CCR7 enhances TGF-β1-induced epithelial-mesenchymal transition and is associated with lymph node metastasis and poor overall survival in gastric cancer. Oncotarget. 2015;6:24348-24360. [PMID: 26176983 PMCID: PMC4695190 DOI: 10.18632/oncotarget.4484]

CCR7 affects the tumor microenvironment by regulating the activation of naïve CD8+ T cells to promote the proliferation of oral squamous cell carcinoma

BACKGROUND

Head and neck cancer is the sixth most common malignancy worldwide, and oral squamous cell carcinoma (OSCC) is the most common head and neck cancer, being one of the leading causes of cancer morbidity and mortality worldwide. CC Chemokine receptor 7(CCR7) is a multifunctional G protein-coupled trans-membrane chemokine that affects immune cell chemotaxis, migration, and cancer progression through its interaction with its ligands C-C motif chemokine ligand 19(CCL19) and C-C motif chemokine ligand 21(CCL21). Numerous studies have demonstrated the involvement of CCR7 in the malignant progression of a variety of cancers, reflecting the pro-cancer properties of CCR7. The Cancer Genome Atlas data suggests CCR7 has elevated expression in oral cancer. Specifically, CCR7 expression in tumor microenvironment (TME) may regulate the ability of some immune cells to engage in anti-tumor immune responses. Since CD8+ T cells have become a key immunotherapeutic target, the role of CCR7 in antitumor immune response of naïve CD8+ T cells in TME has not been thoroughly investigated.

METHODS

A CCR7 knockout mouse model was constructed, and the mechanism of ccr7 on the regulation of tumor microenvironment by naïve CD8+ T cells was verified under the guidance of single-cell RNA sequencing combined with in vivo animal experiments and in vitro cell experiments.

RESULTS

CCR7 is knocked out with impaired tumor growth and altered CD8+ T cell profiles, revealing the importance of this protein in OSCC.

CONCLUSIONS

Inhibition of CCR7 enhances CD8+ T cell activation, proliferation, and anti-tumor function, suggesting its potential as a therapeutic target.

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

CCR7 Mediates Cell Invasion and Migration in Extrahepatic Cholangiocarcinoma by Inducing Epithelial-Mesenchymal Transition

The epithelial-mesenchymal transition (EMT) contributes to the metastatic cascade in various tumors. C-C chemokine receptor 7 (CCR7) interacts with its ligand, chemokine (C-C motif) ligand 19 (CCL19), to promote EMT. However, the association between EMT and CCR7 in extrahepatic cholangiocarcinoma (EHCC) remains unknown. This study aimed to elucidate the prognostic impact of CCR7 expression and its association with clinicopathological features and EMT in EHCC. The association between CCR7 expression and clinicopathological features and EMT status was examined via the immunohistochemical staining of tumor sections from 181 patients with perihilar cholangiocarcinoma. This association was then investigated in TFK-1 and EGI-1 EHCC cell lines. High-grade CCR7 expression was significantly associated with a large number of tumor buds, low E-cadherin expression, and poor overall survival. TFK-1 showed CCR7 expression, and Western blotting revealed E-cadherin downregulation and vimentin upregulation in response to CCL19 treatment. The wound healing and Transwell invasion assays revealed that the activation of CCR7 by CCL19 enhanced the migration and invasion of TFK-1 cells, which were abrogated by a CCR7 antagonist. These results suggest that a high CCR7 expression is associated with an adverse postoperative prognosis via EMT induction and that CCR7 may be a potential target for adjuvant therapy in EHCC.

An Update of G-Protein-Coupled Receptor Signaling and Its Deregulation in Gastric Carcinogenesis

G-protein-coupled receptors (GPCRs) belong to a cell surface receptor superfamily responding to a wide range of external signals. The binding of extracellular ligands to GPCRs activates a heterotrimeric G protein and triggers the production of numerous secondary messengers, which transduce the extracellular signals into cellular responses. GPCR signaling is crucial and imperative for maintaining normal tissue homeostasis. High-throughput sequencing analyses revealed the occurrence of the genetic aberrations of GPCRs and G proteins in multiple malignancies. The altered GPCRs/G proteins serve as valuable biomarkers for early diagnosis, prognostic prediction, and pharmacological targets. Furthermore, the dysregulation of GPCR signaling contributes to tumor initiation and development. In this review, we have summarized the research progress of GPCRs and highlighted their mechanisms in gastric cancer (GC). The aberrant activation of GPCRs promotes GC cell proliferation and metastasis, remodels the tumor microenvironment, and boosts immune escape. Through deep investigation, novel therapeutic strategies for targeting GPCR activation have been developed, and the final aim is to eliminate GPCR-driven gastric carcinogenesis.

Secretome of senescent hepatoma cells modulate immune cell fate by macrophage polarization and neutrophil extracellular traps formation

Presence of dysfunctional senescent hepatocytes is a hallmark feature of liver cirrhosis which finally culminates in liver cancer. We now report the presence of senescent hepatocytes (p21 and p53 positive) in the vicinity of infiltrated immune cells in hepatocellular carcinoma tissue specimens by immunohistochemistry. Hence, we evaluated in vitro, the relevance of senescent hepatoma cells in altering the fate of monocytes and neutrophils by assaying for macrophage polarization and extracellular trap (NETs) formation, respectively. Premature senescence was induced in hepatoma cells (HepG2 and Huh7 cells) by treating cells with doxorubicin. Senescent hepatoma cells showed strong inflammatory phenotype with induced expression of cytokines (IL1β, IL6, IL8 and IL13) as evaluated by flow cytometry. The senescent secretome from hepatoma cells when incubated with healthy monocytes caused it to differentiate predominantly towards M2 fate (CD80^low CD86^low CD163^high CD206^high) when analysed by flow cytometry. This was corroborated by the finding in clinical samples where human hepatocellular carcinoma harbouring senescent hepatocytes showed presence of M2 macrophages, while M1 macrophages were predominant in non-tumorous region. Additionally, the senescent secretome from Huh7 cells enhanced the NETs formation, while HepG2 secretome had an inhibitory effect. In conclusion, the "pro-inflammatory" senescent secretome drives non-inflammatory type M2 macrophage polarization and modulated neutrophil traps which in turn can influence the tumor microenvironment.

