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

Efficacy of Cisplatin-CXCR4 Antagonist Combination Therapy in Oral Cancer

Cisplatin is a platinum-based compound that is widely used for treating inoperable oral squamous cell carcinoma (OSCC) in Japan; however, resistance to cisplatin presents a challenge and innovative approaches are required. We aimed to investigate the therapeutic potential of targeting the chemokine receptor CXCR4, which is involved in angiogenesis and tumor progression, using the CXCR4 inhibitor AMD3100, in combination with cisplatin. AMD3100 induced necrosis and bleeding in OSCC xenografts by inhibiting angiogenesis. We investigated the combined ability of AMD3100 plus cisplatin to enhance the antitumor effect in cisplatin-resistant OSCC. An MTS assay identified HSC-2 cells as cisplatin-resistant cells in vitro. Mice treated with the cisplatin-AMD combination exhibited the most significant reduction in tumor volume, accompanied by extensive hemorrhage and necrosis. Histological examination indicated thin and short tumor vessels in the AMD and cisplatin-AMD groups. These results indicated that cisplatin and AMD3100 had synergistic antitumor effects, highlighting their potential for vascular therapy of refractory OSCC. Antitumor vascular therapy using cisplatin combined with a CXCR4 inhibitor provides a novel strategy for addressing cisplatin-resistant OSCC.

The CXCR4 might be a potential biomarker for esophageal squamous cell carcinoma: A meta-analysis

OBJECTIVE

To evaluate the relationship between CXCL12/CXCR4 and the progress, prognosis of esophageal squamous cell carcinoma (ESCC), providing evidence for potential early diagnosis, clinical treatment, prognosis evaluation, and therapeutic target of ESCC.

METHODS

Databases of PubMed, the Cochrane Library, Embase, and Web of Science were searched for the relationship between CXCL12/CXCR4 and clinicopathological characteristics and survival time of ESCC. Stata16.0 software was used to conduct meta-analysis.

RESULTS

A total of 10 studies involving 1216 cases of patients with ESCC were included in our study. The results indicated that high-level expression of CXCR4 was significantly correlated with tumor differentiation [OR = 0.69, 95% confidence interval (CI): (0.50, 0.97)], tumor infiltration [OR = 0.39, 95% CI: (0.25, 0.61)], lymph node metastasis [OR = 0.36, 95% CI: (0.21, 0.61)], clinical stage [OR = 0.33, 95% CI: (0.24, 0.45)] of ESCC. The expression of CXCR4 was also significantly correlated with OS [HR = 2.00, 95% CI: (1.63, 2.45)] and disease-free survival [HR = 1.76, 95% CI: (1.44, 2.15)] in patients of ESCC after surgical resection. No significant relationship was observed between the expression of CXCL12 and the clinicopathological characteristics of ESCC.

CONCLUSION

CXCR4 might be a potential biomarker for the progress and prognosis evaluation, and therapeutic target for ESCC.

Current Status of 68Ga-Pentixafor in Solid Tumours

Chemokine receptor CXCR4 is overexpressed in neoplasms and its expression is related to tumour invasion, metastasis and aggressiveness. ⁶⁸Ga-Pentixafor is used to non-invasively image the expression of CXCR4 in tumours and has been widely used in haematological malignancies. Recent evidence shows that therapies targeting CXCR4 can increase the chemosensitivity of the tumour as well as inhibit tumour metastasis and aggressiveness. ⁶⁸Ga-Pentixafor has shown promise as an elegant radiotracer to aid in the selection of patients whose tumours demonstrate CXCR4 overexpression and who therefore may benefit from novel therapies targeting CXCR4. In addition, its therapeutic partners ¹⁷⁷Lu- and ⁹⁰Y-Pentixather have been investigated in the treatment of patients with advanced haematological malignancies, and initial studies have shown a good treatment response in metabolically active lesions. ⁶⁸Ga-Pentixafor in solid tumours complements ¹⁸F-FDG by providing prognostic information and selecting patients who may benefit from therapies targeting CXCR4. This review summarises the available literature on the potential applications of ⁶⁸Ga-Pentixafor in solid tumours.

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

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

Epigenetic Regulation of CXCR4 Signaling in Cancer Pathogenesis and Progression

Signaling involving chemokine receptor CXCR4 and its ligand SDF-1/CXL12 has been investigated for many years for its possible role in cancer progression and pathogenesis. Evidence emerging from clinical studies in recent years has further established diagnostic as well as prognostic importance of CXCR4 signaling. CXCR4 and SDF-1 are routinely reported to be elevated in tumors, distant metastases, which correlates with poor survival of patients. These findings have kindled interest in the mechanisms that regulate CXCR4/SDF-1 expression. Of note, there is a particular interest in the epigenetic regulation of CXCR4 signaling that may be responsible for upregulated CXCR4 in primary as well as metastatic cancers. This review first lists the clinical evidence supporting CXCR4 signaling as putative cancer diagnostic and/or prognostic biomarker, followed by a discussion on reported epigenetic mechanisms that affect CXCR4 expression. These mechanisms include regulation by non-coding RNAs, such as, microRNAs, long non-coding RNAs and circular RNAs. Additionally, we also discuss the regulation of CXCR4 expression through methylation and acetylation. Better understanding and appreciation of epigenetic regulation of CXCR4 signaling can invariably lead to identification of novel therapeutic targets as well as therapies to regulate this oncogenic signaling.

