Nuclear expression of CXCR4 in tumor cells of non-small cell lung cancer is correlated with lymph node metastasis

Intracellular and nuclear CXCR4 signaling promotes terminal erythroblast differentiation and enucleation

The chemokine CXCL12 signals through its receptor CXCR4 to induce the migration of all leukocyte types and multiple other cell types. Here, we report that CXCR4 is expressed in mouse erythroblasts, the bone marrow erythroid precursors, in which it stimulates erythrocyte generation instead of chemotaxis. CXCR4 signaling promoted homeostatic erythroblast maturation and increased the expression of genes mainly involved in metabolism and chromatin organization. Consequently, genetic depletion of CXCR4 in erythroblasts inhibited late erythropoiesis and diminished bone marrow erythroid outputs. Binding of CXCL12 to CXCR4 stimulated its rapid endocytosis and translocation together with Gαi or phosphorylated β-arrestin1 into distinct intracellular compartments, including the nuclear envelope and nucleus. CXCL12 signaling promoted erythroblast elongation and the condensation and excentric positioning of nuclei and stimulated rapid perinuclear Ca2+ transients that immediately preceded erythroblast enucleation. These findings highlight previously uncharacterized physiological roles for CXCR4 and bone marrow-derived CXCL12 in erythropoiesis.

Tissue inhibitor of metalloproteinase 1 as a biomarker of venous invasion in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with a poor prognosis. While venous invasion is believed to contribute to liver metastasis and an unfavorable prognosis, the precise mechanisms involved remain unclear. Here, we conducted gene expression profiling on eight PDAC tissue samples exhibiting portal venous invasion (VI group) compared to PDAC samples without portal venous invasion (CA group) and normal portal vein tissues (NV group). A subset of genes, including tissue inhibitor of metalloproteinase 1 (TIMP1), C-X-C motif chemokine receptor 4 (CXCR4), olfactomedin-like 2B (OLFML2B), and cytochrome P450 family 1 subfamily B member 1 (CYP1B1), was found to be specifically expressed in the PDAC group with venous invasion. Immunohistochemical staining of 15 cases revealed significantly higher levels of TIMP1 (P=.026) and CXCR4 (P<.001) in the VI set compared to the CA set. In addition, the PDAC group with strong TIMP1 expression had a higher frequency of lymphovascular invasion (P<.001) and lower 5-year survival rates than the PDAC group with no/weak TIMP1 expression (P=.027). Specific TIMP1 expression in the venous invasion foci was highlighted on 3D reconstruction imaging. Invasion assays and/or Western blot analyses were performed on pancreatic cancer cells (Panc1), cancer-associated fibroblasts (CAFs), and human endothelial cells (EA.hy926). TIMP1 inhibition suppressed cancer cell invasion in the presence of CAFs. TIMP1 expression increased with PI3Kp110, phospho-AKT, and phospho-ERK1/2 in Panc1 cells co-cultured with CAFs and EA.hy926 endothelial cells. Our data demonstrate that TIMP1 in pancreatic cancer cells promotes venous invasion of PDACs by activating the PI3K/AKT and ERK1/2 pathways in collaboration with CAFs and endothelial cells. Therefore, TIMP1 may serve as a biomarker for venous invasion in PDACs.

Understanding the impact of nuclear-localized GPCRs on cellular signalling

G protein-coupled receptors (GPCRs) have historically been associated with signalling events driven from the plasma membrane. More recently, signalling from endosomes has been recognized as a feature of internalizing receptors. However, there was little consideration given to the notion that GPCRs can be targeted to distinct subcellular locations that did not involve an initial trafficking to the cell surface. Here, we focus on the evidence for and the potential impact of GPCR signalling specifically initiated from the nuclear membrane. We also discuss the possibilities for selectively targeting this and other internal pools of receptors as novel venues for drug discovery.

Cancer-Associated-Fibroblast-Mediated Paracrine and Autocrine SDF-1/CXCR4 Signaling Promotes Stemness and Aggressiveness of Colorectal Cancers

Colorectal cancer (CRC) is a leading cause of cancer mortality worldwide, and cancer-associated fibroblasts (CAFs) play a major role in the tumor microenvironment (TME), which facilitates the progression of CRC. It is critical to understand how CAFs promote the progression of CRC for the development of novel therapeutic approaches. The purpose of this study was to understand how CAF-derived stromal-derived factor-1 (SDF-1) and its interactions with the corresponding C-X-C motif chemokine receptor 4 (CXCR4) promote CRC progression. Our study focused on their roles in promoting tumor cell migration and invasion and their effects on the characteristics of cancer stem cells (CSCs), which ultimately impact patient outcomes. Here, using in vivo approaches and clinical histological samples, we analyzed the influence of secreted SDF-1 on CRC progression, especially in terms of tumor cell behavior and stemness. We demonstrated that CAF-secreted SDF-1 significantly enhanced CRC cell migration and invasion through paracrine signaling. In addition, the overexpression of SDF-1 in CRC cell lines HT29 and HCT-116 triggered these cells to generate autocrine SDF-1 signaling, which further enhanced their CSC characteristics, including those of migration, invasion, and spheroid formation. An immunohistochemical study showed a close relationship between SDF-1 and CXCR4 expression in CRC tissue, and this significantly affected patient outcomes. The administration of AMD3100, an inhibitor of CXCR4, reversed the entire phenomenon. Our results strongly suggest that targeting this signaling axis in CRC is a feasible approach to attenuating tumor progression, and it may, therefore, serve as an alternative treatment method to improve the prognosis of patients with CRC, especially those with advanced, recurrent, or metastatic CRC following standard therapy.

Demystifying the CXCR4 conundrum in cancer biology: Beyond the surface signaling paradigm

The oncogenic chemokine duo CXCR4-CXCL12/SDF-1 (C-X-C Receptor 4-C-X-C Ligand 12/ Stromal-derived factor 1) has been the topic of intense scientific disquisitions since Muller et al., in her ground-breaking research, described this axis as a critical determinant of organ-specific metastasis in breast cancer. Elevated CXCR4 levels correlate with distant metastases, poor prognosis, and unfavourable outcomes in most solid tumors. Therapeutic impediment of the axis in clinics with Food and Drug Administration (FDA) approved inhibitors like AMD3100 or Plerixafor yield dubious results, contrary to pre-clinical developments. Clinical trials entailing inhibition of CXCR7 (C-X-C Receptor 7), another convicted chemokine receptor that exhibits affinity for CXCL12, reveal outcomes analogous to that of CXCR4-CXCL12 axis blockade. Of note, the cellular CXCR4 knockout phenotype varies largely from that of inhibitor treatments. These shaky findings pique great curiosity to delve further into the realm of this infamous chemokine receptor to provide a probable explanation. A multitude of recent reports suggests the presence of an increased intracellular CXCR4 pool in various cancers, both cytoplasmic and nuclear. This intracellular CXCR4 protein reserve seems active as it correlates with vital tumor attributes, viz. prognosis, aggressiveness, metastasis, and disease-free survival. Diminishing this entire intracellular CXCR4 load apart from the surface signals looks encouraging from a therapeutic point of view. Transcending beyond the classically accepted concept of ligand-mediated surface signaling, this review sheds new light on plausible associations of intracellularly compartmentalised CXCR4 with various aspects of tumorigenesis. Besides, this review also puts forward a comprehensive account of CXCR4 regulation in different cancers.

The clinicopathological and prognostic value of CXCR4 expression in patients with lung cancer: a meta-analysis

Background

The C-X-C chemokine receptor 4 (CXCR4) has been suggested to play an important role in several types of cancers and is related to biological behaviors connected with tumor progression. However, the clinical significance and application of CXCR4 in lung cancer remain disputable. Thus, we conducted a meta-analysis to investigate the impact of CXCR4 expression on survival and clinicopathological features in lung cancer.

Methods

Comprehensive literature searches were conducted in PubMed, Embase and Web of Science for relevant studies. We pooled hazard ratios (HRs)/odds ratios (ORs) with 95% confidence intervals (CIs) by STATA 12.0 to evaluate the potential value of CXCR4 expression.

