Gene Summary

Gene:CX3CR1; chemokine (C-X3-C motif) receptor 1
Aliases: V28, CCRL1, GPR13, CMKDR1, GPRV28, CMKBRL1
Summary:Fractalkine is a transmembrane protein and chemokine involved in the adhesion and migration of leukocytes. The protein encoded by this gene is a receptor for fractalkine. The encoded protein also is a coreceptor for HIV-1, and some variations in this gene lead to increased susceptibility to HIV-1 infection and rapid progression to AIDS. Four transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, Jan 2010]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:CX3C chemokine receptor 1
Source:NCBIAccessed: 25 June, 2015


What does this gene/protein do?
Show (25)
Pathways:What pathways are this gene/protein implicaed in?
Show (1)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 25 June 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Up-Regulation
  • Receptors, CCR5
  • Oligonucleotide Array Sequence Analysis
  • Pancreatic Cancer
  • Transcription Factors
  • Immunohistochemistry
  • Brain Stem Glioma, Childhood
  • Gene Expression
  • Chemokine CX3CL1
  • Receptors, Chemokine
  • Macrophages
  • Single Nucleotide Polymorphism
  • Chromosome 3
  • Mutation
  • Genetic Predisposition
  • Gene Expression Profiling
  • Spheroids, Cellular
  • Tissue Array Analysis
  • Cell Movement
  • Lung Cancer
  • Chemokines
  • Receptors, Virus
  • Brain Tumours
  • Non-Small Cell Lung Cancer
  • ZAP-70 Protein-Tyrosine Kinase
  • B-Lymphocytes
  • Messenger RNA
  • Membrane Proteins
  • Young Adult
  • Natural Killer Cells
  • Genotype
  • Cell Adhesion
  • Staging
  • Skin Cancer
  • Microglia
  • Cancer Gene Expression Regulation
  • Stromal Cells
  • Tumor Markers
  • Transfection
  • Proportional Hazards Models
  • Brain Tumours
Tag cloud generated 25 June, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CX3CR1 (cancer-related)

Blonska M, Zhu Y, Chuang HH, et al.
Jun-regulated genes promote interaction of diffuse large B-cell lymphoma with the microenvironment.
Blood. 2015; 125(6):981-91 [PubMed] Article available free on PMC after 05/02/2016 Related Publications
Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with a high proliferation rate. However, the molecular and genetic features that drive the aggressive clinical behavior of DLBCL are not fully defined. Here, we have demonstrated that activated Jun signaling is a frequent event in DLBCL that promotes dissemination of malignant cells. Downregulation of Jun dramatically reduces lymphoma cell adhesion to extracellular matrix proteins, subcutaneous tumor size in nude mice, and invasive behavior, including bone marrow infiltration and interaction with bone marrow stromal cells. Furthermore, using a combination of RNA interference and gene expression profiling, we identified Jun target genes that are associated with disseminated lymphoma. Among them, ITGAV, FoxC1, and CX3CR1 are significantly enriched in patients with 2 or more extranodal sites. Our results point to activated Jun signaling as a major driver of the aggressive phenotype of DLBCL.

Shi JY, Yang LX, Wang ZC, et al.
CC chemokine receptor-like 1 functions as a tumour suppressor by impairing CCR7-related chemotaxis in hepatocellular carcinoma.
J Pathol. 2015; 235(4):546-58 [PubMed] Related Publications
Atypical chemokine receptors (ACRs) have been discovered to participate in the regulation of tumour behaviour. Here we report a tumour-suppressive role of a novel ACR member, CC chemokine receptor like 1 (CCRL1), in human hepatocellular carcinoma (HCC). Both mRNA and protein expressions of CCRL1 correlated with the malignant phenotype of HCC cells and were significantly down-regulated in tumour tissue compared with paired normal liver tissue. In both the initial and validation cohorts (n = 240 and n = 384, respectively), CCRL1 deficiency was associated with advanced tumour stage and was an independent index for worse survival and increased recurrence. Furthermore, knock-down or forced expression of CCRL1 revealed that CCRL1 suppressed the proliferation and invasion of HCC cells in vitro and reduced tumour growth and lung metastasis in vivo, with depressed levels of CCL19 and CCL21. By sequestrating CCL19 and CCL21, CCRL1 reduced their binding to CCR7 and consequently mitigated the detrimental impact of CCR7, including Akt-GSK3β pathway activation and nuclear accumulation of β-catenin in tumour cells. Clinically, the prognostic value of the CCR7 expression in HCC depended on the expression level of CCRL1, suggesting that CCRL1 may serve as an upstream switch for the CCR7 signalling cascade. Together, our findings suggest that CCRL1 impairs chemotactic events associated with CCR7 in the progression and metastasis of HCC. Our results also show a potential interplay between typical and atypical chemokine receptors in human cancer. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Gutknecht MF, Bouton AH
Functional significance of mononuclear phagocyte populations generated through adult hematopoiesis.
J Leukoc Biol. 2014; 96(6):969-80 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Tissue homeostasis requires a complete repertoire of functional macrophages in peripheral tissues. Recent evidence indicates that many resident tissue macrophages are seeded during embryonic development and persist through adulthood as a consequence of localized proliferation. Mononuclear phagocytes are also produced during adult hematopoiesis; these cells are then recruited to sites throughout the body, where they function in tissue repair and remodeling, resolution of inflammation, maintenance of homeostasis, and disease progression. The focus of this review is on mononuclear phagocytes that comprise the nonresident monocyte/macrophage populations in the body. Key features of monocyte differentiation are presented, focusing primarily on the developmental hierarchy that is established through this process, the markers used to identify discrete cell populations, and novel, functional attributes of these cells. These features are then explored in the context of the tumor microenvironment, where mononuclear phagocytes exhibit extensive plasticity in phenotype and function.

