Persistent CXCR4 expression after preoperative chemoradiotherapy predicts early recurrence and poor prognosis in esophageal cancer

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.

Immunohistochemical analyses of paraffin-embedded sections after primary surgery or trimodality treatment in esophageal carcinoma

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Changes in the tumor microenvironment of esophageal cancers, both in squamous cell carcinoma and adenocarcinoma, were found when comparing tumor resection specimen having undergone neoadjuvant radiochemotherapy followed by resection or resection only.

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Selected markers of the tumor microenvironment, i.e., Ki67, p53, CXCR4 and PD1 were found to be downregulated in hypoxic regions compared to normoxic regions.

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These findings will be correlated with microscopic tumor extension measurements in a subsequent, prospectively included cohort of esophageal cancer patients.

Background

The microscopic tumor extension before, during or after radiochemotherapy (RCHT) and its correlation with the tumor microenvironment (TME) are presently unknown. This information is, however, crucial in the era of image-guided, adaptive high-precision photon or particle therapy.

Materials and methods

In this pilot study, we analyzed formalin-fixed paraffin-embedded (FFPE) tumor resection specimen from patients with histologically confirmed squamous cell carcinoma (SCC; n = 10) or adenocarcinoma (A; n = 10) of the esophagus, having undergone neoadjuvant radiochemotherapy followed by resection (NRCHT + R) or resection (R)]. FFPE tissue sections were analyzed by immunohistochemistry regarding tumor hypoxia (HIF-1α), proliferation (Ki67), immune status (PD1), cancer cell stemness (CXCR4), and p53 mutation status. Marker expression in HIF-1α subvolumes was part of a sub-analysis. Statistical analyses were performed using one-sided Mann-Whitney tests and Bland-Altman analysis.

Results

In both SCC and AC patients, the overall percentages of positive tumor cells among the five TME markers, namely HIF-1α, Ki67, p53, CXCR4 and PD1 after NRCHT were lower than in the R cohort. However, only PD1 in SCC and Ki67 in AC showed significant association (Ki67: p = 0.03, PD1: p = 0.02). In the sub-analysis of hypoxic subvolumes among the AC patients, the percentage of positive tumor cells within hypoxic regions were statistically significantly lower in the NRCHT than in the R cohort across all the markers except for PD1.

Conclusion

In this pilot study, we showed changes in the TME induced by NRCHT in both SCC and AC. These findings will be correlated with microscopic tumor extension measurements in a subsequent cohort of patients.

Elevated CXCL12 in the plasma membrane of locally advanced rectal cancer after neoadjuvant chemoradiotherapy: a potential prognostic marker

Background: Neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC) has been shown to improve sphincter preservation and local pelvic control, but the efficacy of nCRT plateaus due to metastasis. CXC chemokine ligand 12 (CXCL12) has a critical impact on cancer development and metastasis.

Methods: By investigating public databases containing LARC patient data, CXCL12, CXCR4 and FAPα expression was analyzed via the Tumor Immune Estimation Resource (TIMER) and GSEA. Immunohistochemistry was applied to a total of 121 surgically resected specimens consisting of 61 LARCs after nCRT and 60 LARCs with no nCRT and 16 cases with endoscopic resection of high-grade colorectal adenoma.

Results: By investigating public databases containing LARC patient data, CXCL12 expression is correlated with poor prognosis, immune cell infiltration, epithelial- mesenchymal transition, and angiogenesis in LARC. Furthermore, radiation selectively induced CXCL12, CXCR4 and FAPα expression in tumor tissues. Immunohistochemistry results showed that the levels of CXCL12, CXCR4, and FAPα in LARC cells after nCRT were higher than in LARC cells untreated with nCRT (p < 0.001 for each). Elevated levels of CXCL12 in the plasma membrane of LARC cells after nCRT demonstrated an association with the period of freedom from recurrence (FFR) in univariate and multivariate survival analyses (p = 0.005 and p = 0.031, respectively).

Conclusions: The expression of CXCL12 may influence the survival and invasive properties of LARC cells during nCRT and promote cancer recurrence. We suggest that CXCL12 expression in the plasma membrane of radioresistant LARC cells may be a predictive factor of recurrence and a viable therapeutic strategy to control radioresistant LARC recurrence.

Overexpression of chemokine receptor CXCR4 predicts lymph node metastatic risk in patients with melanoma: A systematic review and meta-analysis

CXCR4 is a member of CXC-type and G protein-coupled receptors that can conduce many biological processes, including hemostasis, migration, and adhesion of different types of immune cells. Also, the contribution of CXCR4 in metastasis cascade and development of various malignancies has been addressed in previous reports. This meta-analysis was performed to explore whether the CXCR4 expression affects prognosis and clinicopathologic features in melanoma cancer. Our study involved 656 melanoma patients from 13 reports by detailed literature search from PubMed, Embase, Web of Science, and Google Scholar up to April 2021. To evaluate the association between CXCR4 expression and clinicopathological features of melanoma, we calculated odds ratios (ORs) with its 95% confidence intervals (CIs). We indicated that the CXCR4 overexpression was obviously correlated with ulceration (OR = 0.56, 95% CI: 0.38 to 0.74; I2 = 0.0%, P = 0.999), tumor thickness (OR = 0.56, 95% CI: 0.38 to 0.74; I2 = 0.0%, P = 0.999) and lymph node metastasis (OR = 8.54, 95% CI: 1.04 to 16.04; I2 = 98.9, P < 0.0001). In conclusion, our results reveal that CXCR4 is involved in enhancing the progression and metastasis of melanoma, and further clinical studies are necessary to investigate the role of CXCR4 as a diagnostic and therapeutic biomarker through the progress of melanoma cancer.