Results

Twenty-seven relevant articles involving 2932 patients with lung cancer were included in our meta-analysis. The results revealed that CXCR4 expression was apparently associated with poor overall survival (OS) (HR 1.61, 95% CI 1.42–1.82) and disease-free survival (HR 3.39, 95% CI 2.38–4.83). Furthermore, a significant correlation with poor OS was obvious in non-small cell lung cancer patients (HR 1.59, 95% CI 1.40–1.81) and in patients showing CXCR4 expression in the cytoplasm (HR 2.10, 95% CI 1.55–2.84) and the membrane (HR 1.74, 95% CI 1.24–2.45). CXCR4 expression was significantly associated with men (OR 1.32, 95% CI 1.08–1.61), advanced tumor stages (T3-T4) (OR 2.34, 95% CI 1.28–4.28), advanced nodal stages (N > 0) (OR 2.34, 95% CI 1.90–2.90), distant metastasis (OR 3.65, 95% CI 1.53–8.69), advanced TNM stages (TNM stages III, IV) (OR 3.10, 95% CI 1.95–4.93) and epidermal growth factor receptor (EGFR) expression (OR 2.44, 95% CI 1.44–4.12) but was not associated with age, smoking history, histopathology, differentiation, lymphatic vessel invasion or local recurrence.

Conclusion

High expression of CXCR4 is related to tumor progression and might be an adverse prognostic factor for lung cancer.

Insights into Nuclear G-Protein-Coupled Receptors as Therapeutic Targets in Non-Communicable Diseases

G-protein-coupled receptors (GPCRs) comprise a large protein superfamily divided into six classes, rhodopsin-like (A), secretin receptor family (B), metabotropic glutamate (C), fungal mating pheromone receptors (D), cyclic AMP receptors (E) and frizzled (F). Until recently, GPCRs signaling was thought to emanate exclusively from the plasma membrane as a response to extracellular stimuli but several studies have challenged this view demonstrating that GPCRs can be present in intracellular localizations, including in the nuclei. A renewed interest in GPCR receptors' superfamily emerged and intensive research occurred over recent decades, particularly regarding class A GPCRs, but some class B and C have also been explored. Nuclear GPCRs proved to be functional and capable of triggering identical and/or distinct signaling pathways associated with their counterparts on the cell surface bringing new insights into the relevance of nuclear GPCRs and highlighting the nucleus as an autonomous signaling organelle (triggered by GPCRs). Nuclear GPCRs are involved in physiological (namely cell proliferation, transcription, angiogenesis and survival) and disease processes (cancer, cardiovascular diseases, etc.). In this review we summarize emerging evidence on nuclear GPCRs expression/function (with some nuclear GPCRs evidencing atypical/disruptive signaling pathways) in non-communicable disease, thus, bringing nuclear GPCRs as targets to the forefront of debate.

Clinical association of CXCR4 in primary tumor of papillary thyroid cancer and response to iodine-131 treatment

OBJECT

Papillary thyroid cancer (PTC) has an excellent prognosis. However, patients with such, if refract to radioiodine treatment, increase recurrent and mortality rates. Tumor aggressiveness in primary tumor of PTC expresses CXCR4 chemokine receptor. Thus, CXCR4 expression of the tumor may predict response to radioiodine treatment.

MATERIALS AND METHODS

Retrospective review of seventy-four PTC patients, treated with total/near-total thyroidectomy and radioiodine treatment at King Chulalongkorn Memorial Hospital from January 2007 to 2013, were classified as non-radioiodine-refractory (non-RAIR) or RAIR treatment response. All histopathologic diagnoses were reviewed and paraffin blocks were retrieved for CXCR4 immunostaining, determined by automated digital imaging analysis for intensity and extension. The scores were compared between primary tumour and adjacent normal thyroid tissue as well as between the tissue of non-RAIR and that of RAIR. Factors determining type of RAI response were analyzed.

RESULTS

CXCR4 immunostaining scores of PTC is significantly higher than normal thyroid [2.03 (0.52) and 1.48 (0.75)] [mean (SD)] (P = 0.0001). CXCR4 immunostaining scores in RAIR are potentially higher than non-RAIR [1.95 (0.54) and 2.13 (0.47) (P = 0.149)]. Odds ratio of CXCR4 immunostaining score for predicting RAIR treatment is 1.99 (P = 0.150). CXCR4 immunostaining scores positively associate with tumor size (R = 0.298, P = 0.01); whereas no significant association with other clinicopathologic factors.

CONCLUSION

Our data support the notion that CXCR4 are significantly expressed in PTC tumor over normal thyroid tissues. However, there is no clinical association with radioiodine treatment response.

Neural crest cell-derived pericytes act as pro-angiogenic cells in human neocortex development and gliomas

Central nervous system diseases involving the parenchymal microvessels are frequently associated with a ‘microvasculopathy’, which includes different levels of neurovascular unit (NVU) dysfunction, including blood–brain barrier alterations. To contribute to the understanding of NVU responses to pathological noxae, we have focused on one of its cellular components, the microvascular pericytes, highlighting unique features of brain pericytes with the aid of the analyses carried out during vascularization of human developing neocortex and in human gliomas. Thanks to their position, centred within the endothelial/glial partition of the vessel basal lamina and therefore inserted between endothelial cells and the perivascular and vessel-associated components (astrocytes, oligodendrocyte precursor cells (OPCs)/NG2-glia, microglia, macrophages, nerve terminals), pericytes fulfil a central role within the microvessel NVU. Indeed, at this critical site, pericytes have a number of direct and extracellular matrix molecule- and soluble factor-mediated functions, displaying marked phenotypical and functional heterogeneity and carrying out multitasking services. This pericytes heterogeneity is primarily linked to their position in specific tissue and organ microenvironments and, most importantly, to their ontogeny. During ontogenesis, pericyte subtypes belong to two main embryonic germ layers, mesoderm and (neuro)ectoderm, and are therefore expected to be found in organs ontogenetically different, nonetheless, pericytes of different origin may converge and colonize neighbouring areas of the same organ/apparatus. Here, we provide a brief overview of the unusual roles played by forebrain pericytes in the processes of angiogenesis and barriergenesis by virtue of their origin from midbrain neural crest stem cells. A better knowledge of the ontogenetic subpopulations may support the understanding of specific interactions and mechanisms involved in pericyte function/dysfunction, including normal and pathological angiogenesis, thereby offering an alternative perspective on cell subtype-specific therapeutic approaches.

Neural crest cell-derived pericytes act as pro-angiogenic cells in human neocortex development and gliomas

Central nervous system diseases involving the parenchymal microvessels are frequently associated with a ‘microvasculopathy’, which includes different levels of neurovascular unit (NVU) dysfunction, including blood–brain barrier alterations. To contribute to the understanding of NVU responses to pathological noxae, we have focused on one of its cellular components, the microvascular pericytes, highlighting unique features of brain pericytes with the aid of the analyses carried out during vascularization of human developing neocortex and in human gliomas. Thanks to their position, centred within the endothelial/glial partition of the vessel basal lamina and therefore inserted between endothelial cells and the perivascular and vessel-associated components (astrocytes, oligodendrocyte precursor cells (OPCs)/NG2-glia, microglia, macrophages, nerve terminals), pericytes fulfil a central role within the microvessel NVU. Indeed, at this critical site, pericytes have a number of direct and extracellular matrix molecule- and soluble factor-mediated functions, displaying marked phenotypical and functional heterogeneity and carrying out multitasking services. This pericytes heterogeneity is primarily linked to their position in specific tissue and organ microenvironments and, most importantly, to their ontogeny. During ontogenesis, pericyte subtypes belong to two main embryonic germ layers, mesoderm and (neuro)ectoderm, and are therefore expected to be found in organs ontogenetically different, nonetheless, pericytes of different origin may converge and colonize neighbouring areas of the same organ/apparatus. Here, we provide a brief overview of the unusual roles played by forebrain pericytes in the processes of angiogenesis and barriergenesis by virtue of their origin from midbrain neural crest stem cells. A better knowledge of the ontogenetic subpopulations may support the understanding of specific interactions and mechanisms involved in pericyte function/dysfunction, including normal and pathological angiogenesis, thereby offering an alternative perspective on cell subtype-specific therapeutic approaches.

CXCR4 expression in lung carcinogenesis: Evaluating gender-specific differences in survival outcomes based on CXCR4 expression in early stage non-small cell lung cancer patients

INTRODUCTION

Evidence suggests that the expression of certain cytokine receptors increases with lung cancer evolution. Overexpression of the cytokine receptor CXCR4 is associated with poor outcomes in stage IV non-small cell lung cancer (NSCLC), with shorter survival in females with high CXCR4 expression. This study quantifies CXCR4 expression in early stage disease and evaluates its association with gender-specific recurrence-free (RFS) and overall survival (OS) in resected stage I-III NSCLC patients.

