Chemokine receptor 7 activates phosphoinositide-3 kinase-mediated invasive and prosurvival pathways in head and neck cancer cells independent of EGFR

Sustained Secretion of CCL21 via an Implantable Cell Reservoir Hydrogel Enhances the Systemic Antitumor Effect of Radiotherapy

The combination of radiotherapy (RT) and immunotherapy shows promise in improving the clinical treatment of solid tumors; however, it faces challenges of low response rates and systemic toxicity. Herein, an implantable alginate/collagen hydrogel encapsulating C-C motif ligand 21 (CCL21)-expressing dendritic cells (CCL21-DCs@gel) was developed to potentiate the systemic antitumor effects of RT. The hydrogel functioned as a suitable reservoir for in vivo culture and proliferation of CCL21-DCs, thereby enabling sustained CCL21 release. The local CCL21 gradient induced by CCL21-DCs@gel significantly enhanced the efficacy of RT in suppressing primary tumor growth and inhibiting distant metastasis across several mouse models. Furthermore, the combination of RT with CCL21-DCs@gel provided complete prophylactic protection to mice. Mechanistic investigations revealed that CCL21-DCs@gel potentiated RT by promoting tumor lymphangiogenesis and attracting immune cell infiltration into the tumor. Collectively, these results suggest that CCL21-DCs@gel is a promising adjunct to RT for effectively eradicating tumors and preventing tumor recurrence.

Connecting the Dots: The Cerebral Lymphatic System as a Bridge Between the Central Nervous System and Peripheral System in Health and Disease

As a recently discovered waste removal system in the brain, cerebral lymphatic system is thought to play an important role in regulating the homeostasis of the central nervous system. Currently, more and more attention is being focused on the cerebral lymphatic system. Further understanding of the structural and functional characteristics of cerebral lymphatic system is essential to better understand the pathogenesis of diseases and to explore therapeutic approaches. In this review, we summarize the structural components and functional characteristics of cerebral lymphatic system. More importantly, it is closely associated with peripheral system diseases in the gastrointestinal tract, liver, and kidney. However, there is still a gap in the study of the cerebral lymphatic system. However, we believe that it is a critical mediator of the interactions between the central nervous system and the peripheral system.

A frequent PLCγ1 mutation in adult T-cell leukemia/lymphoma determines functional properties of the malignant cells

BACKGROUND

Development of adult T-cell leukemia/lymphoma (ATL) involves human T-cell leukemia virus type 1 (HTLV-1) infection and accumulation of somatic mutations. The most frequently mutated gene in ATL (36 % of cases) is phospholipase C gamma1 (PLCG1). PLCG1 is also frequently mutated in other T-cell lymphomas. However, the functional consequences of the PLCG1 mutations in cancer cells have not been characterized.

METHODS

We compared the activity of the wild-type PLCγ1 with that of a mutant carrying a hot-spot mutation of PLCγ1 (S345F) observed in ATL, both in cells and in cell-free assays. To analyse the impact of the mutation on cellular properties, we quantified cellular proliferation, aggregation, chemotaxis and apoptosis by live cell-imaging in an S345F+ ATL-derived cell line (KK1) and a KK1 cell line in which we reverted the mutation to the wild-type sequence using CRISPR/Cas9 and homology-directed repair.

FINDINGS

The PLCγ1 S345F mutation results in an increase of basal PLC activity in vitro and in different cell types. This higher basal activity is further enhanced by upstream signalling. Reversion of the S345F mutation in the KK1 cell line resulted in reduction of the PLC activity, lower rates of proliferation and aggregation, and a marked reduction in chemotaxis towards CCL22. The PLCγ1-pathway inhibitors ibrutinib and ritonavir reduced both the PLC activity and the tested functions of KK1 cells.

INTERPRETATION

Consistent with observations from clinical studies, our data provide direct evidence that activated variants of the PLCγ1 enzyme contribute to the properties of the malignant T-cell clone in ATL.

FUNDING

MRC (UK) Project Grant (P028160).

The CC ligand chemokine family members CCL17/CCL22 predict the survival and response to immune checkpoint blockade therapy of patients with head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is considered an immunosuppressive malignancy. Cross-talk between cancer cells and immune cells is modulated in part by CC ligand (CCL) chemokines, having a major effect on tumor progression. However, the predictive value and function of CCL family members in HNSCC have not been elucidated. Here, the predictive value of CCL members in cancer prognosis and Immune checkpoint blockade therapy response was investigated. CCL17 and CCL22 were screened as the key CCL chemokines in HNSCC through co-expression analysis. Further, the correlation between CCL17/CCL22 expression and cancer immune infiltration were evaluated based on TIMER and were validated by a set of scRNA-seq data. Moreover, the expression level of CCL17/CCL22 we evaluated to predict the response to Immune checkpoint blockade therapy in a panel of cancer types by using the TIDE database. Results indicated that CCL17/CCL22 had a high co-expression correlation and had a marginally statistical significance with the overall survival in HNSCC patients (P value = 0.057 and 0.055, respectively). Our findings showed high expression of CCL17/CCL22 was positively correlated with CD4⁺ T cell infiltration levels in HNSCCs and activate mTORC1 signaling pathway in CD4⁺ T cells. Further analysis from TIDE showed the high expression of CCL17/CCL22 might predict favorable responses to immune checkpoint blockade therapy in HNSCC patients. These findings provide an insight into the predictive roles of CCL17/CCL22 in HNSCC.

Development of a human antibody that exhibits antagonistic activity toward CC chemokine receptor 7

Background

CC chemokine receptor 7 (CCR7) is a member of G-protein-coupled receptor family and mediates chemotactic migration of immune cells and different cancer cells induced via chemokine (C-C motif) ligand 19 (CCL19) or chemokine (C-C motif) ligand 21 (CCL21). Hence, the identification of blockade antibodies against CCR7 could lead to the development of therapeutics targeting metastatic cancer.

Methods

CCR7 was purified and stabilized in its active conformation, and antibodies specific to purified CCR7 were screened from the synthetic M13 phage library displaying humanized scFvs. The in vitro characterization of selected scFvs identified two scFvs that exhibited CCL19-competitive binding to CCR7. IgG4’s harboring selected scFv sequences were characterized for binding activity in CCR7+ cells, inhibitory activity toward CCR7-dependent cAMP attenuation, and the CCL19 or CCL21-dependent migration of CCR7+ cells.

Results

Antibodies specifically binding to purified CCR7 and CCR7+ cells were isolated and characterized. Two antibodies, IgG4(6RG11) and IgG4(72C7), showed ligand-dependent competitive binding to CCR7 with KD values of 40 nM and 50 nM, respectively. Particularly, IgG4(6RG11) showed antagonistic activity against CCR7, whereas both antibodies significantly blocked the ligand-induced migration and invasion activity of CCR7+ cancer cells.

Conclusions

Two antibody clones were successfully identified from a synthetic scFv-displaying phage library using purified recombinant CCR7 as an antigen. Antibodies specifically bound to the surface of CCR7+ cells and blocked CCR7+ cell migration. Particularly, 6RG11 showed antagonist activity against CCR7-dependent cAMP attenuation.

Statement of Significance

Antibodies targeting CCR7 were identified and could serve as therapeutic reagents against cancer metastasis.

The Overexpression of Fibronectin 1 Promotes Cancer Progression and Associated with M2 Macrophages Polarization in Head and Neck Squamous Cell Carcinoma Patients

Purpose

This study aimed to investigate the biological roles of fibronectin 1 (FN1) in head and neck squamous cell carcinoma (HNSCC) and its effects on macrophage M2 polarization.

Methods

We analyzed FN1 expression pattern and examined its clinical relevance in HNSCC progression by bioinformatic analysis. Small interfering RNA (siRNA) was utilized to silence FN1 in HNSCC cells. Cell counting kit-8 (CCK-8) assay, colony formation assay, Transwell assay and wound healing assay were performed to reveal the effect of FN1 on malignant behaviors of HNSCC cells. Moreover, a co-culture model of macrophages and HNSCC cells was established to investigate whether FN1 induce macrophage M2 polarization. Finally, we used bioinformatic methods to explore the possible FN1-related pathways in HNSCC.

