Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer and has a poor prognosis and low survival rate. Chemotherapy is the suggested treatment for advanced-stage cancers. Increasing focus is on providing a scientific basis for using these agents as a preventive strategy for people with a high risk of cancer. Autophagy, which is constitutively executed at the basal level in all cells, promotes cellular homeostasis by regulating the turnover of organelles and proteins. Several lines of indirect evidence indicate that autophagy acts as a mechanism for tumor suppression. Andrographis paniculata plant extract exhibits various pharmacological activities. Andrographolide, the major constituent of the extract, is implicated in its pharmacological activity. However, the pharmacological activities of dehydroandrographolide (DA) remain unclear.
In this study, we demonstrated that DA induces oral cancer cell viability and related molecular mechanism by MTT assay, annexin-V assay and Western bloting.
DA significantly increased LC3-II and acidic vesicular organelle expression in oral cancer cells. Treatment with autophagy inhibitors inhibited DA-induced human oral cancer cell death. However, DA failed to reduce cell viability in the presence of the VZV-G pseudotyped lentivirus–shRNA system or siRNA knockdown autophagy-related gene, LC3 or beclin-1. Conversely, treatment with autophagy enhancers increased DA-induced cell death.
DA-induced autophagy was triggered by the activation of JNK1/2 and inhibition of Akt and p38. In conclusion, this study demonstrated that DA induced autophagy in human oral cancer cells by activating JNK1/2, and inhibiting Akt and p38. This is the first study to reveal the novel function of DA in activating autophagy, suggesting that DA could serve as a new and potential chemopreventive agent for treating human oral cancer.
Clinical trial identification
All authors have declared no conflicts of interest.