METHODS

Patient characteristics and clinical outcomes were obtained from the Glans-Look Lung Cancer (G-LLC) database for early stage NSCLC patients diagnosed between 2003-2006 at the Tom Baker Cancer Centre (TBCC). CXCR4 expression was quantified on tissue microarrays (TMA). Median RFS and OS were evaluated by gender using Kaplan-Meier analyses. CXCR4 expression and outcome data were analyzed using Cox proportional hazards (PH) and multi-state models (MSM).

RESULTS

176 stage I-III NSCLC patients were identified. CXCR4 expression was lower in early stage NSCLC patients, with a mean CXCR4 expression of 1729 (SD 1083) compared to 2640 (SD 1541) in stage IV patients. On Kaplan-Meier, median RFS by gender was similar (male 52.8 months vs. female 54.5 months) as was median OS (male 80.9 months vs. female 89.0 months), and there was no significant difference in RFS (p = 0.60) or OS (p = 0.30) by gender and CXCR4 groups over follow-up. By multivariable analysis, CXCR4 expression was not prognostic for RFS (Hazard Ratio (HR) = 1.00, p = 0.73) or OS (HR = 1.00, p = 0.44), and no gender difference was observed.

CONCLUSIONS

CXCR4 expression increases with stage progression in NSCLC but is not prognostic in early stage NSCLC patients of either gender. Mechanisms by which CXCR4 expression increases during lung carcinogenesis warrant further exploration and testing in clinical trials.

HC-HA/PTX3 from amniotic membrane reverts senescent limbal niche cells to Pax6+ neural crest progenitors to support limbal epithelial progenitors

Quiescence and self‐renewal of human corneal epithelial progenitor/stem cells (LEPC) are regulated by the limbal niche, presumably through close interaction with limbal (stromal) niche cells (LNC). Paired box homeotic gene 6 (Pax6), a conserved transcription factor essential for eye development, is essential for proper differentiation of limbal and corneal epithelial stem cells. Pax6 haploinsufficiency causes limbal stem cell deficiency, which leads to subsequent corneal blindness. We previously reported that serial passage of nuclear Pax6+ LNC resulted in the gradual loss of nuclear Pax6+ and neural crest progenitor status, the latter of which was reverted upon recovery of Pax6. These findings suggest Pax6 plays a pivotal role in supporting the self‐renewal of LEPC in limbal niche. Herein, we show that HC‐HA/PTX3, a unique matrix purified from amniotic membrane (AM) and consists of heavy chain 1of inter‐α‐trypsin inhibitor covalently linked to hyaluronic acid and complexed with pentraxin 3, is capable of reverting senescent LNC to nuclear Pax6+ neural crest progenitors that support self‐renewal of LEPC. Such reversion is causally linked to early cell aggregation mediated by activation of C‐X‐C chemokine receptor type 4 (CXCR4)‐mediated signaling followed by activation of bone morphogenetic protein (BMP) signaling. Furthermore, CXCR4‐mediated signaling, but not BMP signaling, controls recovery of the nuclear Pax6+ neural crest progenitors. These findings not only explain why AM helps in vivo and ex vivo expansion of human LEPC, but they also illuminate the potential role of HC‐HA/PTX3 as a surrogate matrix niche that complements stem cell‐based therapies in regenerative medicine.

β-arrestin mediates communication between plasma membrane and intracellular GPCRs to regulate signaling

It has become increasingly apparent that G protein-coupled receptor (GPCR) localization is a master regulator of cell signaling. However, the molecular mechanisms involved in this process are not well understood. To date, observations of intracellular GPCR activation can be organized into two categories: a dependence on OCT3 cationic channel-permeable ligands or the necessity of endocytic trafficking. Using CXC chemokine receptor 4 (CXCR4) as a model, we identified a third mechanism of intracellular GPCR signaling. We show that independent of membrane permeable ligands and endocytosis, upon stimulation, plasma membrane and internal pools of CXCR4 are post-translationally modified and collectively regulate EGR1 transcription. We found that β-arrestin-1 (arrestin 2) is necessary to mediate communication between plasma membrane and internal pools of CXCR4. Notably, these observations may explain that while CXCR4 overexpression is highly correlated with cancer metastasis and mortality, plasma membrane localization is not. Together these data support a model where a small initial pool of plasma membrane-localized GPCRs are capable of activating internal receptor-dependent signaling events.

DeNies et al. identify a new mechanism of intracellular GPCR signalling. Using CXC chemokine receptor 4 (CXCR4) as a model, they show that upon stimulation with receptor agonists that not only plasma membrane-localized receptors, but also intracellular CXCR4 molecules are post-translationally modified and regulate transcription. This study suggests that a small pool of plasma membrane-localized GPCRs can activate internal receptor-dependent signaling, and that β-arrestin-1 mediates this activation.

HC-HA/PTX3 Purified From Human Amniotic Membrane Reverts Human Corneal Fibroblasts and Myofibroblasts to Keratocytes by Activating BMP Signaling

Purpose

Fibrosis or scarring is a pathological outcome of wound healing and is characterized by terminally differentiated myofibroblasts. Heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) is a unique matrix component purified from amniotic membrane that exerts an anti-inflammatory effect. Herein, we investigate whether HC-HA/PTX3 can also exert an antiscarring effect.

Methods

Human corneal fibroblasts and myofibroblasts were seeded on plastic, immobilized HA or HC-HA/PTX3 or on plastic with or without soluble HA and HC-HA/PTX3 in DMEM+10% FBS, with or without AMD3100 or SB431542 in DMEM+ITS with or without transforming growth factor–β1 (TGF-β1). Transcript expression of keratocyte and signaling markers was determined by RT-qPCR. Immunostaining was performed to monitor cytolocalization of signaling markers and α-SMA. Western blotting was used to measure relative protein level.

Results

Human corneal fibroblasts and myofibroblasts cultured in or on HC-HA/PTX3, but not HA, were refrained from cytoplasmic expression of αSMA and nuclear translocation of pSMAD2/3 when challenged with exogenous TGF-β1. Such an antiscarring action by suppressing canonical TGF-β1 signaling was surprisingly accompanied by phenotypic reversal to keratocan-expressing keratocytes through activation of BMP signaling. Further investigation disclosed that such phenotypic reversal was initiated by cell aggregation mediated by SDF1-CXCR4 signaling highlighted by nuclear translocation of CXCR4 and upregulation of CXCR4 transcript and protein followed by activation of canonical BMP signaling.

Conclusions

These findings collectively provide mechanistic understanding explaining how amniotic membrane transplantation exerts an antiscarring action. In addition, HC-HA/PTX3 and derivatives may be developed into a new biologic to treat corneal blindness caused by stromal scar or opacity in the future.

Chemokines and their receptors as biomarkers in esophageal cancer

Esophageal cancer (EC) is one of the most lethal malignancies of the digestive tract and remains to be improved poor prognosis. Two histological subtypes, esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC), are major characteristics of EC. Deep understanding about both subtypes is essential to overcome EC. Here, we focus on chemokines and their receptors as biomarkers and their current applications for the prognosis in EC. We reviewed relevant articles identified using PubMed database for the chemokines and their receptors in EC analyzed by immunohistochemistry. The primary objective is to summarize evidences for them as prognostic biomarkers in EC. A total of twenty-one articles were reviewed after exclusion. Most studies have been done in ESCC, and less in EAC. CXCL12 and its receptor CXCR4 have been shown in both subtypes as biomarkers. CXCR7, CXCL8 and its receptor CXCR2, and CCL21 and its receptor CCR7 have been examined in ESCC. Although it was a small number of reports, CXCL10, CCL4, and CCL5 have been indicated to have anti-tumor effects in ESCC. Chemokines and their receptors have the potential to be the biomarkers in EC. Comparative studies between ESCC and EAC will reveal the similarity and difference in these two subtypes of EC. These studies may indicate whether these molecules play important roles in both subtypes or are unique to one or another.