Results

FN1 is significantly overexpressed in HNSCC patients and has been obviously correlated with higher pathological stage and poor prognosis. Downregulation of FN1 suppressed the proliferation, migration and invasion of HNSCC cells, and inhibited macrophage M2 polarization in vitro. In addition, “PI3K-Akt” and “MAPK” signaling pathways may be involved in the malignant process of FN1 in HNSCC.

Conclusion

The overexpression of FN1 promotes HNSCC progression and induces macrophages M2 polarization. FN1 may serve as a promising prognostic biomarker and therapeutic target in HNSCC.

Evaluation of HSP-27, BAP1, BRAF V600E, CCR7, and PD-L1 expression in uveal melanoma on enucleated eyes and metastatic liver tumors

BACKGROUND

The presence of metastatic disease is one of the most important factors limiting survival in patients with uveal melanoma. Studies on proteins associated with metastatic mechanisms are sparse in the literature.

METHODS

Enucleation samples from 15 patients with metastatic uveal melanoma (Group 1), liver metastasectomy samples from 8 patients with metastatic uveal melanoma (Group 2), and enucleation samples from 20 patients with non-metastatic uveal melanoma as controls (Group 3) were included in the study. Antibodies against heat shock protein 27 (HSP-27), BRCA1-associated protein-1 (BAP1), C-C chemokine receptor 7 (CCR7), B-Raf proto-oncogene serine/threonine-protein kinase V600E (BRAF V600E), and programmed death-ligand 1 (PD-L1) were used to detect immunoreactivity in each sample by immunohistochemical methods. Correlations between these expressed proteins and selected histopathological and clinical features, and metastatic process were investigated.

RESULTS

The frequencies of HSP-27 (median score: Group 1: 8, Group 2: 12, Group 3: 4) and BRAF V600E expressions (number of samples: Group 1: 4 (26.7%), Group 2: 1 (12.5%), Group 3: 0 (0%)), and BAP1 expression loss (number of samples : Group 1: 12 (80%), Group 2: 8 (100%), Group 3: 9 (45%)) were higher in samples from patients with metastatic uveal melanoma (Group 1 + 2) than in those from patients with non-metastatic disease (Group 3) (P = 0.001, P = 0.034, and P = 0.007, respectively). CCR7 expression (median score: Group 1: 0, Group 2: 2, Group 3: 3) was similar among these three groups (P = 0.136). No samples exhibited PD-L1 expression (P = 1.000). One-unit increases in the HSP-27 expression level and BAP1 expression loss were significantly related to 1.375- and 7.855-fold increases in the risk of metastasis, respectively (P = 0.007 and P = 0.017).

CONCLUSION

HSP-27 and BAP1 are considered to be associated with metastasis, indicating these proteins as potential treatment targets in metastatic uveal melanoma.

Specificity protein 1/microRNA-92b forms a feedback loop promoting the migration and invasion of head and neck squamous cell carcinoma

In this study we report a novel specificity protein 1 (SP1)/microRNA-92b (miR-92b) feedback loop regulating the migration and invasion of head and neck squamous cell carcinoma (HNSCC). Microarray and real-time Polymerase Chain Reaction (PCR) were used to detect gene expression in HNSCC tissues and cell lines. Transwell migration, invasion, wound healing and cell counting kit - 8 (CCK-8) cell assays were used to compare cell migration, invasion and proliferation abilities. Chromatin Immunoprecipitation (ChIP) assays were used to detect SP1 binding to the miR-92b promoter. Western blot was used to detect protein levels. An in vivo tumorigenesis experiment was used to evaluate the effect of SP1 knockdown on tumor growth and protein levels were evaluated by immunohistochemistry. We found that the miR-92b expression level was elevated in HNSCC primary focus tissue compared with adjacent normal tissue, and a higher level of miR-92b was related to a higher clinical stage and worse prognosis of HNSCC patients. MiR-92b and SP1 mutually promoted each expression and cooperatively facilitated the migration, invasion and proliferation of HNSCC cells. A decreased level of SP1/miR-92b resulted in a restraint of in vivo tumor growth. In conclusion, our results suggest that the SP1/miR-92b feedback loop generally promotes HNSCC invasion and metastasis, thus presenting a possible therapeutic target in the treatment of HNSCC patients.

Down-regulation of CCR7 via AKT pathway and GATA2 inactivation suppressed trophoblast migration and invasion in recurrent spontaneous abortion†

The underlying mechanism of the chemokine-C receptor 7 (CCR7) that leads to aberrant trophoblast migration and invasion in recurrent spontaneous abortion (RSA) remains unknown. CCR7 is considered crucial for migration and invasion and has been associated with the risk of miscarriage. However, the functional role of CCR7 in RSA is not fully understood. Our study found that CCR7 mRNA and protein abundance were significantly decreased in the villous from RSA patients compared with healthy controls. Knockdown of CCR7 caused a significant reduction of migration and invasion in JAR and JEG-3 cells. Meanwhile, CCR7 functioned as a positive upstream factor of the AKT pathway contributing to the expression of GATA2, promoting trophoblast migration, and invasion via MMP2. Notably, a decreased abundance of CCR7 was positively correlated with the phosphorylation of AKT and with an abundance of GATA2 and MMP2 in human villous specimens of RSA compared with the control group. CCL19, a ligand of CCR7, could promote trophoblast migration and invasion by activating the deregulation of the CCR7-mediated pathway in RSA. We are convinced that CCR7 and its downstream factors may be possible mechanisms for the pathogenesis of RSA.

CCR7 Has Potential to Be a Prognosis Marker for Cervical Squamous Cell Carcinoma and an Index for Tumor Microenvironment Change

The tumor microenvironment (TME) has an essential role in the development of cervical squamous cell carcinoma (CSCC); however, the dynamic role of the stromal and immune cells is still unclear in TME. We downloaded data from The Cancer Genome Atlas (TCGA) database and applied ESTIMATE and CIBERSORT algorithms to measure the quantity of stromal and immune cells and the composition of tumor-infiltrating immune cell (TIC) in 253 CSCC cases. The protein-protein interaction (PPI) network and Cox regression analysis presented the differentially expressed genes (DEGs). Then, C-C chemokine receptor type 7 (CCR7) was screened out as a prognostic marker by the univariate Cox and intersection analysis of PPI. Further analysis showed a positive correlation between the expression of CCR7 and the survival of CSCC patients. The result of the Gene Set Enrichment Analysis (GSEA) of genes in the high CCR7 expression group displayed a predominant enrichment in immune-related pathways. An enrichment in metabolic activities was observed in the low CCR7 expression group. CIBERSORT analysis showed a positive correlation between Plasma cells, CD8⁺ T cells, and regulatory T cells and the CCR7 expression, suggesting that CCR7 might play a crucial role in maintaining the immunological dominance status for TME. Therefore, the expression level of CCR7 might help predict the survival of CSCC cases and be an index that the status of TME transitioned from immunological dominance to metabolic activation, which presented a new insight into the treatment of CSCC.

CXCL9 secreted by tumor-associated dendritic cells up-regulates PD-L1 expression in bladder cancer cells by activating the CXCR3 signaling

Background

Tumor-associated dendritic cells (TADCs) can interact with tumor cells to suppress anti-tumor T cell immunity. However, there is no information on whether and how TADCs can modulate programmed death-ligand 1 (PD-L1) expression by cancer cells.

Methods

Human peripheral blood monocytes were induced for DCs and immature DCs were cultured alone, or co-cultured with bladder cancer T24 or control SV-HUC-1 cells, followed by stimulating with LPS for DC activation. The activation status of DCs was characterized by flow cytometry and allogenic T cell proliferation. The levels of chemokines in the supernatants of co-cultured DCs were measured by CBA-based flow cytometry. The impacts of CXCL9 on PD-L1, STAT3 and Akt expression and STAT3 and Akt phosphorylation in T24 cells were determined by flow cytometry and Western blot.

