OBJECTIVE: Accumulating evidence has suggested that microRNAs play critical 
roles in the development and progression of human glioma. The role of miR-122 in 
glioma tumorigenesis has been poorly defined. The current study is designed to 
investigate whether and how miR-122 affects proliferation and apoptosis of human 
glioma cells.
PATIENTS AND METHODS: 8 normal brain tissues and 19 glioma tissues (7 for low 
grade and 12 for high grade) were collected. The expressions of miR-122 and 
runt-related transcription factors (RUNX2) in normal brain/glioma tissues and 
normal astrocytes (NHA)/multiple glioma cell lines (U87, U251, and U118) were 
analyzed by Real-time polymerase chain reaction (PCR). Western blot and 
luciferase activity assays were performed to validate the predicted relationship 
between miR-122 and RUNX2. The effects of miR-122 on cell proliferation and 
apoptosis were assessed by cell counting kit-8 (CCK-8), colony forming, and 
Annexin V-FITC/PI apoptosis assays using both gain- and loss-of-function 
approaches.
RESULTS: MiR-122 expression is downregulated in glioma tissues compared with 
normal brain tissues, and is negatively correlated with the WHO grade. In 
contrast, the RUNX2 expression is upregulated in glioma tissues, and is 
positively correlated with the WHO grade. In glioma cell lines, the miR-122 
expression is also constantly downregulated. MiR-122 functions as a tumor 
suppressor by inhibiting proliferation and inducing apoptosis, which is achieved 
by directly targeting RUNX2. Overexpression of RUNX2 can partially abrogate the 
effect of miR-122 on glioma cells.
CONCLUSIONS: These results demonstrate a crucial role of miR-122 in regulating 
cell proliferation and apoptosis. Identifying the miR-122/RUNX2 signaling 
provides novel insights into the development of therapeutic targets for glioma.