Ziyu II induces autophagy via inhibiting Akt/mTOR pathway
Akt/mTOR is an important signaling pathway for cell survival, which is
closely associated with cancer progression and development [29]. It
has been previously reported that Ziyu II treatment decreased the
phosphorylation level of Akt in human umbilical vein endothelial cells
[30]. Therefore, we aimed to test whether Akt/mTOR signaling was
involved in Ziyu II-induced autophagy in CRC cells. As shown in Fig. 5A,
Ziyu II treatment significantly inhibited Akt/mTOR signaling pathway, as
evidenced by decreased phosphorylation levels of Akt, mTOR, p70S6K, and
4E-BP1. To further confirm these results, we transfected a
constitutively active form of Akt to rescue Ziyu II-induced Akt/mTOR
inhibition. As expected, Akt reactivation markedly reduced Ziyu
II-induced LC3-II turnover and LC3 puncta accumulation (Fig. 5B-G),
suggesting an important role of the Akt/mTOR signaling pathway in Ziyu
II-induced autophagy. Moreover, most of Ziyu II-treated xenografts
displayed reduced p-Akt staining (Fig. 5H and I). Taken together, these
findings suggest that Ziyu II induces autophagy by inhibiting Akt/mTOR
signaling pathway in CRC cells.