Introduction:
This study was undertaken to determine the expression profile of microRNA-27a (miR-27a) in human skin cancer and to assess its effects on cell viability, migration and invasion.

Material and methods:
Expression analysis was performed by qRT-PCR. Transfections were carried out using Lipofectamine 2000 reagent. AO/EB, DAPI, and Annexin V/PI staining was used for detection of apoptosis. Western blot analysis was performed to detect protein expression.

Results:
The results showed up to 7-fold upregulation of miR-27a in skin cancer tissues and up to 5-fold upregulation in skin cancer cell lines. Inhibition of miR-27a resulted in depletion of A431 cell viability as revealed by MTT assay. Phase-contrast microscopy and AO/EB assay showed signs of apoptosis in A431 cells. Immunohistochemical analysis showed reduction of the Bcl-2, p53 and ki-67 expression in A431 cells. Western blot analysis showed an increase in Bax and caspase-3 and a decrease in Bcl-2 protein expression. The wound healing and transwell assays revealed a remarkable decline of cell migration and invasion upon miR-27a inhibition. The bioinformatics and luciferase assays showed that miR-27a targets MAPK7. The Western blot analysis showed that MAPK7 was significantly downregulated in all skin cancer cells. Nonetheless, the expression of MAPK7 was significantly decreased upon miR-27a inhibition. Furthermore, MAPK7 overexpression increased the viability of A431 cells. However, MAPK1 silencing could avoid the suppressive effects of miR-27a inhibition on A431 cells.

Conclusions:
The evidence suggests that miR-27a may find use in the treatment of skin cancer and warrants further investigation.