C-C Chemokine Receptor 7 in Cancer

C-C chemokine receptor 7 (CCR7) was one of the first two chemokine receptors that were found to be upregulated in breast cancers. Chemokine receptors promote chemotaxis of cells and tissue organization. Since under homeostatic conditions, CCR7 promotes migration of immune cells to lymph nodes, questions immediately arose regarding the ability of CCR7 to direct migration of cancer cells to lymph nodes. The literature since 2000 was examined to determine to what extent the expression of CCR7 in malignant tumors promoted migration to the lymph nodes. The data indicated that in different cancers, CCR7 plays distinct roles in directing cells to lymph nodes, the skin or to the central nervous system. In certain tumors, it may even serve a protective role. Future studies should focus on defining mechanisms that differentially regulate the unfavorable or beneficial role that CCR7 plays in cancer pathophysiology, to be able to improve outcomes in patients who harbor CCR7-positive cancers.

Cytokine Interaction With Cancer-Associated Fibroblasts in Esophageal Cancer

Esophageal cancer (EC) is a highly aggressive cancer with poor outcomes under current treatment regimens. More recent findings suggest stroma elements, specifically cancer-associated fibroblasts (CAFs), play a role in disease occurrence and progression. Cancer-associated fibroblasts are largely the product of converted fibroblasts, but a variety of other local cell types including epithelial cells, endothelial cells, and mesenchymal cells have also been shown to transform to CAFs under the correct conditions. Cancer-associated fibroblasts primarily function in the communication between the tumor microenvironment and cancer cells via cytokine and chemokine secretions that accentuate immunosuppression and cancer growth. Cancer-associated fibroblasts also pose issues for EC treatment by contributing to resistance of current chemotherapeutics like cisplatin. Targeting this cell type directly proves difficult given the heterogeneity between CAFs subpopulations, but emerging research provides hope that treatment is on the horizon. This review aims to unravel some of the complexities surrounding CAFs’ impact on EC growth and therapy.

Expression of the Chemokine Receptor CCR7 in the Normal Adrenal Gland and Adrenal Tumors and Its Correlation with Clinical Outcome in Adrenocortical Carcinoma

BACKGROUND

The chemokine receptor CCR7 is crucial for an intact immune function, but its expression is also associated with clinical outcome in several malignancies. No data exist on the expression of CCR7 in adrenocortical tumors.

METHODS

CCR7 expression was investigated by qRT-PCR and immunohistochemistry in 4 normal adrenal glands, 59 adrenocortical adenomas, and 181 adrenocortical carcinoma (ACC) samples.

RESULTS

CCR7 is highly expressed in the outer adrenocortical zones and medulla. Aldosterone-producing adenomas showed lower CCR7 protein levels (H-score 1.3 ± 1.0) compared to non-functioning (2.4 ± 0.5) and cortisol-producing adenomas (2.3 ± 0.6), whereas protein expression was variable in ACC (1.8 ± 0.8). In ACC, CCR7 protein expression was significantly higher in lymph node metastases (2.5 ± 0.5) compared to primary tumors (1.8±0.8) or distant metastases (2.0 ± 0.4; p < 0.01). mRNA levels of CCR7 were not significantly different between ACCs, normal adrenals, and adrenocortical adenomas. In contrast to other tumor entities, neither CCR7 protein nor mRNA expression significantly impacted patients' survival.

CONCLUSION

We show that CCR7 is expressed on mRNA and protein level across normal adrenals, benign adrenocortical tumors, as well as ACCs. Given that CCR7 did not influence survival in ACC, it is probably not involved in tumor progression, but it could play a role in adrenocortical homeostasis.

The relation between ACKR4 and CCR7 genes expression and breast cancer metastasis

AIMS

Breast cancer is the most severe malignant tumor in women. Chemokines and their receptors appear to be implicated in tumorigenesis and metastatic pattern. Also the scavenger atypical chemokine receptors are emerging as crucial regulators for the availability of chemokines. Therefore the aim of the present study is to evaluate the expression of CCR7, ACKR4 and their ligand; CCL21 in human breast cancer.

MAIN METHODS

In this study, RT-PCR was done to detect the expression of CCR7 and ACKR4 in 50 non-metastatic and 30 metastatic breast cancer tissue. Also CCL21 level in the serum of study group was detected by ELISA. The expression of all markers is compared to 80 control healthy individual.

KEY FINDINGS

Our results revealed the increase in expression of CCR7 and CCL21 level in metastatic group compared to non-metastatic and control groups while ACKR4 expression is significantly increased in breast tissues of non-metastatic patients compared to both control and metastatic groups. Also there was significant positive correlation between CCR7 expression and CCL21 level in cancer patients and significant negative correlation between ACKR4 and both CCR-7 and CCL21 in both non-metastatic and metastatic cancer groups.

SIGNIFICANCE

Thus, it might be elucidating that ACKR4 and CCR7 could be a novel target for tumor therapy as targeting the chemokine-receptors axis might represent a powerful tool to prevent infiltration and metastasis and consequently improve cancer prognosis and treatment.

Cytokine-chemokine network driven metastasis in esophageal cancer; promising avenue for targeted therapy

Esophageal cancer (EC) is a disease often marked by aggressive growth and poor prognosis. Lack of targeted therapies, resistance to chemoradiation therapy, and distant metastases among patients with advanced disease account for the high mortality rate. The tumor microenvironment (TME) contains several cell types, including fibroblasts, immune cells, adipocytes, stromal proteins, and growth factors, which play a significant role in supporting the growth and aggressive behavior of cancer cells. The complex and dynamic interactions of the secreted cytokines, chemokines, growth factors, and their receptors mediate chronic inflammation and immunosuppressive TME favoring tumor progression, metastasis, and decreased response to therapy. The molecular changes in the TME are used as biological markers for diagnosis, prognosis, and response to treatment in patients. This review highlighted the novel insights into the understanding and functional impact of deregulated cytokines and chemokines in imparting aggressive EC, stressing the nature and therapeutic consequences of the cytokine-chemokine network. We also discuss cytokine-chemokine oncogenic potential by contributing to the Epithelial-Mesenchymal Transition (EMT), angiogenesis, immunosuppression, metastatic niche, and therapeutic resistance development. In addition, it discusses the wide range of changes and intracellular signaling pathways that occur in the TME. Overall, this is a relatively unexplored field that could provide crucial insights into tumor immunology and encourage the effective application of modulatory cytokine-chemokine therapy to EC.

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.

