Objectives: To evaluate microRNA-138 (miR-138) gene expression and its target cyclin D1 (CCND1) gene and protein expression in oral lichen planus (OLP) mucosa in an attempt to investigate their possible roles in OLP immunopathogenesis.
Methods: Sixty oral biopsy specimens were harvested from 30 healthy subjects and 30 OLP patients; subdivided into reticular, atrophic and erosive groups (n=10 each). Samples were subjected to quantitative real-time polymerase chain reaction analysis for quantification of miR-138 and CCND1 relative gene expression and immuohistochemical analysis to determine CCND1 protein expression.
Results: Samples from OLP patients had a significant underexpression of miR-138 gene and overexpression of CCND1 at both gene and protein levels compared to normal mucosa samples. The lowest levels of miR-138 expression were observed in atrophic and erosive OLP compared to reticular OLP and the highest levels of CCND1 gene and protein expression was in atrophic OLP. An inverse correlation was demonstrated between the miR-138 expression and both CCND1 gene and protein expression in OLP patients. A significant positive correlation between CCND1 gene and protein expression was also observed.
Conclusion: Down regulation of miR-138 increases the gene and protein expression of its potential target CCND1 in OLP mucosa which might have a pivotal role in the disease pathogenesis.
Clinical relevance: This research implied that miR-138 may have a role in identification of symptomatic OLP lesions. MiR-138 might be considered as a potential tool in future OLP molecular therapy.