Results

Compared with the control DCs, TADCs exhibited immature phenotype and had significantly lower capacity to stimulate allogenic T cell proliferation, particularly in the presence of recombinant CXCL9. TADCs produced significantly higher levels of CXCL9, which enhanced PD-L1 expression in T24 cells. Pre-treatment with AMG487 abrogated the CXCL9-increased PD-L1 expression in T24 cells. Treatment with CXCL9 significantly enhanced STAT3 and Akt activation in T24 cells.

Conclusions

TADCs produced high levels of CXCL9 that increased PD-L1 expression in bladder cancer T24 cells by activating the CXCR3-related signaling. Our findings may shed new lights in understanding the regulatory roles of TADCs in inhibiting antitumor T cell responses and promoting tumor growth.

CCR7 as a therapeutic target in Cancer

The CCR7 chemokine axis is comprised of chemokine ligand 21 (CCL21) and chemokine ligand 19 (CCL19) acting on chemokine receptor 7 (CCR7). This axis plays two important but apparently opposing roles in cancer. On the one hand, this axis is significantly engaged in the trafficking of a number of effecter cells involved in mounting an immune response to a growing tumour. This suggests therapeutic strategies which involve potentiation of this axis can be used to combat the spread of cancer. On the other hand, the CCR7 axis plays a significant role in controlling the migration of tumour cells towards the lymphatic system and metastasis and can thus contribute to the expansion of cancer. This implies that therapeutic strategies which involve decreasing signaling through the CCR7 axis would have a beneficial effect in preventing dissemination of cancer. This dichotomy has partly been the reason why this axis has not yet been exploited, as other chemokine axes have, as a therapeutic target in cancer. Recent report of a crystal structure for CCR7 provides opportunities to exploit this axis in developing new cancer therapies. However, it remains unclear which of these two strategies, potentiation or antagonism of the CCR7 axis, is more appropriate for cancer therapy. This review brings together the evidence supporting both roles of the CCR7 axis in cancer and examines the future potential of each of the two different therapeutic approaches involving the CCR7 axis in cancer.

ACKR4 restrains antitumor immunity by regulating CCL21

Current immunotherapies involving CD8+ T cell responses show remarkable promise, but their efficacy in many solid tumors is limited, in part due to the low frequency of tumor-specific T cells in the tumor microenvironment (TME). Here, we identified a role for host atypical chemokine receptor 4 (ACKR4) in controlling intratumor T cell accumulation and activation. In the absence of ACKR4, an increase in intratumor CD8+ T cells inhibited tumor growth, and nonhematopoietic ACKR4 expression was critical. We show that ACKR4 inhibited CD103+ dendritic cell retention in tumors through regulation of the intratumor abundance of CCL21. In addition, preclinical studies indicate that ACKR4 and CCL21 are potential therapeutic targets to enhance responsiveness to immune checkpoint blockade or T cell costimulation.

The Role of CCL21/CCR7 Chemokine Axis in Breast Cancer Progression

Breast cancer is a leading cause of cancer-related deaths worldwide, predominantly caused by metastasis. It is generally accepted that the pattern of breast cancer metastasis is largely determined by the interaction between the chemokine receptors on cancer cells and the chemokines expressed at the sites of metastatic disease. Chemokine receptors belong to the G-protein-coupled receptors (GPCRs) family that appear to be implicated in inflammatory diseases, tumor growth and metastasis. One of its members, C-C Chemokine receptor 7 (CCR7), binds chemokines CCL19 and CCL21, which are important for tissue homeostasis, immune surveillance and tumorigenesis. These receptors have been shown to induce the pathobiology of breast cancer due to their ability to induce cellular proliferation and migration upon the binding of the cognate chemokine receptors. The underlying signaling pathways and exact cellular interactions within this biological system are not fully understood and need further insights. Thus, in this review, we summarize the essential roles of CCR7 and its receptors in breast cancer progression. Furthermore, we discuss the mechanisms of regulation that may lead to novel opportunities for therapeutic intervention. Despite the enormous advances in our knowledge of the nature of the chemokines in breast cancer metastasis, research about the involvement of CCR7 in cancer progression is still limited. Therefore, further studies are essential to illustrate the distinct roles of CCR7 in cancer progression and validate its potential as a preventive bio-factor for human breast cancer metastasis by targeting chemokine receptor genes.

Gene Expression Profiles in Chemokine (C-C Motif) Ligand 21-Overexpressing Pancreatic Cancer Cells

Chemokine (C-C Motif) ligand 21 (CCL21) plays an important role in tumor immunity. However, the molecular mechanisms by which CCL21 regulates tumor immunity remain largely unknown. In this study, we successfully generated a lentiviral vector expressing human CCL21 (Lenti-hCCL21), which was confirmed by biological assays. The Lenti-hCCL21 was transduced into PANC-1 cells, a chemokine (C-C motif) receptor 7 (CCR7)-positive human pancreatic cancer cell line. We used the scratch wound and transwell assays to measure cell migration of the CCL21-overexpressing PANC-1 cells. A DNA microarray assay was performed to determine gene expression profiles. The results showed that CCL21 lentiviral transduction significantly up- or down-regulated a panel of tumor-associated genes, although CCL21 appeared to have no effect on PANC-1 cell migration. Importantly, CCL21 promoted matrix metallopeptidase-9 (MMP-9) expression in PANC-1 cells. CCL21 regulates pancreatic cancer immunity possibly through governing the expression of a panel of tumor-associated genes, including MMP-9.

Hypoxia modulates CCR7 expression in head and neck cancers

BACKGROUND

The chemokine receptor CCR7 is expressed on lymphocytes and dendritic cells and is responsible for trafficking of these cells in and out of secondary lymphoid organs. It has recently been shown that CCR7 expression is elevated in a number of cancers, including head and neck cancers, and that its expression correlates to lymph node (LN) metastasis. However, little is known about the factors that can induce CCR7 expression in head and neck cancers.

METHOD

We compared the protein expression and functional responses of CCR7 under normoxia and hypoxia in head and neck cancer cell lines OSC-19, FaDu, SCC-4, A-253 and Detroit-562 cultured as monolayers, spheroids, and grown in vivo as xenografts in balb/c mice. In addition, we analysed the correlation between hypoxia marker HIF-1α and CCR7 expression in a tissue microarray comprising 80 clinical samples with various stages and grades of malignant tumour and normal tissue.

RESULTS

Under hypoxia, the expression of CCR7 is elevated in both in vitro and in vivo models. Furthermore, in malignant tissue, a correlation is observed between hypoxia marker HIF-1α and CCR7 across all clinical stages. This correlation is also strong in early histological grade of tumours.

CONCLUSION

Hypoxia plays a role in the regulation of the expression of CCR7 and it may contribute to the development of a metastatic phenotype in head and neck cancers through this axis.

Novel Molecular Targets for Chemoprevention in Malignancies of the Head and Neck

Cancers of the head and neck region are among the leading causes of cancer-related mortalities worldwide. Oral leukoplakia and erythroplakia are identified as precursor lesions to malignancy. Patients cured of an initial primary head and neck cancer are also susceptible to developing second primary tumors due to cancerization of their mucosal field. Multi-step acquisition of genetic mutations leading to tumorigenesis and development of invasive cancer has been previously described. Recently, whole exome sequencing of tumor specimens has helped to identify driver mutations in this disease. For these reasons, chemoprevention or the use of systemic or biologic agents to prevent carcinogenesis is an attractive concept in head and neck cancers. Nonetheless, despite extensive clinical research in this field over the past couple decades, no standard of care option has emerged. This review article reports on targeted interventions that have been attempted in clinical trials to date, and focuses on novel molecular pathways and drugs in development that are worthy of being tested for this indication as part of future endeavors.

