 1 receptor (CSF1R) played an essential role in controlling Lal–/– CD11c+ cell homeostasis and function and PD-L1 expression. Pharmacological inhibition of LAL activity increased CD11c, PD-L1, and CSF1R levels in both normal murine myeloid cells and human blood cells. Tumor-bearing mice and human patients with non–small cell lung cancer also showed CD11c+ cell expansion with PD-L1 and CSF1R upregulation and immunosuppression. There were positive correlations among CD11c, PD-L1, and CSF1R expression and negative correlations with LAL expression in patients with lung cancer or melanoma using The Cancer Genome Atlas database and patient samples. Therefore, CD11c+ cells switched their functions to immune suppression and tumor growth stimulation through CSF1R/PD-L1 upregulation and metabolic reprogramming.

Amino acids suppress macropinocytosis and promote release of CSF1 receptor in macrophages.

ABSTRACTThe internalization of solutes by macropinocytosis provides an essential route for nutrient uptake in many cells. Macrophages increase macropinocytosis in response to growth factors and other stimuli. To test the hypothesis that nutrient environments modulate solute uptake by macropinocytosis, this study analyzed the effects of extracellular amino acids on the accumulation of fluorescent fluid-phase probes in murine macrophages. Nine amino acids, added individually or together, were capable of suppressing macropinocytosis in murine bone marrow-derived macrophages stimulated with the growth factors colony stimulating factor 1 (CSF1) or interleukin 34, both ligands of the CSF1 receptor (CSF1R). The suppressive amino acids did not inhibit macropinocytosis in response to lipopolysaccharide, the chemokine CXCL12, or the tumor promoter phorbol myristate acetate. Suppressive amino acids promoted release of CSF1R from cells and resulted in the formation of smaller macropinosomes in response to CSF1. This suppression of growth factor-stimulated macropinocytosis indicates that different nutrient environments modulate CSF1R levels and bulk ingestion by macropinocytosis, with likely consequences for macrophage growth and function.

Abnormal expression of colony stimulating factor 1 receptor (CSF1R) and transcription factor PU.1 (SPI1) in the spleen from patients with major psychiatric disorders: A role of brain–spleen axis

BackgroundThe colony stimulating factor 1 receptor (CSF1R) regulates microglia/macrophage proliferation, differentiation and survival; however, the precise role of this protein in psychiatric disorders is unknown. CSF1R is also known to interact with the transcription factor PU.1 (SPI1). Here we studied whether the expressions of CSF1R and SPI1 are altered in the postmortem samples (parietal cortex, cerebellum, spleen) from patients with major psychiatric disorders. MethodsProtein expression of CSF1R and SPI1 in the parietal cortex, cerebellum and spleen from control, major depressive disorder (MDD), schizophrenia (SZ), and bipolar disorder (BD) groups was measured. ResultsLevels of CSF1R in the spleen, but not cerebellum and parietal cortex, from MDD and SZ groups were significantly lower than the control group. There was a positive correlation between CSF1R levels in the spleen and CSF1R levels in the parietal cortex in the all subjects from four groups. Furthermore, levels of SPI1 in the cerebellum and spleen from MDD and SZ groups were significantly higher than the control group. Levels of SPI1 in the parietal cortex were not different among the four groups. Interestingly, there was a negative correlation between CSF1R and SPI1 levels in the spleen of the all subjects from four groups. There was also a negative correlation between CSF1R and SPI1 levels in the spleen of MDD group. LimitationsThe small number in each group may limit our interpretation. ConclusionsAbnormalities in CSF1R and SPI1 in the brain–spleen axis might, in part, play a role in the pathophysiology of MDD.

Pharmacological inhibition of CSF1R by GW2580 reduces microglial proliferation and is protective against neuroinflammation and dopaminergic neurodegeneration.

Increased pro-inflammatory cytokine levels and proliferation of activated microglia have been found in Parkinson's disease (PD) patients and animal models of PD, suggesting that targeting of the microglial inflammatory response may result in neuroprotection in PD. Microglial proliferation is regulated by many factors, but colony stimulating factor-1 receptor (CSF1R) has emerged as a primary factor. Using data mining techniques on existing microarray data, we found that mRNA expression of the CSF1R ligand, CSF-1, is increased in the brain of PD patients compared to controls. In two different neurotoxic mouse models of PD, acute MPTP and sub-chronic LPS treatment, mRNA and protein levels of CSF1R and CSF-1 were significantly increased. Treatment with the CSF1R inhibitor GW2580 significantly attenuated MPTP-induced CSF1R activation and Iba1-positive cell proliferation, without a reduction of the basal Iba1-positive population in the substantia nigra. GW2580 treatment also significantly decreased mRNA levels of pro-inflammatory factors, without alteration of anti-inflammatory mediators, and significantly attenuated the MPTP-induced loss of dopamine neurons and motor behavioral deficits. Importantly, these effects were observed in the absence of overt microglial depletion, suggesting that targeting CSF1R signaling may be a viable neuroprotective strategy in PD that disrupts pro-inflammatory signaling, but maintains the beneficial effects of microglia.

