Chulalongkorn University Dental Journal

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Background A Disintegrin and Metalloproteinase-9 (ADAM-9) is a type I transmembrane protein associated with epithelial differentiation. ADAM-9 is involved in wound healing process by controlling keratinocyte migration and tumorigenesis. Proliferating cell nuclear antigen (PCNA) is a useful marker for cell proliferation. Several studies reported increased PCNA expression in oral lichen planus (OLP), but ADAM-9 expression in OLP has not yet been studied. Objectives To compare the expression of ADAM-9 and PCNA in OLP with that in normal oral mucosa and to find correlations between ADAM-9 or PCNA expression and OLP clinical severity. Materials and Methods The expression of ADAM-9 and PCNA was studied in 25 OLP and thirteen normal specimens by immunohistochemistry. The clinical severity of patients with OLP was assessed by a clinical criteria score. Non-parametric statistical tests were used to determine differences in ADAM-9 and PCNA expression between OLP and normal specimens and correlations between ADAM-9 or PCNA expression and OLP severity. Results ADAM-9 expression was significantly decreased in OLP epithelium compared with normal oral epithelium (p<0.001) and inversely correlated with the clinical criteria score (r=-0.476; p<0.01), whereas PCNA expression was significantly increased in OLP epithelium (p<0.001) and positively correlated with the clinical criteria score (r=0.817; p<0.001). Moreover, ADAM-9 expression was inversely correlated with PCNA expression (r=-0.444; p<0.05). Conclusions Decreased ADAM-9 expression in OLP epithelium suggests reduction of epithelial differentiation, whereas enhanced PCNA expression in OLP epithelium suggests induced epithelial proliferation. The differential degrees of ADAM-9 and PCNA expression may be used as prognostic markers for OLP severity.



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