miR-802 inhibits the proliferation, invasion, and epithelial-mesenchymal transition of glioblastoma multiforme cells by directly targeting SIX4.

It is well known that the sine oculis homeobox 4 (SIX4) expression is very relevant to the progression of multiple cancers. Moreover, we found that miR-802 could directly target the SIX4. However, the precise mechanism of miR-802 in glioblastoma multiforme (GBM) is still unknown. The aim of this study is to investigate the roles of miR-802/SIX4 axis in GBM. Here, our results showed that the SIX4 expression was obviously increased in GBM tissues and cell lines, and the miR-802 level was distinctly decreased. What is more, the SIX4 expression was negatively related to the miR-802 level in GBM tissues. Furthermore, increased miR-802 level evidently restrained the proliferation, invasion, and epithelial-mesenchymal transition (EMT) of GBM cells. Next, we confirmed that miR-802 could directly target SIX4 by using luciferase reporter assay. Besides, the knockdown of SIX4 had the similar effects with miR-802 overexpression on GBM cells. The inhibitory effects of miR-802 mimic were partially blocked by SIX4 overexpression. Altogether, the overexpression of miR-802 restrained cell proliferation, invasion, and EMT of GBM cells via the regulation of SIX4. SIGNIFICANCE OF THE STUDY: An elevated expression of SIX4 has been observed in colorectal cancer and nonsmall cell lung cancer. However, the precise roles of SIX4 in GBM have not been elucidated. Our study for the first time demonstrated that SIX4 level was significantly upregulated in GBM. Additionally, the knockdown of SIX4 inhibited cell growth, invasion, and the EMT of GBM. Moreover, our data suggested a significant negative correlation between miR-802 and SIX4 expression in GBM. MiR-802 suppressed GBM cell proliferation, invasion, and EMT by directly targeting SIX4, which suggested important roles for miR-802/SIX4 axis in the GBM pathogenesis and its potential application in cancer therapy.