Expression of sialyl Lewis^a relates to poor prognosis in cholangiocarcinoma

AIM: High levels of serum sialyl Lewisa (sLea) are frequently found in cholangiocarcinoma (CCA) patients and have been suggested to be a serum marker for CCA. However, the significance of this antigen in CCA is unknown. In this study, the clinical significance of sLea expression in CCA tissues and the possible role of sLea in vascular invasion in vitro were elucidated. METHODS: Expression of sLea in tumor tissues of 77 patients with mass-forming CCA and 33 with periductal infiltrating CCA was determined using immunohistochemistry. The in vitro assays on adhesion and transmigration of CCA cells to human umbilical vein endothelial cells were compared between CCA cell lines with and without sLea expression. RESULTS: sLea was aberrantly expressed in 60% of CCA tumor tissues. A significant relationship was found between the frequency of sLea expression and the mass-forming type CCA (P= 0.041), well differentiated histological grading (P=0.029), and vascular invasion (P=0.030). Patients with positive sLea expression had a significantly poorer prognosis (21.28 wk, 95% CI=16.75-25.81 wk) than those negative for sLea (37.30 wk, 95% CI=27.03-47.57 wk) (P<0.001). Multivariate analysis with adjustment for all covariates showed that patients positive for sLea possessed a 2.3-fold higher risk of death than patients negative for sLea (P<0.001). The role of sLea in vascular invasion was demonstrated using in vitro adhesion and transmigration assays. KKU-M213, a human CCA cell-line with a high expression of sLea, adhered and transmigrated to IL-1β-activated endothelial cells of the human umbilical vein more than KKU-100, the line without sLea expression (P<0.001). These processes were significantly diminished when the antibodies specific to either sLea or E-selectin were added to the assays (P<0.001) CONCLUSION: This study demonstrates the clinical significance of sLea expression in vascular invasion, and an unfavorable outcome in CCA. The role of sLea in vascular invasion which may lead to poor prognosis is supported by the in vitro adhesion and transmigration studies.

Inhibition of Adhesion and Metastasis of HepG2 Hepatocellular Carcinoma Cells In Vitro by DNA Aptamer against Sialyl Lewis X

The sialyl Lewis X（SLe;） antigen encoded by the FUT7 gene is the ligand of endotheliam-selectin（E-selectin）. The combination of SLe;antigen and E-selectin represents an important way for malignant tumor metastasis. In the present study, the effect of the SLe;-binding DNA aptamer on the adhesion and metastasis of hepatocellular carcinoma HepG2 cells in vitro was investigated. Reverse transcription-polymerase chain reaction（RT-PCR） and immunofluorescence staining were conducted to detect the expression of FUT7 at both transcriptional and translational levels. The SLe;expression in HepG2 cells treated with different concentrations of SLe;-binding DNA aptamer was detected by flow cytometry. Besides, the adhesion, migration, and invasion of HepG2 cells were measured by cell adhesion assay, and the Transwell migration and invasion assay. The results showed that the FUT7 expression was up-regulated at both mR NA and protein levels in HepG2 cells. SLe;-binding DNA aptamer could significantly decrease the expression of SLe;in HepG2 cells. The cell adhesion assay revealed that the SLe;-binding DNA aptamer could effectively inhibit the interactions between E-selectin and SLe;in the HepG2 cells. Additionally, SLe;-binding DNA aptamers at 20 nmol/L were found to have the similar effect to the monoclonal antibody CSLEX-1. The Transwell migration and invasion assay revealed that the number of penetrating cells on the down-side of Transwell membrane was significantly less in cells treated with 5, 10, 20 nmol/L SLe;-binding DNA aptamer than those in the negative control group（P<0.01）. Our study demonstrated that the SLe;-binding DNA aptamer could significantly inhibit the in vitro adhesion, migration, and invasion of HepG2 cells, suggesting that the SLe;-binding DNA aptamer may be used as a potential molecular targeted drug against metastatic hepatocellular carcinoma.