Hattermann K, Sebens S, Helm O, et al.
Chemokine expression profile of freshly isolated human glioblastoma-associated macrophages/microglia.
Oncol Rep. 2014; 32(1):270-6 [PubMed] Related Publications
Several studies have substantiated the hypothesis that tumor progression is not only driven by the tumor cells themselves but also by their interaction with intrinsic and surrounding stromal cells. Tumor-associated macrophages and microglial cells (TAMs) represent one major stromal cell component of glioblastomas. Additionally, in many gliomas, chemokines are highly expressed and some chemokines were already linked to settlement of TAMs in tumors. However, although chemoattraction mechanisms mediated by chemokines and their receptors are well documented, information on their expression and role in TAMs, particularly in patients, is limited. Therefore, we investigated the transcription of the chemokine-receptor combinations CXCL12-CXCR4-CXCR7, CXCL16-CXCR6 and CX3CL1-CX3CR1 in freshly isolated TAMs from 20 human glioblastomas in relation to in vitro polarized M1- and M2-macrophages. We demonstrated that TAMs express both M1- and M2-markers. Compared to in vitro polarized macrophages, the M1-marker interleukin (IL)-6 was similarly expressed, whereas IL-1β and tumor necrosis factor (TNF)-α were found at lower levels. The M2-marker IL-10 was comparably expressed, while CD163 and transforming growth factor (TGF)-β were detected with one tenth lower intensities in TAMs. All investigated chemokines/receptors were transcribed at moderate to high levels in TAMs as well as in vitro polarized macrophages. However, CX3CR1 was markedly higher and CXCR7 was somewhat higher expressed in TAMs, whereas M2-macrophages were characterized by the highest CXCL12 and a moderate CX3CL1 expression. Collectively, TAMs share properties of M1- and M2-macrophages and show a considerably higher expression of the chemokine receptors CXCR7 and CX3CR1.

Lv CY, Zhou T, Chen W, et al.
Preliminary study correlating CX3CL1/CX3CR1 expression with gastric carcinoma and gastric carcinoma perineural invasion.
World J Gastroenterol. 2014; 20(15):4428-32 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
AIM: To study the relationship between the CX3CL1 chemokine, its receptor CX3CR1, and gastric carcinoma/gastric carcinoma perineural invasion (PNI).
METHODS: Thirty cases of gastric carcinoma were surgically resected (radical resection or palliative resection) between February 2012 and July 2012. Tumour and tumour-adjacent tissues were evaluated for the presence of CX3CL1 (ELISA) and CX3CR1 (immunohistochemistry and Western blotting) in an effort to analyse the relationship between CX3CL1/CX3CR1 and gastric carcinoma/gastric carcinoma PNI.
RESULTS: Of these 30 cases, 14 were PNI-positive (46.7%). No significant differences in CX3CL and CX3CR1 expression in tumour-adjacent tissues were found between the PNI positive and negative groups. Expression levels of CX3CL and CX3CR1 in tumour tissues were significantly higher than those in adjacent tissues (P < 0.01), and were significantly higher in tumour tissues from the PNI-positive group compared to the PNI-negative group (P < 0.01).
CONCLUSION: CX3CL1/CX3CR1 expression may be associated with the occurrence and development of gastric carcinoma as well as gastric carcinoma PNI.

Zhu Y, Tang W, Liu Y, et al.
CCX-CKR expression in colorectal cancer and patient survival.
Int J Biol Markers. 2014 Jan-Mar; 29(1):e40-8 [PubMed] Related Publications
Colorectal cancer is one of the most common malignant cancers, with bad prognosis when distal metastasis occurs. The current study aimed to investigate the potential value of using CCX-CKR expression for the prognosis of colorectal cancer patients. The results showed that CCX-CKR expression was a negative predictor of cancer metastasis, and that it was positively correlated to the patients’ survival rate. Finally, we found that CCX-CKR expression in vitro could modulate cellular migration and invasion abilities, potentially via the regulation of other chemotactic factors/receptors.

Ren H, Zhao T, Sun J, et al.
The CX3CL1/CX3CR1 reprograms glucose metabolism through HIF-1 pathway in pancreatic adenocarcinoma.
J Cell Biochem. 2013; 114(11):2603-11 [PubMed] Related Publications
One of the hallmarks of cancer is revised glucose metabolism that promotes cell survival and proliferation. In pancreatic cancer, the regulatory mechanism of glucose metabolism remains to be elucidated. In this study, we found that CX3CR1 is expressed in pancreatic cancer cells lines. Exogenous or transfected CX3CL1 increased glucose uptake and lactate secretion. CX3CL1 stimulated HIF-1 expression through PI3K/Akt and MAPK pathways. Furthermore, knockdown of HIF-1 blocked CX3CL1-modified glucose metabolism in pancreatic adenocarcinoma cells. In conclusion, the CX3CL1/CX3CR1 reprograms glucose metabolism through HIF-1 pathway in pancreatic cancer cells.