CXCR4 promotes the growth and metastasis of esophageal squamous cell carcinoma as a critical downstream mediator of HIF-1α

C–X–C motif chemokine receptor 4 (CXCR4) belongs to the CXC chemokine receptor family, which mediates the metastasis of tumor cells and promotes the malignant development of cancers. However, its biological role and regulatory mechanism in esophageal squamous cell carcinoma (ESCC) remain unclear. Here, we found that CXCR4 expression was associated with lymph node metastasis and a poor prognosis. In vitro and in vivo studies demonstrated that CXCR4 overexpression promoted ESCC cell proliferation, migration, invasion, and survival, whereas silencing CXCR4 induced the opposite effects. Mechanically, HIF‐1α transcriptionally regulates CXCR4 expression by binding to a hypoxia response element in its promoter. HIF‐1α‐induced ESCC cell migration and invasion were reversed by CXCR4 knockdown or treatment with MSX‐122, a CXCR4 antagonist. Collectively, these data revealed that the HIF‐1α/CXCR4 axis plays key roles in ESCC growth and metastasis and indicated CXCR4 as a potential target for ESCC treatment.

Cardiovascular disease related circulating biomarkers and cancer incidence and mortality: is there an association?

AIMS

Recent studies suggest an association between cardiovascular disease (CVD) and cancer incidence/mortality, but the pathophysiological mechanisms underlying these associations are unclear. We aimed to examine biomarkers previously associated with CVD and study their association with incident cancer and cancer-related death in a prospective cohort study.

METHODS AND RESULTS

We used a proteomic platform to measure 71 cardiovascular biomarkers among 5,032 participants in the Framingham Heart Study who were free of cancer at baseline. We used multivariable-adjusted Cox models to examine the association of circulating protein biomarkers with risk of cancer incidence and mortality. To account for multiple testing, we set a 2-sided false discovery rate (FDR Q-value) <0.05.Growth differentiation factor-15 (GDF15; also known as macrophage inhibitory cytokine-1 [MIC1])) was associated with increased risk of incident cancer (hazards ratio [HR] per 1 standard deviation increment 1.31, 95% CI 1.17-1.47), incident gastrointestinal cancer (HR 1.85, 95% CI 1.37-2.50), incident colorectal cancer (HR 1.94, 95% CI 1.29-2.91) and cancer-related death (HR 2.15, 95% CI 1.72-2.70). Stromal cell-derived factor-1 (SFD1) showed an inverse association with cancer-related death (HR 0.75, 95% CI 0.65-0.86). Fibroblast growth factor-23 (FGF23) showed an association with colorectal cancer (HR 1.55, 95% CI 1.20-2.00), and granulin (GRN) was associated with hematologic cancer (HR 1.61, 95% CI 1.30-1.99). Other circulating biomarkers of inflammation, immune activation, metabolism, and fibrosis showed suggestive associations with future cancer diagnosis.

CONCLUSION

We observed several significant associations between circulating CVD biomarkers and cancer, supporting the idea that shared biological pathways underlie both diseases. Further investigations of specific mechanisms that lead to both CVD and cancer are warranted.

TRANSLATIONAL PERSPECTIVE

In our prospective cohort study, baseline levels of biomarkers previously associated with CVD were found to be associated with future development of cancer. In particular, GDF15 was associated with increased risk of cancer incidence and mortality, including gastrointestinal and colorectal cancers; SDF1 was inversely associated with cancer-related death, and FGF23 and GRN were associated with increased risk of colorectal and hematologic cancers, respectively. Other biomarkers of inflammation, immune activation, metabolism, and fibrosis showed suggestive associations. These results suggest potential shared biological pathways that underlie both development of cancer and CVD.

Increased tumor-infiltrating plasmacytoid dendritic cells promote cancer cell proliferation and invasion via TNF-α/NF-κB/CXCR-4 pathway in oral squamous cell carcinoma

Background: Tumor-infiltrating immune cells are closely associated with tumor occurrence and progression. The present study explored the potential mechanism of tumor-infiltrating plasmacytoid dendritic cells (pDC) mediating the proliferation and metastasis of cancer cells in oral squamous cell carcinoma (OSCC).

Methods: pDC distribution was detected by immunofluorescence and flow cytometry. chemotaxis cytokine receptor-4/7 (CXCR-4/7) expression was detected by quantitative polymerase chain reaction and immunohistochemistry. Cell proliferation and migration were measured by CCK-8, colony formation, wound healing and transwell assay. ELISA and western blotting were used to investigate cytokines secretion and NF-κB pathway activity.

Results: Tumor-infiltrating pDC in OSCC was significantly increased and associated with tumor size, lymph node (LN) metastasis (P <0.05). Tumor-infiltrating-pDC-conditioned medium from OSCC patients significantly promoted tumor cell proliferation and invasion, which was at least partly mediated via enhancing the CXCR-4 expression of tumor cell. In addition, the activation of NF-κB pathway played a decisive role in the overexpression of CXCR-4, which was further regulated by pDC-derived TNF-α secretion.

Conclusions: Tumor-infiltrating pDC promoted oral cancer proliferation and invasion via activating the TNF-α/NF-κB/CXCR-4 pathway, which may serve as a potential immunological target for the treatment of OSCC in the future.

The biological role of the CXCL12/CXCR4 axis in esophageal squamous cell carcinoma

Esophageal cancer is the eighth most common malignant tumor and the sixth leading cause of cancer-related death worldwide. Esophageal squamous cell carcinoma (ESCC) is the main histological type of esophageal cancer, and accounts for 90% of all cancer cases. Despite the progress made in surgery, chemotherapy, and radiotherapy, the mortality rate from esophageal cancer remains high, and the overall 5-year survival rate is less than 20%, even in developed countries. The C-X-C motif chemokine ligand 12 (CXCL12) is a member of the CXC chemokine subgroup, which is widely expressed in a variety of tissues and cells. CXCL12 participates in the regulation of many physiological and pathological processes by binding to its specific receptor, C-X-C motif chemokine receptor type 4 (CXCR4), where it causes embryonic development, immune response, and angiogenesis. In addition, increasing evidence indicates that the CXCL12/CXCR4 axis plays an important role in the biological processes of tumor cells. Studies have shown that CXCL12 and its receptor, CXCR4, are highly expressed in ESCC. This abnormal expression contributes to tumor proliferation, lymph node and distant metastases, and worsening prognosis. At present, antagonists and imaging agents against CXCL12 or CXCR4 have been developed to interfere with the malignant process and monitor metastasis of tumors. This article summarizes the structure, function, and regulatory mechanism of CXCL12/CXCR4 and its role in the malignancy of ESCC. Current results from preclinical research targeting CXCL12/CXCR4 are also summarized to provide a reference for the clinical diagnosis and treatment of ESCC.

