Expression of Cyclin D1 in Oral Leukoplakia Compared with Normal Mucosa, Benign and Malignant Tumors of the Oral Cavity

Introduction: Cyclin D1 is a rate-limiting controller of the G1 phase and the G1 to S transition of the cell cycle. It’s overexpression may cause disturbance in the normal cell cycle, which may lead to an increased proliferation and consecutive tumour formation. Our objective was to analyse the expression of Cyclin D1 in oral leukoplakia – the most frequent potentially malignant disorder of the oral mucosa – in comparison with normal mucosa, benign and malignant tumours of the oral cavity.
Material and methods: For this paper 51 consecutive cases of oral leukoplakia – surgically treated at the Oro-Maxillo-Facial Surgery Clinic from Târgu Mureş – and, for comparison 9 benign tumours and 27 oral squamous cell carcinomas (OSCCs) were selected. Eight normal mucosa samples were obtained from the peripheral regions of the benign tumours, excized with safe surgical margins. Histopathologically leukoplakias were graded as: with no, mild, moderate or severe dysplasia (G0-3), and OSCCs as: well-, moderately- or poorly-differentiated (G1-3). After immunohistochemical staining for Cyclin D1, statistical analysis was performed regarding the expression of the studied marker.
Results and conclusions: In our findings the difference between the expression of Cyclin D1 in normal mucosa, benign tumours and leukoplakias with no dysplasia was not significant, but the expression of this marker increased significantly with the increase of the grade of dysplasia in case of leukoplakias. A statistically significant difference was found also between leukoplakias and OSCCs, without any correlation regarding the histopathological grade of OSCCs.