Overexpressed miR-183 promoted glioblastoma radioresistance via down-regulating LRIG1.

BACKGROUND: Glioma is the most common cause of cancer-related death. Therapy based on radiation seemed to effectively, while the radioresistance of several glioblastoma cells abolished the therapy. Thus, to employ the potential mechanism underlying the radioresistance is essential for glioma treatment.

METHODS: Radioresistant cells were constructed using the X-ray radiation. Cell viability and apoptosis were detect using CCK-8 and Annexin-V/propidium iodide (PI), respectively. Real-time PCR and western blot were performed to determine gene expression. Luciferase reporter assay was carried out to detect the relationship between miR-183 and LRIG1. Mice xenotransplant model of glioma was established to detect the role of miR-183 in vivo.

RESULTS: The expression of miR-183 was increased, while LRIG1 was decreased in resistant tissues rather than in sensitive tissues. The expression of LRIG1 was lower in radioresistant gliblastoma cell line U251R rather than in normal glioblastoma cell line U251. Overexpressed miR-183 suppressed cell apoptosis in radioresistance U251R cells (U251R). MiR-183 targets LRIG1 to regulate its expression. U251R cells transfected miR-183 inhibitor promoted the expression of LRIG1, and decreased the expression of EFGR and p-Akt, while U251R cells co-transfected with shRNA-LRIG1 abolished the effects of miR-183 knockdown. U251 cells transfected with miR-183 mimic decreased the expression of LRIG1, and promoted the expression of EFGR and p-Akt, while cells co-transfected with pcDNA-LRIG1 abolished the effects of miR-183 overexpression. In vivo experiments demonstrated that miR-183 inhibitor suppressed tumor growth, while miR-183 mimic promoted tumor growth.

CONCLUSION: MiR-183 overexpression promoted radioresistance of glioblastoma via down-regulating LRIG1 and increasing the activity of EFGR/Akt.