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.

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.

SDF-1/CXCR4 induces cell invasion through CD147 in squamous cell carcinoma of the hypopharynx

Hypopharyngeal squamous cell carcinoma (SCC) has a poor prognosis due to local invasion and metastasis. The chemokine receptor CXC chemokine receptor type 4 (CXCR4) and its ligand, stromal cell-derived factor 1 (SDF-1), play roles in tumor progression through unclear mechanisms. For the present study, we used a hypopharyngeal SCC cell line, FaDu, expressing CXCR4. We found that SDF-1 promotes migration and invasion of the FaDu cells. In addition, AMD3100, a specific antagonist of CXCR4, inhibited the binding of SDF-1 to CXCR4, resulting in a significant decrease in the FaDu cell migration induced by SDF-1. Stimulation of CXCR4 with SDF-1 induced an increase in the expression of CD147, a cell membrane protein; and this CD147 upregulation was abrogated by AMD3100. CD147 function-blocking antibodies also abolished the SDF-1-induced FaDu invasiveness. Our results suggested that SDF-1/CXCR4 mediate hypopharyngeal SCC cell migration and that CD147 is involved in the SDF-1/CXCR4-related tumor progression.

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.

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.

JMJD3 promotes the epithelial-mesenchymal transition and migration of glioma cells via the CXCL12/CXCR4 axis

Histone H3K27 demethylase Jumonji domain-containing protein 3 (JMJD3) is involved in somatic cell differentiation and tumor progression; however, the underlying mechanisms of JMJD3 in cancer progression are yet to be fully explored. To improve understanding regarding the function of JMJD3 in brain tumor cells, the present study investigated the effects of JMJD3 on the epithelial-mesenchymal transition (EMT) and migration in glioma cells, and the underlying mechanisms involving the C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) axis. Immunohistochemical staining of a tissue microarray of glioma samples confirmed that JMJD3 overexpression could stratify highly metastatic glioma. The overexpression of JMJD3 induced a spindle-shaped morphology, promoted N-cadherin expression, inhibited E-cadherin expression and enhanced the migration ability of U-251MG and U-87MG American Type Culture Collection cells. The expression of E-cadherin and N-cadherin were assessed by western blotting and reverse transcription-quantitative polymerase chain reaction, and cell migration was evaluated using a Transwell migration assay and wound-healing. The overexpression of JMJD3 upregulated CXCL12 expression in a demethylase activity-dependent manner as ChIP assays revealed a decrease in H3K27 trimethylation at the CXCL12 promoter following overexpression of JMJD3 in U-87MG ATCC cells. Accordingly, CXCL12 overexpression was sufficient to rescue the suppressive effects of JMJD3 inhibition on the EMT and migration in glioma cells. In addition, CXCR4 expression was not regulated by JMJD3, but the interruption of CXCR4 caused by the CXCR4 inhibitor AMD3100 abolished the promotional effect of JMJD3 on EMT and migration in glioma cells. Collectively, these results suggested that JMJD3 promoted EMT and migration in glioma cells via the CXCL12/CXCR4 axis. The present study described a novel epigenetic mechanism regulating tumor cell EMT and migration, and provided a novel direction for glioma diagnosis and 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.

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.

Stem cell autocrine CXCL12/CXCR4 stimulates invasion and metastasis of esophageal cancer

Esophageal cancer is one of the most common malignant tumors of the digestive tract. The greatest obstacle to the curing of esophageal cancer is its propensity to spread and metastasize. Esophageal cancer stem cells are considered the source for recurrence and metastasis of the tumors. While clinical evidence suggested that continuous up-regulation of CXCL12/CXCR4 was significantly associated with poor prognosis in patients with esophageal cancer, but the role and mechanism of CXCL12/CXCR4 in the invasion and metastasis of esophageal cancer has not been reported by far. This study found that esophageal cancer stem cells not only autocrine a great amount of CXCL12, but also high expression of its corresponding receptor CXCR4. Most importantly, the ability of esophageal cancer stem cells to spread and metastasize could be inhibited by blockage of CXCR4 with inhibitors or shRNA approaches both in vivo and in vitro studies. The important role of CXCL12 in the invasion and metastasis of esophageal cancer stem cells was also confirmed by loss-of-function and gain-of-function strategies. Mechanistically, we demonstrated that CXCL12/CXCR4 activated the ERK1/2 pathway and thereby ultimately maintained the characteristics of high-level invasion and metastasis of esophageal cancer stem cells. Taken together, our findings suggested that autocrine CXCL12/CXCR4 was one of the major mechanisms underlying the metastatic property of esophageal cancer stem cells through ERK1/2 signaling pathway, and might serve as a therapeutic target for esophageal cancer patients.

