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

J Oral Pathol Med (2011) 40 : 397–404 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.