Jak3 is involved in CCR7-dependent migration and invasion in metastatic squamous cell carcinoma of the head and neck

Patients with cervical lymph node metastasis in squamous cell carcinoma of the head and neck (SCCHN) exhibit a poor prognosis and low 5-year survival rate. It has been proven that chemokine receptor 7 (CCR7) promotes cellular migration and invasion in metastatic SCCHN. In the present study, the metastatic SCCHN PCI-37B cell line was utilized to explore the role of Janus activated kinase-3 (Jak3) in the CCR7-mediated signaling pathway in metastatic SCCHN cells. It was observed that phospho-Jak3 was expressed in SCCHN tissues. In addition, when the PCI-37B cells were analyzed in response to chemokine ligand 19 (CCL19), the ligand of CCR7, at the indicated time points, the results of the present study demonstrated that CCR7 induced Jak3 activation, and inhibition of Jak3 activity using a specific inhibitor, ZM39923, significantly attenuated CCR7-induced Jak3 phosphorylation. Migration and invasion assays and immunofluorescence staining experiments demonstrated that CCL19 promoted cell migration, invasion and F-actin rearrangment in CCR7-expressing SCCHN cells partially due to the activation of the Jak3 signaling pathway. These results demonstrate that the Jak3 signaling pathway is important for the CCR7-induced malignant biological behavior of SCCHN cells.

Expression of chemokine receptor CCR7 is a negative prognostic factor for patients with gastric cancer: a meta-analysis

BACKGROUND

The prognostic significance of CC chemokine receptor type 7 (CCR7) for survival of patients with gastric cancer remains controversial. To investigate the impacts of CCR7 on clinicopathological findings and survival outcome in gastric cancer, we performed a meta-analysis.

METHODS

A comprehensive search in PubMed, Embase, the Cochrane Library, and the CNKI database (1966 to November 2015) was undertaken for relevant studies. The relative risk and hazard ratios with their 95 % confidence intervals were used as measures to investigate the correlation between CCR7 expression and clinicopathological findings and overall survival rate. Sensitivity analysis was conducted to assess the stability of outcomes.

RESULTS

Fifteen eligible studies comprising 1697 participants were included in our analysis. The pooled relative risks indicated CCR7 expression was significantly associated with deeper tumor invasion [0.61, 95 % confidence interval (CI) 0.45-0.84, p = 0.003], advanced stage (0.47, 95 % CI 0.32-0.69, p < 0.001), vascular invasion (2.12, 95 % CI 1.20-3.73, p = 0.009), lymph node metastasis (2.00, 95 % CI 1.48-2.70, p < 0.001), and lymphatic invasion (1.98, 95 % CI 1.43-2.72, p < 0.001) but not with age, tumor size, and histological type. The pooling of hazard ratios showed a significant relationship between positive CCR7 expression and worse 5-year overall survival rate (0.46, 95 % CI 0.31-0.70, p < 0.001).

CONCLUSIONS

Our meta-analysis indicated high CCR7 expression is likely to be a negative clinicopathological prognostic factor for patients with gastric cancer and to predict a worse long-term survival outcome.

CXCR4 and CCR7: Two eligible targets in targeted cancer therapy

Cancer is one of the most common cause of death in the world with high negative emotional, economic, and social impacts. Conventional therapeutic methods, including chemotherapy and radiotherapy, have not proven satisfactory and relapse is common in most cases. Recent studies have focused on targeted therapy with more precise identification and targeted attacks to the cancer cells. For this purpose, chemokine receptors are proper targets and among them, CXCR4 and CCR7, with a crucial role in cancer metastasis, are being considered as desired candidates for investigation. In this review paper, the most important experimental results are highlighted on the potential targeted therapies based on CXCR4 and CCR7 chemokine receptors.

Chemokines accentuating protumoral activities in oral cancer microenvironment possess an imperious stratagem for therapeutic resolutions

Chemokines, the chemotactic cytokines have established their role in tumorigenesis and tumor progression. Studies, which explored their role in oral cancer for protumoral activity, point towards targeting chemokines for oral squamous cell carcinoma therapy. The need of the hour is to emphasize/divulge in the activities of chemokine ligands and their receptors in the tumor microenvironment for augmentation of such stratagems. This progressing sentience of chemokines and their receptors has inspired this review which is an endeavour to comprehend their role as an aid in accentuating hallmarks of cancer and targeted therapy.

The chemotactic interaction between CCL21 and its receptor, CCR7, facilitates the progression of pancreatic cancer via induction of angiogenesis and lymphangiogenesis

BACKGROUND

In this study, we report the influence of CCL21 and its receptor, CCR7, on the progression of pancreatic cancer and illuminates the correlation between the CCL21/CCR7 axis and the angiogenesis and lymphangiogenesis of pancreatic adenocarcinoma (PAC).

METHODS

A total of 30 patients with pancreatic cancer was involved in the current study. The expression of CCL21 and CCR7 in cancerous tissues, paracancerous tissues and normal pancreas were investigated using real-time PCR, Western blot and immunohistochemistry, respectively. In addition, we assessed microvessel density (MVD) and microlymphatic vessel density (MLVD) in tumor tissues using immunohistochemistry.

RESULTS

Compared to paracancerous tissues and normal pancreas, CCL21 expression in cancerous tissues was detected at a significantly low level. In contrast, the CCR7 expression was considerably higher in cancerous tissues than in normal pancreas and paracancerous tissues. Additionally, a significant correlation between the expression pattern of the CCL21/CCR7 axis and clinicopathological features, such as lymph node metastasis, was identified. Furthermore, we found that CCL21 expression was significantly associated with MVD but not significantly associated with MLVD, while CCR7 expression was significantly associated with MLVD but not significantly associated with MVD.

CONCLUSIONS

The chemotactic interaction between CCR7 and its ligand, CCL21, may be a critical event during progression in pancreatic cancer, and its underlying mechanism may be induction of angiogenesis and lymphangiogenesis regulated by this chemotactic interaction.

The role of Pyk2 in the CCR7-mediated regulation of metastasis and viability in squamous cell carcinoma of the head and neck cells in vivo and in vitro

In the present study, we aimed to demonstrate whether praline-rich tyrosine kinase-2 (Pyk2) participates in the chemokine receptor 7 (CCR7) downstream signaling network, and to determine the role of this molecule and the related mechanism in the CCR7-mediated regulation of viability and metastasis in vivo and in vitro of squamous cell carcinoma of the head and neck (SCCHN). We constructed the stable Pyk2 related non-kinase (PRNK)-expressing SCCHN cell line, and examined the viability, apoptosis, migration, invasion and adhesion ability in the transfected and untransfected SCCHN cells. An SCCHN tumor model in nude mice was designed and the tumor growth rate was assayed. E-cadherin and vimentin expression was assessed when Pyk2 was inactivated. We found that the stable PRNK-expressing SCCHN cells exhibited low viability, a high rate of apoptosis, low migratory ability, low invasive ability and low adhesion capacity. In the nude mouse body, the tumors formed by these cells grew slowly when compared to the tumor growth in the control group. When Pyk2 was inactivated, CCR7-induced E-cadherin and vimentin expression levels were altered. Thus, Pyk2 is a key downstream signaling molecules of CCR7 in SCCHN, which promotes SCCHN tumorigenesis and progression.