Lymphatic Metastasis of NSCLC Involves Chemotaxis Effects of Lymphatic Endothelial Cells through the CCR7-CCL21 Axis Modulated by TNF-α

Metastasis and recurrence are the main causes of lung adenocarcinoma patients’ death. Lymphatic metastasis is the main way of non-small cell lung cancer (NSCLC) metastasis. C-C chemokine receptor type 7 (CCR7) overexpression has been demonstrated to mediate occurrence and progression of NSCLC. Moreover, Chemokine ligand 21 (CCL21) was used to activate CCR7. The CCR7–CCL21 axis is one of the most common “chemokine-receptor” modes of action in the development and metastasis of multiple tumors. However, the role of the CCR7–CCL21 axis in lymphatic metastasis of NSCLC is poorly understood. The study was conducted to investigate the molecular mechanism underlying CCR7–CCL21 axis-mediated lymphatic metastasis of NSCLC A549 cells. Tumor necrosis factor α (TNF-α) could regulate the tumor microenvironment balance by promoting chemokine secretion. Our study demonstrated that TNF-α promoted CCL21 production in human lymphatic endothelial cells (HLEC). Results further showed that TNF-α significantly activated the NF-κB pathway in HLEC. NF–κB pathway inhibition with ammonium pyrrolidinedithiocarbamate (PDTC) caused a significant decrease in CCL21 secretion, suggesting that TNF-α-induced CCL21 secretion in HLEC was through NF–κB pathway. Co-culture of A549 cells and TNF-α-treated HLEC confirmed that the metastasis of A549 cells was enhanced, meanwhile, apoptosis-related proteins were hardly affected. The data proved that a co-culture system prevented cell apoptosis while inducing the lymphatic metastasis of A549 cells. However, the situation was reversed after neutralizing CCL21 expression, suggesting that TNF-α-induced CCL21 secretion in HLEC is involved in A549 cells metastasis. Collectively, our finding demonstrated that NF-κB pathway-controlled CCL21 secretion of HLEC contributing to the lymphatic metastasis of A549 cells via the CCR7–CCL21 axis, validating the CCR7–CCL21 axis as a potential target to inhibit metastasis of NSCLC.

Hypoxia Alters the Expression of CC Chemokines and CC Chemokine Receptors in a Tumor-A Literature Review

Hypoxia, i.e., oxygen deficiency condition, is one of the most important factors promoting the growth of tumors. Since its effect on the chemokine system is crucial in understanding the changes in the recruitment of cells to a tumor niche, in this review we have gathered all the available data about the impact of hypoxia on β chemokines. In the introduction, we present the chronic (continuous, non-interrupted) and cycling (intermittent, transient) hypoxia together with the mechanisms of activation of hypoxia inducible factors (HIF-1 and HIF-2) and NF-κB. Then we describe the effect of hypoxia on the expression of chemokines with the CC motif: CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL24, CCL25, CCL26, CCL27, CCL28 together with CC chemokine receptors: CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10. To better understand the effect of hypoxia on neoplastic processes and changes in the expression of the described proteins, we summarize the available data in a table which shows the effect of individual chemokines on angiogenesis, lymphangiogenesis, and recruitment of eosinophils, myeloid-derived suppressor cells (MDSC), regulatory T cells (T_reg), and tumor-associated macrophages (TAM) to a tumor niche.

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.

Ets-1 enhances tumor migration through regulation of CCR7 expression

Ets-1 is a prototype of the ETS protein family. Members of the ETS protein family contain a unique ETS domain. Ets-1 is associated with cancer progression and metastasis in many types of cancer. Many studies have shown a link between elevated expression of Ets-1 in cancer biopsies and poor survival. CCR7 is a chemokine that binds to specific ligand CCL21/CCL19. CCR7 expression is associated with tumor metastasis and infiltration into lymph nodes. The objective of this study was to test whether Ets-1 could regulate CCR7 expression and enhance tumor metastasis. Our data showed that CCR7 expression was downregulated in Ets-1-deficient T cells upon T-cell stimulation. Overexpression of Ets-1 increased CCR7 expression in breast cancer cell lines. In contrast, knockdown of Ets-1 reduced CCR7 expression. Ets-1 could directly bind to CCR7 promoter and mediate CCR7 expression in luciferase reporter assays and chromatin immunoprecipitation assays. Transactivation activity of Ets-1 was independent of the Pointed domain of Ets-1. Ets-1 could also enhance NF-κB and CBP transactivation of CCR7 promoter. Our results also showed that Ets-1 could modulate cancer cell transmigration by altering CCR7 expression in transwell assay and wound healing assay. Taken together, our data suggest that Ets-1 can enhance CCR7 expression and contribute to tumor cell migration.

Gastric Tumor Microenvironment

A compelling body of evidence has demonstrated that gastric cancer has a very particular tumor microenvironment, a signature very suitable to promote tumor progression and metastasis. Recent investigations have provided new insights into the multiple molecular mechanisms, defined by genetic and epigenetic mechanisms, supporting a very active cross talk between the components of the tumor microenvironment and thus defining the fate of tumor progression. In this review, we intend to highlight the role of very active contributors at gastric cancer TME, particularly cancer-associated fibroblasts, bone marrow-derived cells, tumor-associated macrophages, and tumor-infiltrating neutrophils, all of them surrounded by an overtime changing extracellular matrix. In addition, the very active cross talk between the components of the tumor microenvironment, defined by genetic and epigenetic mechanisms, thus defining the fate of tumor progression, is also reviewed.

CCR7 high expression leads to cetuximab resistance by cross-talking with EGFR pathway in PI3K/AKT signals in colorectal cancer

Cetuximab (C225), an anti-Epidermal Growth Factor receptor (EGFR) monoclonal antibody, has been widely used as a routine treatment for patients with metastatic colorectal cancer (mCRC); However, many patients who initially respond to cetuximab acquire resistance. The purpose of this study was to characterize new mechanism of acquired Cetuximab resistance. Firstly, tissue microarrays (TMA) comprising 191 CRC patients was constructed to evaluate the expression of chemokine receptor 7 (CCR7) by using immunohistochemistry (IHC). In CRC tumor tissues, CCR7 was significantly over-expressed compared with paired normal tissues (P < 0.001), and correlated with the infiltration depth (P = 0.03) and the regional lymph node metastasis (P = 0.006). Significant differences were also found in forms of overall survival (OS) and disease-free survival (DFS) between normal and tumor tissues (P < 0.001). More interestingly, EGFR was also highly expressed and co-localized with CCR7 in the tumor tissues from the patients who were insensitive to Cetuximab treatment. Secondly, we further explored the relationship between CCR7 expression and Cetuximab resistance by two CCR7 positive CRC cell lines, Caco-2 with wild-type KRAS (KRAS^wt ) and HCT116 with mutated KRAS (KRAS^G13D ). By the treatment of secondary lymphoid tissue chemokine (SLC, an exogenous high-affinity legend of CCR7), the inhibition rate of Cetuximab significantly decreased in both cells. Furthermore, the activation of SLC/CCR7 axis promoted epithelial mesenchymal transformation (EMT) in CRC tumor cells by increasing the expression of Twist and β-catenin. By using of CCR7 neutralizing antibody and p-AKT inhibitor rescued the above effects. These findings suggested that CCR7 was a key factor in those CRC patients, who have poorer reaction to Cetuximab. So combined inhibition of CCR7 and p-AKT will represent a rational therapeutic strategy for Cetuximab resistance patients.