Prognostic Impact of CXCR7 and CXCL12 Expression in Patients with Esophageal Adenocarcinoma

BACKGROUND

Chemokines are major regulators of cell trafficking and adhesion. The chemokine CXCL12 and its receptors, CXCR4 and CXCR7, have been reported as biomarkers in various cancers, including esophageal cancer; however, there are few studies in esophageal adenocarcinoma (EAC). In this study, we investigated the relationship between expression of CXCL12, CXCR4, and CXCR7, and prognosis in patients with EAC.

METHODS

This study examined 55 patients with EAC who were treated in Toronto General Hospital from 2001 to 2010. Tissue microarray immunohistochemistry was used to evaluate the expression of CXCL12, CXCR4, and CXCR7. Evaluation of immunohistochemistry was performed by a pathologist without knowledge of patients' information and results were compared with the patients' clinicopathological features and survival.

RESULTS

High CXCR7 expression was significantly associated with lymphatic invasion (present vs absent, P = 0.005) and higher number of lymph node metastases (pN0-1 vs pN2-3, P = 0.0014). Patients with high CXCR7 expression (n = 23) were associated with worse overall (OS) and disease-free survival (DFS) (P = 0.0221, P = 0.0090, respectively), and patients with high CXCL12 (n = 24) tended to have worse OS and DFS (P = 0.1091, P = 0.1477, respectively). High expression of both CXCR7 and CXCL12 was an independent prognostic factor for OS and DFS on multivariate analysis (HR = 0.3, 95% CI: 0.1-0.9, P = 0.0246, HR = 0.3, 95% CI: 0.1-0.8, P = 0.0134, respectively).

CONCLUSIONS

High CXCR7 expression was associated with poor prognosis in patients with EAC, and high expression of CXCR7 with its ligand CXCL12 had a stronger association with prognosis. Further study of this potential biomarker using whole tissue samples and a larger sample size is warranted.

Pentixafor PET/CT for imaging of chemokine receptor 4 expression in esophageal cancer - a first clinical approach

Background

Expression of CXCR4, a chemokine (C-X-C motif) receptor that plays a central role in tumor growth and metastasis of circulating tumor cells, has been described in a variety of solid tumors. A high expression of CXCR4 has a prognostic significance with regard to overall and progression-free survival and offers a starting point for targeted therapies. In this context, [68]Ga-Pentixafor-Positron Emission Tomography/Computer Tomography (PET/CT) offers promising possibility of imaging the CXCR4 expression profile. We set out to compare a [18F] fluorodeoxyglucose (FDG)-PET/CT and a [68Ga]Pentixafor-PET/CT in (re-)staging and radiation planning of patients with localized esophageal cancer.

Materials and methods

In this retrospective analysis, ten patients, with adeno- or squamous cell carcinoma of the esophagus (n = 3 and n = 7, respectively), which were scheduled for radio (chemo) therapy, were imaged using both Pentixafor and FDG PET/CT examinations. All lesions were visually rated as Pentixafor and FDG positive or negative. For both tracers, SUVmax was measured all lesions and compared to background. Additionally, immunohistochemistry of CXCR4 was obtained in patients undergoing surgery.

Results

FDG-positive tumor-suspicious lesions were detected in all patients and a total of 26 lesions were counted. The lesion-based analysis brought equal status in 14 lesions which were positive for both tracers while five lesions were FDG positive and Pentixafor negative and seven lesions were FDG negative, but Pentixafor positive. Histopathologic correlation was available in seven patients. The CXCR4 expression of four non-pretreated tumour lesion samples was confirmed immunohistochemically.

Conclusion

Our data shows that additional PET/CT imaging with Pentixafor for imaging the CXCR4 chemokine receptor is feasible but heterogeneous in both newly diagnosed and pretreated recurrent esophageal cancer. In addition, the Pentixafor PET/CT may serve as complementary tool for radiation field expansion in radiooncology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-021-00391-w.

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.

Positive Cross-Talk Between CXC Chemokine Receptor 4 (CXCR4) and Epidermal Growth Factor Receptor (EGFR) Promotes Gastric Cancer Metastasis via the Nuclear Factor kappa B (NF-kB)-Dependent Pathway

BACKGROUND Previous studies have established cross-talk between CXC chemokine receptor 4 (CXCR4) and epidermal growth factor receptor (EGFR) in gastric cancer, however, the effect of dual CXCR4/EGFR tumor status on patient survival and mechanisms regulating expression has yet to be investigated. MATERIAL AND METHODS A total of 56 gastric cancer patients were recruited to reveal the relationship between CXCR4 and EGFR expression, and the clinic-pathological features of samples were investigated by immunohistochemical staining. Two gastric cancer cell lines were treated with CXCL12 or EGF, and expression levels of CXCR4 and EGFR were detected by reverse-transcription-polymerase chain reaction and western blotting. Cells were treated with an NF-kappaB pathway inhibitor to investigate its role in the regulation of CXCL12 or EGF-mediated CXCR4 and EGFR expression and migration ability. RESULTS The results show that CXCL12 upregulated CXCR4 and EGFR. Similarly, EGF could induce the expression of CXCR4 and contribute to gastric cancer cell metastasis. In addition, both CXCL12 and EGF could induce the activation of IKKalphaß and P65. Conversely, suppression of the NF-kappaB pathway remarkably decreased the expression of CXCR4/EGFR and migration ability induced by EGF or CXCL12. Furthermore, a significantly positive correlation between CXCR4 and EGFR expression was observed in gastric cancer patient tissues (r=0.372, P=0.005). Samples expressing both receptors had significantly poorer patient prognosis than other patient groups (P=0.002). CONCLUSIONS Our results showed that the CXCL12/CXCR4 and EGF/EGFR axis can regulate the expression of each other through the NF-kappaB pathway to promote metastasis. These data suggested that simultaneous inhibition of EGFR and CXCR4 may be a potential therapeutic strategy in gastric cancer.