Association of chemokine and chemokine receptor expression with the invasion and metastasis of lung carcinoma

The chemokine system has been reported to be utilized and manipulated by tumor cells in order to promote local tumor growth and distant dissemination. The present study aimed to investigate the expression of three chemokine ligand-receptor axes in lung carcinoma tissues. Tumor and healthy normal tissue samples were obtained from 120 lung carcinoma patients following surgical resection. Immunohistochemistry and reverse transcription quantitative polymerase chain reaction were used in order to identify the protein and messenger (m)RNA expression of chemokines, including chemokine (C-X-C motif) ligand (CXCL)12/stromal cell-derived factor (SDF)-1, CXCL8/interleukin (IL)-8, chemokine (C-C motif) ligand (CCL)19 and CCL21, and the corresponding chemokine receptors, chemokine (C-X-C motif) receptor (CXCR)4, CXCR1, CXCR2 and chemokine (C-C motif) receptor (CCR)7, respectively. The results revealed that compared with the normal lung tissues, lung carcinoma tissues expressed significantly higher mRNA levels of CXCL12/SDF-1, CXCR4, CXCL8/IL-8, CXCR2, CCL19 and CCR7 (P<0.01). In four histological subtypes, adenocarcinoma presented dominant expression of CXCR4, CXCR2, CXCL8/IL-8 and CCL19 (P<0.05). In addition, it was demonstrated that tumor staging was inversely correlated with chemokine receptor CCR7 and CXCR2 mRNA expression as well as positively correlated with CXCL12/SDF-1, CXCL8/IL-8 and CCL19 mRNA levels (P<0.05). Lymph node metastasis presented a positive correlation with CXCR4, CXCR2 and CXCL8/IL-8 expression and a negative correlation with CCL19 and CCR7 expression (P<0.05). Furthermore, vascular invasion was more prevalent in patients with higher expression levels of CXCR4, CCR7 or CCL19 (P<0.01). In conclusion, these data suggested that the ligand-receptor interaction of CXCL8-CXCR2, CXCL12-CXCR4 and CCL19-CCR7 may be involved in the tumorigenesis of lung carcinoma. Higher expression levels of chemokines and lower expression of chemokine receptors indicated poor tumor staging. The CXC chemokine receptors, CXCR4 and CXCR2, promoted lymphatic metastasis through the activation of their specific ligands, while CCL19 and its receptor CCR7 had an essential role in hematogenous metastasis of lung carcinoma.

CCL21/CCR7 enhances the proliferation, migration, and invasion of human bladder cancer T24 cells

Objective

To investigate the effects of CCL21/CCR7 on the proliferation, migration, and invasion of T24 cells and the possible associated mechanisms: expression of MMP-2 and MMP-9, and regulation of BCL-2 and BAX proteins.

Methods

T24 cells received corresponding treatments including vehicle control, antibody (20ng/mL CCR7 antibody and 50 ng/ml CCL21), and 50, 100, and 200 ng/ml CCL21. Proliferation was evaluated by MTT assay; cell migration and invasion were assayed using a transwell chamber. Cell apoptosis was induced by Adriamycin (ADM). The rate of cell apoptosis was examined by flow cytometry using annexin V-FITC/PI staining. Western-blot was used to analyze MMP-2 and MMP-9 and BCL-2 and BAX proteins.

Results

CCL21 promoted T24 cell proliferation in concentration-dependent manner with that 200 ng/mL induced the largest amount of proliferation. Significant differences of cell migration were found between CCL21treatment groups and the control group in both the migration and invasion studies (P < 0.001 for all). The expressions of MMP-2 and MMP-9 proteins were significantly increased after CCL21 treatment (p < 0.05 for all). Protein expression of Bcl-21 follows an ascending trend while the expression of Bax follows a descending trend as the concentration of CCL21 increases. No difference was found between the control group and antibody group for all assessments.

Conclusion

CCL21/CCR7 promoted T24 cell proliferation and enhanced its migration and invasion via the increased expression of MMP-2 and MMP-9. CCL21/CCR7 had antiapoptotic activities on T24 cells via regulation of Bcl-2 and Bax proteins. CCL21/CCR7 may promote bladder cancer development and metastasis.

The role of CCL21/CCR7 chemokine axis in breast cancer-induced lymphangiogenesis

Background

Tumor-induced lymphangiogenesis facilitates breast cancer progression by generating new lymphatic vessels that serve as conduits for tumor dissemination to lymph nodes and beyond. Given the recent evidence suggesting the implication of C-C chemokine ligand 21/chemokine receptor 7 (CCL21/CCR7) in lymph node metastasis, the aim of our study was to define the role of this chemokine pair in breast cancer-associated lymphangiogenesis.

Methods

The expression analysis of CCL21/CCR7 pair and lymphatic endothelial cell (LEC) markers in breast cancer specimens was performed by means of quantitative real-time PCR. By utilizing CCR7 and CCL21 gene manipulated breast cancer cell implants into orthotopic sites of nude mice, lymphatic vessel formation was assessed through quantitative real-time PCR, immunohistochemistry and immunofluorescence assays. Finally, the lymphangiogenic potential of CCL21/CCR7 was assessed in vitro with primary LECs through separate functional assays, each attempting to mimic different stages of the lymphangiogenic process.

Results

We found that CCR7 mRNA expression in human breast cancer tissues positively correlates with the expression of lymphatic endothelial markers LYVE-1, podoplanin, Prox-1, and vascular endothelial growth factor-C (VEGF-C). We demonstrated that the expression of CCL21/CCR7 by breast cancer cells has the ability to promote tumor-induced lymph-vascular recruitment in vivo. In vitro, CCL21/CCR7 chemokine axis regulates the expression and secretion of lymphangiogenic factor VEGF-C and thereby promotes proliferation, migration, as well as tube formation of the primary human LECs. Finally, we showed that protein kinase B (AKT) signaling pathway is the intracellular mechanism of CCR7-mediated VEGF-C secretion by human breast cancer cells.

Conclusions

These results reveal that CCR7 and VEGF-C display a significant crosstalk and suggest a novel role of the CCL21/CCR7 chemokine axis in the promotion of breast cancer-induced lymphangiogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0306-4) contains supplementary material, which is available to authorized users.

Chemokine receptor 7 promotes tumor migration and invasiveness via the RhoA/ROCK pathway in metastatic squamous cell carcinoma of the head and neck

Metastatic squamous cell carcinoma of the head and neck (SCCHN) has been shown to express chemokine receptor 7 (CCR7), which can activate signaling pathways to promote invasion and survival of SCCHN cells. We hypothesized that the RhoA/Rho-associated kinase (ROCK) pathway is involved in the CCR7-induced invasion and migration of metastatic SCCHN cells. Thus, using migration, matrigel invasion and scrape wound-healing assays, we elucidated the role of RhoA in mediating CCR7-associated cellular mobility. Pull-down assays and western blotting were used to measure RhoA and its downstream expression. Immunohistochemical staining and analysis were useful in identifying the correlation between CCR7 and RhoA expression and clinicopathological factors. The results showed that inhibition of RhoA/ROCK reduced the tumor cell migration and invasiveness induced by CCL19. Activated RhoA, proline-rich tyrosine kinase-2 (Pyk2) and cofilin induced by CCL19 were elevated, and increased RhoA, Pyk2 and cofilin activity was eliminated by CCR7mAb, RhoA/ROCK and Pyk2 inhibitors, indicating involvement of the RhoA/ROCK-Pyk2-cofilin cascade. In summary, CCR7 via RhoA/ROCK-Pyk2 cofilin pathway promotes invasion and migration of metastatic SCCHN cells.

Chemokines in tumor progression and metastasis

Chemokines play a vital role in tumor progression and metastasis. Chemokines are involved in the growth of many cancers including breast cancer, ovarian cancer, pancreatic cancer, melanoma, lung cancer, gastric cancer, acute lymphoblastic leukemia, colon cancer, non-small lung cancer, non-hodgkin's lymphoma, etc. The expression of chemokines and their receptors is altered in many malignancies and leads to aberrant chemokine receptor signaling. This review focuses on the role of chemokines in key processes that facilitate tumor progression including proliferation, senescence, angiogenesis, epithelial mesenchymal transition, immune evasion and metastasis.

