Expression and role of p53 in oral lichen planus patients

Oral lichen planus (OLP) is an autoimmune skin and mucosal disorder. The range of malignant transformation in OLP varies between 0.1-3%. p53 is a tumor suppressor protein. Defective p53 could allow abnormal cells to proliferate, resulting in cancer. p53 plays an important role in cell cycle control and apoptosis and loss of p53 function has been demonstrated in about half of all human cancers. The purpose of the study was to investigate the malignant potential of OLP on the basis of p53 expression and to correlate p53 expression with clinical and histopathological features of OLP.

40 patients with OLP underwent biopsy. All tissue samples were treated immunohistochemicaly using avidin-biotin peroxidase complex method.

In 80% of OLP specimens the nuclei of basal and parabasal keratinocytes were p53-positive, but in low numbers. Low percentage of p53-positive cells in older and medium percentage of p53-positive cells in younger group of OLP patients were noted. Higher intensity of p53 stained keratinocytes, no matter their low number, could represent mutant and more stable form of p53 protein, and at the same time signal for monitoring of disease due to potential malignant transformation. Low percentage and weak intensity of p53-positive cells was detected mostly in OLP specimens with highly expressed civatte bodies (CB). Upregulation of apoptosis didn't correspond with the expression of CB.

We believe that low percentage of p53-positive and well-marked keratinocytes in OLP represent the influence of mutant p53 protein, and that increasing expression of this protein could serve as a valuable diagnostic sign of early carcinogenesis. According to our results intensity of p53 coloration of keratinocytes could help assessing the malignant potential of OLP.