Identification of Leukocyte telomere length-related genetic variants contributing to predisposition of Esophageal Squamous Cell Carcinoma

Background: Cancers may arise from cells with dysregulated telomeric functions due to shorten telomere length. We and others previously found that short leukocyte telomere length was associated with markedly evaluated risk of esophageal squamous cell carcinoma (ESCC). Hence, we hypothesized that single nucleotide polymorphisms (SNPs) associated with shorter telomere length may contribute to ESCC predisposition.

Methods: We systematically evaluated association between seven candidate seven SNPs (CXCR4 rs6430612, TERT rs13172201, TERT rs10069690, TERT rs2853676, TERT rs451360, OBFC1 rs4387287, and VPS34 rs2162440) and ESCC risk in two case-control sets consisting of 1588 ESCC cases and 1600 controls. Logistic regression models were utilized to estimate associations between SNPs and ESCC susceptibility and odds ratios (ORs) and their 95% confidence intervals (95% CIs) were computed.

Results: We firstly identified three SNPs (rs6430612, rs13172201 and rs4387287) which are significantly associated with telomere length in Chinese populations (all P<0.05). Importantly, CXCR4 rs6430612 and OBFC1 rs4387287 polymorphisms significantly confer reduced risk of ESCC (P=1.7×10^-7 and P=3.9×10^-5). On the contrary, we observed an evidently increased risk for ESCC development associated with TERT rs13172201 genetic variant (P=2.2×10^-4).

Conclusions: In summary, rs6430612, rs13172201 and rs4387287 might be key genetic components in complicated regulation of telomere length and contributing to ESCC predisposition. Our results elucidate the prevalent involvement of genetic variants in telomere biology and further provide pathogenic insights into the role of telomeres in cancer development.

Chemokines and their receptors as biomarkers in esophageal cancer

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

Enhanced CXCR4 Expression Associates with Increased Gene Body 5-Hydroxymethylcytosine Modification but not Decreased Promoter Methylation in Colorectal Cancer

In colorectal cancer (CRC), upregulation of the C-X-C motif chemokine receptor 4 (CXCR4) is correlated with metastasis and poor prognosis, highlighting the need to further elucidate CXCR4’s regulation in CRC. For the first time, DNA methylation and 5-hydroxymethylcytosine aberrations were investigated to better understand the epigenetic regulation of CXCR4 in CRC. CXCR4 expression levels were measured using qPCR and immunoblotting in normal colon tissues, primary colon cancer tissues and CRC cell lines. Publicly available RNA-seq and methylation data from The Cancer Genome Atlas (TCGA) were extracted from tumors from CRC patients. The DNA methylation status spanning CXCR4 gene was evaluated using combined bisulfite restriction analysis (COBRA). The methylation status in the CXCR4 gene body was analyzed using previously performed nano-hmC-seal data from colon cancers and adjacent normal colonic mucosa. CXCR4 expression levels were significantly increased in tumor stromal cells and in tumor colonocytes, compared to matched cell types from adjacent normal-appearing mucosa. CXCR4 promoter methylation was detected in a minority of colorectal tumors in the TCGA. The CpG island of the CXCR4 promoter showed increased methylation in three of four CRC cell lines. CXCR4 protein expression differences were also notable between microsatellite stable (MSS) and microsatellite instable (MSI) tumor cell lines. While differential methylation was not detected in CXCR4, enrichment of 5-hydroxymethylcytosine (5hmC) in CXCR4 gene bodies in CRC was observed compared to adjacent mucosa.

Clinicopathologic significance of CXCR4 expressions in patients with esophageal squamous cell carcinoma

AIMS

This study was designed to investigate the biological function of CXCR4 in esophageal squamous cell carcinoma and to explore the underlying mechanism to provide potential targets for esophageal squamous cell carcinoma.

METHODS

A total of 101 patients with esophageal squamous cell carcinoma were included, and the relationship between CXCR4 and clinicopathological factors was analyzed. Laser scanning confocal microscopy was used to observe numbers of autophagosomes in TE-1 cell line and the ability of proliferation and invasion were evaluated meanwhile.

RESULTS

CXCR4 is overexpressed in ESCC specimens and is associated with poor differentiation and lymphocyte metastasis. In the survival analysis, CXCR4 predicted a poor overall survival prognosis. The number of autophagosomes in the siR-CXCR4 group was decreased compared with negative group (P < 0.05), while was increased in the pcDNA3.1-CXCR4 group (P < 0.05).Western blot result show upregulation of LC3II, the ratio of LC3II/LC3I and Beclin1 in pcDNA3.1-CXCR4 group and decreased expression of LC3II, the ratio of LC3II/LC3I and Beclin1 in siR-CXCR4 group. Transwell assay show CXCR4 overexpression promote the invasion of TE-1 cells and was attenuated by autophagy inhibitor 3-Methyladenine.On the contrary, invasion cell numbers decreased in siR-CXCR4 group and was rescued by autophagy inducer Rapamycin.

CONCLUSION

CXCR4 is an indicator of poor prognosis for ESCC. CXCR4 promote autophagy and regulate cell invasion through autophagy in ESCC. Our study provides new insights for the treatment of esophageal squamous cell carcinoma and CXCR4 may serve as a therapeutic target for ESCC.

CXCR7, a Prognostic Biomarker in Cervical Squamous Cell Carcinoma, May Be a Screening Index for Treatment Options at Stages IB1 and IIA1

Purpose

Recent studies indicate that CXC chemokine receptor type 7 (CXCR7) is associated with tumorigenesis, progression, and metastasis of various cancers, but its roles and molecular mechanisms of action in cervical squamous cell carcinoma (CSCC) remain unclear. Our purpose was to explore the expression patterns of CXCR7 and epidermal growth factor receptor (EGFR) in CSCC and to identify possible correlations with clinical characteristics. We also tested whether CXCR7 can be a screening index for treatment options for CSCC stages IB1 and IIA1.

