Expression analysis and clinical significance of CXCL16/CXCR6 in patients with bladder cancer

Investigating novel biomarkers in uterine corpus endometrial carcinoma: in silico analysis and clinical specimens validation via RT-qPCR and immunohistochemistry

The rising incidence and mortality rate of Uterine Corpus Endometrial Carcinoma (UCEC) pose significant health concerns. CC and CXC chemokines have been linked to tumorigenesis and cancer progression. Recognizing the growing significance of CC and CXC chemokines' diagnostic and prognostic significance in diverse cancer types, our objective was to comprehensively analyze the diagnostic and prognostic values of hub genes from the CC and CXC chemokines in UCEC, utilizing both in silico and clinical samples and cell lines-based approaches. In silico analyses include STRING, Cytoscape, Cytohubba, The Cancer Genome Atlas (TCGA) datasets analysis via the UALCAN, GEPIA, OncoDB, and MuTarget, SurvivalGenie, MEXPRESS, cBioPoratal, TIMER, ENCORI, and DrugBank. Meanwhile, clinical samples and cell lines based analyses include Reverse transcription-quantitative polymerase chain reaction (RT-qPCR), targeted bisulfite sequencing (bisulfite-seq) analysis, and immunohistochemistry (IHC). Through present study, we identified CCL25 (CC motif chemokine ligand 25), CXCL10 (C-X-C motif chemokine ligand 10), CXCL12 (C-X-C motif chemokine ligand 12), and CXCL16 (C-X-C motif chemokine ligand 16) as crucial hub genes among the CC and CXC chemokines. Analyzing the expression data from TCGA, we observed a significant up-regulation of CCL25, CXCL10, and CXCL16 in UCEC samples compared to controls. In contrast, we noted a significant down-regulation of CXCL12 expression in UCEC samples. On clinical UCEC samples and cell lines analysis, the significant higher expression of CCL25, CXCL10, and CXCL16 and significant lower expression of CXCL12 were also denoted in UCEC samples than the controls via RT-qPCR and IHC analyses. Moreover, in silico analysis also confirmed the abnormal promoter methylation levels of the hub genes in TCGA UCEC samples, which was later validated by the clinical samples using targeted based bisulfite-seq analysis. In addition, various additional aspects of the CCL25, CXCL10, CXCL12, and CXCL16 have also been uncovered in UCEC during the present study. Our findings offer novel insights that contribute to the clinical utility of CCL25, CXCL10, CXCL12, and CXCL16 chemokines as potential diagnostic and prognostic biomarkers in UCEC.

Multiomics analysis of ferroptosis-related molecular subtypes in muscle-invasive bladder cancer immunotherapy

BACKGROUND

The purpose of this study was to identify the ferroptosis-related molecular subtypes in muscle invasive bladder cancer (MIBC) associated with the tumor microenvironment (TME) and immunotherapy.

METHODS

Expression profiles and corresponding clinical information were obtained from The Cancer Genome Atlas (TCGA) dataset and the Gene Expression Omnibus (GEO) dataset. Nonnegative matrix factorization (NMF) analysis was performed to identify two molecular subtypes based on 41 ferroptosis-related prognostic genes. The differences between the two subtypes were compared in terms of prognosis, somatic mutations, gene ontology (GO), cytokines, pathways, immune cell infiltrations, stromal/immune scores, tumor purity and response to immunotherapy. We also constructed a risk prediction model using multivariate Cox regression analysis to analyze survival data based on differentially expressed genes (DEGs) between subtypes. In combination with clinicopathological features, a nomogram was constructed to provide a more accurate prediction for overall survival (OS).

RESULTS

Two molecular subtypes (C1 and C2) of MIBC were identified according to the expression of ferroptosis-related genes. The C2 subtype manifested poor prognosis, high enrichment in the cytokine-cytokine receptor interaction pathway, high abundance of immune cell infiltration, immune/stromal scores and low tumor purity. Additionally, C2 is less sensitive to immunotherapy. The risk prediction model based on five pivotal genes (SLC1A6, UPK3A, SLC19A3, CCL17 and UGT2B4) effectively predicted the prognosis of MIBC patients.

CONCLUSIONS

A novel MIBC classification approach based on ferroptosis-related gene expression profiles was established to provide guidance for patients who are more sensitive to immunotherapy. A nomogram with a five-gene signature was built to predict the prognosis of MIBC patients, which would be more accurate when combined with clinical factors.