The Role of TGF-β and Its Receptors in Gastrointestinal Cancers

Early detection of gastrointestinal tumors improves patient survival. However, patients with these tumors are typically diagnosed at an advanced stage and have poor prognosis. The incidence and mortality of gastrointestinal cancers, including esophageal, gastric, liver, colorectal, and pancreatic cancers, are increasing worldwide. Novel diagnostic and therapeutic agents are required to improve patient survival and quality of life. The tumor microenvironment, which contains nontumor cells, signaling molecules such as growth factors and cytokines, and extracellular matrix proteins, plays a critical role in cancer cell proliferation, invasion, and metastasis. Transforming growth factor beta (TGF-β) signaling has dual roles in gastrointestinal tumor development and progression as both a tumor suppressor and tumor promoter. Here, we review the dynamic roles of TGF-β and its receptors in gastrointestinal tumors and provide evidence that targeting TGF-β signaling may be an effective therapeutic strategy.

Meta-analysis of the prognostic value of C-C chemokine receptor type 7 in patients with solid tumors

Background

Expression of C-C chemokine receptor type 7 (CCR7) is associated with the prognosis of several cancers. The aim of this study was to conduct the meta-analysis to determine the prognostic value of CCR7 expression in solid tumors.

Materials and methods

We searched for relevant literature in the PubMed, Embase, and Cochrane Library databases (last updated on January 15, 2018). The associations of CCR7 expression with overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS), progress-free survival (PFS), and disease-specific survival (DSS) were estimated.

Results

In total, 30 qualified studies including 3,413 patients were enrolled. The results revealed that higher expression of CCR7 predicted poorer OS (pooled HR =1.79; 95% CI =1.49–2.16; P<0.001) and PFS (pooled HR =2.18; 95% CI =1.49–3.18; P<0.001), but was not associated with DFS (pooled HR =1.69; 95% CI =0.79–3.61; P=0.175), RFS (pooled HR =1.29; 95% CI =0.48–3.44; P=0.618), or DSS (pooled HR =3.06; 95% CI =0.38–24.83; P<0.294).

Conclusion

From this meta-analysis, we concluded that high expression of CCR7 in tumor tissue is associated with poor survival in patients with solid tumors, and may be a prognostic biomarker for tumor progression.

MicroRNA-506 inhibits tumor growth and metastasis in nasopharyngeal carcinoma through the inactivation of the Wnt/β-catenin signaling pathway by down-regulating LHX2

Background

Epithelial-mesenchymal transition (EMT)-associated proteins play key roles in cancer progression and metastasis with the involvement of microRNAs (miRNAs). This study aims to assess the role of miR-506 working in tandem with LIM Homeobox 2 (LHX2) in EMT and metastasis through the Wnt/β-catenin signaling pathway in nasopharyngeal carcinoma (NPC).

Methods

Differentially expressed genes associated with NPC were screened using microarray analyses, from which LHX2 was identified. Next, the potential relationship between miR-506 and LHX2 was analyzed. In order to explore the effect of miR-506 or LHX2 on NPC cell proliferation, migration, invasion and apoptosis, serials of mimics, inhibitors or siRNA against LHX2 were transfected into NPC cells. Then, the expression patterns of LHX2, Wnt1, β-catenin, E-cadherin, Vimentin, TCF4 and Twist were determined to assess the influence of miR-506 or LHX2 on EMT as well as the relationship between the Wnt/β-catenin signaling pathway and TCF4. The tumorigenicity and lymph node metastasis (LNM) in xenograft tumors of nude mice were observed.

Results

The has-miR-506-3p was identified as the down-regulated gene in NPC based on the microarray data while LHX2 was negatively regulated by miR-506. Over-expression of miR-506 or silencing of LHK2 inhibited NPC cell proliferation, migration, invasion, tumorigenicity and LNM but promoted apoptosis indicated by decreased Wnt1, β-catenin, Vimentin, TCF4 and Twist expressions along with increased E-cadherin expressions.

Conclusions

miR-506 inhibits tumor growth and metastasis in NPC via inhibition of Wnt/β-catenin signaling by down-regulating LHX2, accompanied by decreased TCF4. Taken together, miR-506 targeted-inhibition LHX2 presents a promising therapeutic strategy for the treatment of NPC.

Trial registration

ChiCTR1800018889. Registered 15 October 2018.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1023-4) contains supplementary material, which is available to authorized users.

High expression of CCR5 in melanoma enhances epithelial-mesenchymal transition and metastasis via TGFβ1

Chemokine receptors are highly expressed in various cancers and play crucial roles in tumor progression. However, their expression patterns and functions in melanoma are unclear. The present study aimed to identify the chemokine receptors that play critical roles in melanoma progression and unravel the underlying molecular mechanisms. We found that CCR5 was more abundant in melanoma cells than normal cells and was positively associated with tumor malignancy in clinical patients. Animal experiments suggested that CCR5 deficiency in B16/F10 or A375 cells suppressed primary tumor growth and lung metastasis, whereas CCR5 overexpression in B16/F0 cells enhanced primary tumor growth and lung metastasis. CCR5 played a critical role in proliferation and migration of melanoma cells in vitro. Importantly, CCR5 was required for maintenance of the mesenchymal phenotype of metastatic melanoma cells. Mechanistically, CCR5 positively regulated expression of TGFβ1, which in turn induced epithelial-mesenchymal transition and migration via PI3K/AKT/GSK3β signaling. Collectively, our results establish a critical role of CCR5 expressed by melanoma cells in cancer progression and reveal the novel mechanisms controlling this process, which suggests the prognostic value of CCR5 in melanoma patients and provides novel insights into CCR5-targeted strategies for melanoma treatment. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Loss of atypical chemokine receptor 4 facilitates C-C motif chemokine ligand 21-mediated tumor growth and invasion in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a common malignant disease that is prevalent in Asian countries. Atypical chemokine receptor 4 (ACKR4) binds to various chemokines, including C-C motif chemokine ligand (CCL)19, CCL21, CCL25 and C-X-C motif chemokine ligand 13, without inducing downstream signaling transduction. However, the role of ACKR4 in modulating NPC development remains unclear. In the present study, the effects of ACKR4 on NPC growth, invasion and metastasis were investigated, as well as the endogenous mechanisms through which ACKR4 mediates NPC development. The results demonstrated that ACKR4 was downregulated in human NPC tumor tissues, as compared with that in adjacent normal tissue. In a subcutaneous tumor animal model, the knockdown of ACKR4 enhanced NPC invasion and metastasis. Furthermore, CCL21 was accumulated in ACKR4 knockdown tumors. In vitro, the loss of ACKR4 increased CCL21-mediated SUNE-1 cell proliferation, epithelial-mesenchymal transition and invasion. In conclusion, the loss of ACKR4 promoted CCL21-mediated NPC development; thus, neutralizing CCL21 in NPC with low ACKR4 expression may be a novel treatment strategy.