Methods

Expression of CXCR7 and EGFR in tumors from 165 patients with CSCC was evaluated by immunohistochemistry and compared with the clinical data including survival.

Results

Patients at CSCC stages IB1 and IIA1 received different treatment options, including radical hysterectomy, pelvic lymph node dissection, and para-aortic lymph node sampling (RH group, 67 patients) or pelvic external-beam radiation therapy with brachytherapy (EBRT group, 34 patients). Disease-free survival (DFS) and overall survival (OS) were compared between two groups at different CXCR7 expression levels. Immunohistochemical staining showed that CXCR7, EGFR, phospho-ERK, and phospho-AKT amounts increased from normal cervical epithelia and cervical intraepithelial neoplasia to CSCC, and CXCR7 was associated with the disease stage, lymph node metastasis, tumor size ≥40 mm, and EGFR expression. Kaplan–Meier analysis revealed that CXCR7 and EGFR expression was associated with shorter DFS and OS. Multivariate analysis suggested that CXCR7 was independently associated with DFS and OS. Prevalence of recurrence and distant metastasis was significantly lower in the EBRT group than in the RH group during CXCR7 expression. Besides, CXCR7 knockdown significantly decreased the proliferation and invasion of CSCC cells.

Conclusion

CXCR7 is coexpressed with EGFR, which may be involved in ERK or AKT pathway activation. CXCR7 may be a screening index for treatment options at CSCC stages IB1 and IIA1.

The Role of Sonic Hedgehog Signaling in the Tumor Microenvironment of Oral Squamous Cell Carcinoma

Sonic hedgehog (SHH) and its signaling have been identified in several human cancers, and increased levels of SHH expression appear to correlate with cancer progression. However, the role of SHH in the tumor microenvironment (TME) of oral squamous cell carcinoma (OSCC) is still unclear. No studies have compared the expression of SHH in different subtypes of OSCC and focused on the relationship between the tumor parenchyma and stroma. In this study, we analyzed SHH and expression of its receptor, Patched-1 (PTCH), in the TME of different subtypes of OSCC. Fifteen endophytic-type cases (ED type) and 15 exophytic-type cases (EX type) of OSCC were used. H&E staining, immunohistochemistry (IHC), double IHC, and double-fluorescent IHC were performed on these samples. ED-type parenchyma more strongly expressed both SHH and PTCH than EX-type parenchyma. In OSCC stroma, CD31-positive cancer blood vessels, CD68- and CD11b-positive macrophages, and α-smooth muscle actin-positive cancer-associated fibroblasts partially expressed PTCH. On the other hand, in EX-type stroma, almost no double-positive cells were observed. These results suggest that autocrine effects of SHH induce cancer invasion, and paracrine effects of SHH govern parenchyma-stromal interactions of OSCC. The role of the SHH pathway is to promote growth and invasion.

Tumor Angiogenic Inhibition Triggered Necrosis (TAITN) in Oral Cancer

CXCR4 is a chemokine receptor crucial in tumor progression, although the angiogenic role of CXCR4 in oral squamous cell carcinoma (OSCC) has not been investigated. Here we show that CXCR4 is crucial for tumor angiogenesis, thereby supporting tumor survival in OSCC. Immunohistochemistry on human clinical specimens revealed that CXCR4 and a tumor vasculature marker CD34 were co-distributed in tumor vessels in human OSCC specimens. To uncover the effects of CXCR4 inhibition, we treated the OSCC-xenografted mice with AMD3100, so-called plerixafor, an antagonist of CXCR4. Notably, we found a unique pathophysiological structure defined as tumor angiogenic inhibition triggered necrosis (TAITN), which was induced by the CXCR4 antagonism. Treatment with AMD3100 increased necrotic areas with the induction of hypoxia-inducible factor-1α in the xenografted tumors, suggesting that AMD3100-induced TAITN was involved in hypoxia and ischemia. Taken together, we demonstrated that CXCR4 plays a crucial role in tumor angiogenesis required for OSCC progression, whereas TAITN induced by CXCR4 antagonism could be an effective anti-angiogenic therapeutic strategy in OSCC treatment.

CXCR4 as a prognostic biomarker in gastrointestinal cancer: a meta-analysis

Background: CXCR4 is a member of the C-X-C chemokine receptor family, which is associated with multiple types of cancer. Although it has been widely reported, the prognostic value of CXCR4 expression in gastrointestinal (GI) cancer remains controversial. Methods: A meta-analysis was conducted to investigate the relationship between CXCR4 and prognosis of patients with GI cancer. Subgroup analysis was also performed according to tumour subtypes and heterogeneity test. Results: A total of 24 studies including 3637 cases suggested that overexpression of CXCR4 is significantly associated with overall survival (OS) for patients with GI cancer (HR = 1.71, 95% CI = 1.45-2.03, p = 0.000). Subgroup analysis also indicated that high CXCR4 expression in oesophagus, gastric and colorectal cancer all predicted a worse prognosis (HR = 1.52, 95% CI = 1.26-1.84, p = 0.001 for oesophagus cancer; HR = 1.59, 95% CI = 1.10-2.30, p = 0.015 for gastric cancer; HR = 2.21, 95% CI = 1.56-3.14, p = 0.000 for colorectal cancer). Conclusions: CXCR4 may serve as a prognostic indicator in GI cancer patients.

Hypoxia-induced cancer stemness acquisition is associated with CXCR4 activation by its aberrant promoter demethylation

Background

A hypoxic microenvironment leads to an increase in the invasiveness and the metastatic potential of cancer cells within tumors via the epithelial-mesenchymal transition (EMT) and cancer stemness acquisition. However, hypoxia-induced changes in the expression and function of candidate stem cell markers and their possible molecular mechanism is still not understood.

