Mechanistic Insights into 16'-DEC-Induced Autophagy and Its Implications for Hepatocellular Carcinoma Treatment

Hepatocellular carcinoma (HCC) is a malignant tumor with a high fatality rate, characterized by a poor prognosis and a low 5-year survival rate. Although significant progress has been made in immunotherapy and targeted therapy for HCC in recent years, the overall survival benefits for patients remain very limited. Therefore, the continuous development of new targets and the screening of specific therapeutic drugs are of great significance for further developing precise treatment methods, exploring more effective combination therapies, overcoming drug resistance. In our preliminary work 272 bioactive compounds have been isolated and identified from edible and medicinal traditional Chinese medicines including Lonicera japonica, Cistanche deserticola and Artemisia capillaris. Through systematic screening, we discovered that 16'-decarbomethoxydihydrovoacamine (16'-DEC), which derived from Tabernaemontana corymbosa, can significantly inhibit hepatoma cell viability and migratory capacity. Furthermore, 16'-DEC can act in combination with lenvatinib, an approved targeted drug for HCC, to further inhibit the proliferation of hepatoma cells in vitro and in vivo. Through transcriptome sequencing, we found that 16'-DEC significantly upregulated the autophagy-related signaling pathway. Mechanism studies have validated that 16'-DEC does induce autophagy in hepatoma cells, and blocking autophagy can significantly reverse the anti-tumor activity of 16'-DEC. Furthermore, we found that 16'-DEC inhibited the activation of the mTOR signaling pathway, and molecular docking experiments indicated that 16'-DEC had a high affinity for the mTOR protein. Biochemical kinase assays confirmed 16'-DEC as a direct mTOR inhibitor, suppressing its kinase activity with an IC50 0.83 μM in cell-free systems. Taken together, these results demenstated that 16’-DEC inhibited hepatocellular carcinoma through inducing autophagy by targeting the mTOR pathway, which make it a potential therapeutic agent for HCC.