CC chemokine receptor 7 promotes triple-negative breast cancer growth and metastasis

Metastasis is the leading cause of breast cancer-related death. Chemokine (C-C motif) receptor 7 (CCR7) plays important roles in breast cancer metastasis. However, the role of CCR7 in triple-negative breast cancer (TNBC) has not been fully elucidated. In this study, we found that CCR7 is highly expressed in both TNBC cell lines and breast cancer tissues. CCR7 was knocked down by shRNA in 4T1 and MDA-MB-231, two TNBC cell lines, and we found that the depletion of CCR7 significantly decreased TNBC cell proliferation, migration and invasion in vitro. Furthermore, we confirmed that the knockdown of CCR7 reduced the distant metastasis of 4T1 cells in an orthotopic mouse model. Proteomic analysis in 4T1 cells indicated that several signaling pathways such as epithelial cell adhesion molecule might contribute to CCR7's function in breast cancer metastasis. Our results suggest that CCR7 promotes TNBC metastasis and may serve as a target for breast cancer diagnosis and treatment.

CCR7 preservation via histone deacetylase inhibition promotes epithelial-mesenchymal transition of hepatocellular carcinoma cells

The effects of Histone deacetylase (HDAC) inhibition on epithelial-mesenchymal transition (EMT) differs in various types of cancers. However, its function in hepatocellular carcinoma (HCC) is not well-explored. In this study, we investigated the effect of HDAC inhibition on EMT in HCC cells by using trichostatin A (TSA) and valproic acid (VPA). The results showed that TSA/VPA significantly induced EMT phenotype, as demonstrated by the decreased level of E-cadherin, increased level of N-cadherin, vimentin, Twist and snail, and enhanced capacity of cell migration and invasion. In addition, CCR7 was speculated and confirmed as a function target of HDAC inhibition. CCR7 promotes the progression of HCC and is associated with poor survival. Knockdown of CCR7 significantly attenuated the effect of TSA on EMT. Moreover, our results demonstrated that HDAC inhibition up-regulates CCR7 via reversing the promoter hypoacetylation and increasing CCR7 transcription. Taken together, our study has identified the function of HDAC in EMT of HCC and suggested a novel mechanism through which TSA/VPA exerts its carcinogenic roles in HCC. HDAC inhibitors require careful caution before their application as new anticancer drugs.

CCR7 regulates ANO6 to promote migration of pancreatic ductal adenocarcinoma cells via the ERK signaling pathway

The increase in migratory ability of pancreatic ductal adenocarcinoma cells is a key event in the development of metastasis to the lymph nodes and distant organs. Although the C-C motif chemokine receptor 7 (CCR7) and its ligand, C-C motif chemokine ligand 21 (CCL21), have been revealed to serve an important role in tumor migration, their precise roles and potential underlying mechanisms remain largely unknown. The present study revealed that overexpression of CCR7 significantly promoted BxPC-3 cell migration, accompanied by the induction of anoctamin 6 (ANO6) expression, indicating that ANO6 is a downstream target of CCR7 signaling. Furthermore, the level of phosphorylated extracellular signal-regulated kinase (ERK) was significantly increased in CCR7-overexpressing BxPC-3 cells, indicating that ERK may be a potential mediator of CCR7-regulated ANO6 expression in BxPC-3 cells. To characterize the receptor-mediated pathway, a specific ERK inhibitor, U0126, was used, which reduced BxPC-3 cell migration and the expression of ANO6. In summary, the results of the present study demonstrate that CCR7 promoted BxPC-3 cell migration by regulating ANO6 expression perhaps via activation of the ERK signaling pathway.

Molecular alterations of cancer cell and tumour microenvironment in metastatic gastric cancer

The term metastasis is widely used to describe the endpoint of the process by which tumour cells spread from the primary location to an anatomically distant site. Achieving successful dissemination is dependent not only on the molecular alterations of the cancer cells themselves, but also on the microenvironment through which they encounter. Here, we reviewed the molecular alterations of metastatic gastric cancer (GC) as it reflects a large proportion of GC patients currently seen in clinic. We hope that further exploration and understanding of the multistep metastatic cascade will yield novel therapeutic targets that will lead to better patient outcomes.

Molecular background of the regional lymph node metastasis of gastric cancer

Gastric cancer (GC) is one of the deadliest types of cancer in the world. Lymph node (LN) metastasis is a complex and malignant behavior of GC, involving a sequence of biological processes, including decreased adherence to adjacent cells, extracellular matrix (ECM) degradation and lymphatic channel permeation. LN metastasis is directly associated with the treatment response, local recurrence and long-term survival of patients with GC. Therefore, the molecular mechanisms of LN metastasis in GC development require further investigation. Recently, a large number of clinical studies have focused on the molecular mechanisms and biological markers of tumor invasion and metastasis. However, few articles have broadly summarized LN metastasis in GC, and the molecular mechanisms of LN metastasis are not yet fully understood. In the present review, the molecular mechanisms of LN metastasis in GC will be discussed, including the following aspects: Cell adhesion and movement, ECM degradation, new vessel formation, and molecular pattern differences between metastatic LNs and the primary tumor. This review may lead to a better understanding of LN metastasis in GC, and the identification of new diagnostic markers.

