Cryptotanshinone Promotes Apoptosis of A549 Cells via Inhibiting Cap-dependent mRNA Translation

Objective To investigate the effect of Cryptotanshinone on the cap-dependent translation in A549 cells and the role of cap-dependent translation in promoting Cryptotanshinone induced A549 cells apoptosis.

Methods A549 cells were treated with various concentrations of Cryptotanshinone. The phosphorylation of mTOR and 4EBP1 were determined using Western blot assay. The formation of eIF4F complex was detected using m7GTP pull down assay. The expression of Bcl-2 was examined by Western blot assay. Cell apoptosis was detected using Annexin V Apoptosis Assay and cell survival was determined using CCK8 assay.

Results Cryptotanshinone inhibited the phosphorylation of mTOR and 4EBP1, the formation of eIF4F complex and Bcl-2 expression of A549 cells in a concentration-dependent manner. Cryptotanshinone profoundly promoted the apoptosis of A549 cells in the control group (4.68±0.77)% vs. (31.1±4.1)%, P < 0.05, while silencing the expression of 4EBP1 suppressed the promoting effect of Cryptotanshinone on cell apoptosis (31.1±4.1)% vs. (8.85±1.2)%, P < 0.05. Cryptotanshinone significantly inhibited A549 cells survival (1±0.09) vs. (0.43±0.05), P < 0.05, while 4EBP1 depletion suppressed the inhibitory effect of Cryptotanshinone on cell survival (0.43±0.05) vs. (0.87±0.06), P < 0.05.

Conclusion Cryptotanshinone suppresses the phosphorylation of 4EBP1 in A549 cells by inhibiting mTOR activity, thus inhibits cap-dependent mRNA translation and the expression of Bcl2 and promotes the apoptosis of A549 cells.