Reduced miRNA‑214 expression in oral mucosa contributes to the pathogenesis of oral lichen planus by targeting CD44

: The present study aimed to investigate the role of miRNAs during the pathogenesis of oral lichen planus (OLP). OLP is a chronic inflammatory disorder, which involves T‑cell mediated autoimmunity and affects the skin, scalp, nails and mucosa. Abundant T lymphocytes have been demonstrated to infiltrate the oral mucosa, in which the activated T cells trigger apoptosis of oral epithelial cells. Overexpression of osteopontin (OPN) and CD44 has been observed in the mucosa of patients with OLP, and it has been confirmed that OPN suppresses the apoptosis of activated CD8+ T cells via CD44. The present study initially detected the protein and mRNA expression of CD44 and OPN in the mucosa of patients with OLP by western blot analysis and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), and confirmed the previously reported overexpression of CD44 and OPN in patients with OLP. The current study demonstrated, by RT‑qPCR, that the expression of microRNA‑214 (miR‑214), miR‑216a and miR‑216b was significantly reduced in patients with OLP. By analyzing the association between the protein level of CD44 and the expression of microRNAs (miRNAs), the present study identified a negative correlation between the expression of miR‑214 and CD44 in the mucosa samples of patients with OLP. Subsequently, the present study confirmed that miR‑214 represses endogenous CD44 expression by targeting the 3'untranslated region in HeLa, Raji and Jurkat cells. The current study indicates that reduced miR‑214 may be associated with OLP and, therefore, may be a candidate for drug development.