Overexpression and activation of colony-stimulating factor 1 receptor in the SIV/macaque model of HIV infection and neuroHIV.

In the present study, we investigated whether colony-stimulating factor 1 receptor (CSF1R) is expressed on brain macrophages and microglia in the human and macaque brain and whether it is upregulated and activated after lentivirus infection in vivo and contributes to development of encephalitic lesions. We examined, using multi-label and semi-quantitative immunofluorescence microscopy, the protein expression level and cellular localization of CSF1R in brain tissues from uninfected controls and SIV-infected adult macaques with or without encephalitis and also from uninfected controls, HIV-infected encephalitic subjects and virally suppressed subjects. In the normal uninfected brain, CSF1R protein was detected only on microglia and brain macrophages but not on neurons, astrocytes or oligodendrocytes. Microglia constitutively expressed CSF1R at low levels, and its expression was largely unchanged in non-encephalitic and encephalitic animals. Brain macrophages, including perivascular macrophages (PVMs), expressed higher levels of CSF1R compared to microglia. Interestingly, we found significantly increased expression of CSF1R on the infected PVMs and lesional macrophages in the brains of encephalitic macaques. Moreover, the per cell expression of CSF1R determined by its mean pixel intensity (MPI) correlated positively with the MPI of SIV Gag p28 in SIV-infected PVMs. Using phosphorylated CSF1R at tyrosine residue 723 and phosphorylated signal transducer and activator of transcription 5 at tyrosine reside 694 as markers for CSF1R activation, we found selective activation of CSF1R signaling in infected brain macrophages in encephalitis. We also found colocalization of CSF1R and its ligand CSF1 in PVMs and lesional macrophages in the brains of encephalitic macaques and humans. Notably, elevated brain CSF1R expression was found in virally suppressed subjects. These findings point to opportunities for developing a specific approach targeting infected brain macrophages, with several brain-penetrant CSF1R inhibitors that are available now, in order to eliminate central nervous system macrophage reservoirs, while not affecting resting uninfected microglia and PVMs that show no CSF1R activation.

Colony-stimulating factor-1 receptor provides a growth advantage in epithelial cancer cell line A431 in the presence of epidermal growth factor receptor inhibitor gefitinib

Although epidermal growth factor receptor (EGFR) has been identified as a potent “oncogenic driver” in various tumors of epithelial origin, EGFR-targeted therapies are often of limited success. One of the challenges of improving targeted therapies is to overcome bypassing signaling pathways.Analysis of RNA-seq data of 1006 cell lines from the Cancer Cell Line Encyclopedia (CCLE) revealed that more than 12% of carcinoma cell lines expressed markedly elevated mRNA levels of colony-stimulating factor (CSF)-1 receptor (CSF-1R). Since epithelial cells also express CSF-1, elevated levels of CSF-1R may participate in providing alternative growth and survival signals under targeted therapies. To address this question, we ectopically expressed CSF-1R in A431 cells that express EGFR at high levels, but no biologically relevant level of CSF-1R. In the presence of EGFR inhibitor gefitinib, CSF-1R provided a significant growth advantage in A431 cells. As expected, activation of both receptors, EGFR or CSF-1R, induced phosphorylation of extracellular signal-regulated kinase (Erk)1/2, Akt, protein kinase C (PKC) and signal transducer and activator of transcription (STAT)3. However, EGFR, but not CSF-1R, also induced STAT5 phosphorylation. Inhibitor of phosphatidylinositol 3–kinase (PI3K) (AZD8186), MAPK/ERK kinase (MEK)1/2 (U0126), PKCs (Bisindolylmaleimide I or Gö6976) or STAT3 (Stattic) partially reduced proliferation of CSF-1R expressing A431 cells in the presence of gefitinib. Moreover, multi-kinase inhibitor, cabozantinib, suppressed CSF-1R activation and drastically reduced cell growth when combined with gefitinib. These data suggest that CSF-1R has the potential to reduce sensitivity to gefitinib and may be involved in resistance development.