Identification of differentially expressed genes between primary lung cancer and lymph node metastasis via bioinformatic analysis

Lung cancer (LC), with its high morbidity and mortality rates, is one of the most widespread and malignant neoplasms. Mediastinal lymph node metastasis (MLNM) severely affects postoperative survival of patients with LC. Additionally, the molecular mechanisms of LC with MLNM (MM LC) remain not well understood. To identify the key biomarkers in its carcinogenesis and development, the datasets GSE23822 and GSE13213 were obtained from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were identified, and the Database for Annotation, Visualization and Integrated Discovery was used to perform functional annotations of DEGs. Search Tool for the Retrieval of Interacting Genes and Cytoscape were utilized to obtain the protein-protein interaction (PPI) network, and to analyze the most significant module. Subsequently, a Kaplan-Meier plotter was used to analyze overall survival (OS). Additionally, one co-expression network of the hub genes was obtained from cBioPortal. A total of 308 DEGs were identified in the two microarray datasets, which were mainly enriched during cellular processes, including the Gene Ontology terms ‘cell’, ‘catalytic activity’, ‘molecular function regulator’, ‘signal transducer activity’ and ‘binding’. The PPI network was composed of 315 edges and 167 nodes. Its significant module had 11 hub genes, and high expression of actin β, MYC, arginine vasopressin, vesicle associated membrane protein 2 and integrin subunit β1, and low expression of NOTCH1, synaptojanin 2 and intersectin 2 were significantly associated with poor OS. In summary, hub genes and DEGs presented in the present study may help identify underlying targets for diagnostic and therapeutic methods for MM LC.

Somatostatin and CXCR4 expression patterns in adenocarcinoma and squamous cell carcinoma of the lung relative to small cell lung cancer

PURPOSE

Lung cancer is highly prevalent and has an especially poor prognosis. Thus, new diagnostic and therapeutic targets are necessary. Two potential targets are somatostatin receptors (SST), which are overexpressed in well-differentiated neuroendocrine neoplasms, and the chemokine receptor CXCR4, which is present mainly in highly proliferative and advanced tumours. Although their expression is relatively well characterized in small cell lung cancer (SCLC), in non-small cell lung cancer (NSCLC), data on SST and CXCR4 expression are scarce and contradictory.

METHODS

We comparatively evaluated 83 tumour samples from a total of 57 lung cancer patients, of which 22 had adenocarcinoma (ADC), 21 had squamous cell carcinoma (SQC), and 15 had SCLC. Samples were evaluated for SST and CXCR4 expression using immunohistochemistry with well-characterized rabbit monoclonal antibodies.

RESULTS

In the samples investigated, the most prominently expressed receptors were CXCR4 and SST5. Specifically, CXCR4 was detected with high expression intensity in more than 60% of ADC samples, about 90% of SQC, and 100% of SCLC. SST5 was present in about 75% of ADC and SQC samples and in more than 90% of SCLC. Although not noticeably expressed in ADC and SQC samples, SST2 was detected in 50% of SCLC cases, with a subset of patients displaying exceptionally high expression. The comparison of the three tumour entities revealed that SCLC samples had higher SST2, SST5, and CXCR4 expression, but lower SST3 and SST1 relative to ADC or SQC samples.

CONCLUSION

CXCR4 may be a promising target for diagnostics and therapy in both SCLC and NSCLC.

Estrogen induces CXCR4 overexpression and CXCR4/CXL12 pathway activation in lung adenocarcinoma cells in vitro

PURPOSE

This study was designed to investigate whether estradiol is related to the expression of the chemokine receptor CXCR4 and its activation in lung adenocarcinoma in vitro, since lung adenocarcinomas from premenopausal women have shown high levels of CXCR4, and this expression has been associated with worse prognosis and poor survival.

METHODS

The effect of 17-β-estradiol (E2) (0.03 nM-10 nM) on CXCR4 expression was analyzed in lung adenocarcinoma cell lines (SK-LU-1, H1435, H23, A549) by immunofluorescence after 24 and 72-h poststimulation. Tamoxifen treatment was applied to corroborate the estrogenic effect. The wound-healing assay was performed to investigate whether E2 treatment increased CXCR4/CXL12 pathway activity. A549 and SK-LU-1 cells were stimulated with E2, CXCL12, and CXCL12 combined with E2. Tamoxifen and AMD3100 were applied to corroborate estrogen and chemokine pathway activation.

RESULTS

Estradiol stimulated significantly CXCR4 overexpression in all the cell lines analyzed in a dose- and a time-dependent manner. Tamoxifen treatment inhibited the CXCR4 overexpression observed in estrogen-treated groups, demonstrating that estrogen strongly influences CXCR4 expression in lung adenocarcinoma cells. Cells treated with E2, CXCL12 and E2 combined with CXCL12 exhibited significant cell migration, which was suppressed when tamoxifen and AMD3100 were present.

CONCLUSION

Overexpression of CXCR4 induced by estrogen and the activity of CXCL12/CXCR4 pathway could be a new mechanism by which this hormone supports tumor progression and metastasis. These findings may partly explain the worse prognosis observed in premenopausal women and suggest considering the role of estrogen in lung cancer for the design of more specific treatment schemes.

Fluorescent CXCR4 targeting peptide as alternative for antibody staining in Ewing sarcoma

Background

Ewing sarcoma is an aggressive, highly metastatic primary bone and soft tissue tumor most frequently occurring in the bone of young adolescents. Patients, especially those diagnosed with a metastatic disease, have a poor overall survival. Chemokine receptor CXCR4 has a key pro-tumorigenic role in the tumor microenvironment of Ewing sarcoma and has been suggested to be involved in the increased metastatic propensity. Earlier studies on CXCR4 protein expression in Ewing sarcoma yielded contradictory results when compared to CXCR4 RNA expression studies. Previously, we demonstrated that CXCR4 expression could be detected in vivo using the fluorescently tagged CXCR4-specific peptide MSAP-Ac-TZ14011. Therefore, we studied the membranous CXCR4 expression in Ewing sarcoma cell lines using MSAP-Ac-TZ14011.

Methods

The CXCR4 membrane expression levels were studied in EWS cell lines by flow cytometry using the hybrid peptide MSAP-Ac-TZ14011 and were correlated to CXCR4 RNA expression levels. The measurements were compared to levels detected using the CXCR4 antibody ab2074 under various cell preparation conditions. In addition, the staining patterns were analyzed by confocal fluorescence microscopy over time.

Results

The hybrid peptide MSAP-Ac-TZ14011 levels showed a strong and better correlation of CXCR4 membrane expression with the CXCR4 RNA expression levels than observed with the anti-CXCR4 antibody ab2074. With the hybrid peptide MSAP-Ac-TZ14011 using live cell confocal microscopy CXCR4 membrane staining and internalization was detected and the signal intensity correlated well with CXCR4 mRNA expression levels.

Conclusions

The fluorescently labeled CXCR4 targeting peptide-based method provides a reliable alternative to antibody staining to study the CXCR4 membrane expression in live cells using either flow cytometry or live cell fluorescence microscopy. The fluorescently tagged CXCR4 targeting peptide could enable in vivo detection of CXCR4 expression in Ewing sarcoma which may help to stratify cases for anti-CXCR4 therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3352-z) contains supplementary material, which is available to authorized users.

Association of CXCR4, CCR7, VEGF-C and VEGF-D expression with lymph node metastasis in patients with cervical cancer

OBJECTIVE

We attempted to investigate the expression of CXCR4, CCR7, VEGF-C and VEGF-D in cervical cancer specimens, and the association between CXCR4, CCR7, VEGF-C and VEGF-D expression with the clinicopathological parameters of patients with cervical cancer.

STUDY DESIGN

57 tissue microarrays including 9 normal cervical tissues and 48 cervical cancer tissues were purchased from Biomax. The association between CXCR4, CCR7, VEGF-C and VEGF-D expression with the clinicopathological parameters were evaluated. Then immunohistochemistry was used to assess the expression of CXCR4, CCR7, VEGF-C and VEGF-D in cervical cancer specimens. Finally, Spearman correlations were used for the correlation analyses between CXCR4, CCR7, VEGF-C and VEGF-D.

RESULTS

We revealed that CXCR4 expression was significantly higher in patients with squamous cell carcinomas (P=0.002) and lymph node metastasis (P=0.038), while CCR7 expression was significantly elevated in patients with lymph node metastasis (P=0.037). VEGF-C expression was markedly up-regulated in patients exhibiting FIGO stage II-III tumors (P=0.015) and lymph node metastasis (P=0.038), while VEGF-D expression was obviously increased in patients displaying FIGO stage II-III tumors (P=0.025), squamous carcinomas (P=0.017) and lymph node metastasis (P=0.037). The correlation analysis indicated that CXCR4, CCR7, VEGF-C and VEGF-D expression have a significant correlation to each other.

CONCLUSION

These results suggested that CXCR4, CCR7, VEGF-C and VEGF-D expression might have synergistic effects on the lymph node metastasis in patients with cervical cancer.

