BACKGROUND: This study investigated the molecular mechanism of the effect of CD44 on the recurrence of EGC after ESD, including the potential regulator and signaling pathways of CD44.

MATERIAL AND METHODS: We searched the miRNA online database (www.mirdb.org) with the “seed sequence” located within the 3’-UTR of the target gene, and performed luciferase assay to test the miRNA/mRNA relationship. We also determined the expression of CD44 in the EGC and control samples. In addition, statistical analysis was used to explore the role of miR-328 as a biomarker to predict the recurrence after ECD.

RESULTS: We validated CD44 to be the direct gene via luciferase reporter assay system. We also established the negative regulatory relationship between miR-328 and CD44 via studying the relative luciferase activity at different concentrations of miR-328 mimics. We also conducted real-time PCR and Western blot analysis to study the mRNA and protein expression level of CD44 among different groups (recurrence-positive and recurrence-negative) or cells treated with different concentrations of miR-328 mimics/inhibitors, indicating the negative regulatory relationship between miR-328 and CD44. We also investigated the relative viability of EGC cells when transfected with miR-328 mimics (50 nM and 100 nM) and miR-328 inhibitors (100 nM) to validate miR-328 to be negatively interfering with the viability of EGC cells. miR-328 was also recognized as a potential biomarker to predict recurrence after ESD in EGC patients via analysis of the recurrence-free rate among different groups of EGC patients.

CONCLUSIONS: The expression level of miR-328 can function as a predictive biomarker of recurrence after ECD in patients with EGC via targeting CD44.

Keywords: Antigens, CD44 - metabolism, Biomarkers, Tumor - genetics, Endoscopic Mucosal Resection - methods, Endoscopy, Gastrointestinal - methods, Gastroscopy - methods, Neoplasm Recurrence, Local - pathology, Stomach Neoplasms - surgery