Increased Microglial CSF1R Expression in the SIV/Macaque Model of HIV CNS Disease.

Chronic microglial activation and associated neuroinflammation are key factors in neurodegenerative diseases including HIV-associated neurocognitive disorders. Colony stimulating factor 1 receptor (CSF1R)-mediated signaling is constitutive in cells of the myeloid lineage, including microglia, promoting cell survival, proliferation, and differentiation. In amyotrophic lateral sclerosis and Alzheimers disease, CSF1R is upregulated. Inhibiting CSF1R signaling in animal models of these diseases improved disease outcomes. In our studies, CNS expression of the CSF1R ligand, colony-stimulating factor 1 (CSF1) was significantly increased in a SIV/macaque model of HIV CNS disease. Using a Nanostring nCounter immune panel, we found CSF1 overexpression was strongly correlated with upregulation of microglial genes involved in antiviral and oxidative stress responses. Using in situ hybridization, we found that CSF1R mRNA was only present in Iba-1 positive microglia. By ELISA and immunostaining with digital image analysis, SIV-infected macaques had significantly higher CSF1R levels in frontal cortex than uninfected macaques (p = 0.018 and p = 0.02, respectively). SIV-infected macaques treated with suppressive ART also had persistently elevated CSF1R similar to untreated SIV-infected macaques. Coordinate upregulation of CSF1 and CSF1R expression implicates this signaling pathway in progressive HIV CNS disease.

CSF1R Is Associated with Poor Overall Survival in AML and Mediates Supportive Interactions Between AML and Stromal Cells in the AML Microenvironment

Bone marrow (BM) stromal cells produce factors important for the growth and maintenance of normal hematopoietic, as well as leukemic cells. Interactions between hematopoietic and stromal cells as mediated by classic ligand-receptor, cytokine and metabolic elements help to create a supportive microenvironmental niche. Colony stimulating factor 1 (CSF1) is a cytokine produced by BM stromal cells. CSF1 exists as both secreted and membrane-bound isoforms, with the latter being predominant in the BM. CSF1 acts on the CSF1 receptor (CSF1R), which is expressed on phagocytic cells to induce their growth and differentiation into monocytes, macrophages and dendritic cells. Acute myeloid leukemia (AML) arises from mutations that lead to a block in differentiation of myeloid cell precursors (myeloblast or blast cells), the accumulation of which interferes with normal hematopoiesis. In this study, we examined the role of the CSF1-CSF1R interaction in AML as related to patient outcome and its influence on AML-stromal cell interactions.Analysis of cell surface protein levels of CSF1R by flow cytometry revealed that a subset of AML patient samples express high levels of CSF1R (CSF1Rhigh). Clinically, we found that CSF1Rhigh patients have shorter overall survival compared to patients with low CSF1R expression. To examine the CSF1-CSF1R interaction experimentally, CSF1Rhigh AML cells (patient samples and cell lines) were grown in in-vitro co-cultures with murine MS5 stromal cells engineered to overexpress the membrane-bound form of human CSF1 (MS5-hCSF1). We found that MS5-hCSF1 stromal cells display an increased growth rate, altered cytokine profile and signaling changes (namely mTOR pathway activation) compared to cells that do not express CSF1. In co-culture assays, we found that MS5-hCSF1 stromal cells enhanced the long-term growth (2 weeks) and survival of CSF1Rhigh AML cells by several fold. This growth advantage was not observed for CSF1RlowAML cells. Pre-culture of AML cells with MS5-hCSF1 stromal cells for 72 hours led to increased colony numbers in colony forming unit (CFU) assays compared to pre-culture on non-CSF1-expressing stroma. This suggests that exposure to CSF1 may enhance the clonogenic potential of AML cells. Co-culture of AML cells with MS5-hCSF1 stromal cells led to increased surface expression of the stem cell markers CD34 and CD117 (c-kit), suggestive of an immature, progenitor-like AML phenotype driven by CSF1. Furthermore, co-culture of AML and MS5-hCSF1 stromal cells led to distinct changes in the cytokine profiles of both AML and stromal cells, with increased levels of IL-8, IL-10 and IL-1 RA and RANTES in AML cells, and increased levels of IL-3, IL-6 and VEGF in stromal cells.Taken together, these results suggest that the CSF1-CSF1R interaction may be important in promoting a pro-leukemic phenotype. In particular, stromal support of AML is enhanced in a CSF1-dependent manner, with effects on AML growth, differentiation and production of signaling molecules. These effects in turn, have implications for modulating stromal cells themselves. Studying and understanding the complex interplays between AML and stromal cells as driven by the CSF1-CSF1R interaction may aid in the development of therapeutic approaches to target AML and its niche environment. DisclosuresJain:Roche Canada: Research Funding.