Interplay between the NF‑κB and hedgehog signaling pathways predicts prognosis in esophageal squamous cell carcinoma following neoadjuvant chemoradiotherapy

Tumor recurrence and metastasis in esophageal squamous cell carcinoma (ESCC) are primary causes of patient mortality. The nuclear factor (NF)‑κB signaling pathway and hedgehog signaling pathway were previously reported to contribute to cell growth and metastasis in ESCC. The present study therefore investigated the roles of the NF‑κB and hedgehog pathways in ESCC tumors following neoadjuvant chemoradiotherapy (NCRT). By immunohistochemistry staining, it was observed that NF‑κB and glioma‑associated oncogene homolog 1 (Gli1), key components of the NF‑κB and hedgehog pathways, respectively, were decreased following NCRT, which was further confirmed by western blotting and reverse transcription‑quantitative polymerase chain reaction analysis. In addition, survival analysis suggested that high expression levels of either NF‑κB or Gli1 were associated with poor overall survival (OS) of patients. In the esophageal cell line TE‑8, NF‑κB and Gli1 formed a positive feedback loop, and inhibition of either NF‑κB or Gli1 may inhibit cell migration, invasion and proliferation. The results of the present study demonstrated that activation of the NF‑κB and hedgehog signaling pathways limited the OS of patients with ESCC following NCRT, and may therefore be suitable targets for ESCC treatment.

Targeting the CXCR4/CXCL12 axis in treating epithelial ovarian cancer

Ovarian carcinoma is the most crucial and difficult target for available therapeutic treatments among gynecological malignancies, and great efforts are required to find an effective solution. Molecular studies showed that the chemokine stromal cell-derived factor-1 (also known as CXCL12) and its receptor, CXCR4, are key determinants of tumor initiation, progression and metastasis in ovarian carcinomas. Hence, it is generally believed that blocking the CXCR4/CXCL12 pathway could serve as a potential therapy for patients with ovarian cancer. Herein, we investigated the role of the CXCR4/CXCL12 axis in regulating ovarian cancer progression. Using flow cytometry, a real-time PCR and western blot analyses, we showed that the chemokine receptor CXCR4 protein and mRNA were overexpressed in human epithelial ovarian cancer cell lines, and these were closely correlated with poor outcomes. Moreover, silencing CXCR4 by small hairpin RNA in HTB75 cells reduced cell proliferation, migration and invasion and significantly reduced RhoA and Rac-1/Cdc42 expressions, whereas overexpression of CXCR4 in SKOV3 cells significantly increased cell migration and markedly increased RhoA, Rac-1/Cdc42 levels. Silencing CXCR4 also led to decreased in vitro cytotoxicity of AMD3100, a specific antagonist of CXCR4, which exerts its effect upon CXCR4 expression. Remarkably, knockdown of CXCR4 in HTB75 cells led to a significantly decreased capability to form tumors in vivo, and the Ki67 proliferation index of xenograft tumors showed a dramatic reduction. Our results revealed that the CXCR4/CXCL12 pathway represents a promising therapeutic target for epithelial ovarian carcinoma.

CXCR4 over-expression and survival in cancer: a system review and meta-analysis

C-X-C chemokine receptor 4 (CXCR4) is frequently over-expressed in various types of cancer; many agents against CXCR4 are in clinical development currently despite variable data for the prognostic impact of CXCR4 expression. Here eighty-five studies with a total of 11,032 subjects were included to explore the association between CXCR4 and progression-free survival (PFS) or overall survival (OS) in subjects with cancer. Pooled analysis shows that CXCR4 over-expression is significantly associated with poorer PFS (HR 2.04; 95% CI, 1.72-2.42) and OS (HR=1.94; 95% CI, 1.71-2.20) irrespective of cancer types. Subgroup analysis indicates significant association between CXCR4 and shorter PFS in hematological malignancy, breast cancer, colorectal cancer, esophageal cancer, renal cancer, gynecologic cancer, pancreatic cancer and liver cancer; the prognostic effects remained consistent across age, risk of bias, levels of adjustment, median follow-up period, geographical area, detection methods, publication year and size of studies. CXCR4 over-expression predicts unfavorable OS in hematological malignancy, breast cancer, colorectal cancer, esophageal cancer, head and neck cancer, renal cancer, lung cancer, gynecologic cancer, liver cancer, prostate cancer and gallbladder cancer; these effects were independence of age, levels of adjustment, publication year, detection methods and follow-up period. In conclusion, CXCR4 over-expression is associated with poor prognosis in cancer.