CXCR6-CXCL16 Axis Promotes Breast Cancer by Inducing Oncogenic Signaling

Simple Summary

Breast cancer (BrCa) is the second leading cause of cancer-related deaths in American women, and its incidence is on the rise. Insufficient understanding of the mechanisms leading to BrCa limits the effectiveness of the treatment. In this article, we show the importance of a chemokine axis-CXCR6/CXCL16 in supporting BrCa progression. We have delineated BrCa-promoting mechanisms induced by this chemokine axis at the molecular level. This work projects the therapeutic significance of CXCR6/CXCL16 signaling for the treatment of BrCa.

Abstract

Precise mechanisms underlying breast cancer (BrCa) metastasis are undefined, which becomes a challenge for effective treatments. Chemokine signaling instigates the trafficking of cancer cells in addition to leukocytes. This study aimed to ascertain the clinical and biological significance of the CXCR6/CXCL16 signaling axis in the pathobiology of BrCa. Our data show a higher expression of CXCR6 in BrCa cell lines and tissues. Stage-III BrCa tissues express significantly higher CXCR6 compared to stage-II tissues. The ligand, CXCL16, could remain tethered to the cell surface, and, after proteolytic shedding of the ectodomain, the N-terminal fragment is released, converting it to its oncogenic, soluble form. Like CXCR6, N-terminal CXCL16 and ADAM-10 were significantly higher in stage-III than stage-II, but no significant difference was observed in the C-terminal fragment of CXCL16. Further, stimulation of the CXCR6/CXCL16 axis activated Src, FAK, ERK1/2, and PI3K signaling pathways, as per antibody microarray analysis, which also underlie CXCL16-induced F-actin polymerization. The CXCR6/CXCL16 axis induces cytoskeleton rearrangement facilitating migration and invasion and supports BrCa cell survival by activating the PI3K/Akt pathway. This study highlights the significance of the CXCR6/CXCL16 axis and ADAM10 as potential therapeutic targets for advanced-stage BrCa.

The Role of CXCL16 in the Pathogenesis of Cancer and Other Diseases

CXCL16 is a chemotactic cytokine belonging to the α-chemokine subfamily. It plays a significant role in the progression of cancer, as well as the course of atherosclerosis, renal fibrosis, and non-alcoholic fatty liver disease (NAFLD). Since there has been no review paper discussing the importance of this chemokine in various diseases, we have collected all available knowledge about CXCL16 in this review. In the first part of the paper, we discuss background information about CXCL16 and its receptor, CXCR6. Next, we focus on the importance of CXCL16 in a variety of diseases, with an emphasis on cancer. We discuss the role of CXCL16 in tumor cell proliferation, migration, invasion, and metastasis. Next, we describe the role of CXCL16 in the tumor microenvironment, including involvement in angiogenesis, and its significance in tumor-associated cells (cancer associated fibroblasts (CAF), microglia, tumor-associated macrophages (TAM), tumor-associated neutrophils (TAN), mesenchymal stem cells (MSC), myeloid suppressor cells (MDSC), and regulatory T cells (T_reg)). Finally, we focus on the antitumor properties of CXCL16, which are mainly caused by natural killer T (NKT) cells. At the end of the article, we summarize the importance of CXCL16 in cancer therapy.

Two novel qualitative transcriptional signatures robustly applicable to non-research-oriented colorectal cancer samples with low-quality RNA

Currently, due to the low quality of RNA caused by degradation or low abundance, the accuracy of gene expression measurements by transcriptome sequencing (RNA‐seq) is very challenging for non‐research‐oriented clinical samples, majority of which are preserved in hospitals or tissue banks worldwide with complete pathological information and follow‐up data. Molecular signatures consisting of several genes are rarely applied to such samples. To utilize these resources effectively, 45 stage II non‐research‐oriented samples which were formalin‐fixed paraffin‐embedded (FFPE) colorectal carcinoma samples (CRC) using RNA‐seq have been analysed. Our results showed that although gene expression measurements were significantly affected, most cancer features, based on the relative expression orderings (REOs) of gene pairs, were well preserved. We then developed two REO‐based signatures, which consisted of 136 gene pairs for early diagnosis of CRC, and 4500 gene pairs for predicting post‐surgery relapse risk of stage II and III CRC. The performance of our signatures, which included hundreds or thousands of gene pairs, was more robust for non‐research‐oriented clinical samples, compared to that of two published concise REO‐based signatures. In conclusion, REO‐based signatures with relatively more gene pairs could be robustly applied to non‐research‐oriented CRC samples.