Association of Cytoplasmic CXCR4 With Loss of Epithelial Marker and Activation of ERK1/2 and AKT Signaling Pathways in Non-Small-Cell Lung Cancer

OBJECTIVES

Compelling evidence demonstrates that CXC-chemokine receptor 4 (CXCR4) is involved in tumor invasion, angiogenesis, metastasis, and resistance to chemotherapy in addition to being one of the coreceptors for T-tropic human immunodeficiency virus entry into T cells. However, it remains controversial as to how to identify functionally activated CXCR4 in tumor biopsies, which would assist in determining which patients may benefit from potential CXCR4-targeted therapy.

MATERIALS AND METHODS

Immunohistochemistry (IHC) staining on archival tissues of patients with non-small-cell lung cancer (NSCLC) was used to detect a panel of biomarkers, including phospho-ERK1/2, phospho-AKT, and E-cadherin, which are relevant to downstream signaling of CXCR4 and epithelial to mesenchymal transition (EMT). We also examined whether subcellular localization of CXCR4 could help define possible activation of CXCR4.

RESULTS

A total of 94 primary tumor tissue samples from patients with NSCLC were included. Sixty-six patients had both cytomembranous and nuclear staining of CXCR4, 22 had solely nuclear staining, 5 had solely cytomembranous staining, and 1 had negative staining. Cytoplasmic location of CXCR4 with or without nuclear location was associated with loss of the epithelial marker E-cadherin (P = .0015) and activation of ERK1/2 (P = .0121) and AKT (P = .0024), suggesting EMT in these tumors; whereas tumors with only nuclear location of CXCR4 were more indolent and preserved an epithelial phenotype.

CONCLUSIONS

Our study suggests that different subcellular localization of CXCR4 may be associated with different activation states; cytoplasmic CXCR4 seems to correlate with biomarker changes associated with EMT in NSCLC.

NMMHC-IIA-dependent nuclear location of CXCR4 promotes migration and invasion in renal cell carcinoma

The chemokine receptor cysteine (C)-X-C receptor (CXCR4) is a G-protein-coupled receptor that exerts a vital role in distant metastasis of renal cell carcinoma (RCC). Emerging evidence demonstrates that CXCR4 as the cytomembrane receptor translocated into the nucleus to facilitate cell migration and, therefore, determine the prognosis of several types of malignancies. However, the biological mechanism of nuclear location of CXCR4 remains unclear. In the present study, we confirmed the significant implications of the putative nuclear localization sequence (NLS) '146RPRK149̓ on CXCR4 subcellular localization and metastatic potential by point-mutation assay in RCC cell lines. Importantly, mass spectrum followed by immunoprecipitation identified non-muscle myosin heavy chain-IIA (NMMHC-IIA) as the CXCR4-interacting protein. Furthermore, pharmaceutical inhibition of NMMHC-IIA by blebbistatin dampened the nuclear translocation of CXCR4 as well as the metastatic capacity of RCC cells. In conclusion, the present study may drive the comprehensive progress toward elucidating the mechanism responsible for CXCR4 nuclear function and metastasis in tumors.

Expression of the CXCR4 ligand SDF-1/CXCL12 is prognostically important for adenocarcinoma and large cell carcinoma of the lung

The SDF-1/CXCR4 axis is associated with tumor progression and has been reported as a prognostic parameter, although with conflicting data for non-small cell lung cancer (NSCLC). This study examines a large cohort of clinically and pathologically well-characterized NSCLC patients and includes the activated form of CXCR4 (pCXCR4), which has not been studied in this context so far. SDF-1, CXCR4, and pCXCR4 were assessed immunohistochemically in 371 surgically resected NSCLC using a standardized tissue microarray platform. Extensive clinical and pathological data and a postoperative follow-up period of 17 years enabled detailed correlations. CXCR4 and pCXCR4 were frequently expressed on squamous cell carcinoma. Membranous expression of SDF-1 was a marker of poor prognosis and proved to be an independent prognostic parameter for the entire cohort and for patients with adenocarcinoma (ACA) and large cell carcinoma (LCC). Targeted cancer therapies blocking SDF-1/CXCR4 interaction already exist, and our data suggest that expression of SDF-1, especially on poorer prognosis subgroups of LCC and ACA, indicates patients that might benefit more than others. This should be taken into account when assessing the effectiveness of such targeted approaches for NSCLC patients and could lead to important implications.

CXCR4 Expression is Associated with Poor Prognosis in Patients with Esophageal Squamous Cell Carcinoma

BACKGROUND

Chemokines and their receptors are known to play important roles in the tumorigenesis of many malignancies. The chemokine CXCL12 and its receptors CXCR4 and CXCR7 were suggested to be involved in cancer invasion and metastasis. The aim of this retrospective study was to evaluate the prognostic impact of the expressions of CXCL12, CXCR4 and CXCR7 in patients with esophageal squamous cell carcinoma (ESCC).

METHODS

We used immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) to evaluate the expressions of CXCL12, CXCR4, and CXCR7 in ESCC patients' tumor biopsy specimens obtained during preoperative endoscopy or surgery. These results were compared with the patients' clinicopathological parameters and survival.

RESULTS

IHC was conducted for 172 patients. High expression of CXCR4 in the cytoplasm and nuclei and that of CXCR7 were associated with poor cause-specific survival (CSS) (P= .002 and .010, respectively). The specimens from 52 of the 172 patients were examined by RT-PCR and quantitative real-time PCR. The expression levels of messenger RNA (mRNA) of CXCR4 and CXCR7 were significantly increased in the tumors compared with normal esophageal mucosae (P < .0001). The expression level of mRNA of CXCR4 was associated with poor recurrence-free survival and CSS (P = .012 and .038, respectively).

CONCLUSIONS

CXCR4 expression is associated with poor prognosis in patients with ESCC.

Positron emission tomographic imaging of CXCR4 in cancer: challenges and promises

Molecular imaging is an attractive platform for noninvasive detection and assessment of cancer. In recent years, the targeted imaging of the C-X-C chemokine receptor 4 (CXCR4), a chemokine receptor that has been associated with tumor metastasis, has become an area of intensive research. This review article focuses on positron emission tomography (PET) and aims to provide useful and critical insights into the application of PET to characterize CXCR4 expression, including the chemical, radiosynthetic, and biological requirements for PET radiotracers. This discussion is informed by a summary of the different approaches taken so far and a comparison of their clinical translation. Finally, our expert opinions as to potential future advances in the field are expressed.

HuR-targeted nanotherapy in combination with AMD3100 suppresses CXCR4 expression, cell growth, migration and invasion in lung cancer

The CXCR4 chemokine receptor plays an important role in cancer cell metastasis. The CXCR4 antagonist, AMD3100, has limited efficacy in controlling metastasis. HuR, an RNA-binding protein, regulates CXCR4 in cancer cells. We therefore investigated whether targeting HuR using a siRNA-based nanoparticle plus AMD3100 would suppress CXCR4 and inhibit lung cancer metastasis. We treated human H1299 lung cancer cell with HuR-specific siRNA contained in a folate-targeted lipid nanoparticle (HuR-FNP) plus AMD3100, and compared this with AMD3100 alone, HuR-FNP alone and no treatment. HuR-FNP plus AMD3100 treatment produced a G1 phase cell-cycle arrest and reduced cell viability above and beyond the effects of AMD3100 alone. HuR and CXCR4 mRNA and protein expression levels were markedly reduced in all treatment groups. Phosphorylated (p) AKT^S473 protein was also reduced. P27 protein expression increased with HuR-FNP and combination treatment. Promoter-based reporter studies showed that the combination inhibited CXCR4 promoter activity more than did either treatment alone. Cell migration and invasion was significantly reduced with all treatment; the combination provided the most inhibition. Reduced matrix metalloprotease (MMP) -2 and -9 expression was associated with reduced invasion in all treatment groups. Thus, we found that combined HuR and CXCR4 targeting effectively controlled lung cancer metastasis.

A meta-analysis for CXCR4 as a prognostic marker and potential drug target in non-small cell lung cancer

Background

Recent reports have shown that C-X-C chemokine receptor type 4 (CXCR4) is a candidate oncogene in several types of human tumors, including non-small cell lung cancer (NSCLC). However, the correlation between CXCR4 expression and clinicopathological characteristics of NSCLC remains controversial and has not been emphasized. The aim of this study is to quantitatively evaluate the association of CXCR4 expression with the incidence of NSCLC and clinicopathological characteristics by performing a meta-analysis.

Methods

A detailed literature search was carried out for related research publications. Only articles in which CXCR4 expression was detected by immunohistochemical staining were included. Odds ratio (OR) and hazard ratio (HR) with 95% confidence intervals (CIs) were calculated and summarized.

