Mechanism of miR-122-5p regulating the activation of PI3K-Akt-mTOR signaling pathway on the cell proliferation and apoptosis of osteosarcoma cells through targeting TP53 gene.

OBJECTIVE To explore the regulatory mechanism of microRNA-122-5p (miR-122-5) targeting tumor protein p53 (TP53) gene to mediate PI3K-Akt-mTOR signaling pathway on the proliferation and apoptosis of osteosarcoma (OS) cells. PATIENTS AND METHODS With the collection of osteosarcoma and normal adjacent tissues, the mRNA of miR-122-5p, TP53, PTEN, PI3K, Akt, mTOR, Bim, Bax, and Bcl-2 was detected by Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), followed by the detection of the protein expression by Western blot. The target relationship between miR-122-5p and TP53 gene was verified. The third generation osteosarcoma cells were divided into Blank group, miR-122-5p mimic negative control (NC) group, miR-122-5p mimic group, miR-122-5p inhibitor NC group, miR-122-5p inhibitor group, rapamycin group and miR-122-5p inhibitor + rapamycin group. Furthermore, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry were used to detect the proliferation ability, cell cycle distribution and apoptosis of each group after transfection. RESULTS The expression level of miR-122-5p in osteosarcoma was lower than that in normal tissues (p 0.05) except for significantly decreased miR-122-5p expression (p < 0.05). CONCLUSIONS Upregulation of miR-122-5p may inhibit the proliferation and promote the apoptosis of osteosarcoma cells by inhibiting the activation of PI3K-Akt-mTOR signaling pathway, which may be related to the targeted up-regulation of TP53 expression.