Hattermann K, Li G, Hugo HH, et al.
Expression of the chemokines CXCL12 and CX3CL1 and their receptors in human nerve sheath tumors.
Histol Histopathol. 2013; 28(10):1337-49 [PubMed] Related Publications
Peripheral nerve sheath tumors are in most cases slowly growing neoplasms that can be adequately cured by surgical resection. However, facing the risk of a neurosurgical intervention and the trend of multiple relapses of nerve sheath tumors the development of additional therapy strategies seems to be favourable, and therefore substantiated knowledge of molecular and cellular mechanisms in nerve sheath tumors should be achieved. Here, we firstly describe the expression of the chemokines CXCL12 (SDF-1) and CX3CL1 (fractalkine) and their respective receptors CXCR4, CXCR7 and CX3CR1 in different entities of human nerve sheath tumors and normal control tissues. Both ligands and their receptors are expressed in high to moderate levels on mRNA and protein level in benign and malignant nerve sheath tumors. While CXCL12 was mainly found in schwannoma cells (S100⁺) in situ, its receptor CXCR4 is also partly found on CD11b-positive macrophages / microglia and its alternative receptor CXCR7 is also expressed by endothelial cells and macrophages. CX3CL1 is expressed by parts of the schwannoma and endothelial cells, whereas its receptor CX3CR1 is expressed by nearly all tumor cells and macrophages, but not by endothelial cells. Taken together, we could show the presence of CXCL12 and CX3CL1 and their respective receptors in benign and malignant human nerve sheath tumors. Further investigations may show their functional role in health and disease.

Courivaud C, Bamoulid J, Loupy A, et al.
Influence of fractalkine receptor gene polymorphisms V249I-T280M on cancer occurrence after renal transplantation.
Transplantation. 2013; 95(5):728-32 [PubMed] Related Publications
BACKGROUND: Fractalkine (CX3CL1) and its receptor (CX3CR1) are involved in antitumor immunity. Two common single nucleotide polymorphisms of the CX3CR1 gene, V249I and T280M, have been associated with reduced fractalkine signaling characterized by decreased adhesive function, signaling, and chemotaxis of leukocytes. We hypothesized that a renal transplant recipient (RTR) carrying the homozygous I249M280 genotype could experience more cancer due to lower CX3CL1-dependent antitumorigenic effects.
METHODS: We studied the association between these polymorphisms and cancer incidence in two independent cohorts of RTR, including a total of 622 patients.
RESULTS: The median follow-up was 8.7 and 7.9 years for the first and second cohorts, respectively. Analysis of 622 patients identified 20 (3.2%) I249M280 homozygous patients, 321 (51.6%) V249T280 homozygous patients, and 281 (45.2%) heterozygous patients. I249M280 homozygotes have an independent increased risk of cancer (hazard ratio [95% confidence interval], 3.3 [1.04-10.52], P=0.043 for cohort 1 and 9.2 [1.67-50.91], P=0.011 for cohort 2) compared with other patients. Age and male gender were also risk factors for cancer occurrence.
CONCLUSIONS: CX3CR1 gene polymorphism is associated with a higher rate of cancer in RTRs. Such findings may be used to influence immunosuppressive strategies and optimize patient management.

Zhao T, Gao S, Wang X, et al.
Hypoxia-inducible factor-1α regulates chemotactic migration of pancreatic ductal adenocarcinoma cells through directly transactivating the CX3CR1 gene.
PLoS One. 2012; 7(8):e43399 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
CX3CR1 is an important chemokine receptor and regulates the chemotactic migration of pancreatic ductal adenocarcinoma (PDAC) cells. Up to now, its regulatory mechanism remains largely undefined. Here, we report that hypoxia upregulates the expression of CX3CR1 in pancreatic cancer cells. When hypoxia-inducible factor (HIF)-1α expression was knocked down in vitro and in vivo, the expression of CX3CR1 was significantly decreased. Chromatin immunoprecipitation assay demonstrated that HIF-1α bound to the hypoxia-response element (HRE; 5'-A/GCGTG-3') of CX3CR1 promoter under normoxia, and this binding was significantly enhanced under hypoxia. Overexpression of HIF-1α significantly upregulated the expression of luciferase reporter gene under the control of the CX3CR1 promoter in pancreatic cancer cells. Importantly, we demonstrated that HIF-1α may regulate cancer cell migration through CX3CR1. The HIF-1α/CX3CR1 pathway might represent a valuable therapeutic target to prevent invasion and distant metastasis in PDAC.

Xiao LJ, Chen YY, Lin P, et al.
Hypoxia increases CX3CR1 expression via HIF-1 and NF‑κB in androgen-independent prostate cancer cells.
Int J Oncol. 2012; 41(5):1827-36 [PubMed] Related Publications
The unique CX3C chemokine CX3CL1 and its cognate receptor CX3CR1 have been implicated in organ-specific metastasis of various types of tumors. Hypoxia, a common phenomenon in solid tumors, is associated with a malignant cancer phenotype. Previous studies have proved that hypoxia facilitates cancer cell metastasis through upregulation of specific chemokine receptors. We hypothesized that hypoxia could upregulate CX3CR1 expression and lead to an increased chemotactic response to CX3CL1 in prostate cancer cells. In the present study, we found that CX3CR1 expression was significantly increased in androgen-independent prostate cancer cells, including DU145, PC-3 and PC-3M, following exposure to hypoxia. This upregulation of CX3CR1 corresponded to a significant increase in migration and invasion of prostate cancer cells under hypoxic conditions, which was attenuated after knocking down CX3CR1 expression. In addition, we examined the possible role of HIF-1 and NF-κB in the process of hypoxia-induced CX3CR1 expression and hypoxia-mediated metastasis. Attenuation of HIF-1 and NF-κB transcriptional activity by siRNAs or pharmacological inhibitors, abrogated hypoxia-induced upregulation of CX3CR1, and also prevented the migration and invasion of DU145 cells under a hypoxic environment. In summary, our study demonstrated that HIF-1 and NF-κB are essential for hypoxia-regulated CX3CR1 expression, which is associated with increased migratory and invasive potential of prostate cancer cells. CX3CR1 signaling is a potential therapeutic target in the adjuvant treatment of prostate cancer.

