Regulation Of Tumor Angiogenesis Research Articles

The Pleiotropic Effects of miRNAs on Tumor Angiogenesis

Angiogenesis, the process of new blood vessel formation and growth from already existing venules is critical in vascular development and homeostasis controlled by the balance of pro- and anti-angiogenic factors. Emerging evidence indicates the development, progression, and metastasis of various human cancers are strongly relied on angiogenesis. However, molecular mechanisms that underlie the complex regulation of angiogenic processes are still not fully elucidated. Recent studies revealed that microRNAs (miRNAs) were important regulators of tumor angiogenesis and the entire research in this area has entered into a so-called "miRNAs era." Thus, miRNAs might be important therapeutic targets or biomarkers for cancer. Due to the complexity of miRNA regulating mechanisms, how specific miRNAs intersect with and modulate tumor angiogenesis is still unclear. The conflicting results of the same miRNAs from different groups indicated that miRNAs might possess potent activity in a cell type or cell context specific manner. Here, we present a summary of latest advances in understanding the roles of angiogenic miRNAs as potential tools or targets in cancer therapy.

Discovery of new 4-alkoxyquinazoline-based derivatives as potent VEGFR2 inhibitors.

VEGFR2 has been proved to play a major role in the regulation of tumor angiogenesis. Twenty-one 4-alkoxyquinazoline-based derivatives have been designed and synthesized as vascular endothelial growth factor receptor 2 (VEGFR2) inhibitors, and their biological activities were evaluated. Among these compounds, compound 3h exhibited the most potent inhibitory activities against VEGFR2 tyrosine kinase and cell proliferation, with the IC50 values of 2.89nm (for VEGFR2) and 0.25μm (for MCF-7), which were comparable with the control compound. Docking simulation was performed to position compound 3h into the 4ASE active site, and the result showed that compound 3h could bind well at the 4ASE active site.

Genetic Variations of Kinase Inserts Domain Receptor (KDR) Gene Are Associated with the Risk of Astrocytomas.

Astrocytomas is one of the most common central nervous system (CNS) tumors with high mortality rate. Kinase insert domain receptor (KDR) is involved in the regulation of tumor angiogenesis, migration, and vascular permeability. The aim of the study was to explore the relationship between KDR polymorphisms and risk of astrocytomas. Blood samples were collected from 157 astrocytomas patients and 160 healthy controls. Three tag-SNPs (rs2071559C/T, rs2305948T/C, and rs1870377A/T) were identified from the International HapMap Project Databases and genotyped using the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We evaluated the astrocytomas risk caused by individual SNPs and haplotype using odds ratios (ORs) and their 95 % confidence intervals (CIs). In the overall individual SNP analysis, the C allele of rs2071559 was correlated with an increased risk of astrocytomas. However, individuals with mutant allele A and genotype TA + AA of rs1870377 showed a protective effect against astrocytomas. Subgroup analysis based on WHO tumor grade revealed that the C allele of rs2071559 had more influence with the risk of astrocytomas in the grade III-IV (OR = 1.91) subgroup than the grade I-II (OR = 1.47) group. Genotype TT of rs2305948 was found to be significantly associated with susceptibility of astrocytomas only in the grade III-IV subgroup. The protective effect of rs1870377 did not reveal significant difference between the grade III-IV and grade I-II subgroups. Meanwhile, stratified analysis demonstrated that mutation of rs2071559 and rs2305948 could elevate the risk of astrocytomas more significantly in the subgroup of smokers than the nonsmokers. Interestingly, the protective effect of rs1870377 was more obvious in the nonsmokers than the smokers. Additionally, haplotype-specific analysis showed that haplotype CCT and CTT were related with an increased risk of astrocytomas. We found that individual with variants of rs2071559*C and rs2305948*T might significantly elevate the risk of astrocytomas, while mutants of rs1870377*A was associated with the decreased risk of astrocytomas. Further studies about ethnically diverse populations with larger sample size should be performed to confirm the correlation between KDR gene polymorphisms and risk of astrocytomas.

