miR-22 is down-regulated in esophageal squamous cell carcinoma and inhibits cell migration and invasion

Background: Esophageal squamous cell carcinoma (ESCC) is one of the most common and deadly forms of cancer. Despite advances in the diagnosis and treatment of this cancer, the survival rate at five years is poor. Lately, miR-22 is identified as a tumor-suppressing microRNA in many human cancers. However, the specific function of miR-22 in ESCC is unclear at this point. Methods: We first measured miR-22 expression level in 30 paired of ESCC and matched normal tissues, ESCC cell lines by real-time quantitative RT-PCR. Invasion assay, MTT proliferation assay and wound-healing assay were performed to test the invasion and proliferation of ESCC cell after overexpression of miR-22. Results: We found that the expression of miR-22 in ESCC tissues and cell lines were much lower than that in normal control, respectively. The expression of miR-22 was inversely correlated with ESCC metastatic ability. Furthermore, transfection of miR-22 expression plasmid could significantly inhibit the cell proliferation, migration and invasion in Eca109 and Kyse410 ESCC cell lines. Conclusions: Our findings suggest that miR-22 act as tumor suppressor and inhibiting ESCC cell migration and invasion. The findings of this study contribute to the current understanding of the functions of miR-22 in ESCC.