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BACKGROUND: Exosomes are 40-nm to 100-nm membrane vesicles that are secreted by various cells, and they play a major role in cell-cell communication. The objective of this study was to clarify the significance of the levels of microRNA in exosomes extracted from the sera of patients with esophageal squamous cell cancer (ESCC). METHODS: The authors isolated exosomes in serum samples from patients who had ESCC and from patients who had benign diseases without systemic inflammation. Total RNA was purified from the exosomes, and expression levels of microRNA-21 (miR-21) were analyzed by quantitative real-time polymerase chain reaction. RESULTS: Serum exosomes from patients with ESCC induced the proliferation of ESCC cells in vitro. The expression levels of exosomal miR-21 were significantly higher in patients with ESCC than those with benign diseases with and without (C-reactive protein <0.3 mg/dL) systemic inflammation. MiR-21 was not detected in serum that remained after exosome extraction. Exosomal miR-21 expression was correlated with advanced tumor classification, positive lymph node status, and the presence of metastasis with inflammation or and clinical stage without inflammation (C-reactive protein <0.3 mg/dL). CONCLUSIONS: The current results confirmed that exosomal miR-21 expression is up-regulated in serum from patients with ESCC versus serum from patients who have benign diseases without systemic inflammation. Exosomal miR-21 was positively correlated with tumor progression and aggressiveness, suggesting that it may be a useful target for cancer therapy.

Purpose: MicroRNAs are f22 nucleotide noncoding RNA molecules that posttranscriptionally regulate gene expression. The aim of this study was (a) to determine a role of microRNA-21 in esophageal squamous cell carcinoma and (b) to elucidate the regulation of the programmed cell death 4 (PDCD4) gene by microRNA-21. Experimental Design: MicroRNA-21 expression was investigated in 20 matched normal esophageal epitheliums and esophageal squamous cell carcinomas and seven esophageal squamous cell carcinoma cell lines (TE6, TE8, TE10, TE11, TE12, TE14, KYSE30) by TaqMan quantitative real-time PCR and in situ hybridization. To evaluate the role of microRNA-21, cell proliferation and invasion were analyzed with anti^microRNA-21^transfected cells. In addition, the regulation of PDCD4 by microRNA-21 was elucidated to identify the mechanisms of this regulation. Results: Of 20 paired samples, 18 cancer tissues overexpressed microRNA-21 in comparison with matched normal epitheliums. Specifically, patients with lymph node metastasis or venous invasion showed significantly high expression of microRNA-21. In situ hybridization for microRNA-21 showed strong positive staining in paraffin-embedded esophageal squamous cell carcinoma tissues. All seven esophageal squamous cell carcinoma cell lines also overexpressed microRNA-21, and anti^microRNA-21^transfected cells showed significant reduction in cellular proliferation and invasion. The PDCD4 protein levels in esophageal squamous cell carcinoma cells have an inverse correlation with microRNA-21expression. Anti^microRNA-21^transfected cells increased PDCD4 protein expression without changing the PDCD4 mRNA level and increased a luciferase-reporter activity containing the PDCD4-3 ¶ untranslated region construct. Conclusions: MicroRNA-21 targets PDCD4 at the posttranscriptional level and regulates cell proliferation and invasion in esophageal squamous cell carcinoma. It may serve as a novel therapeutic target in esophageal squamous cell carcinoma.Esophageal cancer occurs worldwide with a variable geographic distribution and ranks eighth in order of occurrence and the sixth leading cause of cancer mortality, affecting men more than women (1). It has two main forms, each with distinct etiologic and pathologic characteristics, esophageal squamous cell carcinoma and adenocarcinoma. Esophageal squamous cell carcinoma is the most frequent subtype of esophageal cancer, although the incidence of adenocarcinoma in the Western world is increasing faster than other esophageal malignancies.

Although integrins are crucial for migration of leukocytes through endothelium, integrin-independent mechanisms appear to take over and mediate the migration of leukocytes through extracellular matrix (ECM) in a three-dimensional tissue microenvironment. Discoidin domain receptor (DDR) 1 is a receptor tyrosine kinase activated by collagen, the most abundant ECM protein. In the present study, we detected that peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophils were induced to express DDR1 after incubation in RPMI 1640. The expression level of DDR1 in PBMC was increased further by stimulation with tumor necrosis factor-alpha, interleukin-1beta, granulocyte-macrophage colony-stimulating factor, lipopolysaccharide, or phytohemagglutinin, but not with interferon-gamma. In vivo, DDR1 mRNA was detectable in mononuclear leukocytes infiltrating human renal tumor tissue. Among three DDR1 isoforms, DDR1alpha was the major transcript in leukocytes. Functionally, overexpression of either DDR1alpha or DDR1beta in THP-1 cells resulted in increased adherence to collagen-coated plates in a beta1-integrin independent manner. However, only DDR1alpha-, but not DDR1beta-, overexpressing cells exhibited marked pseudopod extension and migrated successfully through three-dimensional collagen lattices. Consequently, we propose that the interaction of DDR1alpha with collagen of the ECM results in a requisite intracellular signaling that enables leukocytes to migrate in a tissue microenvironment and participate in host defense.

Background:F-box and WD repeat domain-containing 7 (FBXW7) is a cell cycle regulatory gene whose protein product ubiquitinates positive cell cycle regulators such as c-Myc, cyclin E, and c-Jun, thereby acting as a tumour-suppressor gene. This study focused on microRNA-223 (miR-223), which is a candidate regulator of FBXW7 mRNA. The aim of this study was to clarify the clinical significance of miR-223 and FBXW7 in oesophageal squamous cell carcinoma (ESCC) patients, and to elucidate the mechanism by which FBXW7 is regulated by miR-223.Methods:The expression levels of miR-223 and the expression of FBXW7 protein was examined using 109 resected specimens to determine the clinicopathological significance. We also investigated the role of miR-223 in the regulation of FBXW7 expression in ESCC cell lines in an in vitro analysis.Results:We found that miR-223 expression was significantly higher in cancerous tissues than in the corresponding normal tissues. There was a significant inverse relationship between the expression levels of miR-223 and FBXW7 protein. Moreover, patients with high miR-223 expression demonstrated a significantly poorer prognosis than those with low expression. On the basis of a series of gain-of-function and loss-of-function studies in vitro, we identified FBXW7 as a functional downstream target of miR-223.Conclusion:Our present study indicates that high expression of miR-223 had a significant adverse impact on the survival of ESCC patients through repression of the function of FBXW7.