Protective Role of Selenium Compounds on the Proliferation, Apoptosis, and Angiogenesis of a Canine Breast Cancer Cell Line

We herein examined the effects of different doses, forms, and compatibilities of selenium on a canine mammary gland tumor cell line, CTM1211, and explored the related mechanisms. Three selenium compounds, sodium selenite (SSE), methylseleninic acid (MSA), and methylselenocysteine (MSC), were selected for these experiments, and cyclophosphamide (CTX) served as a positive control. In the cell viability assay, the cell viability of each group at 48/72h decreased significantly compared with the control group (p < 0.05), and the cell viability of the CTX + MSA group was lower than that of CTX and MSA groups (p < 0.05). Moreover, the inhibitory effect of selenium on cell proliferation was time-dependent but not concentration-dependent. In the cell apoptosis assay, the apoptosis values of each group increased significantly compared with the control group, and the apoptosis values of the CTX + MSA group increased the most significantly (p < 0.01). The protein and mRNA expression levels of vascular endothelial growth factor-alpha (VEGF-alpha), angiopoietin-2 (Ang-2), and hypoxia inducible factor-1 alpha (HIF-1 alpha) were downregulated in each group, while that of phosphatase and tensin homolog (PTEN) were upregulated (p < 0.05). In conclusion, these three selenium compounds, especially MSA, could significantly inhibit the viability and growth of the CTM1211 cell line, which is partly due to the induction of apoptosis and regulation of tumor angiogenesis.

Endothelial Jagged1 promotes solid tumor growth through both pro-angiogenic and angiocrine functions.

Angiogenesis is an essential process required for tumor growth and progression. The Notch signaling pathway has been identified as a key regulator of the neo-angiogenic process. Jagged-1 (Jag1) is a Notch ligand required for embryonic and retinal vascular development, which direct contribution to the regulation of tumor angiogenesis remains to be fully characterized. The current study addresses the role of endothelial Jagged1-mediated Notch signaling in the context of tumoral angiogenesis in two different mouse tumor models: subcutaneous Lewis Lung Carcinoma (LLC) tumor transplants and the autochthonous Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP). The role of endothelial Jagged1 in tumor growth and neo-angiogenesis was investigated with endothelial-specific Jag1 gain- and loss-of-function mouse mutants (eJag1OE and eJag1cKO). By modulating levels of endothelial Jag1, we observed that this ligand regulates tumor vessel density, branching, and perivascular maturation, thus affecting tumor vascular perfusion. The pro-angiogenic function is exerted by its ability to positively regulate levels of Vegfr-2 while negatively regulating Vegfr-1. Additionally, endothelial Jagged1 appears to exert an angiocrine function possibly by activating Notch3/Hey1 in tumor cells, promoting proliferation, survival and epithelial-to-mesenchymal transition (EMT), potentiating tumor development. These findings provide valuable mechanistic insights into the role of endothelial Jagged1 in promoting solid tumor development and support the notion that it may constitute a promising target for cancer therapy.

MMP-9/ANC score as a predictive biomarker for efficacy of bevacizumab plus platinum doublet chemotherapy in patients with advanced or recurrent non-squamous non-small cell lung cancer.

Bevacizumab is a recombinant humanized monoclonal antibody against vascular endothelial growth factor (VEGF), which is a key regulator of tumor angiogenesis. To evaluate biomarkers to predict the benefit of paclitaxel and carboplatin plus bevacizumab (PCB) therapy in patients with advanced or recurrent non-squamous non-small cell lung cancer. Among 21 patients treated with PCB, 10 were included in the good responder group and 11 in the non-responder group. Serum VEGF, MMP-2 and MMP-9 were measured using ELISA. There were no significant differences in these markers levels between groups. However, the good responder group showed a significantly higher pre-treatment MMP-9/ absolute neutrophil count (ANC) score than the non-responder group before the treatment (p= 0.014), and there was a positive correlation between the score and the tumor reduction rate (r= 0.57, p= 0.016). Furthermore, by dividing patients into a high scoring group (MMP-9/ANC ≥ median, n= 11) and a low scoring group (MMP-9/ANC < median, n= 10), former group showed a significant improvement in the median progression-free survival compared with latter group (636 vs. 196 days, p = 0.032). MMP-9/ANC score before PCB treatment may be a suitable biomarker to assess the anti-tumor effects of PCB therapy.

Candidate biomarker analyses in gastric or gastro-esophageal junction carcinoma: REGARD trial of single-agent ramucirumab (RAM) vs. placebo (PL).

4029 Background: Vascular endothelial growth factors (VEGFs) are key regulators of tumor angiogenesis. RAM, a recombinant human IgG1 monoclonal antibody specific for VEGF receptor 2 (VEGFR2), inhib...