Chemokines as the critical factors during bladder cancer progression: an overview

Bladder cancer (BCa) is one of the most frequent urogenital malignancies which is mainly observed among men. There are various genetic and environmental risk factors associated with BCa progression. Transurethral endoscopic resection and open ablative surgery are the main treatment options for muscle invasive BCa. BCG therapy is also employed following the endoscopic resection to prevent tumor relapse. The tumor microenvironment is the main interaction site of tumor cells and immune system in which the immune cells are recruited via chemokines and chemokine receptors. In present review we summarized the main chemokines and chemokine receptors which have been associated with histopathological features of BCa patients in the world. This review highlights the chemokines and chemokine receptors as critical markers in early detection and therapeutic purposes among BCa patients and clarifies their molecular functions during BCa progression and metastasis.

Reversing the Tumor Target: Establishment of a Tumor Trap

Despite the tremendous progress made in the field of cancer therapy in recent years, certain solid tumors still cannot be successfully treated. Alongside classical treatments in the form of chemotherapy and/or radiotherapy, targeted treatments such as immunotherapy that cause fewer side effects emerge as new options in the clinics. However, these alternative treatments may not be useful for treating all types of cancers, especially for killing infiltrative and circulating tumor cells (CTCs). Recent advances pursue the trapping of these cancer cells within a confined area to facilitate their removal for therapeutic and diagnostic purposes. A good understanding of the mechanisms behind tumor cell migration may drive the design of traps that mimic natural tumor niches and guide the movement of the cancer cells. To bring this trapping idea into reality, strong efforts are being made to create structured materials that imitate myelinated fibers, blood vessels, or pre-metastatic niches and incorporate chemical cues such as chemoattractants or adhesive proteins. In this review, the different strategies used (or could be used) to trap tumor cells are described, and relevant examples of their performance are analyzed.

Prostate cancer cells hyper-activate CXCR6 signaling by cleaving CXCL16 to overcome effect of docetaxel

Molecular reprogramming in response to chemotherapeutics leads to poor therapeutic outcomes for prostate cancer (PCa). In this study, we demonstrated that CXCR6-CXCL16 axis promotes DTX resistance and acts as a counter-defense mechanism. After CXCR6 activation, cell death in response to DTX was inhibited, and blocking of CXCR6 potentiated DTX cytotoxicity. Moreover, in response to DTX, PCa cells expressed higher CXCR6, CXCL16, and ADAM-10. Furthermore, ADAM-10-mediated release of CXCL16 hyper-activated CXCR6 signaling in response to DTX. Activation of CXCR6 resulted in increased GSK-3β, NF-κB, ERK1/2 phosphorylation, and survivin expression, which reduce DTX response. Finally, treatment of PCa cells with anti-CXCR6 monoclonal antibody synergistically or additively induced cell death with ∼1.5-4.5 fold reduction in the effective concentration of DTX. In sum, our data imply that co-targeting of CXCR6 would lead to therapeutic enhancement of DTX, leading to better clinical outcomes for PCa patients.

Impaired Th17 cell proliferation and decreased pro-inflammatory cytokine production in CXCR3/CXCR4 double-deficient mice of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is a common observed infection, affecting approximately 75% of women of reproductive age. Drug resistance represents a troublesome stumbling block associated with VVC therapy. Thus the aim of the present study was to provide information regarding the selection of potential drug targets for VVC. CXCR3-, CXCR4-, or CXCR/CXCR4 double-deficient mouse models of VVC were subsequently established, with changes to the load of Candida Albicans evaluated accordingly. The biological behaviors of the vaginal epithelial cells were characterized in response to the CXCR3-, CXCR4-, or CXCR3/CXCR4 double-knockout in vivo. Our initial observations revealed that in mice with VVC, CXCR3-, CXCR4-, or CXCR3 - CXCR4 double-knockout resulted in a decreased load of C. Albicans as well as reduced levels and proportion of Th17 cells. Proinflammatory cytokine production was found to be inhibited by CXCR3-, CXCR4-, or CXCR3/CXCR4 double-knockout whereby the mRNA and protein expressions CXCR3, CXCR4, IL-17, IL-6, and TNF-α exhibited decreased levels. CXCR3-, CXCR4-, or CXCR3/CXCR4 double-knockout appeared to function as positive proliferation factors, while playing a negative role in the processes of apoptosis and the cell cycle of vaginal epithelial cells. Taken together, the key findings of the study suggested that CXCR3/CXCR4 double-knockout could act to hinder the progression of VVC, highlighting its promise as a novel therapeutic target in the treatment of VVC. CXCR3 and CXCR4 genes may regulate Th17/IL-17 immune inflammatory pathways to participate in antifungal immunity.