Results

Final analysis of 1,872 NSCLC patients from 19 eligible studies was performed. We observed that CXCR4 expression was significantly higher in NSCLC than in normal lung tissue, based on the pooled OR from ten studies, including 678 NSCLCs and 189 normal lung tissues (OR =16.66, 95% CI =6.94–40.02, P<0.00001). CXCR4 expression was also significantly associated with clinical stages, metastatic status, and overall survival (OS) in NSCLC patients. In addition, CXCR4 mRNA high expression was found to correlate with worse OS of all NSCLC patients followed for 20 years, HR =1.24, P=0.0047.

Conclusion

The present meta-analysis indicated that CXCR4 protein expression is associated with an increased risk and worse survival in NSCLC patients. The aberrant CXCR4 protein and mRNA expression play an important role in the carcinogenesis and metastasis of NSCLC.

IL-24 inhibits lung cancer cell migration and invasion by disrupting the SDF-1/CXCR4 signaling axis

Background

The stromal cell derived factor (SDF)-1/chemokine receptor (CXCR)-4 signaling pathway plays a key role in lung cancer metastasis and is molecular target for therapy. In the present study we investigated whether interleukin (IL)-24 can inhibit the SDF-1/CXCR4 axis and suppress lung cancer cell migration and invasion in vitro. Further, the efficacy of IL-24 in combination with CXCR4 antagonists was investigated.

Methods

Human H1299, A549, H460 and HCC827 lung cancer cell lines were used in the present study. The H1299 lung cancer cell line was stably transfected with doxycycline-inducible plasmid expression vector carrying the human IL-24 cDNA and used in the present study to determine the inhibitory effects of IL-24 on SDF-1/CXCR4 axis. H1299 and A549 cell lines were used in transient transfection studies. The inhibitory effects of IL-24 on SDF1/CXCR4 and its downstream targets were analyzed by quantitative RT-PCR, western blot, luciferase reporter assay, flow cytometry and immunocytochemistry. Functional studies included cell migration and invasion assays.

Principal Findings

Endogenous CXCR4 protein expression levels varied among the four human lung cancer cell lines. Doxycycline-induced IL-24 expression in the H1299-IL24 cell line resulted in reduced CXCR4 mRNA and protein expression. IL-24 post-transcriptionally regulated CXCR4 mRNA expression by decreasing the half-life of CXCR4 mRNA (>40%). Functional studies showed IL-24 inhibited tumor cell migration and invasion concomitant with reduction in CXCR4 and its downstream targets (pAKT^S473, pmTOR^S2448, pPRAS40^T246 and HIF-1α). Additionally, IL-24 inhibited tumor cell migration both in the presence and absence of the CXCR4 agonist, SDF-1. Finally, IL-24 when combined with CXCR4 inhibitors (AMD3100, SJA5) or with CXCR4 siRNA demonstrated enhanced inhibitory activity on tumor cell migration.

Conclusions

IL-24 disrupts the SDF-1/CXCR4 signaling pathway and inhibits lung tumor cell migration and invasion. Additionally, IL-24, when combined with CXCR4 inhibitors exhibited enhanced anti-metastatic activity and is an attractive therapeutic strategy for lung metastasis.

Clinicopathological significance of CXCR4 in non-small cell lung cancer

Background

Emerging evidence indicates that C-X-C chemokine receptor type 4 (CXCR4) is a candidate oncogene in several types of human tumors including non-small cell lung cancer (NSCLC). However, the correlation between CXCR4 expression and clinicopathological characteristics of NSCLC remains unclear. Here, we conducted a meta-analysis to quantitatively evaluate the association of CXCR4 expression with the incidence of NSCLC and clinicopatho-logical characteristics.

Methods

A detailed literature search was made from Medline and Web of Science for related research publications written in English and Chinese. The methodological quality of the studies was also evaluated. Analyses of pooled data were performed. Odds ratio (OR) and hazard ratio (HR) were calculated and summarized.

Results

The final analysis of 1,446 NSCLC patients from 13 eligible studies was performed. We observed that CXCR4 expression was significantly higher in NSCLC than in normal lung tissue from the pooled OR from five studies including 380 NSCLC and 118 normal lung tissue (OR=12.86, 95% confidence interval =3.63–45.59, P<0.0001). CXCR4 expression was not associated with smoking status and type of pathology. However, CXCR4 expression was significantly associated with clinical stages, metastatic status, and overall survival in NSCLC patients.

Conclusion

The results of this meta-analysis suggest that CXCR4 expression is associated with an increased risk and worse survival in NSCLC patients. The aberrant CXCR4 expression plays an important role in the carcinogenesis and metastasis of NSCLC.

Advanced technologies for studying circulating tumor cells at the protein level

Metastasis is the main cause of cancer death. As the tumor progresses, cells from the primary tumor site are shed into the bloodstream as circulating tumor cells (CTCs). Eventually, these cells colonize other organs and form distant metastases. It is therefore imperative that we gain a better understanding of the biological characteristics of CTCs for development of novel treatment modalities to minimize metastasis-associated cancer deaths. In recent years, rapid developments in technologies for the study of CTCs have taken place. We now have a variety of tools for the isolation and examination of CTCs which were not available before. This review introduces some commonly used protein markers in CTC investigations and summarizes a few advanced technologies which have been successfully applied for studying CTC biology at the protein level.

High CXC chemokine receptor 4 expression is an adverse prognostic factor in patients with clear-cell renal cell carcinoma

Background:

Aberrant CXC chemokine receptor 4 (CXCR4) expressions in malignant tissues have been reported; however, its role in kidney cancer prognosis remains unknown. The aim of this study was to determine the prognostic value of CXCR4 expression in patients with clear-cell renal cell carcinoma (ccRCC).

Methods:

The study included 225 patients with ccRCC. The cohort was split into a training set (n=125) and a validation set (n=100). CXC chemokine receptor 4 expression was analysed by immunohistochemical staining and its correlations with clinicopathologic features and prognosis were evaluated.

Results:

CXCR4-staining intensity increased gradually accompanied with disease progression from TNM stages I to IV in 225 patients with ccRCC. Moreover, high CXCR4 expression indicated reduced overall survival (OS) in the training (P<0.001) and validation (P<0.001) sets, especially for patients with early-stage (TNM stage I+II) diseases. Furthermore, CXCR4 expression was identified as an independent prognostic factor for OS, and combining TNM stage with CXCR4 expression showed a better prognostic value for OS in both sets.

Conclusions:

High CXCR4 expression, an independent adverse prognostic factor, could be combined with TNM stage to generate a predictive nomogram for clinical outcome in patients with ccRCC.

Intracellular coexpression of CXC- and CC- chemokine receptors and their ligands in human melanoma cell lines and dynamic variations after xenotransplantation

Background

Chemokines have been implicated in tumor progression and metastasis. In melanoma, chemokine receptors have been implicated in organ selective metastasis by regulating processes such as chemoattraction, adhesion and survival.

Methods

In this study we have analyzed, using flow cytometry, the systems formed by the chemokine receptors CXCR3, CXCR4, CXCR7, CCR7 and CCR10 and their ligands in thirteen human melanoma cell lines (five established from primary tumors and eight established from metastasis from different tissues). WM-115 and WM-266.4 melanoma cell lines (obtained from a primary and a metastatic melanoma respectively) were xenografted in nude mice and the tumors and cell lines derived from them were also analyzed.

Results

Our results show that the melanoma cell lines do not express or express in a low degree the chemokine receptors on their cell surface. However, melanoma cell lines show intracellular expression of all the aforementioned receptors and most of their respective ligands. When analyzing the xenografts and the cell lines obtained from them we found variations in the intracellular expression of chemokines and chemokine receptors that differed between the primary and metastatic cell lines. However, as well as in the original cell lines, minute or no expression of the chemokine receptors was observed at the cell surface.

Conclusions

Coexpression of chemokine receptors and their ligands was found in human melanoma cell lines. However, this expression is intracellular and receptors are not found at the cell membrane nor chemokines are secreted to the cell medium. The levels of expressed chemokine receptors and their ligands show dynamic variations after xenotransplantation that differ depending on the origin of the cell line (from primary tumor or from metastasis).

Estrogen receptor beta and CXCR4/CXCL12 expression: differences by sex and hormonal status in lung adenocarcinoma

BACKGROUND AND AIMS

Studies have reported differences in lung cancer behavior between sex and hormonal status that suggest a role of estrogens and estrogen receptor beta (ERβ) in lung carcinogenesis. In some types of hormone-dependent cancer, estrogens may regulate CXCL12/CXCR4 expression through ERβ signaling. High expression of CXCL12/CXCR4 is associated with poor prognosis in lung cancer because it promotes tumor growth and metastasis. Therefore, in this study we investigated whether lung adenocarcinoma tissues from pre- and postmenopausal women and from men exhibit different ERβ, CXCR4/CXCL12 expression and whether this expression is associated with clinicopathological features.