Kim M, Rooper L, Xie J, et al.
Fractalkine receptor CX(3)CR1 is expressed in epithelial ovarian carcinoma cells and required for motility and adhesion to peritoneal mesothelial cells.
Mol Cancer Res. 2012; 10(1):11-24 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Epithelial ovarian carcinoma (EOC) is a deadly disease, and little is known about the mechanisms underlying its metastatic progression. Using human specimens and established cell lines, we determined that the G-protein-coupled seven-transmembrane fractalkine receptor (CX(3)CR1) is expressed in primary and metastatic ovarian carcinoma cells. Ovarian carcinoma cells robustly migrated toward CX(3)CL1, a specific ligand of CX(3)CR1, in a CX(3)CR1-dependent manner. Silencing of CX(3)CR1 reduced migration toward human ovarian carcinoma ascites fluid by approximately 70%. Importantly, adhesion of ovarian carcinoma cells to human peritoneal mesothelial cells was dependent on CX(3)CL1/CX(3)CR1 signaling. In addition, CX(3)CL1 was able to induce cellular proliferation. Together, our data suggest that the fractalkine network may function as a major contributor to the progression of EOC, and further attention to its role in the metastasis of this deadly malignancy is warranted.

Eckl J, Buchner A, Prinz PU, et al.
Transcript signature predicts tissue NK cell content and defines renal cell carcinoma subgroups independent of TNM staging.
J Mol Med (Berl). 2012; 90(1):55-66 [PubMed] Related Publications
Clear cell renal cell carcinoma (ccRCC) is an aggressive and difficult to manage cancer. Immunotherapy has the potential to induce long-lasting regression in a small group of patients. However, severe side effects limit broad application which highlights the need for a marker to distinguish responder from nonresponder. TNMG staging, referring to tumor size, lymph node involvement, presence of metastasis, and grade of tumor differentiation, represents an important prognostic system but is not useful for predicting responders to immunotherapy. NK cells are potent antitumor effector cells, and a role as prognostic marker in some solid tumors has been suggested. As NK cells are responsive to various immune modifiers, they may be important mediators of patient response to immunotherapies, in particular those including IL-2. We report that the NK cell percentage within RCC-infiltrating lymphocytes, as determined by flow cytometry, allows ccRCC subgrouping in NK(high)/NK(low) tissues independent of TNMG classification. Quantitative reverse transcriptase polymerase chain reaction using whole-tissue RNA identified four markers (NKp46, perforin, CX(3)CL1, and CX(3)CR1) whose transcript levels reproduced the NK(high)/NK(low) tissue distinction identified by flow cytometry with high selectivity and specificity. Combined in a multiplex profile and analyzed using neural network, the accuracy of predicting the NK(high)/NK(low) groups was 87.8%, surpassing that of each single marker. The tissue transcript signature, based on a robust high-throughput methodology, is easily amenable to archive material and clinical translation. This now allows the analysis of large patient cohorts to substantiate a role of NK cells in cancer progression or response to immunotherapy.

Tsaur I, Noack A, Waaga-Gasser AM, et al.
Chemokines involved in tumor promotion and dissemination in patients with renal cell cancer.
Cancer Biomark. 2011; 10(5):195-204 [PubMed] Related Publications
BACKGROUND: Chemokines play a critical role in tumor initiation, progression, and metastasis and have been associated with poor prognosis in diverse malignancies. The prognostic impact of chemokines for renal cell cancer (RCC) remains to be defined.
METHODS: Patients diagnosed with RCC and operated between 07/07 and 05/11 were differentially assessed for expression profiles of a series of chemokines and their receptors by RT-qPCR and Western Blot analysis (tumor and adjacent normal tissue, n=37) and by Luminex for corresponding serum expression levels. Results were statistically correlated with clinicopathologic parameters.
RESULTS: Gene expression of CCL2, CCR7, CXCL12, CXCR3, CXCR5 and CX3CL1 chemokines was significantly down-regulated in tumor compared to normal tissue. The gene profile for CCR6 was positively correlated with tumor size and stage. A positive linear correlation was found between CXCL12 and tumor stage as well as between CX3CR1 and C-reactive protein. In contrast to clear cell RCCs those of a chromophobe type showed a significantly down-regulated gene expression for CCR6, CCL20, and CXCL12. The CXCR7 serum level was significantly increased in patients with tumor-related mortality during postoperative follow-up.
CONCLUSIONS: Chemokines may serve as novel diagnostic and prognostic biomarkers for RCC. Studies on larger collectives are required for further assessment of potential clinical application.

Gawron AJ, Fought AJ, Lissowska J, et al.
Polymorphisms in chemokine and receptor genes and gastric cancer risk and survival in a high risk Polish population.
Scand J Gastroenterol. 2011; 46(3):333-40 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
OBJECTIVE: To examine if genetic variations in chemokine receptor and ligand genes are associated with gastric cancer risk and survival.
METHODS: The study included 298 cases and 417 controls from a population-based study of gastric cancer conducted in Warsaw, Poland in 1994-1996. We investigated seven single nucleotide polymorphisms in a chemokine ligand (CXCL12) and chemokine receptor (CCR2, CCR5, CX3CR1) genes and one frameshift deletion (CCR5) in blood leukocyte DNA in relation to gastric cancer risk and survival. Genotyping was conducted at the NCI Core Genotyping Facility. Odds ratios and 95% confidence intervals were computed using univariate and multivariate logistic regression models. Survival analysis was performed using Cox proportional hazards models.
RESULTS: Gastric cancer risk was not associated with single chemokine polymorphisms. A CCR5 haplotype that contained the common alleles of IVS1+151 G>T (rs2734648), IVS2+80 C>T (rs1800024) and minor allele of IVS1+246 A>G (rs1799987) was associated with a borderline significantly increased risk (OR = 1.5, 95% CI: 1.0?2.2). For gastric cancer cases, there was a greater risk of death for carriers of the minor alleles of CCR2 Ex2+241 G>A (rs1799864) (HR = 1.5, 95% CI: 1.1-2.1) and CCR5 IVS2+80 C>T (rs1800024) (HR = 1.5, 95% CI: 1.1-2.1). Carriers of the CCR5 minor allele of IVS1+151 G>T (rs2734648) had a decreased risk of death compared to homozygote carriers of the common allele (HR = 0.8, 95% CI: 0.6-1.0).
CONCLUSIONS: Our findings do not support an association between gastric cancer risk and single chemokine genetic variation. The observed associations between cancer risk and a CCR5 haplotype and between survival and polymorphisms in CCR2 and CCR5 need replication in future studies.

