No differences in caspase-3 and Bax expression in atrophic-erosive vs. reticular oral lichen planus.

BACKGROUND: Caspase-3 (CPP32) and Bax expression levels in oral lichen planus (OLP) lesions are considered reliable markers of apoptosis. The malignant transformation of OLP remains a very controversial matter. The objective of this study was to compare histological and apoptotic phenomena between atrophic-erosive and reticular forms of OLP. METHODS: Analysis was conducted of biopsy samples from 18 patients with reticular and 14 with atrophic-erosive OLP. Conventional histology techniques were used to quantify histological markers of OLP and peroxidase/anti-peroxidase techniques to determine apoptosis markers caspase-3 (CPP32) and Bax. RESULTS: More Civatte bodies and lymphocyte exocytosis were observed in atrophic-erosive than reticular OLP samples, without any statistical difference. No statistical significant differences in caspase-3 expression were found between these OLP forms in suprabasal layer (58.3% vs. 43.8%), basal layer (83.3% vs. 68.8%) or infiltrate (69.2% vs. 46.6%). Bax expression was relatively infrequent, and no differences were observed between atrophic-erosive and reticular forms. CONCLUSIONS: The low frequency of apoptotic phenomena (caspase-3 and Bax) in epithelial cells of OLP may create a favourable substrate for malignant transformation. However, there does not seem to be an association with the clinical form (atrophic-erosive or reticular).

Cell cycle regulating mechanisms in oral lichen planus: molecular bases in epithelium predisposed to malignant transformation.

OBJECTIVE: Expression of p53, p21, ki-67, Bcl-2 and caspase-3 proteins in oral lichen planus (OLP) was studied to investigate cell cycle regulation mechanisms in this disease. MATERIAL AND METHODS: Oral biopsies were obtained from 51 patients with OLP and 26 controls for immunohistochemical analysis (peroxidase antiperoxidase) to quantify expression of the proteins under study (-: 0%, +: <10%, ++: 10-25%, +++: 26-50%, ++++: >50% positive cells). RESULTS: Basal expression of caspase-3 was negative in 22 cases (46.8%) and positive in <10% of basal cells in 22 cases (46.8%); caspase-3 expression in inflammatory infiltrate was negative in 22 cases (46.8%) and positive in <10% of lymphocytes in 20 cases (42.5%). Basal expression of Bcl-2 was negative in 35 cases (74.5%); Bcl-2 was expressed in inflammatory infiltrate in 34 cases (72.3%) and was positive in <25% of lymphocytes in 14 of these (29.7%). Basal expression of p53 and p21 was positive in 32 (67.9%) and 23 (48.8%) cases, respectively. Basal expression of ki-67 was positive in 45 cases (95.7%), of which 20 (42.5%) showed positivity in >25% of cells; ki-67 was expressed in inflammatory infiltrate in 23 cases (48.9%). Significant associations were found between basal expressions of p53 and ki-67 (p<0.001) and between Bcl-2 expression in infiltrate and basal expression of ki-67 (p<0.001). No association was observed between basal expressions of p53 and caspase-3 (p=0.08). Bcl-2 expression in infiltrate and basal expression of ki-67 were independently associated with presence of OLP. CONCLUSIONS: Epithelial cells in OLP do not preferentially develop apoptosis but rather cycle arrest or an increased proliferation rate, which may create a suitable substrate for malignant transformation.

Multifocal epithelial hyperplasia: A potentially precancerous disease? (Review).

Multifocal epithelial hyperplasia (MEH), also known as Heck's disease, manifests as a papulonodular lesion in the oral mucosa and has been associated with the human papillomavirus, a virus related to various precancerous diseases in the oral cavity. It has a predisposition for the female gender and for children. Although the majority of reported cases have been among American Indians and Eskimos, it has been described in multiple ethnic groups in various geographical locations. The objective of this review was to report on the clinical characteristics and epidemiology of MEH and its possible correlation with oral cancer. It is based on a search of articles in international journals published prior to April 2011, using the PubMed database and selecting articles related to the epidemiology and clinical characteristics of MEH. The review revealed a higher number of cases in individuals of American Indian origin and a predilection of the disease for the female gender and for patients between the 1st and 2nd decades of life. The most frequent lesion site was the lower lip. The disease has been associated with socio-economic and genetic factors, among others. No cases of malignant transformation have been reported.

Significance of liquefaction degeneration in oral lichen planus: a study of its relationship with apoptosis and cell cycle arrest markers.

OBJECTIVE: To assess the utility of liquefaction degeneration as a marker of apoptosis in oral lichen planus (OLP). METHODS: TdT-mediated dUTP-biotin nick-end labelling (TUNEL) assay and immunohistochemical methods were used to detect p21 proteins and the active form of caspase 3 in 32 tissue samples of oral mucosa with OLP and 20 samples of normal oral mucosa. RESULTS: Liquefaction degeneration was moderate or intense in 27.5% (n=8) and slight in 72.4% (n=21) of OLP samples. There was low expression of apoptosis markers (TUNEL, active caspase 3 form), which was not significantly associated with liquefaction degeneration of the basal cell layer. Basal and suprabasal expression of p21 was significantly more frequent in samples with more intense liquefaction degeneration of basal cells (P<0.01). CONCLUSIONS: Our results demonstrate that liquefaction degeneration, as a morphological expression of T lymphocyte attack, does not unequivocally indicate apoptosis. Attacked basal cells more frequently respond with cell-cycle arrest or senescence than with apoptosis.