Role of endothelial-specific growth-factors in efficacy of cetuximab in pts with head and neck squamous cell carcinoma (HNSCC).

e17013 Background: The EGFR transduction pathway is known to regulate tumor angiogenesis. Impairments in this growth factor system could be a reason for inappropriate tumor response. The aim of the...

Serum Angiopoietin Levels are Different in Acute and Chronic Myeloid Neoplasms: Angiopoietins do not only Regulate Tumor Angiogenesis.

Molecular balance between Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2) has important effects in tumor angiogenesis. Ang-2 was shown to be elevated and proved to be a prognostic factor in acute myeloid leukemia (AML). To date studies revealed increased angiogenesis in bone marrows (BMs) of both myeloproliferative neoplasm (MPN) and AML patients. We conducted this study to demonstrate circulating levels of Ang-1 and Ang-2 in MPN patients since no data exists in literature. Thirty-three newly diagnosed MPN, 27 newly diagnosed AML patients and 25 controls (HC) were enrolled and Angiopoietin levels were determined with ELISA. We found that Ang-1 levels were higher whereas Ang-2 levels were lower in MPN and HC when compared to AML. Our results suggest that though angiogenesis is increased in both AML and MPN, angiopoietin serum level profile of the two diseases are different, and MPN patients have similar Ang-1 and Ang-2 levels as HC. We conclude that, according to our results Ang-1 and Ang-2 do not only regulate tumor angiogenesis and the difference between angiopoietin levels of acute and chronic myeloid neoplasms could be a reflection of other effects of these growth factors on tumor malignancy.

SGK3 (CISK) may induce tumor angiogenesis (Hypothesis).

Serum- and glucocorticoid-inducible protein kinase 3 (SGK3), also known as cytokine-independent survival kinase (CISK), encoded by chromosome 8q12.2, is a downstream mediator of phosphatidylinositol 3-kinase (PI3K) oncogenic signaling. As a downstream target of PI3K, SGK3 has been reported to mediate pivotal roles in oncogenic progress in various cancers, including breast cancer, ovarian cancer and hepatocellular carcinoma. Functionally parallel to v-akt murine thymoma viral oncogene homolog (AKT)/protein kinase B, SGK3 serves as a hallmark mediating glycogen synthase kinase-β (GSK3-β), B-cell lymphoma (Bcl)-2-associated death promoter, forkead family of transcription factors, Bcl-extra large, Bcl-2, mammalian target of rapamycin, C-X-C chemokine receptor type 4 (CXCR4) and numerous other molecules in cell proliferation, growth, survival, migration and even tumor angiogenesis. Tumor angiogenesis is recognized as an essential step for tumor growth, invasion and metastasis, and it has become an intriguing target for anticancer drug development for tumor investigators worldwide. An abundance of experiments have been performed to investigate the role of the phosphoinositide 3-kinase (PI3K)/AKT pathway in regulating tumor angiogenesis. The mechanism of angiogenesis regulated by the PI3K/AKT pathway is, to a certain extent, clear. Although a number of SGK3 target molecules, including CXCR4 and GSK3β, have demonstrated potential roles in promoting angiogenesis, the exact association between angiogenesis and SGK3 remains unclear. Thus, we hypothesize that SGK3, parallel to AKT, may also be important in mediating angiogenesis. Identifying the role of SGK3 in tumor angiogenesis will certainly present a novel perspective on the malignant transformation of tumors, as well as a target for tumor therapy.

Abstract 141: The Role of Macrophage Epsins in the Regulation of LRP-1 in Atherosclerosis