Construction of a CXCL12-KDEL fusion gene to inhibit head and neck squamous cell carcinoma metastasis by intracellular sequestration of CXCR4

The CXCL12-CXCR4 biological axis consisting of the chemotactic factor CXCL12 and its specific receptor CXCR4 plays an important role in oral cancer metastasis. High expression of CXCR4 may help oral squamous cancer cells invade local tissues and metastasize to lymph nodes. No obvious association was observed between CXCL12 expression and lymph node metastasis, suggesting that CXCL12 chemotaxis may only be related to CXCR4 expression on the tumor cell membrane. KDEL can be retained by receptors on the surface of the intracellular endoplasmic reticulum (ER) and also be called an ER retention signal sequence. So we adopted the KDEL sequence in this study to generate a CXCL12-KDEL fusion protein in combination with a traceable E-tag label. As such, CXCL12 was retained in the ER. Specific receptor CXCR4 binds to the CXCL12-KDEL, was also retained in the ER, and was thus prevented from reaching the oral squamous cancer cell surface. We reduced the cell surface level of CXCR4 and called the technique “intracellular sequestration.” By this way, we have finished blocking of CXCL12-CXCR4 biological axis and inhibiting lymph node metastasis of oral carcinoma.

Chemokine receptor-specific antibodies in cancer immunotherapy: achievements and challenges

The 1990s brought a burst of information regarding the structure, expression pattern, and role in leukocyte migration and adhesion of chemokines and their receptors. At that time, the FDA approved the first therapeutic antibodies for cancer treatment. A few years later, it was reported that the chemokine receptors CXCR4 and CCR7 were involved on directing metastases to liver, lung, bone marrow, or lymph nodes, and the over-expression of CCR4, CCR6, and CCR9 by certain tumors. The possibility of inhibiting the interaction of chemokine receptors present on the surface of tumor cells with their ligands emerged as a new therapeutic approach. Therefore, many research groups and companies began to develop small molecule antagonists and specific antibodies, aiming to neutralize signaling from these receptors. Despite great expectations, so far, only one anti-chemokine receptor antibody has been approved for its clinical use, mogamulizumab, an anti-CCR4 antibody, granted in Japan to treat refractory adult T-cell leukemia and lymphoma. Here, we review the main achievements obtained with anti-chemokine receptor antibodies for cancer immunotherapy, including discovery and clinical studies, proposed mechanisms of action, and therapeutic applications.

MicroRNA-381 increases radiosensitivity in esophageal squamous cell carcinoma

BACKGROUND

Radiation resistance poses a major clinical challenge in treatment of esophageal squamous cell carcinoma (ESCC). However, the mechanisms of radioresistance has not been fully elucidated. Since accumulating evidence demonstrates that aberrant expression of microRNAs (miRNAs) contributes to cancer sensitivity to radiation, we aimed to identify miRNAs associated with radioresistance of ESCC.

METHODS

In this study, we used GeneChip miRNA Array to perform an comparison of miRNAs expression in tissues from primary ESCC and recurrent ESCC in situ after radiotherapy. Differential expressions of miRNAs were comfirmed by quantitative Real-Time PCR in tissues and six ESCC cell lines. Cell radiosensitivity were determined by colony formation assay. Functional analyses of miRNA-381 in ESCC cells growth and metastasis were performed by MTT and Transwell Assays. In vivo assays of the functions of miRNA-381 were performed in tumor xenografts.

RESULTS

One miRNA candidate, miRNA-381, was found to be downregulated in radiation resistance tissues and cells. Enforced expression of miRNA-381 increased radiosensitivity of ESCC cells and promoted nonaggressive phenotype including decreased cellular proliferation and migration. In contrast, inhibition of miRNA-381 in ESCC cells promoted radiation resistance and development of an aggressive phenotype. In vivo assays extended the significance of these results, showing that miRNA-381 overexpression decreased the tumor growth and the resistance to radiation treatment in tumor xenografts.

CONCLUSIONS

Together, our work reveals miRNA-381 expression as a critical determinant of radiosensitivity in esophageal cancer cells.

Chemokines in tumor progression and metastasis

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

The oncoprotein and stem cell renewal factor BMI1 associates with poor clinical outcome in oesophageal cancer patients undergoing preoperative chemoradiotherapy

Background

The polycomb group (PcG) family BMI1, acting downstream of the hedgehog (Hh) pathway, plays an essential role in the self-renewal of haematopoietic, neural, and intestinal stem cells, and is dysregulated in many types of cancer. Our recent report has demonstrated that Hh signalling activation can predict very earlier relapse of oesophageal cancers. As data were not available on the clinical role of BMI1 expression in oesophageal cancers after chemoradiotherapy (CRT), we analysed whether it could be also used to predict disease progression and prognosis in oesophageal cancer patients undergoing trimodality therapy of preoperative CRT and oesophagectomy.

Methods

Expressions of BMI1 and p16^INK4A, a downstream target of PcG, were analysed in 78 patients with histologically confirmed oesophageal squamous cell carcinoma (ESCC) after preoperative CRT by immunohistochemical staining. The association of BMI1 and p16^INK4A expression with clinicopathologic characteristics was analysed by χ²-test. Survival analysis was carried out by the log-rank test using Kaplan-Meier method.