C-C motif chemokine receptors in gastric cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-associated mortality worldwide. Despite recent advances in molecular and clinical research, patients with gastric cancer at an advanced stage have a dismal prognosis and poor survival rates, and systemic treatment relies predominantly on traditional cytotoxic chemotherapy. To improve patients' quality of life and survival, an improved understanding of the complex molecular mechanisms involved in gastric cancer progression and treatment resistance, and of its clinical application in the development of novel targeted therapies, is urgently required. Chemokines are a group of small chemotactic cytokines that interact with seven-transmembrane G-protein-coupled receptors, and this interaction serves a crucial role in various physiological processes, including organ development and the host immune response, to recruit cells to specific sites in the body. There is also accumulating evidence that chemokines and chemokine receptors (CCRs) contribute to tumor development and progression, as well as metastasis. However, research regarding the functional roles of chemokines and their receptors in cancer is dynamic and context-dependent, and much remains to be elucidated, although various aspects have been explored extensively. In gastric cancer, C-C motif CCRs are involved in the biological behavior of tumor cells, including the processes of growth, invasion and survival, as well as the epithelial-mesenchymal transition. In the present review, attention is given to the clinical relevance of C-C motif CCRs in the development, progression, and metastasis of gastric cancer, particularly CCR7 and CCR5, which have been investigated extensively, as well as their potential therapeutic implications.

Soluble interleukin‑2 receptor as a factor associated with angiogenesis in gastric cancer

Angiogenesis serves a role in the growth, metastasis and prognosis of tumors. The aim of the present study was to evaluate the angiogenic ability and clinical significance of the immune biomarker soluble interleukin‑2 receptor (sIL‑2R) in gastric cancer (GC) patients. Serum levels of sIL‑2R were measured in 35 GC patients with different stages of disease and 32 healthy individuals, and it was investigated whether the levels were associated with angiogenesis factors, including vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)‑β1. Human umbilical vein endothelial cells (HUVECs) were pretreated with or without recombinant human (rh)sIL‑2R, VEGF and TGF‑β1 for 24 h, and then the HUVECSs were harvested to determine the degree of angiogenesis. The supernatants were also collected for VEGF and TGF‑β1 testing. Serum levels of sIL‑2R were higher in GC patients than in healthy individuals, as were the levels of VEGF and TGF‑β1. In addition, serum levels of sIL‑2R were positively associated with the levels of VEGF and TGF‑β1. Angiogenesis of HUVECs was also increased by rhsIL‑2R pretreatment. VEGF and TGF‑β1 secretion were also incre-ased in supernatants that were pretreated with rhsIL‑2R. The results of the present study suggested that serum levels of sIL‑2R contributes to the pathophysiology of GC progression and may be used as a prognostic biomarker for GC.

CCR7 enhances the angiogenic capacity of esophageal squamous carcinoma cells in vitro via activation of the NF-κB/VEGF signaling pathway

High levels of angiogenesis are associated with poor prognosis and a highly invasive phenotype in esophageal squamous carcinoma. C-C chemokine receptor type 7 (CCR7) is overexpressed in multiple tumor types and has been suggested to act as an oncogene and pro-angiogenic factor. This study aimed to elucidate the effect of CCR7 on the angiogenic capacity of esophageal squamous carcinoma cells in vitro. Expression of CCR7 in esophageal squamous carcinoma cell lines and normal human esophageal epithelial cell line was examined by western blotting and quantitative real-time PCR. CCR7 was stably overexpressed or transiently knocked down in esophageal squamous carcinoma cell lines. Overexpressing CCR7 enhanced the capacity of esophageal squamous carcinoma cell conditioned media to induce human umbilical vein endothelial cells (HUVEC) proliferation and migration and neovascularization in the chicken chorioallantoic membrane (CAM) assay. While silencing CCR7 caused an opposite outcome. Moreover, we demonstrated that CCR7 activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling and regulated its targets, including vascular endothelial growth factor A (VEGF-A), VEGF-C, tumor necrosis factor-α (TNFα), interleukin (IL)-6, IL-8 and transforming growth factor-β (TGF-β) expression. Additionally, CCR7 down-regulation reduced tumor volume and weight in xenograft mouse model, and significantly decreased NF-κB signaling pathway. This study suggests that CCR7 plays an important pro-angiogenic role in esophageal squamous carcinoma via a mechanism linked to activation of the NF-κB pathway; CCR7 may represent a potential target for anti-angiogenic therapy in esophageal squamous carcinoma.

MicroRNA-146a promotes gastric cancer cell apoptosis by targeting transforming growth factor β-activated kinase 1

Accumulating evidence suggests that microRNA (miR)-146a functions as an oncogene or tumor suppressor in various cancers. However, the role of miR-146a in gastric cancer (GC) remains to be elucidated. The present study investigated the function of miR-146a in GC cells. The results of the present study revealed that miR-146a modulates GC cell apoptosis. Overexpression of miR-146a significantly increased apoptosis of SGC-7901 cells, whereas inhibition of miR-146a protected cells from apoptosis. miR-146a expression in GC cells was inversely correlated with transforming growth factor β-activated kinase 1 (TAK1) expression, at the mRNA and protein levels. Furthermore, small interfering RNA-mediated silencing of TAK1 enhanced GC cell apoptosis, whereas overexpression of TAK1 promoted survival of GC cells. Overexpression of miR-146a or knockdown of TAK1 led to a marked increase in inhibitor of κBα (IκBα) and a decrease in B-cell lymphoma 2 (Bcl-2) expression levels in SGC-7901 cells. By contrast, silencing of miR-146a or TAK1 overexpression downregulated IκBα and upregulated Bcl-2 expression levels. Therefore, the results of the present study demonstrated a novel negative feedback mechanism to promote GC cell apoptosis involving the miR-146a/TAK1/nuclear factor-κB axis.

CCL21/CCR7 interaction promotes cellular migration and invasion via modulation of the MEK/ERK1/2 signaling pathway and correlates with lymphatic metastatic spread and poor prognosis in urinary bladder cancer

Lymph node metastasis in patients with urinary bladder cancer (UBC) is always associated with poor prognosis and is the determinant for tumor staging and the development of treatment regimens; however, its underlying mechanisms remain to be studied. Immunohistochemical staining of tumor sections from 62 UBC patients was performed using CCR7, D2-40 and CD34 antibodies. We showed that increased CCR7 expression was significantly associated with positive lymph node status (P=0.008), pT3-T4 tumor stage (P=0.015), tumor grade (P=0.010) and worse overall survival (OS, P<0.001) and that both CCR7 expression and lymph node metastasis were independent prognostic factors for OS (P=0.031 and P=0.001, respectively) based on multivariate analysis. We found that there was a significant association between MLVD and lymph node status (P=0.006), but this relation was not observed for MVD. Furthermore, we showed that increased CCR7 expression correlated significantly with higher MLVD (P=0.014) and MVD (P=0.002). Wound-healing and Matrigel Transwell assays indicated that activation of CCR7 with CCL21 significantly enhanced the invasion and migration abilities of UM-UC-3 cells, and this enhanced effect was significantly abrogated by CCR7 knockdown using siRNA. Western blot analysis revealed that the phospho-ERK1/2 level was markedly increased when UM-UC-3 cells were treated with CCL21 and significantly decreased when the CCR7 gene was silenced. MEK/ERK1/2 inhibition with PD98059 significantly suppressed the migration and invasion abilities of UM-UC-3 cells and also significantly abrogated the effects of CCL21/CCR7 on cell migration and invasion. Based on these results, we conclude that activation of the CCL21/CCR7 chemoaxis promotes lymph node metastasis of UBC in at least two ways. Firstly, although CCR7 is a promoting factor that induces both lymphangiogenesis and angiogenesis, it may promote lymph node metastasis through its lymphangiogenic effect rather than through its angiogenic effect. Secondly, the CCL21/CCR7 chemoaxis promotes the migration and invasion of UBC cells via the MEK/ERK1/2 signaling pathway rather than the PI3K/AKT pathway.

