OCT3-4 and SOX2 in Oral Lichen Planus Compared to Oral Leukoplakia: An Immunohistochemical Study

Background and objective Cancer stem cells (CSCs) initiate carcinogenesis. This study aimed to examine them via immunohistochemistry in oral potentially malignant disorders (OPMDs). Methods The study involved 54 samples of OPMDs, which were compared with five cases of normal oral epithelium. The study was approved by the Ethics Committee of the School of Dentistry, Aristotle University of Thessaloniki, Greece (protocol number: 8/03.07.2019). The CSC-related proteins octamer-binding transcription factor (OCT)3-4 and SRY-related HMG-box (SOX)2 were examined with immunohistochemical methods. In the case of SOX2 and OCT3-4, the samples were evaluated through a scale of 1 to 3 depending on the presence of positive cells, and this scale was further multiplied by the intensity of staining (multipliers 1 and 2). The statistical analysis was performed with Fisher's exact test, and the significance level was set at p≤0.05.  Results The nuclear staining of OCT3-4 was not expressed in any of the samples. The nuclear staining of SOX2 was observed mostly in the basal and parabasal layer of the epithelium. Statistically significantly higher expression of SOX2 was observed in the erosive oral lichen planus (EOLP) group than in the reticular OLP (ROLP) group (p=0.05) and the mild and non-dysplastic leukoplakia group than in the reticular OLP group (p=0.024). Conclusions The characteristic expression of SOX2 in OLP suggests the presence of CSCs and might imply oral tumorigenesis even in lichenoid lesions. Erosive lichen planus outperformed the mild and non-dysplastic leukoplakia, regarding the expression of CSC biomarkers.