Marchesi F, Locatelli M, Solinas G, et al.
Role of CX3CR1/CX3CL1 axis in primary and secondary involvement of the nervous system by cancer.
J Neuroimmunol. 2010; 224(1-2):39-44 [PubMed] Related Publications
CX3CL1 or Fractalkine is a peculiar chemokine that can exist either in a soluble form, like all the other chemokines, and as a cell membrane molecule. CX3CL1 is one of the most expressed chemokines in the central nervous system, where it regulates the communication between neurons, glia and microglia. CX3CR1-expressing microglia may have an important role in limiting tissue injury during inflammation and neuro-degeneration. Recent evidence has implicated CX3CL1 and its cognate receptor CX3CR1 in cancer. Tumors of neural origin (glioma, neuroblastoma) express CX3CR1 which is involved in the adhesion, transendothelial migration and mobilization of tumor cells. In addition, tumors of non-neural origin, like prostate, pancreas and breast carcinoma express high levels of the CX3CR1 receptor. As for other chemokine receptors, CX3CR1 expression is associated with increased migration and site specific dissemination. In pancreatic cancer, receptor expression is involved in the perineural invasion and dissemination of neoplastic cells along intra- and extra-pancreatic nerves. This peculiar route of tumor spread is used also by other carcinomas (e.g. prostate, head and neck) and may represent a target for therapeutic intervention.

Raynaud CM, Mercier O, Dartevelle P, et al.
Expression of chemokine receptor CCR6 as a molecular determinant of adrenal metastatic relapse in patients with primary lung cancer.
Clin Lung Cancer. 2010; 11(3):187-91 [PubMed] Related Publications
BACKGROUND: Recent studies suggest that chemokines are involved in organ-specific metastatic relapse. We evaluated the potential implications of chemokine receptors in the development of adrenal metastasis after complete resections of primary non-small-cell lung cancer.
PATIENTS AND METHODS: We studied a unique cohort of 21 primary lung cancers with matched adrenal metastases for the expression of CX3CR1, CXCR4, CCR6, and CCR7, using immunohistochemistry.
RESULTS: Although CXCR4, CX3CR1, and CCR7 were independently expressed in primary and corresponding metastases, CCR6 was clearly overexpressed in adrenal metastases, compared with corresponding primary tumors. Moreover, CCL20, the ligand of CCR6, was preferentially expressed in adrenal tissues that developed metastases.
CONCLUSION: We report for the first time (to the best of our knowledge) a potential role for the CCR6 receptor in the organ orientation of the development of metastases in lung cancer. We demonstrated a statistically significant overexpression of CCR6 in adrenal metastases compared with primary lung tumors, indicating that the increased production of CCL20 in adrenal glands might contribute to the selective recruitment of CCR6-expressing cancer cells in lung cancer. This study, in concordance with the data obtained in animal models, suggests that the chemokine receptor family constitutes a biologic support of the "seed and soil" theory.

Huang F, Geng XP
Chemokines and hepatocellular carcinoma.
World J Gastroenterol. 2010; 16(15):1832-6 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Chemokines play a paramount role in tumor progression. In hepatocellular carcinoma (HCC) progression, chemokines and their receptors play an intricate role. Currently, chemokines and their receptors such as the CXCL12-CXCR4 axis, CX3CL1-CX3CR1 axis and the CCL20-CCR6 axis have received much research attention. Although a large number of studies show that these axes are strongly associated with HCC, the exact mechanism by which these axes promote the growth and progression of HCC remains unknown. In this paper, several chemokines and their receptor interactions in HCC progression, growth and metastasis and immune response to HCC are reviewed.

Zeng XH, Ou ZL, Yu KD, et al.
Coexpression of atypical chemokine binders (ACBs) in breast cancer predicts better outcomes.
Breast Cancer Res Treat. 2011; 125(3):715-27 [PubMed] Related Publications
Some evidence suggests that atypical chemokine binders (ACBs) including DARC, D6, and CCX-CKR play an important role in inhibiting invasion and metastasis of cancer cells; however, their expression in breast cancer has not been well characterized. The purpose of this study was to determine the predictive value of ACBs for relapse-free survival and overall survival in breast cancer. The expressions of the three molecules were analyzed immunohistochemically in a total of 558 consecutive breast specimens comprising 12 normal breast tissues, 29 noninvasive (carcinoma in situ), and 517 invasive breast carcinoma and their relationships to clinicopathological features and survival were investigated in invasive breast cancer. Coexpression of ACBs in invasive breast carcinoma (55.9%) was much lower that of noninvasive breast carcinoma (93.1%) and normal breast tissue (100.0%), P = 0.0004, 0.0096, respectively. Their separate stainings in invasive cancer were significantly conversely correlated with lymph node status and tumor stage. In univariate analysis, the three proteins and their coexpression were significantly associated with higher relapse-free survival and overall survival. In multivariate analysis, each of these molecules was favorable for relapse-free survival, but not overall survival. Surprisingly, their coexpression was not only independently prognostic factor for relapse-free survival (RR = 0.182, 95% CI: 0.101-0.327, P < 0.001), but also for overall survival (RR = 0.271, 95% CI: 0.081-0.910, P = 0.035). These findings highlight that the multiple loss of ACBs may occur during the development of tumorigenesis and their coexpression in breast cancer is predictive of favorable outcomes.