CCR7 mediates human breast cancer cell invasion, migration by inducing epithelial-mesenchymal transition and suppressing apoptosis through AKT pathway

Chemokine and the chemokine receptor have a key role in the tumor progress. Here, we supposed that CCR7 might induce the invasion, migration, and epithelial–mesenchymal transition (EMT) process of breast cancer. In this research, human breast cancer MCF‐7 and MDA‐MB‐231cells were treated with CCL19 and small‐interfering RNA (CCR7 siRNA) for activation and inhibition of CCR7, respectively. Cell invasion and transwell assays were used to detect the effect of CCR7 on invasion and migration. The results demonstrated that CCL19 mediated cell invasion and migration by inducing the EMT, with downregulation of E‐cadherin and up‐regulation of N‐cadherin and vimentin levels. On the other hand, knockdown of CCR7 revealed the changes compared with CCL19 group and the control group. Knockdown of CCR7 inhibits CCL19‐induced breast cancer cell proliferation, the cell cycle, migration, invasion and EMT. Moreover, we demonstrated that CCL19‐induced AKT phosphorylation; however, CCR7 siRNA suppressed CCL19‐induced AKT phosphorylation, a key regulator of tumor metastasis. In conclusion, all findings demonstrated that CCL19/CCR7 axis regulated EMT progress in breast cancer cells and mediated the tumor cell invasion and migration process via activation of AKT signal pathway. Our results suggested that CCR7 may regard as a therapeutic target for the breast cancer treatment.

SphK1 modulates cell migration and EMT-related marker expression by regulating the expression of p-FAK in colorectal cancer cells

Sphingosine kinase 1 (SphK1) plays an important role in colorectal carcinoma metastasis. However, whether SphK1 modulates epithelial-mesenchymal transition (EMT)-related marker expression and the underlying mechanisms remain unclear. In this study, in order to clarify this issue, we used various colorectal cancer (CRC) cell lines, Caco2, HT29, RKO and HCT116. Each of the cell lines was divided into 3 groups as follows: the control group, SKI-Ⅱ (SphK1 inhibitor) group and PF-562271 [focal adhesion kinase (FAK) inhibitor] group. The migratory ability of the cells was examined by Transwell chamber assay. The mRNA and protein expression levels of SphK1, FAK (p-FAK), Slug, vimentin, N-cadherin and E-cadherin were detected by PCR and western blot analysis, respectively. The results revealed that the suppression of SphK1 reduced the cell migratory ability, and decreased the expression of Slug, vimentin and N-cadherin; however, the expression of E-cadherin was increased. Moreover, the inhibition of SphK1 reduced the expression of p-FAK. The inhibition of FAK (p-FAK) also decreased the cell migratory ability, and decreased the expression of Slug, vimentin and N-cadherin, whereas the expression of E-cadherin was increased. Thus, our data suggest that SphK1 modulates the expression of EMT-related markers and cell migration by regulating the expression of p-FAK in CRC cells. Thus, SphK1 may play a functional role in mediating the EMT process in CRC.

Overexpression of SASH1 Inhibits TGF-β1-Induced EMT in Gastric Cancer Cells

The epithelial–mesenchymal transition (EMT) is considered to be one of the critical steps in gastric cancer cell invasion and metastasis. SAM- and SH3-domain containing 1 (SASH1), a member of the SLY family of signal adapter proteins, is a candidate for tumor suppression in several cancers. However, the biological role of SASH1 in gastric cancer remains largely unknown. Therefore, the purpose of this study was to investigate the impact of SASH1 on the biological behavior of gastric cancer cells treated with transforming growth factor (TGF)-β1. In the current study, we provide evidence that SASH1 was lowly expressed in human gastric cancer cells, and TGF-β1 also inhibited the expression of SASH1 in TSGH cells. We found that SASH1 inhibited TGF-β1-mediated EMT in TSGH cells, as well as cell migration and invasion. Furthermore, SASH1 obviously inhibited the phosphorylation of PI3K and Akt in TGF-β1-stimulated TSGH cells. In summary, our study is the first to show that overexpression of SASH1 inhibits TGF-β1-induced EMT in gastric cancer cells through the PI3K/Akt signaling pathway. These results suggest that SASH1 may be a potential therapeutic target for the treatment of gastric cancer.

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.

Chemokine Receptor Signaling and the Hallmarks of Cancer

The chemokines are a family of chemotactic cytokines that mediate their activity by acting on seven-transmembrane-spanning G protein-coupled receptors. Both the ability of the chemokines and their receptors to form homo- and heterodimers and the promiscuity of the chemokine-chemokine receptor interaction endow this protein family with enormous signaling plasticity and complexity that are not fully understood at present. Chemokines were initially identified as essential regulators of homeostatic and inflammatory trafficking of innate and adaptive leucocytes from lymphoid organs to tissues. Chemokines also mediate the host response to cancer. Nevertheless, chemokine function in this response is not limited to regulating leucocyte infiltration into the tumor microenvironment. It is now known that chemokines and their receptors influence most-if not all-hallmark processes of cancer; they act on both neoplastic and untransformed cells in the tumor microenvironment, including fibroblasts, endothelial cells (blood and lymphatic), bone marrow-derived stem cells, and, obviously, infiltrating leucocytes. This review begins with an overview of chemokine and chemokine receptor structure, to better define how chemokines affect the proliferation, survival, stemness, and metastatic potential of neoplastic cells. We also examine the main mechanisms by which chemokines regulate tumor angiogenesis and immune cell infiltration, emphasizing the pro- and antitumorigenic activity of this protein superfamily in these interrelated processes.