Background: Epsins are a family of ubiquitin-binding endocytic clathrin adaptors. We recently published that endothelial epsins function as critical regulators of tumor angiogenesis by controlling VEGF signaling (JCI, 2012; ATVB, 2013). Our goal is to define the novel role of epsins in macrophages in regulating atherogenesis. Methods and Results: We engineered mice with specific deletion of epsins in myeloid cells (MΦ-DKO). Strikingly, MΦ-DKO mice on ApoE-/- background fed western diet significantly reduced atherosclerotic lesion formation and foam cell accumulation. In macrophages, epsin deficiency did not alter LDL scavenger receptors, CD36, Lox1 or SRB1, or reverse cholesterol transport proteins, ABCA1 or ABCG1, but did significantly reduce Lucifer Yellow pinocytosis, indicating a major defect in lipid uptake. Epsin deficiency did decrease total and surface protein levels of LRP-1, a protein with anti-inflammatory and anti-atherosclerotic properties. Oil Red O staining of isolated ApoE-/-/M[[Unable to Display Character: &amp;#1060;]]-DKO macrophages showed little lipid accumulation, suggesting a mechanism in which epsin deficiency impairs foam cell formation. In addition, epsin 1 and LRP-1 interact in macrophages. Furthermore, this interaction is abolished in the absence of epsin’s UIM domain and LPS treatment increases LRP-1 ubiquitination, suggesting that epsin promotes the ubiquitin-dependent internalization of LRP-1. Epsin deficiency also significantly suppressed the pro-inflammatory M1 macrophage phenotype found in plaques and increased the anti-inflammatory macrophage phenotype, thus suggesting an important pro-inflammatory role for epsins in macrophages. Our finding implicates epsin as a potential therapeutic target for atherosclerosis treatment. Conclusions: We demonstrate epsins promote atherogenesis by potentiating foam cell formation and maintaining pro-inflammatory macrophages within the atherosclerotic plaque, thus suggesting epsins as a novel therapeutic target to combat atherogenesis.

YBX1/YB-1 induces partial EMT and tumourigenicity through secretion of angiogenic factors into the extracellular microenvironment.

Epithelial-mesenchymal transition (EMT) describes a morphogenetic program which confers mesenchymal cell properties, such as reduced cell-cell contact and increased cell migration and invasion, to epithelial cells. Here we investigate the role of the pleiotropic transcription/splicing factor and RNA-binding protein nuclease-sensitive element-binding protein 1 (YBX1/YB-1) in increasing the oncogenic potential of epithelial MDCK cells. Characterization of MDCK cells expressing YBX1 (MDCKYBX1 cells) revealed a partial EMT phenotype, including cytosolic relocalization of E-cadherin, increased cell scattering, and anchorage-independent growth. Subcutaneous injection of parental MDCK cells into NOD/SCID mice did not form tumours. Critically, MDCKYBX1 cells established viable tumour xenografts, and immuno-histochemical staining indicated murine vascularization by CD31+ endothelial cells. We analysed the total secretome (containing soluble and extracellular vesicles) of MDCKYBX1 cells to investigate regulation of the tumour microenvironment. YBX1 expression elevated release of secreted factors known to enhance angiogenesis (TGF-β, CSF-1, NGF, VGF, ADAM9 and ADAM17), compared to MDCK cells. Importantly, treatment with MDCKYBX1 cell-derived secretome increased recipient 2F-2B endothelial cell motility. This defines YBX1 as an oncogenic enhancer that can regulate tumour angiogenesis via release of secreted modulators into the extracellular microenvironment.

Activation of mechanosensitive ion channel TRPV4 normalizes tumor vasculature and improves cancer therapy.

Tumor vessels are characterized by abnormal morphology and hyper-permeability that together cause inefficient delivery of chemotherapeutic agents. Although VEGF has been established as a critical regulator of tumor angiogenesis, the role of mechanical signaling in the regulation of tumor vasculature or tumor endothelial cell (TEC) function is not known. Here, we show that the mechanosensitive ion channel TRPV4 regulates tumor angiogenesis and tumor vessel maturation via modulation of TEC mechanosensitivity. We found that TEC exhibit reduced TRPV4 expression and function, which is correlated with aberrant mechanosensitivity towards ECM stiffness, increased migration and abnormal angiogenesis by TEC. Further, syngeneic tumor experiments revealed that the absence of TRPV4 induced increased vascular density, vessel diameter and reduced pericyte coverage resulting in enhanced tumor growth in TRPV4 KO mice. Importantly, overexpression or pharmacological activation of TRPV4 restored aberrant TEC mechanosensitivity, migration and normalized abnormal angiogenesis in vitro by modulating Rho activity. Finally, a small molecule activator of TRPV4, GSK1016790A, in combination with anti-cancer drug Cisplatin, significantly reduced tumor growth in WT mice by inducing vessel maturation. Our findings demonstrate TRPV4 channels to be critical regulators of tumor angiogenesis and represent a novel target for anti-angiogenic and vascular normalization therapies.

Microarray profiling of L1-overexpressing endothelial cells reveals STAT3 activation via IL-6/IL-6Rα axis.

