MicroRNA-802 Plays a Tumour Suppressive Role in Tongue Squamous Cell Carcinoma Through Directly Targeting MAP2K4

Objectives: Tongue squamous cell carcinoma (TSCC) is the most common oral tumours. MicroRNAs play crucial roles in many cell processes including cell viability, development, apoptosis, migration and invasion. The role of miR-802 in the TSCC is still unknown.

Materials And Methods: The miR-802 expression in TSCC tissues and cell lines was determined by quantitative real-time polymerase chain reaction. CCK-8 assay was performed to measure the cell viability, while the cell invasion assay was used to determine the cell invasion. Dual-luciferase reporter and western blot were used to confirm the potential target gene of miR-802.

Results: In our study, we demonstrated that miR-802 expression was downregulated in TSCC tissues and cell lines. Elevated expression of miR-802 suppressed the TSCC cell viability and invasion. Moreover, enforced expression of miR-802 increased the expression of E-cadherin, while suppressed the expression of N-cadherin, Snail and Vimentin in the TSCC cell. In addition, we identified the mitogen-activated protein kinase 4 (MAP2K4) as a direct target gene of miR-802 in the TSCC cell. We also demonstrated that the expression of MAP2K4 was higher in the TSCC tissues than that in the adjacent normal tissues. Furthermore, the expression level of MAP2K4 was inversely associated with the expression of miR-802 in TSCC tissues. We also demonstrated that the MAP2K4 expression was upregulated in TSCC cell lines. Elevated expression of miR-802 inhibited TSCC cell viability and invasion through inhibiting MAP2K4 expression.

Conclusions: Our data revealed that miR-802 played as a tumour suppressor gene and might act as a therapeutic target in TSCC patients.