METHODS

Sixty primary tumor samples of lung adenocarcinoma from pre- and postmenopausal women and from men were collected for this study. Thirty samples of healthy lung tissue adjacent to the tumor site were used as controls. ERβ and CXCL12/CXCR4 expression was analyzed by immunohistochemistry. Expression of these proteins was measured by digital image software and compared between sex and hormonal status.

RESULTS

Lung adenocarcinomas overexpressed ERβ, CXCR4 and CXCL12 compared to normal lung. Moreover, lung adenocarcinomas from premenopausal women exhibited higher signals for ERβ, CXCL12 and CXCR4 compared to postmenopausal women and to men, who showed lower signals for these proteins. A multivariate analysis revealed a strong association between the immunoreactivity level of ERβ, CXCL12/CXCR4 and both sex and hormonal status, but not with tumor stage and smoking.

CONCLUSION

These results demonstrated that ERβ and CXCL12/CXCR4 expression in lung adenocarcinoma depends on sex and hormonal status, which may partly explain the sex and hormonal differences in lung cancer behavior.

The CXCL12/CXCR4/CXCR7 ligand-receptor system regulates neuro-glio-vascular interactions and vessel growth during human brain development

This study investigates glio-vascular interactions in human fetal brain at midgestation, specifically examining the expression and immunolocalization of the CXCL12/CXCR4/CXCR7 ligand-receptor axis and its possible role in the vascular patterning of the developing brain. At midgestation, the telencephalic vesicles are characterized by well developed radial glia cells (RGCs), the first differentiated astrocytes and a basic vascular network mainly built of radial vessels. RGCs have been recognized to contribute to cerebral cortex neuro-vascular architecture and have also been demonstrated to act as a significant source of neural cells (Rakic, Brain Res 33:471-476, 1971; Malatesta et al, Development 127:5253-5263, 2000). According to our hypothesis CXCL12, a potent migration and differentiation chemokine released by RGCs, may act as a linking factor coordinating neuroblast migration with vessel growth and patterning through the activation of different ligand/receptor axes. The obtained results support this hypothesis showing that together with CXCR4/CXCR7-reactive neuroblasts, which migrate in close association with CXCL12 RGCs, layer-specific subsets of CXCL12 RGCs and astrocytes specifically contact the microvessel wall. Moreover, the CXCL12/CXCR4/CXCR7 system appears to be directly involved in microvessel growth, its members being differentially expressed in angiogenically activated microvessels and vascular sprouts.

CXCR4/CXCL12 in non-small-cell lung cancer metastasis to the brain

Lung cancer represents the leading cause of cancer-related mortality throughout the world. Patients die of local progression, disseminated disease, or both. At least one third of the people with lung cancer develop brain metastases at some point during their disease, even often before the diagnosis of lung cancer is made. The high rate of brain metastasis makes lung cancer the most common type of tumor to spread to the brain. It is critical to understand the biologic basis of brain metastases to develop novel diagnostic and therapeutic approaches. This review will focus on the emerging data supporting the involvement of the chemokine CXCL12 and its receptor CXCR4 in the brain metastatic evolution of non-small-cell lung cancer (NSCLC) and the pharmacological tools that may be used to interfere with this signaling axis.

High expression of CXCR4, CXCR7 and SDF-1 predicts poor survival in renal cell carcinoma

Background

Chemokines and their receptors are known to play important roles in the tumorigenesis of many malignancies. The aim of this study was to evaluate the prognostic impact of the expression of the chemokine SDF-1 and its receptors CXCR4 and CXCR7 in patients with renal cell carcinoma.

Methods

The expression of CXCR4, CXCR7 and SDF-1 in specimens from 97 renal cell carcinoma patients was evaluated by immunohistochemistry on a tissue microarray. These results were correlated with the clinicopathological parameters and survival of the patients.

Results

CXCR4 and CXCR7 were expressed in all patients, whereas SDF-1 was expressed in 61 patients (62.9%). No association was observed between the expression of CXCR4, CXCR7 or SDF-1 and the clinical or pathological data except between SDF-1 expression and Fuhrman’s grade (P = 0.015). Patients with high expression of CXCR4, CXCR7 and SDF-1 had shorter overall survival and recurrence-free survival than those with low expression. In a multivariate analysis, the high expression of CXCR4, CXCR7 and SDF-1 correlated with poor overall survival and recurrence-free survival independent of gender, age, AJCC stage, lymph node status, metastasis, histologic variant and Fuhrman’s grade.

Conclusions

High levels of CXCR4, CXCR7 and SDF-1 were associated with poor overall survival and recurrence-free survival in renal cell carcinoma patients. CXCR4, CXCR7 and SDF-1 may serve as useful prognostic markers and therapeutic targets for renal cell carcinoma.

Serum level of CC-chemokine ligand 18 is increased in patients with non-small-cell lung cancer and correlates with survival time in adenocarcinomas

CC-chemokine ligand 18 (CCL18) is mainly expressed by alternatively activated macrophages and DCs and plays an important role in lung fibrosis, arthritis and other diseases. Here CCL18 was measured in sera of 31 healthy volunteers and 170 patients with lung cancer and correlated these data with histology, tumor stage and clinical parameters. Mean CCL18 serum level of the patients with non-small-cell lung cancer was 150(857) ng/ml vs. 32(61) ng/ml in the healthy control group. Patient groups differ significantly according their histology (adenocarcinoma 143(528) ng/ml vs squamous cell carcinoma 187(857) ng/ml, p<0.02). In addition, we found a significant difference between patients with lower versus higher T-stage (p<0.003). Receiver operating characteristic (ROC) analyses revealed a cutoff point of 83 ng/ml (area under the curve (AUC): 0.968; p<0.0001) to discriminate between healthy controls and non-small-cell lung cancer patients. ROC analyses to discriminate between patients, who died because of cancer related death and those who died for other reasons did not lead to a valid AUC. To stratify the tumor patients, a criterion value plot was performed leading to a point of equal sensitivity and specificity (54%) of 162 ng/ml. Patients with a CCL18 serum level higher than 160 ng/ml had a mean survival time of 623 days. In contrast, those in patients with a baseline level between 83 ng/ml and 160 ng/ml the mean survival time was 984 days (p<0.005). Survival-analysis revealed in adenocarcinoma a mean survival of 1152 days in the group below 83 ng/ml. In the median group the mean survival time was 788 days and in the group with the highest levels the mean survival time was 388 days (p<0.001). In contrast, we found no correlation between the FEV1 and the CCL18 baseline level. In conclusion, in patients suffering from adenocarcinoma increased serum CCL18 levels predict a diminished survival time.

Imaging agents for the chemokine receptor 4 (CXCR4)

The interaction between the chemokine receptor 4 (CXCR4) and stromal cell-derived factor-1 (SDF-1, also known as CXCL12) is a natural regulatory process in the human body. However, CXCR4 over-expression is also found in diseases such as cancer, where it plays a role in, among others, the metastatic spread. For this reason it is an interesting biomarker for the field of diagnostic oncology, and therefore, it is gaining increasing interest for applications in molecular imaging. Especially "small-molecule" imaging agents based on T140, FC131 and AMD3100 have been extensively studied. SDF-1, antibodies, pepducins and bioluminescence have also been used to visualize CXCR4. In this critical review reported CXCR4 targeting imaging agents are described based on their affinity, specificity and biodistribution. The level wherein CXCR4 is up-regulated in cancer patients and its relation to the different cell lines and animal models used to evaluate the efficacy of the imaging agents is also discussed (221 references).

Expression of chemokine receptors on circulating tumor cells in patients with solid tumors

Background

The study was performed to investigate the expression of chemokine receptors (CR) on circulating tumor cells (CTC), which may be of importance for organ-specific metastases and cancer treatment since CR are potential drug-targets.

Methods

Blood samples from patients with metastatic carcinoma (MC) or melanoma (MM) were enriched for CTC and expression of CR (CXCR4, CCR6, CCR7 and CCR9) was evaluated by flow cytometry.

Results

CTC were detected in 49 of 68 patients (72%) [28 MC; 21 MM] with a median number of 3 CTC (range: 1-94)/10 mL of blood. CXCR4 was expressed on CTC in 82% (40/49) of patients [median number 1 CTC/10 mL blood; range 1-14] and CCR6 in 29 patients (59%; median 1, range: 1-14). In MM patients, CCR7 was expressed on CTC in 6 (29%) samples and CCR9 in 12 (57%). A positive correlation between surface expression of CR and organ-specific metastatic pattern was not observed.

