Tanshinone IIA Affects Autophagy and Apoptosis of Glioma Cells by Inhibiting Phosphatidylinositol 3-Kinase/Akt/Mammalian Target of Rapamycin Signaling Pathway

Abstract

Objective: To test the effects of Tanshinone IIA (Tan IIA) on cell viability, cycle, apoptosis, and autophagy of human glioma cell U251 by regulating phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signal pathway. Methods: Tan IIA and PI3K agonist (740 Y-P) were used to treat glioma cells U251. MTT assay was used to assess cell viability and flow cytometry was used to detect cell apoptosis and cell cycle. The expressions of apoptosis-related proteins (Bcl-2 and Bax), autophagy-related proteins (LC3B and Beclin 1) and PI3K/Akt/mTOR signal pathway-associated proteins (p-PI3K, p-Akt and p-mTOR) were evaluated by Western blotting. Results: Tan IIA decreased the expression of p-PI3K and p-Akt proteins, inhibited cell viability and promoted apoptosis. Meanwhile, the expression of Bax increased, while the expression of Bcl-2 decreased. In addition, Tan IIA promoted autophagy in U251 glioma cells and raised the expression of LC3B and Beclin 1. However, 740 Y-P played a reversed role of Tan IIA in cell viability, cycle, apoptosis, and autophagy of U251 cells. Conclusion: Tan IIA could suppress the viability of U251 cells and induce cell apoptosis and autophagy, which might be related to the inhibition of the PI3K/Akt/mTOR signal pathway.