High CXC Chemokine Ligand 16 (CXCL16) Expression Promotes Proliferation and Metastasis of Lung Cancer via Regulating the NF-κB Pathway

BACKGROUND CXC chemokine ligand 16 (CXCL16) is a soluble chemokine with a transmembrane domain, playing an important role in inflammatory regulation. NF-κB has a critical role in tumor progression. Recent studies focused on the effect of CXCL16 on tumor progression. However, few reports showed the influence of CXCL16 on lung cancer, especially in regulating NF-κB activity. Here we investigated CXCL16 expression and its clinical significance in lung cancer, as well as the effect on lung cancer cell biological characteristics by regulating NF-κB. MATERIAL AND METHODS CXCL16 expression in lung cancer was detected and its associations with clinical characteristics were analyzed. Proliferation and invasion of A549 and PC-9 cells was measured before and after silencing CXCL16 or inhibiting the NF-κB pathway, separately. RESULTS The positive rate of CXCL16 in lung cancer tissue was significantly higher than that in adjacent tissue, and that in patients with lymphatic metastasis was significantly higher than that in patients without (all, P<0.05). The positive rate of CXCL16 was significantly (P<0.05) positively corrected with poor prognosis of lung cancer. Silencing CXCL16 not only suppressed proliferation and invasion of A549 and PC-9 cells, but also significantly (P<0.05) inhibited c-Rel, p105, and Rel-B in the NF-κB pathway. Inhibiting NF-κB also suppressed proliferation and invasion of A549 and PC-9 cells, which was similar to the results after silencing CXCL16. CONCLUSIONS Enhanced CXCL16 expression in lung cancer tissue promoted the proliferation and invasion of lung cancer cells. CXCL16 might promote proliferation and invasion of lung cancer by regulating the NF-κB pathway.

Association between CXCL16/CXCR6 expression and the clinicopathological features of patients with non-small cell lung cancer

Lung cancer is a major cause of morbidity and mortality worldwide, therefore identifying biomarkers for the early detection, grading or postoperative follow-up of lung cancer is of clinical significance. In the present study, expression of lung tissue (t)-CXCL16 and t-CXCR6 was examined in 58 patients with non-small cell lung cancer (NSCLC) using immunohistochemical staining, and serum (s)-CXCL16 levels were detected in 58 patients with NSCLC and in 32 normal volunteers using an ELISA. A follow-up was performed every 4 months between January 2014 and January 2015. Compared with the normal volunteers, the s-CXCL16 concentration in patients with NSCLC significantly increased (329.47±135.38 vs. 572.82±116.05 pg/ml, respectively; P<0.001). When grouped according to TNM stage, the expression of t-CXCL16 (60 vs. 85.71%; P=0.029), t-CXCR6 (53.33 vs. 78.57%; P=0.043) and s-CXCL16 (26.67 vs. 57.14%, P=0.019) in the stage I-II subgroup was significantly lower compared with that of the stage III-IV subgroup. The positive expression rate of t-CXCL16 (91.18%) and t-CXCR6 (79.41%) in the lymph node metastasis subgroup was significantly higher compared with that of the corresponding non-lymph node metastasis subgroup (50 and 45.83%, respectively; P<0.01). Additionally, the positive expression rate of t-CXCL16 in the smoking subgroup was 100%, which was significantly higher compared with that of the non-smoking subgroup (23.81%) (P<0.001). The follow-up and mortality rates were 100% (58/58) and 13.79% (8/58), respectively. Within the time period of the present study, the survival time was 4-18 months, and the mean survival time was 16.6 months. In conclusion, the expression of t-CXCL16 and t-CXCR6 is positively correlated with the TNM stage and lymph node metastasis in patients with NSCLC. Additionally, there was a significant increase in s-CXCL16 levels in patients with NSCLC, suggesting that CXCL16 could be used as a supplementary biomarker for the early detection of NSCLC.