CSF-1 receptor signalling is governed by pre-requisite EHD1 mediated receptor display on the macrophage cell surface

Colony stimulating factor-1 receptor (CSF-1R), a receptor tyrosine kinase (RTK), is the master regulator of macrophage biology. CSF-1 can bind CSF-1R resulting in receptor activation and signalling essential for macrophage functions such as proliferation, differentiation, survival, polarization, phagocytosis, cytokine secretion, and motility. CSF-1R activation can only occur after the receptor is presented on the macrophage cell surface. This process is reliant upon the underlying macrophage receptor trafficking machinery. However, the mechanistic details governing this process are incompletely understood. C-terminal Eps15 Homology Domain-containing (EHD) proteins have recently emerged as key regulators of receptor trafficking but have not yet been studied in the context of macrophage CSF-1R signalling. In this manuscript, we utilize primary bone-marrow derived macrophages (BMDMs) to reveal a novel function of EHD1 as a regulator of CSF-1R abundance on the cell surface. We report that EHD1-knockout (EHD1-KO) macrophages cell surface and total CSF-1R levels are significantly decreased. The decline in CSF-1R levels corresponds with reduced downstream macrophage functions such as cell proliferation, migration, and spreading. In EHD1-KO macrophages, transport of newly synthesized CSF-1R to the macrophage cell surface was reduced and was associated with the shunting of the receptor to the lysosome, which resulted in receptor degradation. These findings reveal a novel and functionally important role for EHD1 in governing CSF-1R signalling via regulation of anterograde transport of CSF-1R to the macrophage cell surface.

Pathologic and Protective Roles for Microglial Subsets and Bone Marrow- and Blood-Derived Myeloid Cells in Central Nervous System Inflammation.

Inflammation is a series of processes designed for eventual clearance of pathogens and repair of damaged tissue. In the context of autoimmune recognition, inflammatory processes are usually considered to be pathological. This is also true for inflammatory responses in the central nervous system (CNS). However, as in other tissues, neuroinflammation can have beneficial as well as pathological outcomes. The complex role of encephalitogenic T cells in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE) may derive from heterogeneity of the myeloid cells with which these T cells interact within the CNS. Myeloid cells, including resident microglia and infiltrating bone marrow-derived cells, such as dendritic cells (DC) and monocytes/macrophages [bone marrow-derived macrophages (BMDM)], are highly heterogeneous populations that may be involved in neurotoxicity and also immunoregulation and regenerative processes. Better understanding and characterization of myeloid cell heterogeneity is essential for future development of treatments controlling inflammation and inducing neuroprotection and neuroregeneration in diseased CNS. Here, we describe and compare three populations of myeloid cells: CD11c+ microglia, CD11c− microglia, and CD11c+ blood-derived cells in terms of their pathological versus protective functions in the CNS of mice with EAE. Our data show that CNS-resident microglia include functionally distinct subsets that can be distinguished by their expression of CD11c. These subsets differ in their expression of Arg-1, YM1, iNOS, IL-10, and IGF-1. Moreover, in contrast to BMDM/DC, both subsets of microglia express protective interferon-beta (IFNβ), high levels of colony-stimulating factor-1 receptor, and do not express the Th1-associated transcription factor T-bet. Taken together, our data suggest that CD11c+ microglia, CD11c− microglia, and infiltrating BMDM/DC represent separate and distinct populations and illustrate the heterogeneity of the CNS inflammatory environment.

ADAM17 limits the expression of CSF1R on murine hematopoietic progenitors

All-lymphoid progenitors (ALPs) yield few myeloid cells in vivo, but readily generate such cells in vitro. The basis for this difference remains unknown. We hypothesized that ALPs limit responsiveness to in vivo concentrations of myeloid-promoting cytokines by reducing expression of the corresponding receptors, potentially through posttranscriptional mechanisms. Consistent with such a mechanism, ALPs express higher levels of CSF1R transcripts than their upstream precursors, yet show limited cell-surface protein expression of colony-stimulating factor 1 receptor (CSF1R). All-lymphoid progenitors and other hematopoietic progenitors deficient in A disintegrin and metalloproteinase domain 17 (ADAM17), display elevated cell surface CSF1R expression. ADAM17(-/-) ALPs, however, fail to yield myeloid cells upon transplantation into irradiated recipients. Moreover, ADAM17(-/-) ALPs yield fewer macrophages in vitro than control ALPs at high concentrations of macrophage colony stimulating factor. Mice with hematopoietic-specific deletion of ADAM17 have normal numbers of myeloid and lymphoid progenitors and mature cells in vivo. These data demonstrate that ADAM17 limits CSF1R protein expression on hematopoietic progenitors, but that compensatory mechanisms prevent elevated CSF1R levels from altering lymphoid progenitor potential.