Locatelli M, Boiocchi L, Ferrero S, et al.
Human glioma tumors express high levels of the chemokine receptor CX3CR1.
Eur Cytokine Netw. 2010; 21(1):27-33 [PubMed] Related Publications
The chemokine receptor CX3CR1 and its cognate ligand CX3CL1 (also known as fractalkine), are involved in central nervous system pathophysiology, in particular, in the cross-talk between neurons and microglia. It was therefore important to investigate the expression of CX3CR1 in gliomas, the most frequently occurring, malignant brain tumors. In a consecutive series of 70 patients with primary, central nervous glial tumors, CX3CR1 was highly expressed in tumor cells as assessed by RT-PCR mRNA and protein levels, and by immunohistochemistry, while the corresponding normal cells were negative. Receptor immuno-positivity did not correlate with histology, grade, chromosomal (1p,19q) deletion, or with methylation of the DNA repair gene promoter MGMT (O6-methylguanine-DNA methyltransferase). Thus, CX3CR1 expression is a frequent event in gliomas, irrespective of tumor classification and clinical severity. The molecular basis underlying CX3CR1 up-regulation and its functional biological significance remain to be determined.

Feng LY, Ou ZL, Wu FY, et al.
Involvement of a novel chemokine decoy receptor CCX-CKR in breast cancer growth, metastasis and patient survival.
Clin Cancer Res. 2009; 15(9):2962-70 [PubMed] Related Publications
PURPOSE: The biological axes of chemokines and chemokine receptors, such as CXCR4/CXCL12, CCR7/CCL19 (CCL21), CCR9/CCL25, and CXCR5/CXCL13, are involved in cancer growth and metastasis. This study is aimed at the potential regulatory role of atypical chemokine binder CCX-CKR, as a scavenger of CCL19, CCL21, CCL25, and CXCL13, in human breast cancer.
EXPERIMENTAL DESIGN: The role of CCX-CKR in human breast cancer was investigated in cell lines, animal models, and clinical samples.
RESULTS: Overexpression of CCX-CKR inhibited cancer cell proliferation and invasion in vitro and attenuated xenograft tumor growth and lung metastasis in vivo. CCX-CKR can be regulated by cytokines such as interleukin-1beta, tumor necrosis factor-alpha, and IFN-gamma. Lack or low expression of CCX-CKR correlated with a poor survival rate in the breast cancer patients. A significant correlation between CCX-CKR and lymph node metastasis was observed in human breast cancer tissues. CCX-CKR status was an independent prognostic factor for disease-free survival in breast cancer patients.
CONCLUSION: We showed for the first time that CCX-CKR is a negative regulator of growth and metastasis in breast cancer mainly by sequestration of homeostatic chemokines and subsequent inhibition of intratumoral neovascularity. This finding may lead to a new therapeutic strategy against breast cancer.

Iwakiri S, Mino N, Takahashi T, et al.
Higher expression of chemokine receptor CXCR7 is linked to early and metastatic recurrence in pathological stage I nonsmall cell lung cancer.
Cancer. 2009; 115(11):2580-93 [PubMed] Related Publications
BACKGROUND: The authors elucidated particular chemokine receptors that are expressed on lung cancer cells, as well as the clinical significance of the expression of these chemokine receptors in completely resected nonsmall cell lung cancer (NSCLC).
METHODS: The authors examined gene expression of chemokine receptors (CCR1-11, CXCR1-7, XCR1, and CX3CR1) in 11 cell lines of lung cancer, and gene expression of CXCR3, CXCR4, and CXCR7 (CXCR3/4/7) in surgical specimens of 127 patients who underwent complete resection for their NSCLC between May 2001 and December 2002, using quantitative real-time reverse transcriptase-polymerase chain reaction (PCR). Mutation detection analysis of the EGFR genes using the PCR single-strand conformational polymorphism method was evaluated in patients with pathological (p-) stage I adenocarcinoma.
RESULTS: Substantial expression of CXCR3/4/7 mRNA was observed in all NSCLC cell lines examined. In p-stage I NSCLC, CXCR4 and CXCR7 expression values in patients with postoperative metastatic recurrence (Rec-Distant) were significantly higher than in those without recurrences (P = .003 and P = .007, respectively). In addition, the 5-year disease-free survival (DFS) rate of high CXCR7-expressing patients (63.2%) was significantly lower than that of low CXCR7-expressing patients (84.8%) (P = .033). The EGFR mutation was significantly more frequent in patients with higher CXCR7 expression (14 of 21 patients) than in those with lower CXCR7 expression (12 of 32 patients) (P = .038). A multivariate analysis confirmed that high CXCR7 expression was an independent and significant factor predicting a poor DFS in p-stage I NSCLC patients (P = .041).
CONCLUSIONS: Higher expression of CXCR7 is associated with Rec-Distant and poor DFS in patients with p-stage I NSCLC.