CXCR6-CXCL16 axis promotes prostate cancer by mediating cytoskeleton rearrangement via Ezrin activation and αvβ3 integrin clustering

Cytoskeletal rearrangement is required for migration and invasion, which are the key steps of cancer metastasis. Ezrin and integrin co-ordinate these processes by regulating cellular adhesion and cytoskeletal polymerization-depolymerization. It is also well established that chemokine-chemokine receptor axis plays a crucial role in regulating cancer cell migration and invasion. In this study, we show involvement of CXC chemokine receptor 6 (CXCR6) and its only natural ligand CXCL16 in pathobiology of prostate cancer (PCa). CXCR6 is highly expressed in PCa tissues and cell lines (LNCaP and PC3), relative to normal tissue and cells. CXCR6 expression in PCa tissues correlated with higher Gleason score. Similarly, aggressive PCa cells (PC3) show high CXCR6 compared to less aggressive LNCaP. Besides, PC3 cells show higher MMPs expression compared to LNCaP cells following CXCL16 stimulation. Intriguingly, CXCR6-CXCL16 interaction in PCa cells promotes Ezrin activation, &alpha;_v&beta;₃ integrin clustering and capping at the leading edge in FAK/PI3K/PKC dependent manner, thereby modifying cellular adhesion as well as motility. Together these results demonstrate that CXCL16 stimulation changes cytoskeletal dynamics resulting in enhanced migration, invasion and adhesion to endothelial cells, ultimately enabling PCa cells to achieve their metastatic goal.

CXCR6 promotes tumor cell proliferation and metastasis in osteosarcoma through the Akt pathway

Chemokine (C-X-C motif) receptor 6 (CXCR6) is up-regulated in many malignancies, indicating that CXCR6 plays an important role in tumor progression. However, the expression and function of CXCR6 in osteosarcoma (OS) remains unclear. This study aimed to explore the expression levels and function of CXCR6 in OS tissues and osteosarcoma cell lines MG-63, HOS and U2OS. The protein expression levels of CXCR6 in OS patient tissues and three osteosarcoma cell lines MG-63, HOS and U2OS were assessed. CXCR6-overexpression MG-63 cell lines were established and then the proliferation, invasion and the epithelial-mesenchymal transition (EMT) in those cells were assessed. CXCR6 mRNA levels in OS tissues were significantly higher than those in normal bone tissues. Consistently, both of the mRNA and protein levels of CXCR6 in OS cell lines MG-63, HOS and U2OS were higher than those in normal bone cells hFOB1.19. CXCR6 overexpression not only promoted cell proliferation, invasion and EMT, but also enhanced the phosphorylation of Akt in MG-63 cells. After inhibition of Akt-phosphorylation by Akt inhibitor, LY2940023, CXCR6-induced cell proliferation and invasion were dramatically attenuated. In conclusion, the present study demonstrated that CXCR6 enhances OS cell proliferation and invasion through the Akt pathway.

CXCL16/CXCR6 chemokine signaling mediates breast cancer progression by pERK1/2-dependent mechanisms

Our previous studies demonstrate that CXCL6/CXCR6 chemokine axis induces prostate cancer progression by the AKT/mTOR signaling pathway; however, its role and mechanisms underlying invasiveness and metastasis of breast cancer are yet to be elucidated. In this investigation, CXCR6 protein expression was examined using high-density tissue microarrays and immunohistochemistry. Expression of CXCR6 shows a higher epithelial staining in breast cancer nest site and metastatic lymph node than the normal breast tissue, suggesting that CXCR6 may be involved in breast cancer (BC) development. In vitro and in vivo experiments indicate that overexpression of CXCR6 in BC cells has a marked effect on increasing cell migration, invasion and metastasis. In contrast, reduction of CXCR6 expression by shRNAs in these cells greatly reduce its invasion and metastasis ability. Mechanistic analyses show that CXCL16/CXCR6 chemokine axis is capable of modulating activation of RhoA through activating ERK1/2 signaling pathway, which then inhibits the activity of cofilin, thereby enhancing the stability of F-actin, responsible for invasiveness and metastasis of BC.

Taken together, our data shows for the first time that the CXCR6 / ERK1/2/ RhoA / cofilin /F-actin pathway plays a central role in the development of BC. Targeting the signaling pathway may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for BC.

