engleski

Proliferative activity of eoithelial cells in oral lichen ruber detected by PCNA and Ki-67

Information about the cells proliferation and its kinetics is necessary to the understanding of biology of premalignant and malignant lesions. Proliferating cell nuclear antigen (PCNA) is 36 kD polypeptide. It is located in the nucleus of proliferating cells. Intracellular localization of this protein, with different degree, takes place during the S phase of cell cycle (1). Monoclonal antibody Ki-67 identifies the homonymous proliferating cells nucleus antigen which is absent in all other cells . It exists in all phases of cell cycle G1, S, G2 and during mitosis except in G0 phase (2). Intensified expression of antigens can be found in numerous malignant and premalignant lesions, lesions with chronic inflammation, fibrous hyperplasia, displasia and in lesions of the epithelium adjacent to cancer lesion (3, 4, 5). Assuming that oral lichen ruber is precancerous lesion, potential malignant transformation of cells in pathologically changed oral epithelium and increased malignant potential of lesions especially in erosive and atrophic forms of OLR, we determined the aim of the study depending on various clinical forms of OLR and clinical intensity of inflammation and hyperkeratosis of oral mucosa. MATERIALS AND METHODS Subjects. This study included 30 patients with oral lichen ruber, 15 with clinical manifestations of lichen ruber planus (LRP) and 15 with clinical manifestations of erosive lichen ruber (LRE). Control group included 15 patients diagnosed with homogenous oral leukoplakia (OL). Clinical status of OLR and OL was evaluated through the clinical parameters of the disease, inflammation, hyperkeratosis, lesion volume (erosions, bullae) and graded 0, 1, 2 and 3. The clinical diagnosis of OLR and OL determined on a basis of described clinical oral tests and parameters was confirmed in all patients through the pathohistologic diagnosis. Biopsy samples. Biopsy samples were collected from the pathologically changed oral mucosal membrane, from the border between healthy and diseased tissue, after the administration of 1 ml of local anesthetic solution (3% Mepivastein, ESPE, Germany). Immunohistochemical analysis of biopsy samples. Tissue samples were fixated in purified 4% paraformaldehyde for 24 h, embedded in paraffin and sectioned with cryo-microtome to 4 nm thick slices. After deparaffination and rehydration, tissue slices were processed and stained with haematoxylin-eosin and mounted on a slide with Canada balsam. For the purpose of immunohistochemical analysis antigen demasking was performed by heating tissues sections in a microwave oven (MOULINEX) 3x5' at 800 W and processed with APAAP (DAKO) and LSAB (DAKO) method. The final product of the reaction was either blue (APAAP) or brown (LSAB) precipitate in cellular membrane depending on method used. The intensity of immunohistochemical reaction of tissue antigen c-erbB-2 expression was evaluated semiquantitatively and marked as a reaction of negative intensity (-), low positive intensity (+), moderate positive intensity (++) and high positive intensity (+++). RESULTS The reaction on tested tissue antigens was mosaic, intracellular and focal positive reaction in two or more cell populations. Antigen PCNA was discovered in basal and parabasal layer of epithelium and in inflammation infiltrate of lamina propria. The reaction was intensely high in OLR lesions regardless on the clinical form of the lesion. The reaction intensity on this tissue antigen positively correlated with the inflammation grade and the degree of hyperkeratosis in lesions. The reaction on Ki-67 tissue antigen ranged from low to moderately high intensity. Intensely high reaction was observed in lesions of lichen ruber erosivus. The reaction positively correlated with the inflammation grade and the degree of hyperkeratosis in lesions. CONCLUSION Modified expression of tissue antigens PCNA and Ki-67 in OLR lesions was observed, where continuous reaction in parabasal and basal layer of the epithelium and focal positive reaction in spinous layer point to certain activity of those lesions. Intensely higher reaction intensity on Ki-67 antigen in LRE lesions compared with the intensity of this antigen in LRP lesions with the positive correlation with the inflammation grade confirms the existence of certain malignant potential in erosive lesions of oral lichen.

proliferative cell nuclear antigens; oral lichen ruber; oral leukoplakia

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