Rodero M, Marie Y, Coudert M, et al.
Polymorphism in the microglial cell-mobilizing CX3CR1 gene is associated with survival in patients with glioblastoma.
J Clin Oncol. 2008; 26(36):5957-64 [PubMed] Related Publications
PURPOSE: Few reliable prognostic molecular markers have been characterized for glioblastoma multiforme (GBM), considered the deadliest of human cancers. We hypothesized that genetic polymorphisms in chemokines and their receptors, which together control microglial cell mobilization, may influence survival.
METHODS: Distributions of one polymorphism of the chemokine CCL2 (-2518ARESULTS: Survival analysis showed that the common CX3CR1-I249 allele was an independent favorable prognostic factor in both groups, prospective and retrospective, with hazard ratios of 0.619 (95% CI, 0.451 to 0.850; P = .0031) and 0.354 (95% CI, 0.217 to 0.580; P < .0001), respectively. This beneficial effect was observed only in patients who underwent surgery. Patients with only this CX3CR1-I249 allele had a substantially longer mean survival (23.5 v 14.1 months; P < .0001). The CCL2-2518G allele was not associated with patient survival. Immunohistochemical analysis of primary tumor biopsies showed that the common CX3CR1 variant allele was associated with reduced microglial cell infiltration.
CONCLUSION: The common CX3CR1 allelic variant was associated with increased GBM survival and with reduced tumor infiltration by microglia. The CX3CR1 polymorphism does not seem to be a risk factor for GBM but may prove useful in predicting survival.

Nevo I, Sagi-Assif O, Meshel T, et al.
The involvement of the fractalkine receptor in the transmigration of neuroblastoma cells through bone-marrow endothelial cells.
Cancer Lett. 2009; 273(1):127-39 [PubMed] Related Publications
Transendothelial migration (TEM) of tumor cells is a crucial step in metastasis formation. The prevailing paradigm is that the mechanism underlying TEM of tumor cells is similar to that of leukocytes involving adhesion molecules and chemokines. Fractalkine (CX3CL1) is a unique membrane-bound chemokine that functions also as an adhesion molecule. CX3CL1 can be cleaved to a soluble fragment, capable of attracting fractalkine receptor (CX3CR1)-expressing cells. In the present study, we asked if CX3CR1 is involved in the TEM of neuroblastoma cells. We demonstrated that biologically functional CX3CR1 is expressed by several neuroblastoma cell lines. Most importantly, CX3CR1-expressing neuroblastoma cells were stimulated by CX3CL1 to transmigrate through human bone-marrow endothelial cells. A dose dependent phosphorylation of ERK1/2 and AKT was induced in CX3CR1-expressing neuroblastoma cells by soluble CX3CL1. In addition to CX3CR1, neuroblastoma cells also express the CX3CL1 ligand. Membrane CX3CL1 expression was downregulated and the shedding of soluble CX3CL1 was upregulated by PKC activation. Taken together, the results of this study indicate that CX3CR1 plays a functional role in transmigration of neuroblastoma cells through bone-marrow endothelium. These results led us to hypothesize that the CX3CR1-CX3CL1 axis takes part in bone-marrow metastasis of neuroblastoma.

Andréasson U, Ek S, Merz H, et al.
B cell lymphomas express CX3CR1 a non-B cell lineage adhesion molecule.
Cancer Lett. 2008; 259(2):138-45 [PubMed] Related Publications
To study the differential expression of cell membrane-bound receptors and their potential role in growth and/or survival of the tumor cells, highly purified follicular lymphoma cells were analyzed, using gene expression analysis, and compared to non-malignant B cell populations. Filtering the genome for overexpressed genes coding for cell membrane-bound proteins/receptors resulted in a hit list of 27 identified genes. Among these, we have focused on the aberrant over expression of CX3CR1, in different types of B cell lymphoma, as compared to non-malignant B cells. We show that CX3CR1, which normally is not expressed on B cells, is expressed both at the mRNA and protein level in several subtypes of lymphoma. CX3CR1 has also shown to be involved in the homing to specific tissues that express the ligand, CX3CL1, in breast and prostate cancer and may thus be involved in dissemination of lymphoma.

Shimizu K, Karube K, Arakawa F, et al.
Upregulation of CC chemokine ligand 18 and downregulation of CX3C chemokine receptor 1 expression in human T-cell leukemia virus type 1-associated lymph node lesions: Results of chemokine and chemokine receptor DNA chip analysis.
Cancer Sci. 2007; 98(12):1875-80 [PubMed] Related Publications
Adult T-cell leukemia/lymphoma (ATLL) is a human malignancy associated with human T-cell leukemia virus type 1 (HTLV-1). The pathological features of the lymph nodes of ATLL change from those of lymphadenitis to Hodgkin's-like features and those of lymphoma. Chemokines and their receptors are closely associated with T-cell subgroups and immune responses. To clarify the relationship between chemokines and their receptor expression, as well as the development of ATLL, 17 cases with ATLL were analyzed using DNA chips of chemokines and their receptors. All cases showed a varied and mixed pattern of upregulated and downregulated gene expression of Th1, Th2, naïve, and cytotoxic cell-associated chemokine genes. As CC chemokine ligand 18 (CCL18) accounted for the most upregulated gene and CX3C chemokine receptor 1 (CX3CR1) for the most downregulated gene, they were selected for immunohistochemical analysis. Immunohistochemical staining showed expression of the two genes in immunological cells, with a positive expression for reticulum cells, but not for ATLL cells. HTLV-1-associated lymphadenitis type (n = 13) and Hodgkin's-like type (n = 12) cases showed significantly higher CCL18 expression than the non-specific lymphadenitis cases (n = 10) (P < 0.05). However, all HTLV-1-associated cases showed significantly lower CX3CR1 expression than the non-specific lymphadenitis cases (P < 0.05). These results suggest that upregulation of CCL18 expression and downregulation of CX3CR1 expression play a role in immune responses against the ATLL cells.

