MicroRNA expression profiling and functional annotation analysis of their targets associated with the malignant transformation of oral leukoplakia

• MicroRNA microarray was performed on OLK and mtOLK samples.
• MiRNA–mRNA interaction network was constructed using CyTargetLinker.
• 3-MiRNA signature involved in the malignant transformation.
• Dysregulation of the immune response correlated with mtOLK progression.

In spite the tremendous achievements that have been acquired in the field of molecular biology, the underlying mechanism associated with malignant transformed oral leukoplakia (OLK) is still unclear and poorly understood. The aim of this study is to investigate the microRNA (miRNA) expression profiles in OLK and its aggressive transformed tissues from the white lesion of human oral mucosa. The original miRNA expression dataset was downloaded from Gene Expression Omnibus (GEO) database and differentially expressed miRNAs were identified using two-sample t test method. Unsupervised hierarchical clustering and principal component analysis of these differentially expressed miRNAs indicated that 38-miRNA candidates could significantly discriminate OLK from malignant transformed oral mucosa samples. Besides, potential transcription factors were predicted using CyTargetLinker plugin and the miRNA–mRNA regulatory network associated with the malignant pathogenesis was visualized in Cytoscape environment. Totally, 3-miRNA signatures (miR-129-5p, miR-339-5p and miR-31*) were found to be hubs that mediated the initiation and progression of OLK from the non-malignant to the aggressive one via targeting various transcription factors. Functional enrichment analysis based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) suggested that the dysregulation of immune response was responsible for oral carcinogenesis. In conclusion, we constructed a miRNA–mRNA regulatory network associated with the malignant transformation of OLK, and screened out some miRNAs and transcription factors that may have prominent roles during OLK malignant progression.