We recently identified a novel role for the L1 transmembrane glycoprotein (also known as L1CAM or CD171) in the regulation of tumor angiogenesis and vessels stabilization. L1 overexpression in cultured endothelial cells of the lung (luECs) exerted a pleiotropic effect in that it regulated proliferation, migration, tubulogenesis, vascular permeability, and endothelial-to-mesenchymal transition (EndMT). In addition, we provided strong evidence that antibody-mediated targeting of L1 may be an effective strategy for vessel normalization with the potential to increase efficacy of chemotherapeutic agents.High-throughput microarray expression profile revealed that L1 modulates the expression of hundreds of genes mainly involved in cell cycle regulation, DNA replication, cellular assembly, migration, development and organization. By using a ‘pathway-oriented’ analysis strategy we were able to identify a network of 105 genes modulated by L1 through the predicted activation of five transcription factors: STAT1, STAT2, STAT3, IRF7, and ATF4. Indeed, L1 overexpression resulted in the strong induction of STAT3 phosphorylation which was abolished by antibody-mediated neutralization of IL-6Rα. These results indicated that L1 promoted STAT3 activation via the IL-6/IL-6Rα axis.

Overexpression of Roundabout4 predicts poor prognosis of primary glioma patients via correlating with microvessel density

Roundabout4 (Robo4), a new member of Robo proteins family, is specifically expressed in endothelial cells. Recent studies have indicated that Robo4 could regulate tumor angiogenesis and vascular permeability. However, the role and function of Robo4 are not well understood. This study was performed to investigate the expression of Robo4 in primary glioma patients, and thus to determine the association of Robo4 expression with microvessel density and survival of glioma patients. In this study, real-time PCR and immunohistochemistry were performed to examine the mRNA level and protein expression of Robo4 in both 43 cases of glioma samples and 10 cases of normal brain tissue samples. The results demonstrated that Robo4 was significantly up-regulated in glioma tissues compared with normal brain tissues. In addition, double immunofluorescent staining revealed that Robo4 expression co-localized with CD34 expression in the vessel of glioma tissues. The expression of Robo4 positively correlated with patients' age (P = 0.0139) and glioma grade (P < 0.0001). A linear correlation was observed between the relative mRNA expression of Robo4 values and corresponding microvessel density values (r = 0.9735, P < 0.0001). Kaplan-Meier analysis and log-rank test result showed that the overall survival of patients with Robo4 high expression was significantly shorter than that of patients with Robo4 low expression (P < 0.001). The results of present study verify that overexpression of Robo4 is related to poor prognosis of primary gliomas patients through correlating with microvessel density.

The cholesterol biosynthesis enzyme oxidosqualene cyclase is a new target to impair tumour angiogenesis and metastasis dissemination.

Aberrant cholesterol homeostasis and biosynthesis has been observed in different tumour types. This paper investigates the role of the post-squalenic enzyme of cholesterol biosynthesis, oxidosqualene cyclase (OSC), in regulating tumour angiogenesis and metastasis dissemination in mouse models of cancer. We showed that Ro 48-8071, a selective inhibitor of OSC, reduced vascular density and increased pericyte coverage, with a consequent inhibition of tumour growth in a spontaneous mouse model of pancreatic tumour (RIP-Tag2) and two metastatic mouse models of human colon carcinoma (HCT116) and pancreatic adenocarcinoma (HPAF-II). Remarkably, the inhibition of OSC hampered metastasis formation in HCT116 and HPAF-II models. Ro 48-8071 induced tumour vessel normalization and enhanced the anti-tumoral and anti-metastatic effects of 5-fluorouracil (5-FU) in HCT116 mice. Ro 48-8071 exerted a strong anti-angiogenic activity by impairing endothelial cell adhesion and migration, and by blocking vessel formation in angiogenesis assays. OSC inhibition specifically interfered with the PI3K pathway. According to in vitro results, Ro 48-8071 specifically inhibited Akt phosphorylation in both cancer cells and tumour vasculature in all treated models. Thus, our results unveil a crucial role of OSC in the regulation of cancer progression and tumour angiogenesis, and indicate Ro 48-8071 as a potential novel anti-angiogenic and anti-metastatic drug.

TRF2 acts as a transcriptional regulator in tumor angiogenesis

We recently showed that telomeric repeat-binding factor 2 (TRF2) regulates gene expression to promote angiogenesis. We found that TRF2 is highly expressed in tumor vessels and transcriptionally activates platelet-derived growth factor receptor β to promote endothelial cell angiogenic properties independently of its function in telomere protection. This work identifies TRF2 as a promising dual target for cancer therapy.