Dimberg J, Dienus O, Löfgren S, et al.
Polymorphisms of Fractalkine receptor CX3CR1 and plasma levels of its ligand CX3CL1 in colorectal cancer patients.
Int J Colorectal Dis. 2007; 22(10):1195-200 [PubMed] Related Publications
BACKGROUND AND AIMS: The chemokine Fractalkine/CX3CL1, which is expressed by epithelial cells within normal colorectal mucosa and in colorectal cancer (CRC), is thought to have a crucial role in colorectal mucosal immunity by recruiting leucocytes via the receptor CX3CR1. The purpose of this study was to investigate two single-nucleotide polymorphisms of the Fractalkine receptor/CX3CR1 gene, V249I and T280M, in CRC to find out whether they occur more often in patients with CRC than in non-CRC individuals. In the search for tumour markers, we also intended to determine whether plasma levels of Fractalkine were correlated with parameters such as Dukes' stage, tumour localisation, gender and age in CRC patients.
MATERIALS AND METHODS: Genomic deoxyribonucleic acid from 223 CRC patients and 229 controls was amplified by polymerase chain reaction, and the polymorphisms were detected by the restriction fragment length polymorphism analysis. Fractalkine/CX3CL1 was analysed in plasma from 62 CRC patients and 78 controls using enzyme-linked immunosorbent assay.
RESULTS: The variant V249I was significantly different in genotype and allelic distribution between CRC patients and control subjects, P = 0.028 and P = 0.048, respectively. We also found that individuals with the I249 allele in homozygote state were less frequent in the CRC group (3.1%) compared with controls (9.2%; P = 0.008). No significant difference was observed regarding Fractalkine/CX3CL1 levels in plasma between patients and the control group.
CONCLUSION: Our results suggest that the lack of the allele I249 of the CX3CR1 gene may play a partial or minor role in CRC and that plasma Fractalkine/CX3CL1 does not seem to be a useful tumour marker that reflects the disease outcome of CRC.

Baj-Krzyworzeka M, Szatanek R, Weglarczyk K, et al.
Tumour-derived microvesicles carry several surface determinants and mRNA of tumour cells and transfer some of these determinants to monocytes.
Cancer Immunol Immunother. 2006; 55(7):808-18 [PubMed] Related Publications
This study was designed to determine the characteristics of tumour cell-derived microvesicles (TMV) and their interactions with human monocytes. TMV were shed spontaneously by three different human cancer cell lines but their release was significantly increased upon activation of the cells with phorbol 12-myristate 13-acetate (PMA). TMV showed the presence of several surface determinants of tumour cells, e.g. HLA class I, CD29, CD44v7/8, CD51, chemokine receptors (CCR6, CX3CR1), extracellular matrix metalloproteinase inducer (EMMPRIN), epithelial cell adhesion molecule (EpCAM), but their level of expression differed from that on cells they originated from. TMV also carried mRNA for growth factors: vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), interleukin-8 (IL-8) and surface determinants (CD44H). TMV were localized at the monocytes surface following their short exposure to TMV, while at later times intracellularly. TMV transferred CCR6 and CD44v7/8 to monocytes, exerted antiapoptotic effect on monocytes and activated AKT kinase (Protein Kinase B). Thus, TMV interact with monocytes, alter their immunophenotype and biological activity. This implicates the novel mechanism by which tumour infiltrating macrophages may be affected by tumour cells not only by a direct cell to cell contact, soluble factors but also by TMV.

Stievano L, Piovan E, Amadori A
C and CX3C chemokines: cell sources and physiopathological implications.
Crit Rev Immunol. 2004; 24(3):205-28 [PubMed] Related Publications
Within the fascinating world of chemokines, C and CX3C chemokines have long been regarded as two minor components, even though they present unique features and show less redundancy than the other chemokine families. Nevertheless, the body of data on their expression and role in various inflammatory disorders has grown in the past few years. The C chemokine family is represented by two chemokines, XCL1/lymphotactin-alpha and XCL2/lymphotactin-beta, whereas the CX3C chemokine family contains only one member, called CX3CL1/ fractalkine. In this review, we present an overview on the structure, expression and signaling properties of these chemokines and their respective receptors and examine how they contribute to inflammation and the regulation of leukocyte trafficking, as well as their potential role in the pathophysiology of human inflammatory diseases. Taken together, these data expand the biological importance of C and CX3C chemokines from that of simple immune modulators to a much broader biological role, even though their precise commitment within the framework of immune responses has still to be determined.

Ferrer A, Ollila J, Tobin G, et al.
Different gene expression in immunoglobulin-mutated and immunoglobulin-unmutated forms of chronic lymphocytic leukemia.
Cancer Genet Cytogenet. 2004; 153(1):69-72 [PubMed] Related Publications
The mutation status of the immunoglobulin heavy chain variable regions (IgVH) has been found to be a good prognostic indicator for B-cell chronic lymphocytic leukemia (CLL) because unmutated VH genes are associated with rapid disease progression and shorter survival time. To study the differences in gene expression between the Ig-unmutated and Ig-mutated CLL subtypes, we performed gene expression profiling on 31 CLL cases and investigated the VH gene mutation status by sequencing. The array data showed that the greatest variances between the unmutated (20 cases) and the mutated (11 cases) group were in expressions of ZAP70, RAF1, PAX5, TCF1, CD44, SF1, S100A12, NUP214, DAF, GLVR1, MKK6, AF4, CX3CR1, NAFTC1, and HEX. ZAP70 was significantly more expressed in the Ig-unmutated CLL group, whereas the expression of all the other genes was higher in the Ig-mutated cases. These results corroborate a recent finding, according to which the expression of ZAP70 can predict the VH mutation status and suggest that RAF1, PAX5, and other differentially expressed genes may offer good markers for differentiating unmutated cases from mutated cases and thus serve as prognostic markers.

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