High nuclear SOX2 expression is associated with radiotherapy response in small (T1/T2) oral squamous cell carcinoma

Abstract

Objective: Expression of the stem cell transcription factor SOX2 is often used to imply stemness and poor prognosis in cancer. However, its role in oral squamous cell carcinoma (OSCC) is not fully elucidated. Material and methods: Tumour tissues from 62 patients with primary, node negative and non-metastatic OSCCs were used to evaluate SOX2 expression by immunohistochemistry. The results were correlated to clinicopathology, treatment and disease recurrences. Results: The majority of the OSCCs (88%) expressed SOX2. Patients with higher nuclear SOX2 staining intensity in the invasive front compared to the adjacent normal epithelium, had a remarkable longer disease-free period if they received adjuvant post-operative radiotherapy (P = 0.001). This was in particular evident for highly differentiated OSCCs, as none of the high SOX2-expressing tumours reoccurred in contrast to all low SOX2-expressing OSCCs. Conclusions: High nuclear SOX2 expression in the invasive front was associated with dramatic longer disease-free period than low SOX2-expressing carcinomas after post-operative radiotherapy in small OSCCs. The result suggested that high nuclear SOX2 expression at the invasive front may predict radiosensitivity.