Results

Among 78 ESCC patients, 24 patients (30.8%) showed BMI1 positivity, mainly localised in the nuclei of tumour cells. Patients harbouring BMI1-positive tumour cells showed significantly poorer prognoses than those without such cells or residual tumours (mean disease-free survival (DFS) time 16.8 vs 71.2 months; 3-yr DFS 13.3% vs 49.9%, P=0.002; mean OS time 21.8 vs 76.6 months; 3-yr OS 16.2% vs 54.9%, P=0.0005). There was no significant correlation between p16^INK4A expression and BMI1 expression.

Conclusions

Our study shows that BMI1 expression is a predictor of early relapse and poor prognosis in ESCC after CRT. These findings suggest that BMI1 signal activation might be involved in promoting cancer regrowth and progression after CRT, and might be indicative of emergence of ‘more aggressive’ cancer progenitor cells.

The role of CXC chemokines in the transition of chronic inflammation to esophageal and gastric cancer

Chronic inflammation may increase the risk to develop cancer, for instance esophagitis or gastritis may lead to development of esophageal or gastric cancer, respectively. The key molecules attracting leukocytes to local inflammatory sites are chemokines. We here provide a systematic review on the impact of CXC chemokines (binding the receptors CXCR1, CXCR2, CXCR3 and CXCR4) on the transition of chronic inflammation in the upper gastrointestinal tract to neoplasia. CXCR2 ligands, including GRO-α,β,γ/CXCL1,2,3, ENA-78/CXCL5 and IL-8/CXCL8 chemoattract pro-tumoral neutrophils. In addition, angiogenic CXCR2 ligands stimulate the formation of new blood vessels, facilitating tumor progression. The CXCR4 ligand SDF-1/CXCL12 also promotes tumor development by stimulating angiogenesis and by favoring metastasis of CXCR4-positive tumor cells to distant organs producing SDF-1/CXCL12. Furthermore, these angiogenic chemokines also directly enhance tumor cell survival and proliferation. In contrast, the CXCR3 ligands Mig/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11 are angiostatic and attract anti-tumoral T lymphocytes and may therefore mediate tumor growth retardation and regression. Thus, chemokines exert diverging, sometimes dual roles in tumor biology as described for esophageal and gastric cancer. Therefore extensive research is needed to completely unravel the complex chemokine code in specific cancers. Possibly, chemokine-targeted cancer therapy will have to be adapted to the individual's chemokine profile.

Correlation between Chemokine Receptor CXCR4 Expression and Prognostic Factors in Patients with Prostate Cancer

PURPOSE

We evaluated the correlation between the expression of CXCR4 and prognostic factors in patients with prostate cancer.

MATERIALS AND METHODS

A total of 57 patients who had undergone surgery for prostate cancer were enrolled. Specimens were obtained before any treatment and were stained with antihuman CXCR4 antibody. The intensity of staining was graded as low or high. The age, pretreatment prostate-specific antigen (PSA) level, Gleason score, T stage, biochemical recurrence, local recurrence, and distant metastasis were compared according to the expression of CXCR4 in patients with prostate cancer.

RESULTS

Local recurrence was higher in the group with high expression, in 11 of 36 cases (30.6%), than in the group with low expression, in 1 of 21 cases (4.8%), with statistical significance (p=0.040). Distant metastasis was also associated with expression, occurring in 10 of 36 cases (27.8%) in the group with high expression and in 1 of 21 cases (4.8%) in the group with low expression (p=0.041). In the logistic regression test, CXCR4 expression was the only factor in determining local recurrence (p=0.016) and distant metastasis (0.022). Furthermore, the group with high CXCR4 expression showed significantly longer cancer-specific survival than did the low expression group (p=0.041). CXCR4 showed no association with age (p=0.881), pretreatment PSA level (p=0.584), Gleason score (p=0.640), T stage (p=0.967), or biochemical recurrence (p=0.081).

CONCLUSIONS

The high expression of CXCR4 was associated with local recurrence and distant metastasis. CXCR4 expression was shown to be a useful prognostic factor for patients with prostate cancer.

Homeostatic chemokine receptors and organ-specific metastasis

It has been 10 years since the role of a chemokine receptor, CXCR4, in breast cancer metastasis was first documented. Since then, the field of chemokines and cancer has grown significantly, so it is timely to review the progress, analyse the studies to date and identify future challenges facing this field. Metastasis is the major factor that limits survival in most patients with cancer. Therefore, understanding the molecular mechanisms that control the metastatic behaviour of tumour cells is pivotal for treating cancer successfully. Substantial experimental and clinical evidence supports the conclusion that molecular mechanisms control organ-specific metastasis. One of the most important mechanisms operating in metastasis involves homeostatic chemokines and their receptors. Here, we review this field and propose a model of 'cellular highways' to explain the effects of homeostatic chemokines on cancer cells and how they influence metastasis.

Silencing of CXCR4 blocks progression of ovarian cancer and depresses canonical Wnt signaling pathway

OBJECTIVE

CXC chemokine receptor 4 (CXCR4) was considered to be an important factor in cancer cell metastasis. This study was aimed to examine the expression of CXCR4 in ovarian cancer and determine the functions and the possible mechanisms of CXCR4 in the progression of ovarian cancer.

