Background: External auditory canal (EAC) squamous cell carcinoma (SCC) is a rare disease, and the survival rate is low in the advanced stages. It has been reported that miR-34a expression is low in many cancers and acts as a tumor suppressor, but its function in EACSCC has not yet been reported.
Aims: To analyze the miR-34a expression levels in EACSCC specimens using in situ hybridization (ISH).
Material and methods: We performed microRNA ISH for miR-34a detection and immunohistochemical analysis of p53 and Ki67 in the EACSCC and otitis externa (OE) specimens.
Results: miR-34a was expressed in the basal and suprabasal layers in the OE epidermis. The pronounced expression of miR-34a was observed in the two cases of T2 (Stage II). In the one case of T3 (Stage III), it was almost the same as that of the OE. On the other hand, the expression levels of miR-34a in the one case of T3 (Stage IV) and two cases of T4 (Stage IV) were apparently reduced.
Conclusion: We demonstrated that the expression level of miR-34a was higher in early-stage EACSCC and lower in advanced-stage EACSCC.
Significance: The expression level of miR-34a may predict a prognosis in patients with advanced-stage EACSCC.
Keywords: biomarker; external auditory canal squamous cell carcinoma; in situ hybridization; miR-34a; microRNA; prognosis.