Tanshinone IIA induces cell death via Beclin-1-dependent autophagy in oral squamous cell carcinoma SCC-9 cell line
Authors: Ye Qiu
Qinhua Wang
Conghua Li
Ping Ji
Xingqi Zeng
Journal: Cancer Medicine (2018)
Discipline: CLINICAL MEDICINE
Keywords: mTOR; Akt; Atg12-Atg5; Atg7; Beclin-1
Affiliations: Stomatological Hospital of Chongqing Medical University, North Songshi Road #426, Chongqing, 401147, China., Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, North Songshi Road #426, Chongqing, 401147, China., Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, North Songshi Road #426, Chongqing, 401147, China.

Abstract:  Tanshinone IIA (TAN) is one of the major functional compounds of Salvia miltiorrhiza Bunge and possesses the ability to suppress the growth of multiple cancer cell types via its apoptosis- and autophagy-inducing functions. In this study, the effect of TAN therapy on the survival of oral squamous cell carcinoma (OSCC) was evaluated, and the underlying mechanism involved in the treatment was investigated. Human oral squamous cell carcinoma cell SCC-9 was used for in vitro assays and induction in an OSCC xenograft mouse model. The tumor cells were subjected to TAN administration at different concentrations. Then the apoptosis and autophagy processes in SCC-9 cells were evaluated and the activities of Beclin-1/Atg7/Atg12-Atg5 and PI3K/Akt/mTOR pathways were determined. In addition, by knocking down the expression of Beclin-1 in SCC-9 cells, the study also assessed the role of the indicator in the anti-OSCC effect of TAN. Results of in vitro assays were further validated with an OSCC xenograft mouse model. Administration of TAN-induced cell apoptosis and upregulated the expression of cleaved-caspase-3. Simultaneously, the autophagy process in SCC-9 cells was initiated by TAN, which was signaled by the formation of autophagosomes and increase in the ratio of LC3 II/LC3I. The above processes were associated with the activation of Beclin-1/Atg7/Atg12-Atg5 signaling and inhibition of PI3K/Akt/mTOR signaling. Our results also inferred a partially Beclin-1-dependent mechanism of action of TAN in OSCC cells: knockdown of the Beclin-1 blocked the effect of TAN on SCC-9 cells both in vivo and in vitro. Our study provided a preliminary explanation of the mechanism involved in TAN effect: the agent exerted its autophagy-inducing effect against OSCC in a multipronged manner, by both inducing the Beclin-1/Atg7/Atg12-Atg5 pathway and suppressing the PI3K/Akt/mTOR pathway. 

Retracted: No

PubPeer comments:
 Fig 3D: ![] Later manifestations include *[left]* Fig 3 a,b from [Du et al (2020)] . *[right]* Figure 8 from [Wang et al (2019)] .  Effect of Acetylshikonin on the mTOR PI3K AKT signalling pathway as depicted by western blot analysis. Acetylshikonin caused dose-dependent decrease in the expression of p-mTOR, p-PI3K and p-AKT, while no visible effect was found on the expression of mTOR, PI3K and AKT. ![] *[left]* Figure 4 from [Wang et al (2019)] .  Effect of Acetylshikonin on the autophagy-related protein expression as revealed by western blot analysis. The Figure shows that the expression of LC3-I, LC30II and Beclin-1 increases with increasing drug doses, while the expression of p62 decreased and the expression of Vps34 remained almost unchanged. *[right]* Figure 6 from [Zhu, Li Chen (2020)] .  Effect of nootkatone on the cell cycle related protein cyclin-B1 in HXO-Rb44 human retinoblastoma cells. The Figure depicts that nootkatone suppresses cyclin B1 expression dose-dependently. ![file] , 
 Fig 3C.  Administration of TAN-induced autophagy-dependent cell death in SCC-9 cells and the effect was dose-dependent. ... (C) Representative images of indicators associated with autophagy. Signaling of Beclin-1 Atg7 Atg12-Atg5 was activated while signaling of PI3K Akt mTOR was inhibited . ![] Reappears as *[left]* Fig 4 from [Wang et al (2019)] .  Effect of Acetylshikonin on the autophagy-related protein expression as revealed by western blot analysis. The Figure shows that the expression of LC3-I, LC30II and Beclin-1 increases with increasing drug doses, while the expression of p62 decreased and the expression of Vps34 remained almost unchanged. ![] ,