METHODS

CXC chemokine receptor 4 messenger RNA expression in normal ovarian tissues, malignant epithelial ovarian tumors, and 3 ovarian cancer cell lines was analyzed. Immunohistochemical analysis was used to detect the protein expression of CXCR4 and β-catenin in normal and malignant ovarian tissues. The effect of CXCR4 inhibition on cell proliferation and invasion was determined.

RESULTS

CXC chemokine receptor 4 was highly expressed in malignant ovarian tumors and ovarian cancer cell lines, and the different expression of CXCR4 was observed between the ovarian cancers with lymph node metastasis and without lymph node metastasis. Furthermore, The CXCR4 expression was correlated with β-catenin expression in ovarian tissues. Moreover, knockdown of CXCR4 could obviously reduce proliferation and invasion of ovarian cancer cell and inhibit Wnt target genes and mesenchymal markers such as vimentin and SLUG expression.

CONCLUSIONS

CXC chemokine receptor 4 plays a critical role in the metastasis of human ovarian cancer possibly through modulating the Wnt/β-catenin pathway. CXC chemokine receptor 4 is a potential therapeutic target for treatment of ovarian cancer.

CXCR4 promotes oral squamous cell carcinoma migration and invasion through inducing expression of MMP-9 and MMP-13 via the ERK signaling pathway

The increased migration and invasion of oral squamous cell carcinoma cells are key events in the development of metastasis to the lymph nodes and distant organs. Although the chemokine receptor CXCR4 and its ligand, stromal cell-derived factor-1α, have been found to play an important role in tumor invasion, its precise role and potential underlying mechanisms remain largely unknown. In this study, we showed that knockdown of CXCR4 significantly decreased Tca8113 cells migration and invasion, accompanied with the reduction of MMP-9 and MMP-13 expression. Inhibition of ligand binding to CXCR4 by a specific antagonist TN14003, also led to reduced cancer cell migration and invasion. Because the degradation of the extracellular matrix and the basement membrane by proteases, such as matrix metalloproteinases (MMP) is critical for migration and invasion of cancer cells, we investigated the expression of several MMPs and found that the expression of functional MMP-9 and MMP-13 was selectively decreased in CXCR4 knockdown cells. More importantly, decreased cell migration and invasion of CXCR4 knockdown cells were completely rescued by exogenous expression of MMP-9 or MMP-13, indicating that the two MMPs are downstream targets of CXCR4-mediated signaling. Furthermore, we found the level of phosphorylated extracellular signal-regulated kinase (ERK) was significantly decreased in CXCR4-silenced cells, suggesting that ERK may be a potential mediator of CXCR4-regulated MMP-9 and MMP-13 expression in Tca8113 cells. Taken together, our results strongly suggest the underlying mechanism of CXCR4 promoting Tca8113 migration and invasion by regulating MMP-9 and MMP-13 expression perhaps via activation of the ERK signaling pathway.

CXCR4 and cancer

The chemokine receptor CXCR4 belongs to the large superfamily of G protein-coupled receptors and has been identified to play a crucial role in a number of biological processes, including the trafficking and homeostasis of immune cells such as T lymphocytes. CXCR4 has also been found to be a prognostic marker in various types of cancer, including leukemia and breast cancer, and recent evidence has highlighted the role of CXCR4 in prostate cancer. Furthermore, CXCR4 expression is upregulated in cancer metastasis, leading to enhanced signaling. These observations suggest that CXCR4 is important for the progression of cancer. The CXCR4-CXCL12 (stromal cell-derived factor 1 (SDF-1)) axis has additionally been identified to have a role in normal stem cell homing. Interestingly, cancer stem cells also express CXCR4, indicating that the CXCR4-SDF-1 axis may direct the trafficking and metastasis of these cells to organs that express high levels of SDF-1, such as the lymph nodes, lungs, liver, and bone. This review focuses on the current knowledge of CXCR4 regulation and how deregulation of this protein may contribute to the progression of cancer.

Mechanism of chemoresistance mediated by miR-140 in human osteosarcoma and colon cancer cells

In this study, high-throughput microRNA (miRNA) expression analysis revealed that the expression of miR-140 was associated with chemosensitivity in osteosarcoma tumor xenografts. Tumor cells ectopically transfected with miR-140 were more resistant to methotrexate and 5-fluorouracil (5-FU). Overexpression of miR-140 inhibited cell proliferation in both osteosarcoma U-2 OS (wt-p53) and colon cancer HCT 116 (wt-p53) cell lines, but less so in osteosarcoma MG63 (mut-p53) and colon cancer HCT 116 (null-p53) cell lines. miR-140 induced p53 and p21 expression accompanied with G(1) and G(2) phase arrest only in cell lines containing wild type of p53. Histone deacetylase 4 (HDAC4) was confirmed to be one of the important targets of miR-140. The expression of endogenous miR-140 was significantly elevated in CD133(+hi)CD44(+hi) colon cancer stem-like cells that exhibit slow proliferating rate and chemoresistance. Blocking endogenous miR-140 by locked nucleic acid-modified anti-miR partially sensitized resistant colon cancer stem-like cells to 5-FU treatment. Taken together, our findings indicate that miR-140 is involved in the chemoresistance by reduced cell proliferation through G(1) and G(2) phase arrest mediated in part through the suppression of HDAC4. miR-140 may be a candidate target to develop novel therapeutic strategy to overcome drug resistance.

