MiR-122 exerts anti-proliferative and apoptotic effects on nasopharyngeal carcinoma cells via the PI3K/AKT signaling pathway

To investigate the effects of microRNA-122 (miR-122) on the proliferation and apoptosis of nasopharyngeal carcinoma (NPC) HONE-1 cells, and its correlation with the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. Human NPC cell line (HONE-1) was transfected with miR-122 inhibitor (anti-miR-122 group), negative controls (vector control group) via lipofectamines, and HONE-1 cell lines undergoing no transfection were selected (non-transfection group). The expression of miR-122, cell proliferation, apoptosis, and expressions of PI3K/AKT pathway and downstream target proteins in the three groups were determined using fluorescence quantitative polymerase chain reaction (qPCR), cell counting kit-8 (CCK8), immunofluorescence (IF) and Western blotting, respectively. The expression of miR-122 in the anti-miR-122 group was significantly lower than corresponding expressions in the non-transfection and vector control groups after 48h of transfection (p <0.05). The proliferation of cells in the anti-miR-122 group was significantly reduced with time after transfection (p <0.05). After 48h of transfection, the extent of apoptosis in the anti-miR-122 group (47.11 ± 1.95%) was significantly higher than that in normal control (7.37 ± 0.82%) and vector control group (8.54 ± 0.96%; p <0.05). There were no significant differences in the expressions of PI3K, AKT, mTOR protein, and the downstream signal proteins (p70S6K and 4E-BP1) in the three groups (p >0.05). However, the expressions of phosphorylated forms of these proteins were significantly lower in the anti-miR-122 group than in the non-transfection and vector control groups (p <0.05). IF results revealed that there were no significant differences in the fluorescence intensity value of PI3K and Akt among the three groups of patients (p>0.05). Inhibition of the expression of miR-122 in NPC suppresses the proliferation, and promotes their apoptosis through the PI3K/AKT signal transduction pathway.