Identification of miR-199a-5p target genes in the skin keratinocyte and their expression in cutaneous squamous cell carcinoma.

BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNA molecules that mediate the biological cellular processes via regulation of target genes through translational repression or mRNA degradation. Among various miRNAs, miRNA-199a (miR-199a) has been known to be involved in cancer development and progression, protection of cardiomyocyte, and skeletal formation.

OBJECTIVE: Although miR-199a-5p was studied in various cell types, the role of miR-199a-5p and its target genes in skin keratinocyte have not been documented. In this study, we identified target genes of miR-199a-5p in skin keratinocyte.

METHODS: In order to identify the target of miR-199a-5p in keratinocyte, microarray analysis was performed. The relative expression of candidate target genes was investigated using quantitative RT-PCR and western blot analysis. To determine whether their expression was directly regulated by miR-199a-5p, luciferase reporter assay was performed. In order to investigate expression of target genes in cutaneous squamous cell carcinoma, immunohistochemistry was performed.

RESULTS: We identified new target genes, Bcam, Fzd6, and Wnt7a, as well as previously known targets, Ddr1 and Podxl. We found that their expressions were directly regulated by miR-199a-5p in the skin keratinocyte using in vitro study and observed that expression of miR-199a-5p was inversely correlated with those of BCAM, FZD6 and DDR1 in the cSCC. In addition, overexpression of miR-199a-5p resulted in inhibition of the migratory capability of the skin keratinocyte.

CONCLUSION: These results suggested that miR-199a-5p plays a role in pathogenesis of cSCC via inhibition of invasiveness through regulation of BCAM, FZD6 and DDR1 expression.