Investigation of colony stimulating factor-1 receptor (CSF-1R) expression in peripheral monocytes of breast cancer patients for tumor associated macrophages (TAM): A pilot study

22221 Background: Colony stimulating factor-1 (CSF-1) mediates macrophage (MØ) differentiation, proliferation, and survival through colony stimulating factor-1 receptor (CSF-1R, c-FMS, CD115). Tumor associated MØ (TAM) express CSF-1R, promote angiogenesis, tumor growth, metastasis, and correlate with adverse prognosis in breast cancer (BC). We asked if CSF-1R+ monocytes (MN) were detectable in the peripheral blood (PB) of patients (pts) with BC and if their presence correlated with adverse prognosis. Methods: From 8/30/05–9/28/07, 228 pts undergoing surgery for stage I-III invasive BC consented to participate in a biomarker trial. Blood samples from 44 pts were sent for analysis of MØ markers. Flow cytometry was used to analyze PB CSF-1R, recorded as the percent of CSF-1R+ MN/total MN. CSF-1R levels from 15 pts without invasive cancer (4 normal, 11 DCIS) and 27 pts treated with neoadjuvant (NA) chemotherapy (CTX) were used as comparison groups. Estimates of 10-year (yr) recurrence and mortality were calculated using Adjuvant! Online program. Linear regression was performed using STATA 9. Results: Mean age was 53 yrs (range 33 - 78 yr). Pts presented with stage I (59%), stage II (29.5%), and stage III (11%) invasive BC. Mean tumor size was 1.8 cm (range 0.2–6.5 cm), 82% of tumors were ER+ and 23% were her2/neu+. Mean percent CSF-1R+ was 24.2% of total MN (range 0–85%). Higher levels of CSF-1R+ correlated with higher estimated 10 yr recurrence and 10 yr mortality (p=0.049, and p=0.004, respectively, by Adjuvant! Online). The mean CSF-1R values were significantly lower for both pts without invasive cancer (7.9% of total monocytes (range 0–32%), p=0.003) and for pts treated with NACTX (14.6% of total MN (range 0–53%), p=0.03). Conclusions: CSF-1R+ MØ are found in tumors that have adverse prognosis and may be part of pathogenesis. We have demonstrated that CSF-1R+ MN can be detected in the PB of BC pts. We are currently validating CSF-1R levels of 100 pts with and without invasive BC, and pts pre and post NA therapy. Correlation between CSF-1R levels in the PB and tumor are underway and will be reported. Agents targeting CSF-1R are in phase I/II trials and CSF-1R+ MN could be an important biomarker for TAM targeted therapy. No significant financial relationships to disclose.

Expression of colony-stimulating factor 1 receptor during prostate development and prostate cancer progression.

Colony-stimulating factor-1 receptor (CSF-1R) is the major regulator of macrophage development and is associated with epithelial cancers of the breast and ovary. Immunohistochemistry analysis of murine prostate development demonstrated epithelial expression of CSF-1R during the protrusion of prostatic buds from the urogenital sinus, during the prepubertal and androgen-driven proliferative expansion and branching of the gland, with a decline in older animals. Models of murine prostate cancer showed CSF-1R expression in areas of carcinoma- and tumor-associated macrophages. Several human prostate cancer cell lines and primary cultures of human prostate epithelial cells had low but detectable levels of CSF-1R. Human prostatectomy samples showed low or undetectable levels of receptor in normal glands or benign prostatic hypertrophy specimens. Staining was strongest in areas of prostatic intraepithelial neoplasia or carcinoma of Gleason histological grade 3 or 4. The activated form of the receptor reactive with antibodies specific for phosphotyrosine modified peptide sequences was observed in samples of metastatic prostate cancer. Immunohistochemistry showed strong expression of CSF-1R by macrophage lineage cells, including villous macrophages and the syncytiotrophoblast layer of placenta, Kupper cells in the liver, and histiocytes infiltrating near prostate cancers. These observations correlate CSF-1R expression with changes in the growth and development of the normal and neoplastic prostate.