Interleukin-17 Could Promote Breast Cancer Progression at Several Stages of the Disease.

Metastatic disease accounts for more than 90% of deaths from breast cancer. Yet the factors that trigger metastasis, often years after primary tumor removal, are not understood well. Recently the proinflammatory cytokine interleukin- (IL-) 17 family has been associated with poor prognosis in breast cancer. Here we review current literature on the pathogenic mechanisms driven by IL-17 during breast cancer progression and connect these findings to metastasis. These include (1) direct effects of IL-17 on tumor cells promoting tumor cell survival and invasiveness, (2) regulation of tumor angiogenesis, and (3) interaction with myeloid derived suppressor cells (MDSCs) to inhibit antitumor immune response and collaborate at the distant metastatic site. Furthermore, IL-17 might also be a culprit in bone destruction caused by late stage bone metastasis. Interestingly, in addition to these potential prometastasis functions, there is also evidence for an opposite, antitumor role of IL-17 during cancer therapies. We hypothesize that these contradictory roles may be due to chronic, imbalanced versus acute transient nature of the immune reactions, as well as differences in the cells that interact with IL-17+ cells under different circumstances.

The Latent Membrane Protein 1 (LMP1).

Almost exactly twenty years after the discovery of Epstein-Barr virus (EBV), the latent membrane protein 1 (LMP1) entered the EBV stage, and soon thereafter, it was recognized as the primary transforming gene product of the virus. LMP1 is expressed in most EBV-associated lymphoproliferative diseases and malignancies, and it critically contributes to pathogenesis and disease phenotypes. Thirty years of LMP1 research revealed its high potential as a deregulator of cellular signal transduction pathways leading to target cell proliferation and the simultaneous subversion of cell death programs. However, LMP1 has multiple roles beyond cell transformation and immortalization, ranging from cytokine and chemokine induction, immune modulation, the global alteration of gene and microRNA expression patterns to the regulation of tumor angiogenesis, cell-cell contact, cell migration, and invasive growth of tumor cells. By acting like a constitutively active receptor, LMP1 recruits cellular signaling molecules associated with tumor necrosis factor receptors such as tumor necrosis factor receptor-associated factor (TRAF) proteins and TRADD to mimic signals of the costimulatory CD40 receptor in the EBV-infected B lymphocyte. LMP1 activates NF-κB, mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3-K), IRF7, and STAT pathways. Here, we review LMP1's molecular and biological functions, highlighting the interface between LMP1 and the cellular signal transduction network as an important factor of virus-host interaction and a potential therapeutic target.

Abstract A21: Thrombin-processed Ecrg4 recruits myeloid cells and induces anti-tumorigenic inflammation

Abstract Myeloid cells regulate tumor angiogenesis and promote tumor invasion, yet few strategies exist to exploit their presence to reverse the overall immunosuppressive tumor microenvironment. Based on bioinformatic mining of sentinel genes encoding biologically active peptides, we have recently identified Ecrg4 (Esophageal Cancer-Related Gene 4), as a novel secreted pro-inflammatory mediator of macrophage activation. While higher Ecrg4 expression levels correlate with improved survival in cancers of the esophagus, prostate and breast, indicating a role as a candidate tumor suppressor gene, we have demonstrated that the biological activity of Ecrg4 in cancer functions through a paracrine mechanism, in which Ecrg4 regulates myeloid cells in brain tumors. Moreover, mutational analysis reveals that the biological activity of Ecrg4 is dependent on a thrombin-processing site at the C-terminus, inducing monocyte invasion in vivo and in vitro, demonstrating its role as a novel chemoattractant. Here we establish Ecrg4 as a thrombin-processed chemoattractant using subcutaneous tumor models. Ecrg4 gene delivery or Ecrg4 (133-148) peptide administration to tumor reduced melanoma progression through mobilization and activation of myeloid cells to tumor site. Furthermore, in Ecrg4-knockout mice, myeloid cell recruitment is impaired, leading to increased tumor burden. Together, these results identify Ecrg4 as a paracrine factor that is chemotactic for monocytes, with translational potential as an anti-tumor therapeutic. Citation Format: Jisook Lee, Alexandra Borboa, Andrew Baird, Brian Eliceiri. Thrombin-processed Ecrg4 recruits myeloid cells and induces anti-tumorigenic inflammation. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A21. doi:10.1158/1538-7445.CHTME14-A21