Conclusions

CR were expressed on CTC of patients with solid tumors. Along with our findings, the observation that CR could be involved in CTC proliferation and migration of tumor cells appoints CTC as potential CR-antagonist therapeutic target.

Upregulation of CXCR4 is functionally crucial for maintenance of stemness in drug-resistant non-small cell lung cancer cells

The hypothesis of cancer stem cells has been proposed to explain the therapeutic failure in a variety of cancers including lung cancers. Previously, we demonstrated acquisition of epithelial-mesenchymal transition, a feature highly reminiscent of cancer stem-like cells, in gefitinib-resistant A549 cells (A549/GR). Here, we show that A549/GR cells contain a high proportion of CXCR4+ cells that are responsible for having high potential of self-renewal activity in vitro and tumorigenicity in vivo. A549/GR cells exhibited strong sphere-forming activity and high CXCR4 expression and SDF-1α secretion compared with parent cells. Pharmacological inhibition (AMD3100) and/or siRNA transfection targeting CXCR4 significantly suppressed sphere-forming activity in A549 and A549/GR cells, and in various non-small cell lung cancer (NSCLC) cell lines. A549/GR cells showed enhanced Akt, mTOR and STAT3 (Y705) phosphorylation. Pharmacological inhibition of phosphatidyl inositol 3-kinase or transfection with wild-type PTEN suppressed phosphorylation of Akt, mTOR and STAT3 (Y705), sphere formation, and CXCR4 expression in A549/GR cells, whereas mutant PTEN enhanced these events. Inhibition of STAT3 by WP1066 or siSTAT3 significantly suppressed the sphere formation, but not CXCR4 expression, indicating that STAT3 is a downstream effector of CXCR4-mediated signaling. FACS-sorted CXCR4+ A549/GR cells formed many large spheres, had self-renewal capacity, demonstrated radiation resistance in vitro and exhibited stronger tumorigenic potential in vivo than CXCR4- cells. Lentiviral-transduction of CXCR4 enhanced sphere formation and tumorigenicity in H460 and A549 cells, whereas introduction of siCXCR4 suppressed these activities in A549/GR cells. Our data indicate that CXCR4+ NSCLC cells are strong candidates for tumorigenic stem-like cancer cells that maintain stemness through a CXCR4-medated STAT3 pathway and provide a potential therapeutic target for eliminating these malignant cells in NSCLC.

High expression of CXCR4 and CXCR7 predicts poor survival in gallbladder cancer

Chemokine receptors play a prominent role in cancer progression and metastasis. This study investigated whether the expression of CXC chemokine receptor types 4 and 7 (CXCR4 and CXCR7, respectively), determined immunohistochemically, was associated with clinicopathological characteristics and postoperative survival in gallbladder cancer specimens from 72 patients. CXCR4 was detected in the cytoplasm and/or nucleus of gallbladder cancer cells, but CXCR7 was detected only in the cytoplasm. Expression of either CXCR7 or CXCR4 in the cytoplasm was associated with tumour stage. Expression of nuclear CXCR4 was associated with lymph node metastases and lymphatic invasion. Cytoplasmic expression of CXCR4 and CXCR7 were each independent risk factors for worse postoperative survival. Further research is required to clarify the mechanisms involved in these associations and to determine their potential prognostic and therapeutic implications.

CXCR4/CXCL12 expression profile is associated with tumor microenvironment and clinical outcome of liver metastases of colorectal cancer

Interaction between CXCR4 and CXCL12 plays a role in tumor progression. The present study examined CXCR4, CXCL12 and CD133 expression in liver metastases of colorectal cancer (CLM) and determined whether the expression profiles affect the tumor microenvironment and thus progression, and whether they could serve as a prognostic marker for survival. Liver metastases of colorectal cancer collected from 92 patients were evaluated by CXCR4, CXCL12 and CD133 immunohistochemistry and clinicopathological data were analyzed. The expression profile of CXCR4 was determined in the colorectal cancer cell line, SW48. The expression of cytoplasmic CXCR4 was higher in 36 (39%) patients than that indicated by CXCR4 staining intensity of hepatocytes. High levels of nuclear CXCR4 expression in 23 (25%) patients significantly correlated with CXCL12 expression in hepatocytes. Nuclear CXCR4 expression was increased in the cancer cells after exposure to CXCL12. Univariate and multivariate analyses demonstrated that the high levels of nuclear CXCR4 and CXCL12 expression in hepatocytes were significantly better prognostic factors for overall and hepatic disease-free survival in patients with CLM. The expression of CXCR4 and CXCL12 in CLM may have an interactive effect that could alter the tumor microenvironment. CXCR4 expression in metastatic liver tumors together with the upregulation of CXCL12 in hepatocytes may help to predict the clinical outcomes of patients with CLM after hepatectomy.

Nef from SIV(mac239) decreases proliferation and migration of adenoid-cystic carcinoma cells and inhibits angiogenesis

The HIV/SIV accessory protein Nef is known to down-modulate cell surface receptors that are required for virus entry such as CD4, CCR5 and CXCR4 to block lethal viral superinfection of the infected cell. The chemokine receptor CXCR4 also plays an important role in promoting cell proliferation, metastasis and tumor angiogenesis. Therefore it was of interest to evaluate if Nef can down-regulate CXCR4 in tumor cells since this could affect these critical prognostic parameters. The CXCR4-expressing cell line ACC3 that was derived from a salivary gland adenoid cystic carcinoma (ACC) of the head and neck was transfected with Nef from SIV(mac239) and cell surface expression of the receptor was monitored by FACS analysis. Real time proliferation of cells was measured with the xCELLigence system (Roche, Mannheim, Germany). Cell migration was detected by an in vitro scratch assay. Similarly, COS-7 cells were co-transfected with CXCR4 and Nef and were treated as described for ACC3. In vitro tube formation was deployed to assess the effect of Nef on angiogenesis. siRNA was used for CXCR4 knockdown. Cell surface down-modulation of endogenous CXCR4 could be observed in ACC3 cells after Nef-transfection as well as in COS-7 cells after co-transfection of CXCR4 and Nef. Proliferation as well as migration of Nef-transfected ACC3 tumor cells appeared significantly reduced. In vitro tube formation was significantly lowered after Nef-transfection or CXCR4 knockdown with siRNA. SIV-Nef could serve as an interesting tool to study the biologic behavior of CXCR4-expressing tumors such as ACC. Deploying SIV-Nef thereby could help in the discovery of new therapeutic approaches for the treatment of ACC and other CXCR4-expressing tumors.

Leukocytes as paracrine regulators of metastasis and determinants of organ-specific colonization

It is now well recognized that tumor cell-host interactions regulate all aspects of cancer development. Amongst the various host response programs that facilitate primary cancer development, an emerging body of literature points to a critical role for leukocytes and their soluble mediators as regulating discrete events during primary tumor development and metastasis. This review focuses on the multiple aspects of leukocytes and their effector molecules as regulators of the metastatic process.

Significance of CXCR4, phosphorylated STAT3 and VEGF-A expression in resected non-small cell lung cancer

C-X-C chemokine receptor type 4 (CXCR4) plays an important role in determining the metastatic potential of non-small cell lung cancer. In order to elucidate the effect and mechanism of CXCR4 in tumor angiogenesis we evaluated the clinical significance of CXCR4, phosphorylated signal transducer and activator of transcription 3 (P-STAT3), and vascular endothelial growth factor (VEGF) expression in patients with completely resected non-small cell lung cancer (NSCLC). A total of 208 cases of resected NSCLC were collected, and expression of CXCR4, P-STAT3 and VEGF-A in tumor tissue was investigated using immunohistochemistry (IHC). We reviewed the patient clinical records to determine the association of the expression of these proteins with the clinical course of the disease. Expression of CXCR4, P-STAT3 and VEGF-A was detected in 56.3, 46.2 and 51.9% of the samples, respectively. We observed co-expression between CXCR4, P-STAT3 and VEGF-A. Using multivariate analysis, the expression levels of CXCR4 and VEGF-A were identified as independent prognostic factors that affected overall survival. In conclusion, the results of this study suggest that CXCR4, P-STAT3 and VEGF-A expression may play a role in tumor progression and angiogenesis of NSCLC. However, further studies are needed to uncover the detailed mechanism that underlies the role of these proteins in NSCLC.