Cell proliferation activity and the expression of cell cycle regulatory proteins in oral lichen planes

Background: In oral lichen planus (OLP), destruction of the basal cell layer, which is one of the characteristic histological features, is seen and many changes in cell proliferation, cell repair and cell death occur in the injured mucosal epithelium. Methods: We studied mucosal tissues from 19 patients of OLP and 10 controls, with immunohistochemistry for Ki-67, p53, cyclin dependent kinase inhibitors (CDKI) and cyclins. Mitotic count was calculated. TUNEL assay was also performed for evaluation of apoptotic cell death. Results: Mitotic count, Ki-67 and cyclin D1 labeling indices in the basal and parabasal layers of OLP mucosa were elevated in comparison with those of controls. p53, p21 and TUNEL indices of OLP mucosa were also increased. Conclusions: These complex changes, which concomitantly occur in the injured mucosal epithelium, could contribute to the development and maintenance of characteristic mucosal epithelial architectures seen in OLP.