CCR7 regulates cell migration and invasion through JAK2/STAT3 in metastatic squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) frequently involves metastasis at diagnosis. Our previous research has demonstrated that CCR7 plays a key role in regulating SCCHN metastasis, and this process involves several molecules, such as PI3K/cdc42, pyk2, and Src. In this study, the goals are to identify whether JAK2/STAT3 also participates in CCR7's signal network, its relationship with other signal pathways, and its role in SCCHN cell invasion and migration. The results showed that stimulation of CCL19 could induce JAK2/STAT3 phosphorylation, which can be blocked by Src and pyk2 inhibitors. After activation, STAT3 was able to promote low expression of E-cadherin and had no effect on vimentin. This JAk2/STAT3 pathway not only mediated CCR7-induced cell migration but also mediated invasion speed. The immunohistochemistry results also showed that the phosphorylation of STAT3 was correlated with CCR7 expression in SCCHN, and CCR7 and STAT3 phosphorylation were all associated with lymph node metastasis. In conclusion, JAk2/STAT3 plays a key role in CCR7 regulating SCCHN metastasis.

CCR7 regulates cell migration and invasion through MAPKs in metastatic squamous cell carcinoma of head and neck

Migration and invasion of tumor cells are essential prerequisites for the formation of metastasis in malignant diseases. Previously, we have reported that CC chemokine receptor 7 (CCR7) regulates the mobility of squamous cell carcinoma of head and neck (SCCHN) cells through several pathways, such as integrin and cdc42. In this study, we investigated the connection between CCR7 and mitogen-activated protein kinase (MAPK) family members, and their influence on cell invasion and migration in metastatic SCCHN cells. Western blotting, immunostaining and fluorescence microcopy were used to detect the protein expression and distribution of MAPKs, and the Migration assay, Matrigel invasion assay and wound-healing assay to detect the role of MAPKs in CCR7 regulating cell mobility. To analyze the correlation between CCR7 and MAPK activity and clinicopathological factors immunohistochemical staining was emplyed. The results showed stimulation of CCL19 and the activation of CCR7 could induce ERK1/2 and JNK phosphorylation, while it had no efect on p38. After activation, ERK1/2 and JNK promoted E-cadherin low expression and Vimentin high expression. The MAPK pathway not only mediated CCR7 induced cell migration, but also mediated invasion speed. The immunohistochemistry results showed that CCR7 was correlated with the phosphorylation of ERK1/2 and JNK in SCCHN, and these molecules were all associated with lymph node metastasis. Therefore, our study demonstrates that MAPK members (ERK1/2 and JNK) play a key role in CCR7 regulating SCCHN metastasis.

CCR7: roles in cancer cell dissemination, migration and metastasis formation

The CC-chemokine receptor 7 (CCR7) coordinates the migration of cancer cells as well as immune cells towards lymphatic organs where its two ligands CCL19 and CCL21 are constitutively expressed. Here we provide a topological model of CCR7, which belongs to the class A of G-protein coupled, seven-transmembrane spanning receptors, and describe how CCR7 expression is regulated. We focus on its role in cancer cell migration and metastasis formation and discuss how cancer cells can utilize CCR7 or its ligands to escape from immune surveillance.

Chemokine receptor 7 enhances cell chemotaxis and migration of metastatic squamous cell carcinoma of head and neck through activation of matrix metalloproteinase-9

The mechanisms leading to squamous cell carcinoma of head and neck (SCCHN) metastasis are not fully understood. Although evidence shows that the chemokine receptor 7 (CCR7) and its ligand CCL19 may regulate tumor dissemination, their role is not clearly defined in SCCHN. Matrix metalloproteinases break consisting of tissue barrier to the surrounding tissue invasion and metastasis by destroying the balance of matrix degradation of the basement membrane of tumor cells and extracellular matrix (ECM). We used chemotaxis and migration assays, western blotting, gelatin zymography, actin polymerization assay, immunofluorescence staining and immunohistochemical analysis to explore whether MMP-9 can be activated by CCL19 (CCR7's ligand) and its role in SCCHN. The experiments were performed in the metastatic SCCHN cell line PCI-37B after pre-incubation of the cells with CCL19 and SB-3CT (inhibitor of MMP-9). Our results demonstrated that CCR7 favors PCI-37B cell chemotaxis and migration, upregulation of MMP-9 protein and motivates the activity of MMP-9 protein, induces reorganization of the actin cytoskeleton and upregulation of MMP-9 protein. SB-3CT can block all these effects. Collectively, our data indicated that CCR7 regulates cell chemotaxis and migration via MMP-9 in metastatic SCCHN, and these results provide a basis for new strategies in preventing metastases of SCCHN.

Fine mapping reveals that promotion susceptibility locus 1 (Psl1) is a compound locus with multiple genes that modify susceptibility to skin tumor development

Although it is well known that the majority of human cancers occur as the result of exposure to environmental carcinogens, it is clear that not all individuals exposed to a specific environmental carcinogen have the same risk of developing cancer. Considerable evidence indicates that common allelic variants of low-penetrance, tumor susceptibility genes are responsible for this interindividual variation in risk. We previously reported a skin tumor promotion susceptibility locus, Psl1, which maps to the distal portion of chromosome 9, that modified skin tumor promotion susceptibility in the mouse. Furthermore, Psl1 was shown to consist of at least two subloci (i.e., Psl1.1 and Psl1.2) and that glutathione S-transferase alpha 4 (Gsta4), which maps to Psl1.2, is a skin tumor promotion susceptibility gene. Finally, variants of human GSTA4 were found to be associated with risk of nonmelanoma skin cancer. In the current study, a combination of nested and contiguous C57BL/6 congenic mouse strains, each inheriting a different portion of the Psl1 locus from DBA/2, were tested for susceptibility to skin tumor promotion with 12-O-tetradecanoylphorbol-13-acetate. These analyses indicate that Psl1 is a compound locus with at least six genes, including Gsta4, that modify skin tumor promotion susceptibility. More than 550 protein-coding genes map within the Psl1 locus. Fine mapping of the Psl1 locus, along with two-strain haplotype analysis, gene expression analysis, and the identification of genes with amino acid variants, has produced a list of fewer than 25 candidate skin tumor promotion susceptibility genes.

Chemokines and squamous cancer of the head and neck: targets for therapeutic intervention?

The biological properties of squamous carcinoma cells are intimately regulated by a multitude of cytokines and growth factors; the most well studied of these include epidermal growth factor receptor agonists and members of the transforming growth factor-beta family. The recent explosion of research in the field of chemokine function as a mediator of tumor progression has led to the possibility that these small, immunomodulatory proteins also play key roles in squamous carcinogenesis and may, therefore, be potential targets for novel therapeutic approaches.

CCR7 expression correlates with subcutaneous involvement in mycosis fungoides skin lesions and promotes migration of mycosis fungoides cells (MyLa) through mTOR activation

BACKGROUND

The molecular pathogenesis of mycosis fungoides (MF) is currently poorly understood. The chemokine receptor CCR7 has been demonstrated to be involved in the development and progression of certain cancers, but its role in MF has rarely been investigated.

OBJECTIVES

We seek to determine whether CCR7 is expressed in MF skin lesions. In addition, we evaluate whether CCR7 plays a role in MF cell proliferation and migration, and which signaling pathways are involved.

METHODS

Immunohistochemical staining of 21 cases of MF pathology specimens with CCR7 was performed. Medical charts and pathology slides of these cases were reviewed. Surface expression of CCR7 on MyLa cells (MF cell line) and peripheral blood mononuclear cells (PBMCs) was assessed by flow cytometry. Cell proliferation and migration were evaluated with the Alamar Blue assay and transwell chemotaxis assay, respectively.

RESULTS

CCR7 was found to be expressed in 62% (13 out of 21) of MF pathology specimens, and its expression correlated with subcutaneous extension of lymphoma cells. CCR7 expression was increased on the surface of MyLa cells compared to that on PBMCs. Addition of CCL21 (CCR7 agonist) enhanced MyLa cell migration but not proliferation. The CCL21-induced MyLa cell migration was found to be mediated by the mTOR pathway.

