Inhibition of adhesion and metastasis of HepG2 hepatocellular carcinoma cells in vitro by DNA aptamer against sialyl Lewis X.

The sialyl Lewis X (SLe^x) antigen encoded by the FUT7 gene is the ligand of endotheliam-selectin (E-selectin). The combination of SLe^x antigen and E-selectin represents an important way for malignant tumor metastasis. In the present study, the effect of the SLe^x-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^x expression in HepG2 cells treated with different concentrations of SLe^x-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 mRNA and protein levels in HepG2 cells. SLe^x-binding DNA aptamer could significantly decrease the expression of SLe^x in HepG2 cells. The cell adhesion assay revealed that the SLe^x-binding DNA aptamer could effectively inhibit the interactions between E-selectin and SLe^x in the HepG2 cells. Additionally, SLe^x-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^x-binding DNA aptamer than those in the negative control group (P<0.01). Our study demonstrated that the SLe^x-binding DNA aptamer could significantly inhibit the in vitro adhesion, migration, and invasion of HepG2 cells, suggesting that the SLe^x-binding DNA aptamer may be used as a potential molecular targeted drug against metastatic hepatocellular carcinoma.