Downregulation of miR-221/222 by a microRNA sponge promotes apoptosis in oral squamous cell carcinoma cells through upregulation of PTEN

: MicroRNA-221 and microRNA-222 (miR-221/222) have been identified as oncogenes and confirmed to be overexpressed in various types of cancer. However, the regulation mechanism of miR-221/222 in oral squamous cell carcinoma (OSCC) remains to be fully elucidated. Previously, an miR-221/222 sponge was successfully constructed and its effect on the downregulation of miR-221/222 expression was investigated. In the present study, the dual luciferase reporter assay revealed a phosphatase and tensin homolog (PTEN) deletion on chromosome 10 to be a target gene of miR-221/222. It was also demonstrated that miR-221/222 suppression by transfection with an miR-221/222 sponge in vitro resulted in upregulation of PTEN. Notably, the proliferation and invasiveness of the miR-221/222 sponge-transfected cells was significantly inhibited, while apoptosis was promoted, when determined by Cell Counting Kit-8, Transwell assays and flow cytometry. The results of the present study prove that miR-221/222 may downregulate the expression of PTEN in OSCC cells and function as oncogenes, providing a novel insight into the underlying mechanism of OSCC tumorigenesis. The present study suggests that upregulating the expression of PTEN by downregulation of miR-221/222 may be a potential treatment for OSCC.