In situ measurement of miR‐138 expression in oral squamous cell carcinoma tissue supports the role of this micro RNA as a tumor suppressor

BACKGROUND: Oral squamous cell carcinoma is the eighth most common cancer worldwide with a relatively high rate of metastasis (~40%). Previously, we showed that microRNA-138 serves as a functional tumor suppressor and plays an important role in oral squamous cell carcinoma metastasis. However, to date, microRNA-138 expression has not been examined in this tumor tissue. Herein, we demonstrated that microRNA-138 expression is downregulated in metastatic oral squamous cell carcinoma specimens using tissue microarray technology with in situ hybridization. METHODS: The study included 254 oral squamous cell carcinoma patients from two centers (160 from the Chengdu center and 90 from the Guangzhou center) and four healthy volunteers. RESULTS: Multivariate analysis showed that microRNA-138 expression was independent of tumor stage, age, gender, smoking, and alcohol consumption in oral squamous cell carcinoma patients. Interestingly, patients that expressed lower levels of microRNA-138 (determined by in situ hybridization) were more prone to regional lymph node metastasis and exhibited poorer outcomes. These findings support the role of microRNA-138 as a tumor suppressor in oral squamous cell carcinoma. CONCLUSION: In summary, the expression level of microRNA-138 is negatively correlated with oral squamous cell carcinoma metastasis; the lower the expression of microRNA-138, the higher the rate of metastasis and the poorer the prognosis of the patients. Therefore, our study confirms that microRNA-138 serves as a tumor suppressor and plays a functional role in oral squamous cell carcinoma tumor metastasis; microRNA-138 constitutes a promising prognosis biomarker and therapeutic target for oral squamous cell carcinoma with metastasis potential.