CONCLUSIONS

CCR7 is more likely to be expressed in MF skin lesions with subcutaneous involvement. Activation of CCR7 promotes migration of MyLa cells (MF cell line) through the mTOR pathway. These findings provide new insights into the significance of CCR7 in the pathophysiology of MF.

Anti-CCR7 therapy exerts a potent anti-tumor activity in a xenograft model of human mantle cell lymphoma

Background

The chemokine receptor CCR7 mediates lymphoid dissemination of many cancers, including lymphomas and epithelial carcinomas, thus representing an attractive therapeutic target. Previous results have highlighted the potential of the anti-CCR7 monoclonal antibodies to inhibit migration in transwell assays. The present study aimed to evaluate the in vivo therapeutic efficacy of an anti-CCR7 antibody in a xenografted human mantle cell lymphoma model.

Methods

NOD/SCID mice were either subcutaneously or intravenously inoculated with Granta-519 cells, a human cell line derived from a leukemic mantle cell lymphoma. The anti-CCR7 mAb treatment (3 × 200 μg) was started on day 2 or 7 to target lymphoma cells in either a peri-implantation or a post-implantation stage, respectively.

Results

The anti-CCR7 therapy significantly delayed the tumor appearance and also reduced the volumes of tumors in the subcutaneous model. Moreover, an increased number of apoptotic tumor cells was detected in mice treated with the anti-CCR7 mAb compared to the untreated animals. In addition, significantly reduced number of Granta-519 cells migrated from subcutaneous tumors to distant lymphoid organs, such as bone marrow and spleen in the anti-CCR7 treated mice. In the intravenous models, the anti-CCR7 mAb drastically increased survival of the mice. Accordingly, dissemination and infiltration of tumor cells in lymphoid and non-lymphoid organs, including lungs and central nervous system, was almost abrogated.

Conclusions

The anti-CCR7 mAb exerts a potent anti-tumor activity and might represent an interesting therapeutic alternative to conventional therapies.

Chemokines, chemokine receptors and the gastrointestinal system

The biological properties of tumor cells are known to be regulated by a multitude of cytokines and growth factors, which include epidermal growth factor receptor agonists and members of the transforming growth factor β family. Furthermore, the recent explosion of research in the field of chemokine function as mediators of tumor progression has led to the possibility that these small, immunomodulatory proteins also play key roles in carcinogenesis and may, therefore, be potential targets for novel therapeutic approaches. In this review, we will summarize recently reported findings in chemokine biology with a focus on the gastrointestinal tract.

Fusion of CCL21 non-migratory active breast epithelial and breast cancer cells give rise to CCL21 migratory active tumor hybrid cell lines

The biological phenomenon of cell fusion has been linked to tumor progression because several data provided evidence that fusion of tumor cells and normal cells gave rise to hybrid cell lines exhibiting novel properties, such as increased metastatogenic capacity and an enhanced drug resistance. Here we investigated M13HS hybrid cell lines, derived from spontaneous fusion events between M13SV1-EGFP-Neo breast epithelial cells exhibiting stem cell characteristics and HS578T-Hyg breast cancer cells, concerning CCL21/CCR7 signaling. Western Blot analysis showed that all cell lines varied in their CCR7 expression levels as well as differed in the induction and kinetics of CCR7 specific signal transduction cascades. Flow cytometry-based calcium measurements revealed that a CCL21 induced calcium influx was solely detected in M13HS hybrid cell lines. Cell migration demonstrated that only M13HS hybrid cell lines, but not parental derivatives, responded to CCL21 stimulation with an increased migratory activity. Knockdown of CCR7 expression by siRNA completely abrogated the CCL21 induced migration of hybrid cell lines indicating the necessity of CCL21/CCR7 signaling. Because the CCL21/CCR7 axis has been linked to metastatic spreading of breast cancer to lymph nodes we conclude from our data that cell fusion could be a mechanism explaining the origin of metastatic cancer (hybrid) cells.

Development of a unique small molecule modulator of CXCR4

Background

Metastasis, the spread and growth of tumor cells to distant organ sites, represents the most devastating attribute and plays a major role in the morbidity and mortality of cancer. Inflammation is crucial for malignant tumor transformation and survival. Thus, blocking inflammation is expected to serve as an effective cancer treatment. Among anti-inflammation therapies, chemokine modulation is now beginning to emerge from the pipeline. CXC chemokine receptor-4 (CXCR4) and its ligand stromal cell-derived factor-1 (CXCL12) interaction and the resulting cell signaling cascade have emerged as highly relevant targets since they play pleiotropic roles in metastatic progression. The unique function of CXCR4 is to promote the homing of tumor cells to their microenvironment at the distant organ sites.

Methodology/Principal Findings

We describe the actions of N,N′-(1,4-phenylenebis(methylene))dipyrimidin-2-amine (designated MSX-122), a novel small molecule and partial CXCR4 antagonist with properties quite unlike that of any other reported CXCR4 antagonists, which was prepared in a single chemical step using a reductive amination reaction. Its specificity toward CXCR4 was tested in a binding affinity assay and a ligand competition assay using ¹⁸F-labeled MSX-122. The potency of the compound was determined in two functional assays, Matrigel invasion assay and cAMP modulation. The therapeutic potential of MSX-122 was evaluated in three different murine models for inflammation including an experimental colitis, carrageenan induced paw edema, and bleomycin induced lung fibrosis and three different animal models for metastasis including breast cancer micrometastasis in lung, head and neck cancer metastasis in lung, and uveal melanoma micrometastasis in liver in which CXCR4 was reported to play crucial roles.

Conclusions/Significance

We developed a novel small molecule, MSX-122, that is a partial CXCR4 antagonist without mobilizing stem cells, which can be safer for long-term blockade of metastasis than other reported CXCR4 antagonists.

CCL21/CCR7 prevents apoptosis via the ERK pathway in human non-small cell lung cancer cells

Previously, we confirmed that C-C chemokine receptor 7 (CCR7) promotes cell proliferation via the extracellular signal-regulated kinase (ERK) pathway, but its role in apoptosis of non-small cell lung cancer (NSCLC) cell lines remains unknown. A549 and H460 cells of NSCLC were used to examine the effect of CCL21/CCR7 on apoptosis using flow cytometry. The results showed that activation of CCR7 by its specific ligand, exogenous chemokine ligand 21 (CCL21), was associated with a significant decline in the percent of apoptosis. Western blot and real-time PCR assays indicated that activation of CCR7 significantly caused upregulation of anti-apoptotic bcl-2 and downregulation of pro-apoptotic bax and caspase-3, but not p53, at both protein and mRNA levels. CCR7 small interfering RNA significantly attenuated these effects of exogenous CCL21. Besides, PD98059, a selective inhibitor of MEK that disrupts the activation of downstream ERK, significantly abolished these effects of CCL21/CCR7. Coimmunoprecipitation further confirmed that there was an interaction between p-ERK and bcl-2, bax, or caspase-3, particularly in the presence of CCL21. These results strongly suggest that CCL21/CCR7 prevents apoptosis by upregulating the expression of bcl-2 and by downregulating the expression of bax and caspase-3 potentially via the ERK pathway in A549 and H460 cells of NSCLC.

Role of dendritic cells in progression and clinical outcome of colon cancer

PURPOSE

The dendritic cells (DCs) are key players in the initiation and regulation of immune responses including antitumor immunity. In the current study, we aimed to elucidate the role of different subtypes of DCs infiltrating the tumor stroma and invasive margin for tumor progression and survival of patients with colon cancer.

METHODS

The presence of immature (CD1a- and S100 protein+) and mature (CD83- and HLA-DR+) DCs was evaluated by immunohistochemistry in tissue samples from 145 patients with colon cancer. Patients were dichotomized according to the number of DCs in the tumor stroma and invasive margin, and clinical, histological, and survival data were compared between the two groups of patients.

