EphA8 is a Prognostic Factor for Oral Tongue Squamous Cell Carcinoma

BACKGROUND Oral tongue squamous cell carcinoma (OTSCC) is the most common malignancy of the oral cavity. Here we explore the potential effects of EphA8, which is one of the receptors in Ephs subfamily of RTKs (receptor tyrosine kinases), in the progression and prognosis of OTSCC. MATERIAL AND METHODS A total of 119 OTSCC patients were enrolled in this retrospective study. Immunohistochemistry (IHC) staining and quantitative polymerase chain reaction (Q-PCR) were utilized to examine the expression of EphA8 in OTSSC tissues and adjacent non-tumor tissues. The relationship between EphA8 expression and the clinicopathological features of OTSCC patients were analyzed by chi-square. Survival analysis was carried out with Kaplan-Meier curve and the related log-rank test. Multivariate analysis was then undertaken to assess the prognosis factor by utilizing the Cox proportional hazard regression model. In addition, MTT assay and Matrigel invasion assay were performed to examine the effects of EphA8 on the proliferation and invasion capacities of human oral squamous carcinoma cells (SCC-25) and human tongue squamous cell carcinoma cells (H357). RESULTS Q-PCR and IHC staining revealed that EphA8 was highly expressed in OTSCC tissues, especially in advanced stage OTSCC tissues. Kaplan-Meier curve showed that high EphA8 expression was significantly associated with poor prognosis, similar to age, smoking habit, drinking habit, tumor size, and TNM stage. Multivariate analysis indicated that EphA8 expression could serve as an independent prognostic factor in OTSCC. In vitro experiments revealed that overexpression of EphA8 might promote the progression of OTSCC via enhancing the invasion capacity but not proliferation capacity of tumor cells. CONCLUSIONS EphA8 was highly expressed in OTSCC tissues and was significantly associated with poor prognosis of OTSCC.