Methods

Lung cell lines were analyzed in normoxic or hypoxic conditions. For screening among the stem cell markers, a transcriptome analysis using next-generation sequencing was performed. For validation, the EMT and stem cell characteristics were analyzed. To determine whether an epigenetic mechanism was involved, the cell lines were treated with a DNA methyltransferase inhibitor (AZA), and methylation-specific PCR and bisulfite sequencing were performed.

Results

Next-generation sequencing revealed that the CXCR4 expression was significantly higher after the hypoxic condition, which functionally resulted in the EMT and cancer stemness acquisition. The acquisition of the EMT and stemness properties was inhibited by treatment with CXCR4 siRNA. The CXCR4 was activated by either the hypoxic condition or treatment with AZA. The methylation-specific PCR and bisulfite sequencing displayed a decreased CXCR4 promoter methylation in the hypoxic condition.

Conclusions

These results suggest that hypoxia-induced acquisition of cancer stem cell characteristics was associated with CXCR4 activation by its aberrant promoter demethylation.

Prognostic significance of CXCR7 in cancer patients: a meta-analysis

Background

CXC chemokine receptor 7 (CXCR7) is frequently overexpressed in a variety of tumors. Nevertheless, whether CXCR7 can be used as a tumor prognosis marker has not been systematically assessed. The current meta-analysis was performed to obtain an accurate evaluation of the relationship between CXCR7 level and the prognosis of cancer patients.

Methods

Embase, Web of Science, and PubMed were systematically searched according to a defined search strategy up to June 11, 2018. Then, the required data were extracted from all qualified studies which were screened out based on the defined inclusion and exclusion criteria. Finally, the hazard ratios (HR) with 95% confidence intervals (CI) were used to evaluate the prognostic significance of CXCR7 in tumor patients.

Results

A total of 28 original research studies comprising 33 cohorts and 5685 patients were included in this meta-analysis. The results showed that CXCR7 overexpression was significantly related to worse overall survival (OS) (HR 1.72; 95% CI 1.49–1.99), disease-free survival (DFS) (HR 5.58; 95% CI 3.16–9.85), progression-free survival (PFS) (HR 2.83; 95% CI 1.66–4.85) and recurrence-free survival (RFS) (HR 1.58; 95% CI 1.34–1.88) in cancer patients. Furthermore, for certain types of cancer, significant associations between higher CXCR7 expression and worse OS of glioma (HR 1.77; 95% CI 1.43–2.19), breast cancer (HR 1.45; 95% CI 1.28–1.63), esophageal cancer (HR 2.72; 95% CI 1.11–6.66) and pancreatic cancer (HR 1.46; 95% CI 1.12–1.90) were found. However, for lung cancer and hepatocellular cancer, there was no significant relationship between CXCR7 expression level and OS, (HR 2.40; 95% CI 0.34–17.07) and (HR 1.37; 95% CI 0.84–2.24) respectively.

Conclusions

Increased CXCR7 level could predict poor prognosis of tumor patients and might be regarded as a novel prognostic biomarker for tumor patients.

Long Noncoding RNA GAS5 Promotes Proliferation, Migration, and Invasion by Regulation of miR-301a in Esophageal Cancer

Long noncoding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) has been revealed to be associated with the progression of various cancers. However, the biological roles of GAS5 in esophageal cancer (EC) remain unclear. We aimed to thoroughly explore the functions of GAS5 in EC. The results showed that GAS5 expression was increased in EC cells (ECA109, TE-1, TE-3, and EC9706) compared to SHEE cells. Knockdown of GAS5 decreased cell viability, migration, and invasion and induced apoptosis in EC9706 cells. Moreover, miR-301a appeared to be directly sponged by GAS5, and miR-301a suppression obviously alleviated the protumor effects of GAS5. Furthermore, miR-301a positively regulated CXCR4 expression, and overexpression of CXCR4 induced apoptosis and abolished the promoting effect of miR-301a inhibition on cell viability, migration, and invasion. Besides, miR-301a blocked Wnt/β-catenin and NF-κB signaling pathways by regulation of CXCR4. Our results indicated that GAS5 promoted proliferation and metastasis and inhibited apoptosis by regulation of miR-301a in EC. These data contributed to our understanding of the mechanisms of miRNA-lncRNA interaction and provides a novel therapeutic strategy for EC.

Role of CXCL12-CXCR4 axis in ovarian cancer metastasis and CXCL12-CXCR4 blockade with AMD3100 suppresses tumor cell migration and invasion in vitro

Ovarian cancer (OC) is a lethal gynecologic tumor, which brings its mortality to the head. CXCL12 and its receptor chemokine receptor 4 ( CXCR4) have been found to be highly expressed in OC and contribute to the disease progression by affecting tumor cell proliferation and invasion. Here, in this study, we aim to explore whether the blockade of CXCL12-CXCR4 axis with AMD3100 (a selective CXCR4 antagonist) has effects on the progression of OC. On the basis of the gene expression omnibus database of OC gene expression chips, the OC differentially expressed genes were screened by microarray analysis. OC (nonmetastatic and metastatic) and normal ovarian tissues were collected to determine the expressions of CXCL12 and CXCR4. A series of AMD3100, shRNA against CXCR4, and pCNS-CXCR4 were introduced to treat CAOV3 cells with the highest CXCR4 was assessed. Cell viability, apoptosis, migration, and invasion were all evaluated. The microarray analysis screened out the differential expression of CXCL12-CXCR4 in OC. CXCL12 and CXCR4 expressions were increased in OC tissues, particularly in the metastatic OC tissues. Downregulation of CXCR4 by AMD3100 or shRNA was observed to have a critical role in inhibiting cell proliferation, migration, and invasion of the CAOV3 OC cell line while promoting cell apoptosis. Overexpressed CXCR4 brought significantly promoting effects on the proliferation and invasiveness of OC cells. These results reinforce that the blockade of CXCL12-CXCR4 axis with AMD3100 inhibits the growth of OC cells. The antitumor role of the inhibition of CXCL12-CXCR4 axis offers a preclinical validation of CXCL12-CXCR4 axis as a therapeutic target in OC.

