miR-181 as a putative biomarker for lymph-node metastasis of oral squamous cell carcinoma

Background: Oral squamous cell carcinoma (OSCC) is an important malignant disease around the world. Aberrant expression of MicroRNAs (miRNAs) has been implicated in carcinogenesis of various cancers. In previous studies, up-regulation of miR-181 was observed when OSCC progressed from leukoplakia, dysplasia to invasive carcinoma. However, the function of miR-181 in oral tumorigenesis remains unclear. Materials and methods: The expression levels of miR-181 in the tissue and plasma of OSCC patients were measured by quantitative RT-PCR. The correlation between miR-181 level and multiple clinical variables were then checked by Mann-Whitney test and Wilcoxon matched pairs test. To study the functional meaning of up-regulated miR-181, migration assay and invasion assay by transwells and colony forming assay were applied to analyze the tumorigenic phenotypes of OSCC cells with ectopical expression of miR-181. Results: Among different clinical variables, over-expression of miR-181 was correlated with lymph-node metastasis, vascular invasion, and a poor survival. Functional assays revealed ectopically over-expressed miR-181 would enhance cell migration and invasion, but not the ability of anchorage-independent growth of OSCC cells. In addition, the up-regulation of miR-181 could be detected both in tumor tissues and plasma. Conclusion: miR-181 may enhance lymph-node metastasis through regulating migration, which could potentially be exploited as a putative biomarker for patients with OSCC.