PEG10 is imperative for TGF-β1-induced epithelial‑mesenchymal transition in hepatocellular carcinoma

Substantial evidence indicates that transforming growth factor-beta 1 (TGF-β1) plays a vital role in epithelial-mesenchymal transition (EMT). PEG10 has been shown involved in invasion and metastasis of tumors. The present study investigated the role of PEG10 in TGF-β1-triggered EMT in hepatocellular carcinoma (HCC) progression. Immunohistochemistry and real-time PCR were used to measure the expression level of PEG10 in clinical HCC tissues with or without lymph node metastasis, and normal tissues. The results showed that PEG10 expression is higher in HCC tissues and associated with overall survival (OS) and lymph node metastasis. Moreover, PEG10 expression level was remarkably higher in hepatic cancer cells than the normal hepatic cell line L02. In the present study, we constructed an adenovirus vector containing the coding area of PEG10 (Ad-PEG10) and infected HepG2 cells and found that overexpression of PEG10 promoted the cell migration, invasion ability and EMT of HepG2 cells. TGF-β1 acted on HepG2 cells by enhancing cell migration, invasion, EMT and upregulating PEG10 expression level. However, cells pretreated with adenovirus vector of PEG10 shRNAs (Ad-shRNA1 and Ad-shRNA2) did not occur EMT prior to TGF-β1 stimulation. Moreover, TGF-β1 did not increase the migration and invasion of cells with PEG10 knockdown and overexpression of PEG10 confers chemoresistance to HepG2 cells. Accordingly, sufficient PEG10 expression level is essential for TGF-β1 induced EMT and associated with the chemoresistance in HepG2 cells.

TP53INP1 3'-UTR functions as a ceRNA in repressing the metastasis of glioma cells by regulating miRNA activity

OBJECTIVES

To explore the effects of the competitive endogenous RNA (ceRNA) network between TP53INP1 and E-cadherin on the invasion and migration of glioma.

RESULTS

TP53INP1 and E-cadherin mRNA and protein were significantly overexpressed in normal brain tissues compared with glioma tissue specimens and correlated with the grades of glioma negatively. The expression of TP53INP1 and E-cadherin were correlated positively. Patients with higher TP53INP1 or E-cadherin expression had longer overall survival. Moreover, TP53INP1 3'-UTR inhibited glioma cell proliferation, invasion and proliferation; Furthermore, the 3'-UTRs of TP53INP1 and E-cadherin harboured seven identical miRNAs binding sites, and TP53INP1 3'-UTR could increase the expression of E-cadherin and decrease the expression of vimentin thus repressing the epithelial-mesenchymal transition (EMT). However, the coding sequence of TP53INP1 could not increase the expression of E-cadherin and the inhibitory effect on EMT of TP53INP1 3'-UTR was reversed by the siRNA against Dicer.

CONCLUSIONS

TP53INP1 3'-UTR could inhibit the EMT, thus hindering the migration and invasion of glioma via acting as a ceRNA for E-cadherin.

Inflammatory microenvironment contributes to epithelial-mesenchymal transition in gastric cancer

Gastric cancer (GC) is the fifth most common malignancy in the world. The major cause of GC is chronic infection with Helicobacter pylori (H. pylori). Infection with H. pylori leads to an active inflammatory microenvironment that is maintained by immune cells such as T cells, macrophages, natural killer cells, among other cells. Immune cell dysfunction allows the initiation and accumulation of mutations in GC cells, inducing aberrant proliferation and protection from apoptosis. Meanwhile, immune cells can secrete certain signals, including cytokines, and chemokines, to alter intracellular signaling pathways in GC cells. Thus, GC cells obtain the ability to metastasize to lymph nodes by undergoing the epithelial-mesenchymal transition (EMT), whereby epithelial cells lose their epithelial attributes and acquire a mesenchymal cell phenotype. Metastasis is a leading cause of death for GC patients, and the involved mechanisms are still under investigation. In this review, we summarize the current research on how the inflammatory environment affects GC initiation and metastasis via EMT.

DEC2 suppresses tumor proliferation and metastasis by regulating ERK/NF-κB pathway in gastric cancer

Differentiated embryonic chondrocyte expressed gene 2 (DEC2; BHLHE41/Sharp1) is a helix-loop-helix (bHLH) transcription factor, and its deregulation has been observed in several tumors. However, this gene's effects on tumor progression are controversial, and its roles in gastric cancer (GC) remain unclear. In the present study, we found that DEC2 expression level is lower in GC tissues compared with adjacent non-tumor tissues, and negatively correlated with tumor invasion, lymph node metastasis, TNM stage, and poor survival of GC patients. Positive clinical correlations of DEC2 with EMT regulator, E-cadherin, were also observed in the tissue sections. Overexpression of DEC2 inhibits cell proliferation and EMT in vitro, as well as tumor growth and metastasis in vivo. DEC2 expression also induces cell apoptosis. Furthermore, the anti-metastatic effect of DEC2 was mediated by inhibiting ERK/NF-κB/EMT axis. After treatment with ERK1/2 chemical inhibitor (U0126), DEC2's inhibitory effect on ERK/NF-κB/EMT was further decreased. Collectively, these data helped to characterize DEC2, which might be a potential molecular target for diagnostic and therapeutic approaches for GC.

MicroRNA-505 suppresses proliferation and invasion in hepatoma cells by directly targeting high-mobility group box 1

AIMS

MicroRNA-505 (miR-505) expressions have been reported to be altered in the serum of HCC patients. However, the effect and underlying mechanism of miR-505 in hepatoma cells remains poorly understood. The present study intended to investigate the expression levels and the probable role and molecular basis of miR-505 in hepatoma cells.

MAIN METHODS

Real-time PCR was used to determine the miR-505 expressions in hepatoma cell lines QGY-7703, SMMC-7721 and MHCC97. Furthermore, an up-or down-regulation of miR-505 was performed in MHCC97 by transfected with miR-505 mimics or anti-miR-505, respectively. Cell proliferation, cell invasion, and epithelial-mesenchymal transition were determined. Moreover, the target gene of miR-505 was also investigated.

KEY FINDINGS

The expressions of miR-505 were down-regulated in three hepatoma cell lines. MHCC97 possessed the lowest miR-505 levels among the three hepatoma cell lines. Furthermore, the up-regulation of miR-505 suppressed, whereas the down-regulation of miR-505 promoted proliferation, invasion and epithelial-mesenchymal transition in MHCC97. Moreover, miR-505 could directly bind to the 3'-untranslated region of High-Mobility Group Box 1. Notably, High-Mobility Group Box 1 knockdown apparently promoted cell proliferation and invasion in MHCC97.

SIGNIFICANCE

We investigated that MiR-505 regulates proliferation and invasion in MHCC97 cells via targeting High-Mobility Group Box 1.