Blockade of CXCR6 reduces invasive potential of gastric cancer cells through inhibition of AKT signaling

Chemokines and their receptors have been implicated in cell migration and metastasis of multiple malignant tumors. But the function of CXCR6 signaling in gastric cancer is not comprehensively understood. In the present study, we hypothesized that CXCR6 signaling might play an essential role in the progression of gastric cancer. The expression of CXCR6 was examined by immunohistochemical assay in human gastric cancer, and lentivirus-mediated CXCR6 knockdown by shRNA (Lv-shCXCR6) was used for investigating cell migration and invasion indicated by Wound-healing and Transwell assays. Consequently, the expression level of CXCR6 was increased in gastric cancer compared with the adjacent non-tumor tissues (54.2% vs. 27.1%, P = 0.006), and was closely associated with the metastatic lymph node in gastric cancer (P = 0.021). Furthermore, blockade of the CXCR6 signaling reduced the migration and invasion of gastric cancer cells followed by decreased expression of AKT, MMP-2, and MMP-9. In conclusion, these findings demonstrate that CXCR6 may promote the development of gastric cancer cells through regulation of AKT signaling.

Blockade of the CXCR6 signaling inhibits growth and invasion of hepatocellular carcinoma cells through inhibition of the VEGF expression

Chemokines have been shown to play a critical role in tumor development and progression. However, little is known about the function and molecular mechanisms of CXCR6 in multiple malignancies. In the present study, we aimed to investigate the role of CXCR6 in human hepatocellular carcinoma (HCC). The expression of CXCR6 was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects of lentivirus-mediated CXCR6 shRNA (shCXCR6) on cell proliferation and invasive potential by MTT and Transwell assays in HCC cell line (SMMC-7721). It was found that the expression of CXCR6 protein was significantly increased in HCC tissues compared with that in adjacent non-cancerous tissues (ANCT) (63.04&#x0025; vs 36.96&#x0025;, P=0.019), and correlated with the lymph-vascular space invasion in HCC patients (P=0.038). Knockdown of CXCR6 repressed cell proliferation and invasion of HCC cells followed by the down-regulation of vascular endothelial growth factor (VEGF). Taken together, our findings show that high expression of CXCR6 is positively associated with distant invasion of HCC patients, and blockade of CXCR6 signaling suppresses the growth and invasion of HCC cells through inhibition of the VEGF expression, suggesting that CXCR6 may represent a promising therapeutic target for the treatment of HCC.

The role of chemoattractant receptors in shaping the tumor microenvironment

Chemoattractant receptors are a family of seven transmembrane G protein coupled receptors (GPCRs) initially found to mediate the chemotaxis and activation of immune cells. During the past decades, the functions of these GPCRs have been discovered to not only regulate leukocyte trafficking and promote immune responses, but also play important roles in homeostasis, development, angiogenesis, and tumor progression. Accumulating evidence indicates that chemoattractant GPCRs and their ligands promote the progression of malignant tumors based on their capacity to orchestrate the infiltration of the tumor microenvironment by immune cells, endothelial cells, fibroblasts, and mesenchymal cells. This facilitates the interaction of tumor cells with host cells, tumor cells with tumor cells, and host cells with host cells to provide a basis for the expansion of established tumors and development of distant metastasis. In addition, many malignant tumors of the nonhematopoietic origin express multiple chemoattractant GPCRs that increase the invasiveness and metastasis of tumor cells. Therefore, GPCRs and their ligands constitute targets for the development of novel antitumor therapeutics.

CXCL16 and CXCR6 in Ewing sarcoma family tumor

Chemokines are a family of peptide mediators that play an essential role in cellular migration and intracellular communication in tumor cells as well as immune cells. We hypothesized that the CXCL16-CXCR6 ligand-receptor system plays an important role in Ewing sarcoma (ES) family tumor (ESFT) progression. Using real-time quantitative reverse transcription-polymerase chain reaction, we investigated the mRNA expression of CXCL16, CXCR6, and ADAM 10 in various cell lines. We also investigated the expression of CXCL16, CXCR6, ADAM 10, and ADAM 17 in tissue samples from 61 ESFT patients using immunohistochemistry. The mRNA expression levels of CXCL16 and CXCR6 in the ES cell line were higher than those in the other cell lines. Immunohistochemical staining revealed that CXCL16 and CXCR6 were highly expressed in tumor cells of ESFT and showed a positive correlation between them. The expression of CXCL16 and CXCR6 was associated with the occurrence of lung metastasis. Univariate analysis revealed that CXCL16 or CXCR6 expression was associated with worse prognosis of ESFT patients. In addition, CXCL16 and CXCR6 expression was associated with shorter overall survival irrespective of other prognostic factors. Our results suggest that the CXCL16/CXCR6 axis appears to be important in the progression of ESFT, resulting in more aggressive clinical behavior. Furthermore, there may be a decrease in the overall survival in ESFT patients who have tumors that stain strongly for CXCL16 and CXCR6.