Chemokine receptor CXCR4 as a therapeutic target for neuroectodermal tumors

Chemokines (chemotactic cytokines) are a family of proteins associated with the trafficking and activation of leukocytes and other cell types in immune surveillance and inflammatory response. Besides their roles in the immune system, they play pleiotropic roles in tumor initiation, promotion, and progression. Chemokines can be classified into four subfamilies of chemokines, CXC, CC, C, or CX3C, based on their number and spacing of conserved cysteine residues near the N-terminus. This CXC subfamily can be further subclassified into two groups, depending on the presence or absence of a tripeptide motif glutamic acid-leucine-arginine (ELR) in the N-terminal domain. ELR(-)CXCL12, which binds to CXCR4 has been frequently implicated in various cancers. Over the past several years, studies have increasingly shown that the CXCR4/CXCL12 axis plays critical roles in tumor progression, such as invasion, angiogenesis, survival, homing to metastatic sites. This review focuses on involvement of CXCR4/CXCL12 interaction in neuroectodermal cancers and their therapeutic potentials. As an attractive therapeutic target of CXCR4/CXCL12 axis for cancer chemotherapy, development history and application of CXCR4 antagonists are described.

Hedgehog signal activation in oesophageal cancer patients undergoing neoadjuvant chemoradiotherapy

The zinc finger protein glioma-associated oncogene homologue 1 (Gli-1) is a critical component of the Hedgehog (Hh) signalling pathway, which is essential for morphogenesis and stem-cell renewal, and is dysregulated in many cancer types. As data were not available on the role of Gli-1 expression in oesophageal cancer progression, we analysed whether it could be used to predict disease progression and prognosis in oesophageal cancer patients undergoing neoadjuvant chemoradiotherapy (CRT). Among 69 patients with histologically confirmed oesophageal squamous cell carcinomas (ESCCs), 25 showed a pathological complete response after preoperative CRT. Overall survival (OS) was significantly associated with lymph-node metastasis, distant metastasis, and CRT, and was further correlated with the absence of both Gli-1 nuclear expression and residual tumour. All patients with Gli-1 nuclear expression (10.1%) had distant or lymph-node metastasis, and six out of seven died within 13 months. Furthermore, patients with Gli-1 nuclear-positive cancers showed significantly poorer prognoses than those without (disease-free survival: mean DFS time 250 vs 1738 months, 2-year DFS 0 vs 54.9%, P=0.009; OS: mean OS time 386 vs 1742 months, 2-year OS 16.7 vs 54.9%, P=0.001). Our study provides the first evidence that Gli-1 nuclear expression is a strong and independent predictor of early relapse and poor prognosis in ESCC after CRT. These findings suggest that Hh signal activation might promote cancer regrowth and progression after CRT.

Inhibition of CXCR4 activity with AMD3100 decreases invasion of human colorectal cancer cells in vitro

AIM: To investigate the effect and mechanism of blockade of the CXC chemokine receptor-4 (CXCR4) signaling pathway by AMD3100, a small non-peptide CXCR4 inhibitor, on invasion and metastasis of colorectal cancer cells in vitro.

METHODS: Human colorectal cancer cell line SW480 was treated with AMD3100 at different final concentrations. 3-(4,5-dimethylthiazol-2-yl)-2.5-dipheny-tetrazolium bromide (MTT) assay was used to detect the effect of AMD3100 on cell proliferation. The invasion ability of SW480 cells was determined by cell invasion assay kit. In the presence of AMD3100, the CXCL12-mediated migratory response of SW480 cells was tested by classical chemotaxis assays. RT-PCR analysis and Western blotting were used to detect the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in SW480 cells.

RESULTS: Cell viability was significantly suppressed by AMD3100 in a dose-dependent manner. AMD3100 (100 and 1000 ng/mL) significantly inhibited the invasion ability of SW480 cells. Treatment with AMD3100 markedly reduced the expression of VEGF and MMP-9 but not MMP-2 in SW480 cells.

CONCLUSION: The CXCL12/CXCR4 system is an important mediator of proliferation and invasion of CXCR4-expressing colorectal cancer cells. AMD3100 inhibited invasion and metastasis activity of the colorectal cancer cell line SW480 through down-regulation of VEGF and MMP-9 expression.