Role of CXCR7 as a Common Predictor for Prognosis in Solid Tumors: a Meta-Analysis

Background: Accumulating evidence indicated that the CXC chemokine receptor (CXCR) 7 (CXCR7) was overexpressed in a variety of tumors. However, the value of the CXCR7 expression in predicting prognosis in solid tumors remains controversial. Therefore, we performed this meta-analysis to evaluate the correlation between CXCR7 expression and lymph node metastasis (LNM), tumor pathological grade and survival, including overall survival (OS), disease-free survival (DFS) and recurrence-free survival (RFS). Methods: Eligible studies were searched in PubMed, Web of Science, and PMC up to April 2018. A total of 27 studies were included in this meta-analysis. Odds ratio (OR), hazard ratio (HR) and 95 % confidence intervals (CI) were used as effect measures. Results: The meta-analysis showed that high expression of CXCR7 predicted a high risk of LNM (pooled OR = 2.22, 95%CI: 1.41-3.50), high tumor grade (pooled OR = 1.94, 95%CI: 1.20-3.13), poor OS (pooled HR = 1.66, 95%CI: 1.30-2.03), and poor DFS/RFS (pooled HR = 1.82, 95%CI: 1.21-2.43). Subgroup analysis showed that CXCR7 expression had a positive correlation with LNM in pan-adenocarcinoma subgroup (pooled OR = 3.73, 95%CI: 2.21-6.30), while no correlation was found in pan-squamous cancer subgroup (pooled OR = 1.29, 95%CI: 0.56-2.96). Subgroup analysis of tumor grade revealed that high expression of CXCR7 predicted high tumor grade both in pan-squamous cancer and pan-adenocarcinoma (pooled OR = 3.58, 95%CI: 1.39-9.22, pooled OR = 2.25, 95%CI: 1.20-4.20). As in OS group, we divided the data based on analysis method and it turned out that overexpressed CXCR7 predicted worse OS both in multivariate analysis (pooled HR =1.57, 95%CI: 1.12-2.01) and univariate analysis subgroup (pooled HR =1.86, 95%CI: 1.23-2.49). Conclusions: Our meta-analysis revealed that high expression of CXCR7 predicted unfavorable prognosis and may serve as potential targets of cancer therapy.

CD271+, CXCR7+, CXCR4+, and CD133+ Stem/Progenitor Cells and Clinical Characteristics of Acute Ischemic Stroke Patients

Ischemic stroke causes mobilization of various groups of progenitor cells from bone marrow to bloodstream and this correlates with the neurological status of stroke patients. The goal of our study was to identify the activity of chosen progenitor/stem cells in the peripheral blood of acute ischemic stroke patients in the first 7 days after the incident, through associations between the levels of the cells and clinical features of the patients. Thirty-three acute ischemic stroke patients and 15 non-stroke control subjects had their venous blood collected repeatedly in order to assess the levels of the CD45–CD34 + CD271+, the CD45–CD34 + CXCR4+, the CD45–CD34 + CXCR7+, and the CD45–CD34 + CD133+ stem/progenitor cells by means of flow cytometry. The patients underwent repeated neurological and clinical assessments, pulse wave velocity (PWV) assessment on day 5, and MRI on day 1 and 5 ± 2. The levels of the CD45–CD34 + CXCR7+ and the CD45–CD34 + CD271+ cells were lower in the stroke patients compared with the control subjects. Only the CD45–CD34 + CD271+ cells correlated positively with lesion volume in the second MRI. The levels of the CD45–CD34 + CD133+ cells on day 2 correlated negatively with PWV and NIHSS score on day 9. The patients whose PWV was above 10 m/s had significantly higher levels of the CD45–CD34 + CXCR4+ and the CD45–CD34 + CXCR7+ cells on day 1 than those with PWV below 10 m/s. This study discovers possible activity of the CD45–CD34 + CD271+ progenitor/stem cells during the first 7 days after ischemic stroke, suggests associations of the CD45–CD34 + CD133+ cells with the neurological status of stroke patients, and some activity of the CD45–CD34 + CD133+, the CD45–CD34 + CXCR4+, and the CD45–CD34 + CXCR7+ progenitor/stem cells in the process of arterial remodeling.

IL6 derived from cancer-associated fibroblasts promotes chemoresistance via CXCR7 in esophageal squamous cell carcinoma

Various factors and cellular components in the tumor microenvironment are key drivers associated with drug resistance in many cancers. Here, we analyzed the factors and molecular mechanisms involved in chemoresistance in patients with esophageal squamous cell carcinoma (ESCC). We found that interleukin 6 (IL6) derived mainly from cancer-associated fibroblasts played the most important role in chemoresistance by upregulating C-X-C motif chemokine receptor 7 (CXCR7) expression through signal transducer and activator of transcription 3/nuclear factor-κB pathway. CXCR7 knockdown resulted in the inhibition of IL6-induced proliferation and chemoresistance. In addition, CXCR7 silencing significantly decreased gene expression associated with stemness, chemoresistance and epithelial-mesenchymal transition and suppressed the proliferation ability of ESCC cells in three-dimensional culture systems and angiogenesis assay. In clinical samples, ESCC patients with high expression of CXCR7 and IL6 presented a significantly worse overall survival and progression-free survival upon receiving cisplatin after operation. These results suggest that the IL6-CXCR7 axis may provide a promising target for the treatment of ESCC.