RESULTS

The number of the mature CD83+ DCs in the tumor stroma and in the invasive margin significantly correlated with the tumor stage: the lower level of infiltration was found in patients that have advanced tumor stage. The frequency of distant metastases was higher in patients who had lower numbers of immature CD1a+ DCs in tumor stroma and of CD83+ DCs in invasive margin. Patients showing a relatively high number of S100+ DCs in the tumor stroma and HLA-DR+ DCs in the invasive margin had a longer overall survival (p < 0.05). Patients with lower CD83+ DCs infiltration in invasive margin had worse prognosis after surgical therapy compared with those with higher CD83+ DCs infiltration (p = 0.0397).

CONCLUSIONS

Our results demonstrate that the infiltration of colon cancer with DCs is related with tumor progression and patient prognosis, suggesting a central role for DCs in controlling local antitumor immunity.

Chemokine receptor 7 (CCR7) gene expression is regulated by NF-κB and activator protein 1 (AP1) in metastatic squamous cell carcinoma of head and neck (SCCHN)

The chemokine receptor CCR7 is a seven-transmembrane domain G-protein-coupled receptor that facilitates leukocyte migration to regional lymph nodes. Aberrant CCR7 expression in a number of human malignancies has been linked to pro-survival, -invasive, and -metastatic pathways. We demonstrate here that up-regulation of CCR7 in squamous cell carcinoma of the head and neck (SCCHN) patient tumors correlates with lower survival because of metastatic disease. Because of this important oncogenic phenotype, we investigated the mechanisms that regulate CCR7 expression in these tumors. Interestingly, the inflammatory transcription factor NF-κB has been associated with a more aggressive SCCHN phenotype. Immunohistochemical staining of a SCCHN tumor cohort (n = 47) strongly linked NF-κB staining and CCR7 expression in SCCHN. Thus, we investigated whether NF-κB contributes to metastatic disease by promoting CCR7 expression in SCCHN tumor cells. We characterized four novel, potential NF-κB binding sites in the 1000-bp promoter region upstream of the CCR7 gene, using luciferase, ChIP, and EMSA. However, NF-κB inhibition only resulted in partial reduction in CCR7 expression, prompting consideration of other co-regulators of CCR7. Indeed, cooperation between NF-κB and AP1 transcription factors, which are often co-activated, is crucial to the regulation of CCR7 mRNA expression in metastatic SCCHN cells. Thus, our findings support an important biological role for inflammatory NF-κB and AP1 in the regulation of CCR7 expression in metastatic SCCHN. As such, CCR7, NF-κB, and AP1 could be potentially useful therapeutic targets in controlling the progression and metastasis of SCCHN tumors.

Defective NF-κB signaling in metastatic head and neck cancer cells leads to enhanced apoptosis by double-stranded RNA

Ligands to several Toll-like receptors (TLR), which mediate innate immune responses and chronic inflammation have been used as adjuvants to immunotherapy to enhance their antitumor activity. In particular, double-stranded RNAs that are cognate ligands of TLR3 have been used to trigger proapoptotic activity in cancer cells. However, a mechanistic understanding of TLR3-mediated apoptosis and its potential involvement in controlling tumor metastasis has been lacking. In this study, we used paired cell lines and fresh tumor specimens, derived from autologous primary and metastatic head and neck squamous cell carcinoma, to investigate the role of TLR3 signaling in metastatic progression. Compared with primary tumor cells, metastatic tumor cells were highly sensitive to TLR3-mediated apoptosis after double-stranded RNA treatment. Enhanced apoptosis in metastatic cells was dependent on double-stranded RNA and TLR3 and also the TLR3 effector signaling protein TRIF. Downstream responses requiring NF-κB were critical for apoptosis in metastatic cells, the defects in which could be resuscitated by alternative pathways of NF-κB activation. By elucidating how TLR3 ligands trigger apoptosis in metastatic cells, our findings suggest insights into how to improve their clinical use.

CCL21/CCR7 promotes G2/M phase progression via the ERK pathway in human non-small cell lung cancer cells

C-C chemokine receptor 7 (CCR7) contributes to the survival of certain cancer cell lines, but its role in the proliferation of human non-small cell lung cancer (NSCLC) cells remains vague. Proliferation assays performed on A549 and H460 NSCLC cells using Cell Counting Kit-8 indicated that activation of CCR7 by its specific ligand, exogenous chemokine ligand 21 (CCL21), was associated with a significant linear increase in cell proliferation with duration of exposure to CCL21. The CCL21/CCR7 interaction significantly increased the fraction of cells in the G₂/M phase of the cell cycle as measured by flow cytometry. In contrast, CCL21/CCR7 had no significant influence on the G₀/G₁ and S phases. Western blot and real-time PCR indicated that CCL21/CCR7 significantly upregulated expression of cyclin A, cyclin B1, and cyclin-dependent kinase 1 (CDK1), which are related to the G₂/M phase transition. The expression of cyclin D1 and cyclin E, which are related to the G₀/G₁ and G₁/S transitions, was not altered. The CCL21/CCR7 interaction significantly enhanced phosphorylation of extracellular signal-regulated kinase (P-ERK) but not Akt, as measured by Western blot. LY294002, a selective inhibitor of PI3K that prevents activation of the downstream Akt, did not weaken the effect of CCL21/CCR7 on P-ERK. Coimmunoprecipitation further confirmed that there was an interaction between P-ERK and cyclin A, cyclin B1, or CDK1, particularly in the presence of CCL21. CCR7 small interfering RNA or PD98059, a selective inhibitor of MEK that disrupts the activation of downstream ERK, significantly abolished the effects of exogenous CCL21. These results suggest that CCL21/CCR7 contributes to the time-dependent proliferation of human NSCLC cells by upregulating cyclin A, cyclin B1, and CDK1 potentially via the ERK pathway.

Molecular mechanisms of metastasis

The mechanism of metastasis is a complex set of events that build upon each other to achieve successful growth in organ sites beyond the primary tumor. The cumulative events for metastasis of different cancers have both common and specific cancer specific events. This review discusses several key factors in different cancers that are responsible in metastasis, which includes epigenetic regulation of tumor suppressor genes, functional activity of tumor-related chemokine receptors, and circulating tumor cells.

Analysis of chemokine and chemokine receptor expression in squamous cell carcinoma of the head and neck (SCCHN) cell lines

The purpose of this work was to analyze chemokine and chemokine receptor expression in untreated and in irradiated squamous cell carcinoma of the head and neck (SCCHN) tumor cell lines, aiming at the establishment of assays to test for the relevance of chemokine and chemokine receptor expression in the response of SCCHN to radiotherapy and radiochemotherapy. Five low passage and 10 established SCCHN lines, as well as two normal cell lines, were irradiated at 2 Gy or sham-irradiated, and harvested between 1 and 48 h after treatment. For chemokines with CC and CXC structural motifs and their receptors, transcript levels of target and reference genes were quantified relatively by real-time PCR. In addition, CXCL1 and CXCL12 protein expression was analyzed by ELISA. A substantial variation in chemokine and chemokine receptor expression between SCCHN was detected. Practically, all cell lines expressed CCL5 and CCL20, while CCL2 was expressed in normal cells and in some of the tumor cell lines. CXCL1, CXCL2, CXCL3, CXCL10, and CXCL11 were expressed in the vast majority of the cell lines, while the expression of CXCL9 and CXCL12 was restricted to fibroblasts and few tumor cell lines. None of the analyzed cell lines expressed the chemokines CCL3, CCL4, or CCL19. Of the receptors, transcript expression of CCR1, CCR2, CCR3, CCR5, CCR7, CCXR2, and CCXR3 was not detected, and CCR6, CXCR1, and CXCR4 expression was restricted to few tumor cells. Radiation caused up- and down-regulation with respect to chemokine expressions, while for chemokine receptor expressions down-regulations were prevailing. CXCL1 and CXCL12 protein expression corresponded well with the mRNA expression. We conclude that the substantial variation in chemokine and chemokine receptor expression between SCCHN offer opportunities for the establishment of assays to test for the relevance of chemokine and chemokine receptor expression in the response of SCCHN to radiotherapy and radiochemotherapy.