Chemokine receptor CXCR4 expression and prognosis in patients with metastatic prostate cancer

The chemokine receptor CXCR4 has been reported to be aberrantly expressed in human cancers and has also been shown to participate in the development of cancer metastasis. The present study was carried out to assess immunohistochemically the pattern of CXCR4 expression in patients with metastatic prostate cancer. We analyzed whether there may be an association between CXCR4 expression and prognosis. Fifty-two patients who received hormonal therapy were enrolled. Specimens were obtained from transperineal needle biopsy before treatment, and were stained with antihuman CXCR4 antibody. We also evaluated the pathological grade, extent of bony metastasis, clinical response to hormonal therapy, and patient prognosis. CXCR4 was detected in 94.2% patients. Its expression showed no association with pathological grade, extent of bony metastasis, or clinical response to hormonal therapy. Patients with a high expression of CXCR4 in tumors had poorer cancer-specific survival than those with low expression of CXCR4. CXCR4 expression is a useful prognostic factor for patients with metastatic prostate cancer treated with androgen-withdrawal therapy.

In vitro characterization and inhibition of the CXCR4/CXCL12 chemokine axis in human uveal melanoma cell lines

Purpose

The CXCR4/CXCL12 chemokine axis may play a critical role in guiding CXCR4+ circulating malignant cells to organ specific locations that actively secrete its ligand CXCL12 (SDF-1) such as bone, brain, liver, and lungs. We sought to characterize the presence of the CXCR4/CXCL12 axis in five uveal melanoma (UM) cell lines in vitro. The ability of TN14003, a synthetic peptide inhibitor that targets the CXCR4 receptor complex, to inhibit this axis was also assessed.

Methods

Immunocytochemistry was performed against CXCR4 to confirm expression of this chemokine receptor in all five UM cell lines. Flow cytometry was preformed to evaluate CXCR4 cell surface expression on all five UM cell lines. A proliferation assay was also used to test effects TN14003 would have on cellular proliferation. Inhibition of cellular migration by specifically inhibiting the CXCR4/CXCL12 axis with TN14003 was also investigated. The binding efficacy of TN14003 to the CXCR4 receptor was assessed through flow cytometric methods.

Results

The CXCR4 receptor was present on all five UM cell lines. All five cell lines expressed different relative levels of surface CXCR4. TN14003 did not affect the proliferation of the five cell lines (p > 0.05). All cell lines migrated towards the chemokine CXCL12 at a level greater than the negative control (p < 0.05). All 5 cell lines pre-incubated with TN14003 prevented cellular migration towards chemokine CXCL12 (p < 0.01). TN14003 preferentially binds CXCR4 to native ligand CXCL12.

Conclusion

Interfering with the CXCR4/CXCL12 axis, using TN14003 was shown to effectively down regulate UM cell migration in vitro. Knowing that UM expresses the CXCR4 receptor, these CXCR4+ cells may be less likely to colonize distant organs that secrete the CXCL12 ligand, if treated with an inhibitor that binds CXCR4. Further studies should be pursued in order to test TN14003 efficacy in vivo.

Effect of specific suppression of chemokine receptor CXCR4 by short interference RNA on the invasion capability and proliferation of colorectal cancer cells

AIM: To study the inhibitory effect of chemokine receptor CXCR4 short interference RNA (siRNA) on the invasion capability and proliferation of colorectal cancer cell line SW480.

METHODS: SiRNA specifically targeting CXC chemokine receptor CXCR4 was designed in vitro using T7 RNA polymerase. Colorectal cancer SW480 cells were cultured under standard condition and the siRNA was transfected into SW480 cells with Lipofectamine 2000. Negative control and mock control were used at the same time. The levels of CXCR4 mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting 48 h after transfection respectively. The changes of invasion capability and MT1-MMP protein in SW480 cells were evaluated using Boyden Chamber invasion assay and Western blotting respectively. The cell cycle distribution and proliferation status were detected by flow cytometry and MTT assay respectively.

RESULTS: Forty-eight hours after transfection with CXCR4 siRNA, in comparison with those in negative and mock control group, the levels of CXCR4 mRNA (51.53% ± 6.1% vs 78.4% ± 3.3%, P < 0.01; 51.53% ± 6.1% vs 87.4% ± 5.3%, P < 0.01) and protein (47.3% ± 3.7% vs 107.2% ± 3.6%, P < 0.01; 47.3% ± 3.7% vs 114.7% ± 4.8%, P < 0.01) decreased significantly (47.3% ± 3.7% vs 107.2% ± 3.6%, P < 0.01; 47.3% ± 3.7% vs 114.7% ± 4.8%, P < 0.01); the invasion capability (26.5% ± 6.1% vs 73.7% ± 3.4%, P < 0.01; 26.5% ± 6.1% vs 64.5% ± 5.7%, P < 0.01) and the MT1-MMP protein expression (43.8% ± 2.5% vs 64.4% ± 4.4%, P < 0.01; 43.8% ± 2.5% vs 67.0% ± 2.9%, P < 0.01) in SW480 cells decreased significantly, but the cell cycle distribution didn't change remarkably. At the absence of SDF-1, cell proliferation status was similar to that in control and mock control group. After stimulation by SDF-1, the proliferation of SW480 cells increased in all the groups, but it was much less active in the CXCR4 siRNA group than in the other two control groups.

CONCLUSION: CXCR4 siRNA can inhibit the expression of CXCR4 and decrease the invasion capability and proliferation of SW480 cells.