Gene function analysis and underlying mechanism of esophagus cancer based on microarray gene expression profiling

Esophageal cancer (EC) is one of the most common digestive malignant tumors worldwide. Over the past decades, there have been minimal improvements in outcomes for patients with EC. New targets and novel therapies are needed to improve outcomes for these patients. This study aimed to explore the molecular mechanisms of EC by integrated bioinformatic analyses of the feature genes associated with EC and correlative gene functions which can distinguish cancerous tissues from non-cancerous tissues. Gene expression profile GSE20347 was downloaded from Gene Expression Omnibus (GEO) database, including 17 EC samples and their paired adjacent non-cancerous samples. The differentially expressed genes (DEGs) between EC and normal specimens were identified and then applied to analyze the GO enrichment on gene functions and KEGG pathways. Corresponding Pathway Relation Network (Pathway-net) and Gene Signal Network (signal-net) of DEGs were established based on the data collected from GCBI datasets. The results showed that DEGs mainly participated in the process of cell adhesion, cell proliferation, survival, invasion, metastasis and angiogenesis. Aberrant expression of PTK2, MAPK signaling pathway, PI3K-Akt signaling pathway, p53 signaling pathway and MET were closely associated with EC carcinogenesis. Importantly, Interleukin 8 (IL8) and C-X-C chemokine receptor type 7 (CXCR-7) were predicted to be significantly related to EC. These findings were further validated by analyzing both TCGA database and our clinical samples of EC. Our discovery provides a registry of genes and pathways that are disrupted in EC, which has the potential to be used in clinic for diagnosis and target therapy of EC in future.

A meta-analysis of CXCL12 expression for cancer prognosis

Background:

CXCL12 (SDF1) is reported to promote cancer progression in several preclinical models and this is corroborated by the analysis of human tissue specimens. However, the relationship between CXCL12 expression and cancer survival has not been systematically assessed.

Methods:

We conducted a systematic review and meta-analysis of studies that evaluated the association between CXCL12 expression and cancer survival.

Results:

Thirty-eight studies inclusive of 5807 patients were included in the analysis of overall, recurrence-free or cancer-specific survival, the majority of which were retrospective. The pooled hazard ratios (HRs) for overall and recurrence-free survival in patients with high CXCL12 expression were 1.39 (95% CI: 1.17–1.65, P=0.0002) and 1.12 (95% CI: 0.82–1.53, P=0.48) respectively, but with significant heterogeneity between studies. On subgroup analysis by cancer type, high CXCL12 expression was associated with reduced overall survival in patients with oesophagogastric (HR 2.08; 95% CI: 1.31–3.33, P=0.002), pancreatic (HR 1.54; 95% CI: 1.21–1.97, P=0.0005) and lung cancer (HR 1.37; 95% CI: 1.08–1.75, P=0.01), whereas in breast cancer patients high CXCL12 expression conferred an overall survival advantage (HR 0.5; 95% CI: 0.38–0.66, P<0.00001).

Conclusions:

Determination of CXCL12 expression has the potential to be of use as a cancer biomarker and adds prognostic information in various cancer types. Prospective or prospective–retrospective analyses of CXCL12 expression in clearly defined cancer cohorts are now required to advance our understanding of the relationship between CXCL12 expression and cancer outcome.

The adjuvant value of Andrographis paniculata in metastatic esophageal cancer treatment - from preclinical perspectives

Esophageal cancer (EC) is the fourth and sixth leading cause of cancer-related deaths in China and United States, respectively. The dismal prognosis of EC is mainly attributed to distant metastases, which may not be overcome by chemotherapy alone. Hence, the use of alternative adjuvant treatments, such as herbal medicines, for metastatic EC remains a great desire of patients. Our previous study demonstrated the in vivo anti-tumor and in vitro anti-invasion activities of Andrographis paniculata (AP) in esophageal cancer. In the present study, the chemical constituents of absorbed AP components through human intestinal Caco-2 cell monolayer were verified for the first time. The anti-migratory activities and suppressive effects on metastasis-related factors such as HER2, MMP2, MMP9, TM4SF3, CXCR4 of the absorbed AP components were revealed in esophageal cancer cells EC-109. The anti-tumor and anti-metastatic effects of AP water extract (1600 mg/kg) were further confirmed in metastatic esophageal xenograft-bearing mice. Besides, AP water extract acted synergistically with cisplatin plus 5-fluorouracil on inhibiting tumor nodule growth (with combination index <0.7). Meanwhile, chemotherapeutics-induced side-effects could also be reduced by AP water extract. The present findings provide evidence on safety and advantages of the combined use of AP with chemotherapeutics in pre-clinical setting.

CXCL12 expression promotes esophageal squamous cell carcinoma proliferation and worsens the prognosis

BACKGROUND

The chemokine CXCL12 and its corresponding receptor CXCR4 are key players in the development of several cancers. Therefore, we hypothesized that there is a functional causality between CXCL12 expression and tumor progression in patients with esophageal squamous cell carcinoma (ESCC).

METHODS

We performed an immunohistochemical analysis in 79 consecutive patients with ESCC. We performed in vitro and in vivo cell proliferation assays using ESCC cell lines and a newly established transfectant stably overexpressing CXCL12.

RESULTS

Immunohistochemistry revealed positive CXCR4 and CXCL12 expression in 48 (61 %) and 62 (78 %) patients, respectively. Additionally, the expression levels did not significantly correlate with any clinicopathological factors. The MIB-1 proliferation index was markedly higher in ESCC with a positive expression of CXCR4 or CXCL12. Positive CXCL12 expression was significantly correlated with lower recurrence-free survival (RFS, p = 0.02). Cox's hazard models revealed CXCL12 expression as an independent predictive factor for recurrence. In vitro, CXCL12 exposure or overexpression enhanced ESCC proliferation; and AMD3100, a specific inhibitor of CXCR4, equally decreased proliferation irrespective of CXCL12 exposure or overexpression. In the mouse model, AMD3100 significantly decreased ESCC tumor size (p = 0.03).

CONCLUSIONS

CXCL12 stimulates ESCC proliferation, and its expression levels are related to lower RFS in patients with ESCC. Our findings indicate that positive CXCL12 expression may be a useful marker for predicting the outcome in patients with ESCC and is a potentially new therapeutic target for ESCC.